MC6.T03: Beam Diagnostics and Instrumentation
SUPM065
Developments and Characterization of a Gas Jet Ionization Imaging Optical Column
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Standard methods of measuring the transverse beam profile are not adaptable for sufficiently high-intensity beams. Therefore, the development of non-invasive techniques for extracting beam parameters is necessary. Here we present experimental progress on developing a transverse profile diagnostic that reconstructs beam parameters based on images of an ion distribution generated by beam-induced ionization. Laser-based ionization is used as an initial step to validate the electrostatic column focusing characteristics, and different modalities, including velocity map imaging. This paper focuses on measurements of the ion imaging performance, as well as the dependence of Ion intensity on gas density and incident beam current for low-energy electron beams (<10 MeV).
About: Received: 03 May 2023 — Revised: 19 May 2023 — Accepted: 19 May 2023 — Issue date: 26 Sep 2023
SUPM066
A 5 MeV Compton transmission polarimeter designed for a SRF photogun
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The production of high-current and intense spin polarized electron beams is of great importance in electron-based facilities. Tests are planned to produce such beams in 2023 using GaAs-based photocathodes installed in the Brookhaven National Lab RHIC Coherent electron Cooling superconducting radiofrequency (SRF) photogun [1]. A fast and efficient electron polarimeter operating in the MeV energy range is required to measure the beam spin polarization. While Mott polarimeters provide larger measured asymmetries, a Compton Transmission polarimeter is well suited in the few MeV energy range. In this work, we report on a relatively compact and cost-effective Compton transmission polarimeter which has been built and calibrated at Jefferson Lab (JLab). First, we present the design of the polarimeter radiator, polarized target analyzing magnet, BGO detector assembly and data acquisition system. Next, results of a two-week commissioning study performed at the JLab Upgraded Injector Test Facility will be described. Here, a well-known polarized electron beam produced from a bulk GaAs photocathode in a dc high-voltage photogun was first measured in a 180 keV Mott scattering polarimeter, then used to characterize and calibrate the Compton transmission polarimeter as a function of the polarized target magnetization and beam properties. Finally, we report an effective analyzing power of the Compton polarimeter and compare experimental results with those produced via Geant4 simulations.
About: Received: 01 May 2023 — Revised: 19 Jun 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
SUPM086
Optical Transition Radiation Measurements of a High Intensity Low Energy Hollow Electron Beam on Electron Beam Test Facility
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Optical Transition Radiation (OTR) is commonly used in imaging systems of highly relativistic charged particle beams as the light yield and collection efficiency would increase with beam energy. For low beam energies, scintillating screens are typically preferred but would saturate or even get damaged when using high beam current. For such a beam, OTR screens can, therefore, still be an attractive diagnostic tool when using thermally resistant materials such as Glassy Carbon. This work presents the OTR based beam imaging measurements of a high-intensity low energy (7keV) hollow electron beam at the Electron Beam Test Stand at CERN. The mechanical design of the monitor as well as the expected OTR angular distribution are presented. Beam images performed with an aluminium oxide scintillating screen are also shown and compared to the OTR results.
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
WEODB2
5D phase-space reconstruction of an electron beam
2605
The complete knowledge of electron bunch properties is of great interest to understand and optimize the performance of accelerators and their applications. A new tomographic beam diagnostics method to reconstruct the full 5-dimensional phase space (x, x', y, y', t) of bunches has recently been proposed. This method combines a quadrupole-based transverse phase-space tomography with the variable streaking angle of a polarizable X-band transverse deflection structure (PolariX TDS). In this contribution, we show preliminary data of the first experimental demonstration of the method including the reconstruction of the full 5-dimensional phase space distribution of an electron bunch at FLASHForward.
Paper: WEODB2
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEODB2
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEODB3
Understanding the beam quality requirement for high energy electron microscopy
2609
Commercial electron microscopes with a few hundred keV energies are fundamental tools for understanding the micro- to nano-scale world. One of the frontiers in electron microscopy development is to push the beam energy to MeV range to achieve improved lateral resolution for thick samples. Here we show the theoretical and preliminary experimental analysis of the electron beam quality required in the imaging and diffraction processes with different beam energy. By correlating the diffraction and imaging modalities, we use the focused beam scheme to characterize the beam emittance of a 200 keV TEM and a MeV UED. The quantitative correlation between the measured emittance and the obtained image resolution are established. This work demonstrates a characterization technique for electron microscopy and provides a guidance for designing a MeV electron diffraction and imaging beamline.
Paper: WEODB3
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEODB3
About: Received: 01 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
WEPM134
A novel fiber-optic beam monitor
3890
Organic and inorganic Optical Fibers (OFs) are increasingly utilized in space and medical applications, including accelerator and reactor environments to monitor beam currents and shapes, doses, temperatures, and pressures [1-5]. OFs are ideal as they can be radiation hard, small in size, independent from electro-magnetic environments, and linear over a large measurement range. Here we present a new application in conjunction with a medical cyclotron, where a collar of four Ce-doped silica fibers is mounted onto a beam line. In our experiments, measurements of the OF scintillation signal from prompt neutrons and gammas produced by the proton beam as its bombardment position changes in a beam dump are made. This is an extension of our previous work with a similar setup to monitor beam delivery onto a medical isotope target at a cyclotron [6]. The advantage is that the OFs are outside of the vacuum and do not need to intercept the beam. Initial testing shows that monitoring of a 150 nA beam of 18 MeV protons into a beam dump is possible. The monitor can measure relative beam current and beam displacement in X and Y as a function of magnetic steering. Further testing is underway.
Paper: WEPM134
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM134
About: Received: 28 Mar 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPA002
Optical transition radiation measurements of a high intensity low energy hollow electron beam on electron beam test facility
3952
Optical Transition Radiation (OTR) is commonly used in imaging systems of highly relativistic charged particle beams as the light yield and collection efficiency increase with beam energy. For low beam energies, scintillating screens are typically preferred but they saturate or even get damaged when using a high beam current. For such a beam, OTR screens can, therefore, still be an attractive diagnostic tool when using thermally resistant materials such as Glassy Carbon. This work presents the OTR-based beam imaging measurements of a high-intensity low energy (7~keV) hollow electron beam at the Electron Beam Test Facility (EBTF) at CERN. The mechanical design of the monitor, as well as the expected OTR angular distribution, are presented. Beam images obtained with an aluminium oxide scintillating screen are also shown and compared to the OTR results. This contribution presents the design of the monitor and discusses the initial results obtained with a hollow electron beam at the EBTF.
Paper: THPA002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA002
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
THPA003
Synchrotron radiation simulations for the development of a coherent synchrotron radiation bunch length monitor
3956
High resolution bunch length monitors are an important diagnostic for the optimisation of any accelerator, from typical linacs or storage rings to novel acceleration systems. Given the availability of synchrotron radiation (SR) in these systems, studies have been carried out into how the spatial profile of the radiation changes with bunch length. Understanding these profile variations offers a non-invasive method of studying bunch profile characteristics. This contribution presents coherent SR simulations carried out in Synchrotron Radiation Workshop (SRW) for bunch lengths less than 100 fs, which are of interest to free electron lasers and novel acceleration facilities. These simulations have been carried out for the short pulse facility (SPF) situated in MAX IV. This is the location of a previously developed coherent transition radiation (CTR) monitor, which is currently being utilised as a compression monitor. The results of these simulations will be used to train a machine learning model to predict bunch profile characteristics, following the application of this process with the CTR monitor.
Paper: THPA003
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA003
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPA004
A Compton transmission polarimeter for DC and SRF electron photo-injectors
3959
The production of high-current and intense spin polarized electron beams is of great importance in electron-based facilities. Tests are planned to produce such beams in 2023 using GaAs-based photocathodes installed in the Brookhaven National Lab RHIC Coherent electron Cooling superconducting radiofrequency (SRF) photogun [1]. A fast and efficient electron polarimeter operating in the MeV energy range is required to measure the beam spin polarization. While Mott polarimeters provide larger measured asymmetries, a Compton Transmission polarimeter is well suited in the few MeV energy range. In this work, we report on a relatively compact and cost-effective Compton transmission polarimeter which has been built and calibrated at Jefferson Lab (JLab). First, we present the design of the polarimeter radiator, polarized target analyzing magnet, BGO detector assembly and data acquisition system. Next, results of a two-week commissioning study performed at the JLab Upgraded Injector Test Facility will be described. Here, a well-known polarized electron beam produced from a bulk GaAs photocathode in a dc high-voltage photogun was first measured in a 180 keV Mott scattering polarimeter, then used to characterize and calibrate the Compton transmission polarimeter as a function of the polarized target magnetization and beam properties. Finally, we report an effective analyzing power of the Compton polarimeter and compare experimental results with those produced via Geant4 simulations.
Paper: THPA004
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA004
About: Received: 01 May 2023 — Revised: 19 Jun 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPA005
Study and simulation of cavity bunch length monitor based on monopole mode
3962
Bunch length measurement is an essential diagnostic for FEL facilities and now the interest of ultrashort bunch is continuously rising. The nondestructive methods with high resolution are now the favorite design for short bunches less than 1 ps. The technique of cavity bunch length measurement based on the monopole mode is discussed is this article. The influence of many factors on the amplitude of TM010 mode are analyzed, such as energy and beam offset. For 1 ps beam length measurement, a cavity of 19.04 GHz is design using CST software, which may provide a resolution of 10 fs with an 80 dB signal-to-noise ratio.
Paper: THPA005
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA005
About: Received: 03 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
Emittance Tomography with multiple wire scanners at RAON facility
Emittance is one of the most important beam parameters in accelerators. Therefore, many emittance measurement methods such as Allison-type scanners, pepper pots, slit-scan methods, quadrupole scan methods, etc. have been widely used. In the case of the RAON heavy ion accelerator, an Allison-type emittance scanner is installed at the low-energy beam transport section. However, there is no other equipment that can measure 2D phase space downstream. To complement the measurements by the Allison-type emittance scanner, we suggest the emittance tomography with multiple wire scanners. By using feedback loop and tracking simulations, we reconstruct the 2D phase space of the beam and discuss the emittance evolution.
THPA009
Optical pepper-pots: developing single-shot emittance diagnostics
3966
Emittance measurements are a universal requirement when operating particle accelerators. Many techniques exist to achieve these measurements, each suiting the specific requirements of a machine. Most are multi-shot or invasive, and struggle to function with low energy beams or where space-charge effects are dominant. Generally, these limitations can be restricting, but especially so in emerging sectors such as novel acceleration or energy recovery linacs. To this end, two all-optical single-shot emittance measurements are being developed. In both cases the measurement is analogous to an optical version of the common pepper-pot diagnostic. The two methods are complementary: the first uses a micro-lens array (MLA); the second a digital micro-mirror device (DMD). Both systems can operate away from a beam waist and separate the optical beam radiation into beamlets rather than the beam itself; leaving potential for a non-invasive measurement. The benefits of using optical beam radiation are reduced beam scattering, simple designs, and suitability for low-energy/space-charge dominant beams. Presented is a series of benchmarking measurements and simulations with laser sources. Initial beam simulations, plans for first measurements, and the application to a machine learning virtual diagnostic are also discussed.
Paper: THPA009
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA009
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
THPA011
Study of noise impact on AI-based ptychography for beam characterization
3970
Coherent X-ray beam focus can be characterized using ptychography, a lensless imaging technique used at synchrotron X-ray light sources and free-electron lasers. Ptychography relies on collecting X-ray diffraction from a thin sample at overlapping regions and reconstructing an image from the data. Since the phase is not measured by the detector, ptychography can solve for the phase of the sample and the probe. This is useful for characterizing the beam focus, coherence, and energy dependence, and for exploring experimental conditions. Ptychography, however, is challenging due to the time to collect data from each sample point and also for iterative reconstruction of the phase. Recently, AI-based ptychographic methods have shown promise in making ptychography-based beam characterization faster and more efficient. This poster presents a study on the effect of various types of noise present in ptychographic data. A number of noise sources occur in ptychographic setups and include noise from parasitic scattering (background), outliers, correlated noise sources, cosmic rays, bad frames, beam jitter, motor jitter, fluctuating dark noise, beam miscentering, a static sloped background and fluence jitter. This study explores the effect of random noise in experimental data used for AI-based ptychographic reconstruction and how it impacts reconstructed probe and object image accuracy. Results on noise impact using both AI-based and iterative ptychographic methods are compared.
Paper: THPA011
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA011
About: Received: 30 Apr 2023 — Revised: 08 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPA012
Initial application of machine learning for beam parameter optimization at the Hefei Light Source II
3974
Machine learning techniques have developed rapidly in the last decade and are widely used to solve complex scientific and engineering problems. Many accelerator laboratories internationally have begun to experiment with machine learning and big data techniques for processing accelerations. This paper presented the application of machine learning to the Hefei Light Source. Including the simulation of the tune and the calibration of the online experiment that met the design requirements and simulation of the beta parameter correction with deep learning. Based on this, online beta calibration will be carried out in the future.
Paper: THPA012
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA012
About: Received: 02 May 2023 — Revised: 14 Jun 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPA013
Study on beam orbit shift due to synchrotron radiation
3978
The beam orbit stability is the crucial indicator to evaluate the performance of the synchrotron radiation source. In order to obtain higher beam quality, higher stability requirements are placed on the beam orbit. The stability can be improved through accurate meas-urement of beam orbit by beam position monitors (BPMs) and appropriate feedback system. However, due to radiation of the synchrotron beams on the vac-uum chamber, the thermal effect of synchrotron radia-tion causes the thermal deformation of the vacuum chamber. The thermal deformation drives the BPM fixed on the vacuum chamber to move, which will induce error to the beam orbit. We analyze the effect of beam current on the vacuum chamber movement and the effect of vacuum chamber movement on the beam orbit. We also built an online vacuum chamber displacement measurement system on Hefei Light Source II (HLS II), which is used to validate and cor-rect our analysis. After analysis and verification, the vacuum chamber moves with the change of current. The larger the change of current, the larger the vacuum chamber displacement. The vacuum chamber dis-placement has a hysteresis compared to the current change.
Paper: THPA013
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA013
About: Received: 27 Apr 2023 — Revised: 07 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPA014
Study on beam position measurement based on diode-detection in HLS-II
3982
In order to improve the sensitivity and long-term sta-bility of Hefei Light Source – II (HLS-II) for beam posi-tion measurement, it is necessary to improve the meas-urement method. The beam position monitor (BPM) electronics is used to measure the beam position and is an important part of the beam position measurement system. In this paper, we propose a beam position meas-urement system based on the compensated diode detec-tion (CDD) technology for electron storage ring. Since HALF under construction, we used the parameter of HLS-II to design the system and simulate the system circuits to verify its feasibility.
Paper: THPA014
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA014
About: Received: 30 Apr 2023 — Revised: 07 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
The ThomX diagnostics in the machine commissioning phase
We report on the behaviour and tuning of the diagnostics of the ThomX Compact source during the accelerator commissioning. These diagnostics consist of Beam Position Monitors, screens used to measure the beam profile (YAG and OTR), charge monitors, bunch length monitors, beam loss monitors and synchrotron radiation monitors. For each diagnostics we report on the performances measured with the beam and the difficulties encountered.
THPL051
Automated Faraday cup readings at ATLAS
4547
Since its commissioning, operators at the Argonne Tandem Linear Accelerator System (ATLAS) have used an analog current meter to manually record beam current measurements from Faraday cups along the beamline. Recently an automated process using a digital picoammeter was developed for beam current measurements. This automation has streamlined daily operations, increased the precision of measurements, and expedited the generation of digital data for use with ongoing artificial intelligence and machine learning work (AI/ML).
Paper: THPL051
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL051
About: Received: 03 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
THPL052
Resonant Cavity for Beam Current Diagnostics in Medical Accelerators
4550
Beam currents of particle accelerators used for cancer treatment are often on the nanoampere level. These currents are too low for standard beam current diagnostics used in other fields of particle accelerator science, e.g. current transformers. This led to the general adoption of ionization chambers for beam current and dose rate determination in medical accelerators. However, the development of the so-called FLASH radiation therapy requires beam currents too high for normal ionization chambers yet still too low for standard current transformers. Resonant cavities have shown their capability to precisely detect nanoampere to microampere beam currents which renders them interesting for FLASH radiation therapy accelerators. After the design of a resonant cavity at Paul Scherrer Institut (PSI), a collaboration between PSI, Instrumentation Technologies, and Bergoz Instrumentation was established with the goal to develop a complete turn-key beam current diagnostics system readily available for medical accelerators. Two prototype systems were manufactured, installed, and tested at PROSCAN/PSI. We discuss the layout of the measurement systems and compare expected performance to beam current measurements.
Paper: THPL052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL052
About: Received: 28 Apr 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL060
Impact of dipole component change on quadrupole beam-based alignment accuracy for circular accelerators
4557
Beam-based alignment (BBA) for quadrupoles is a routine process for circular accelerators to steer beam orbit through the magnetic centers such that the orbit is unperturbed when the strengths of quadrupoles are varied. The random errors associated with BBA are well known, but a type of systematic error appears to be neglected by the community. A standard measurement procedure involves variation of the quadrupole gradient. This systematic error is introduced when there is a non-zero dipole component after quadrupole strength is changed. This dipole component can be also interpreted as a shift in the magnetic center. The analytical formulas for this error and its amplification factor with respect to the magnetic center motion have been derived and confirmed with simulations. We demonstrate the significance of this error, potentially on the order of hundreds of microns, through both simulations and recent experimental results at NSLS-II. In addition, a special term in this error that is not extractable from orbit measurements alone will be discussed in detail.
Paper: THPL060
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL060
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
THPL061
Absolute calibration of BSI monitors in the SPS North Area at CERN
4561
Developments in current and future experiments in the SPS North Area (NA) and PS East Area (EA) fixed target beam lines at CERN, including the “Physics Beyond Colliders” (PBC) program, require accurate determination of the number of protons on target (POT). The re-calibration of Beam Secondary Emission Intensity monitors (BSI), recently completed in one of the NA branches, reduced the estimated uncertainty on the absolute POT to a few percent. The calibration is based on an activation technique, applied to metal foils (Al, Cu), installed in front of the BSI and irradiated with the nominal proton intensity for a short period. The number of protons is determined from offline gamma spectrometry analysis of the foils and compared to the total integrated signal of the BSI. A description of the method, data analysis and results, will be presented and followed by considerations intended to standardise the procedure for future regular use in all SPS NA beamlines.
Paper: THPL061
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL061
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
THPL062
An effective use of calibration measurements for the CNAO pickup
4565
The CNAO orbit measurement system consists of 20 electrostatic pickups. They are based on a nineties’ design and reliably working from over fifteen years, despite a not very effective calibration system. At beginning 2020, a new control software was installed, with two significant improvements: firstly, pickups signal is acquired continuously and beam orbit is saved every cycle; secondly, it allows to perform the calibration procedure very simply, from the pickup user’s interface, in a fast and non-invasive way. These features gave us the instruments for a comparative study of position and calibration measurements, that brought about the definition of a quantity able to predict accurately position fake shifts caused by changes of eletronics transfer function. This allows to isolate the electronics contribution from the true beam shift, resulting in a more reliable orbit measurement system. Calibration measurements have revealed some causes of electronics response variations, while others have to be understood yet. Anyway, a new monitoring plan has been started from a few months, to follow the trends closely, to better understand the causes and to promptly intervene with a software compensation, aiming to an increasingly reliable orbit measurement system.
Paper: THPL062
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL062
About: Received: 28 Apr 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL063
Design of an electron energy spectrometer and energy selector for laser-plasma driven beams at EPAC
4568
The Extreme Photonics application Centre (EPAC) is a new national facility to support UK science, technology, innovation and industry currently under construction at the Rutherford Appleton Laboratory, UK. EPAC is designed to facilitate a wide variety of user experiments with 1PW 10Hz laser systems. It is anticipated that early experiments will include laser-plasma acceleration of electrons to energies ranging from 100 MeV up to 10 GeV, with later experiments using these electrons as a beam once stable generation is achieved. EPAC is designed to be flexible, allowing users to select the relevant central electron energy for their experiment. To achieve this goal EPAC and the Accelerator Science & Technology Centre (ASTeC) at STFC Daresbury Laboratory have been working on the design of a beamline to capture laser-plasma driven electrons with broad energy spread, measure their energy spectrum, perform selection of specific energies if necessary and deliver these electrons to a user interaction point. We present here the conceptual design of the proposed spectrometer and energy selection system.
Paper: THPL063
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL063
About: Received: 27 Apr 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL064
Design of a broadband modular permanent magnet electron energy spectrometer for FEBE
4572
The CLARA accelerator facility at Daresbury Laboratory, UK, was originally designed to operate as a free-electron laser test facility. To improve the user exploitation of the facility a dedicated full energy beam exploitation (FEBE) area has been designed and is currently being installed in a separate experimental bunker on the CLARA accelerator. This facility will allow users to conduct experiments combining a 250 MeV electron beam of up to 250 pC bunch charge with laser pulses up to 100 TW in a large target chamber. A second downstream chamber contains room for a number of diagnostics that are customisable to the experiments being conducted. The ability to combine a laser and electron beam in FEBE presents the possibility of novel acceleration experiments. FEBE is designed to allow user experiments which aim to further accelerate the electron beam from 250 MeV to 600 MeV, or 2 GeV at a reduced repetition rate. To measure the output of these experiments an innovative in-vacuum permanent magnet spectrometer dipole has been designed with modular construction to measure broadband electron energy spectra. The modular nature allows the length of the installed dipole to be tailored to the experiment, allowing room for additional diagnostics in experiments where maximum energies below 2 GeV are expected.
Paper: THPL064
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL064
About: Received: 27 Apr 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL065
Optimisation of a gas jet-based beam profile monitor for high intensity electron beams
4576
A beam profile monitor using gas jet technology is being designed and manufactured at the Cockcroft Institute for high intensity electron beams. It generates a thin, supersonic gas sheet that traverses the beam at a 45-degree orientation and measures the beam-induced fluorescence interactions to produce a 2D beam profile image. The gas sheet acts similar to a scintillating screen, but remains non-invasive. This contribution summarises the method developed towards optimising the injection of a gas jet monitor for the example use-case of the Hollow Electron Lens. A multi-objective genetic algorithm is used with a Monte-Carlo particle tracking simulation to optimise the geometric features of the jet injection chambers. The algorithm optimises for several key features of the jet that will improve it as a diagnostic tool. Specifically, at the point of interaction, the jet’s density, uniformity and geometric dimensions are considered. The work developed in this contribution is not limited to diagnostics and can be expanded upon in other disciplines such as plasma wakefield gas injections.
Paper: THPL065
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL065
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPL066
Imaging a high-power hollow electron beam non-invasively with a gas-jet-based beam profile monitor
4580
The Hollow Electron Lens (HEL) was proposed to actively remove the beam halo of the proton beam for the HL-LHC upgrade. Currently, the concept of generating such an electron beam is being tested in a dedicated Electron Beam Test Stand (EBTS) at CERN. It currently produces a hollow electron beam with 7 keV energy and 0.4 A current 25 us pulsed with 2 Hz which will be confined in a strong solenoid field. A gas curtain-based beam profile monitor was developed to characterize the beam non-invasively during operation. It injects a directional gas sheet at 45 degrees to interact with the electron beam. Gas particles are excited and emit fluorescent photons which are collected by an intensified camera system. This allows the reconstruction of the profile of the hollow electron beam. This contribution presents the design of the monitor and discusses the initial results obtained with a hollow electron beam at the EBTS.
Paper: THPL066
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL066
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL067
Development and testing of quantum gas jet beam profile scanner
4584
A quantum gas jet-based beam scanner is under development at the Cockcroft Institute (CI) in the UK. This device is based on detecting the ionisation induced in a gas jet by a beam of charged particles. It aims at generating a dense gas jet with a diameter of less than 100 μm by exploiting the quantum wave nature of neutral gas atoms to generate an interference pattern with a single maximum. Work analogously to a mechanical wire scanner while being minimally interceptive, a tightly focused gas jet promises superior position resolution and high signal intensity. This contribution gives an overview of the design and functioning principle of the monitor, presents initial modification in the system for gas density measurement, as well as results from beam profile measurements obtained with a 5 keV electron beam.
Paper: THPL067
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL067
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL068
Characterisation and analysis of supersonic gas jets using interferometric measurement methods
4588
Supersonic gas jets are useful tools in particle accelerators used in both scientific and medical applications. They can provide real-time, longitudinal and transverse beam profile measurements for charged particle beams in accelerators and are also being used as a plasma source in wakefield accelerators. For gas jets to be used effectively as beam profile monitors, the density profile of the jet must also be well-known. This can be calculated by measuring the phase shift produced by the gas jet inside a laser beam due to the difference in density between the gas and the surrounding vacuum environment from the Lorentz-Lorenz relation. In this contribution, multiple techniques for measuring gas jet profile and density will be compared and analysed; Mach-Zehnder and Nomarski interferometry. A 532 nm laser will be used for both of these methods, with a gas jet backing pressure of 7 bar. Multi-pass interferometry will also be used to increase the phase shifts by a factor of 4, and therefore sensitivity to lower density gas jets. This method involves retro-reflecting the interferometry beams, passing them through the gas jet multiple times. These techniques will be compared and their suitability for gas jet density characterisation will be assessed.
Paper: THPL068
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL068
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
Optimization of EPURE LINAC performances and time characterization using electronic/photonic focal spot size correlation
Following works aiming at optimizing photonic focal spot size measurement conditions on AIRIX, we decided to improve our electron beam picture processing software with a goal of studying a potential relationship between AIRIX electronic and photonic focal spot size dimensions. AIRIX electronic focal spot size is obtained from an OTR measurement chain established by adapted optics and an intensified camera. One of the photonic focal spot size measurement techniques is built by inserting an annulus pinhole into the AIRIX source collimation. Pictures are obtained from a gamma-camera. Our new electron beam picture processing software calculates physical electron beam dimensions (up to now, these dimensions were given as the statistic projection = “RMS dimensions”) and allows to define a transformation coefficient allowing us to find again the photonic focal spot size values (established from a Lorentz fit of the photonic PSF) from electronic ones. We also showed the conservation of the electron PSF inclination degree after interaction with the AIRIX X-ray conversion target. A first photonic spot size estimation is given for the last hydrodynamic experiment at EPURE facility and implies great potential of such a diagnostic for the second stage of EPURE project, mainly in terms of duration optimization for the operating process of our next three radiographic axes.
THPL070
Exploring time-of-flight energy filtering possibilities for ultrafast electron single-pixel imaging
4592
Achieving a high signal-to-noise ratio is challenging in electron scattering experiments that require low average probe current or low total electron dose, e.g., time resolved hard-matter or radiation-sensitive soft matter experiments. A promising method for improving the signal-to-noise ratio when electron counts are low is to structure the electron wavefunction with optical fields and then retrieve the image via reconstruction algorithms in a single pixel imaging approach. When the electron-optical interaction is inelastic, such a scheme requires an electron energy filter. Here, we present numerical simulations of a time-of-flight energy filtering scheme for use in ultrafast electron microscopy, where a radiofrequency deflector cavity placed at the bottom of an electron microscope column provides a time-dependent momentum kick, dispersing the energy bands of the beam on a downstream detector. We estimate the filtering performance for electron single pixel imaging with an electron beam wavefunction shaped by a high intensity, highly coherent ultrafast light pulse and discuss future practical aspects.
Paper: THPL070
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL070
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPL071
Reconstructing 4D source momentum space via aperture scans
4595
The brightness of the beam in any linear accelerator can be no greater than at its source. Thus characterization of source initial conditions, including spatial and momentum distributions, is then critical to understand brightness evolution in a linac. Often measurement of the initial momentum distribution is hampered by imperfect knowledge of either the spatial source distribution or the downstream particle optics. Here we describe a method of recovering the transverse momentum space of a beam at the particle source without prior knowledge of the electron optics used to obtain the phase space or any source parameters; only linearity of the transport is assumed. We then demonstrate this method experimentally by measuring a 4D phase space using an aperture scan and subsequently recover the transverse phase space of a beam emitted by an alkali antimonide photocathode.
Paper: THPL071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL071
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
THPL072
Experimental design for beam motion measurements in the Crocker Nuclear Laboratory cyclotron at UC Davis
4598
Older cyclotrons still find a variety of applications in research and education, but in many cases the beam dynamics of these machines is not well understood, which can be a limitation to achieving their ultimate performance. The cyclotron at the Crocker Nuclear Laboratory at UC Davis is a capable of accelerating protons, deuterons, or alpha particles to variable energies up to a maximum of 67 MeV for protons. Recently, we have been trying to improve the performance of the machine for a variety of applications, with particular emphasis on increasing the alpha beam, for use in producing the isotope 211-At, which has great promise for cancer treatment. This effort is hampered by the lack of an accurate model of the cyclotron and extremely limited instrumentation for the beam as it accelerates. This poster describes a series of beam measurements made using a segmented beam probe with the time resolution to measure individual bunch structures and sufficient lateral segmentation to measure horizontal and vertical motion of the beam as it accelerates. These are compared with models to try to understand such motion at a fundamental level.
Paper: THPL072
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL072
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL073
Improvements in longitudinal phase space tomography at PITZ
4601
Methodical studies to improve the existing e-beam Longitudinal Phase Space (LPS) tomography were performed at the Photo Injector Test facility at DESY in Zeuthen. Proof-of-principle simulations were done to address some core concerns e.g. booster phase range, space charge effects and noisy artefacts in results. Phase advance analysis was done with the help of an analytical model that determined the booster phase range and step size. A slit was introduced before the booster to truncate the beam and reduce space charge forces. The reconstruction method adopted was image space reconstruction algorithm owing to its assurance of non-negative solution. An initial scientific presumption of LPS from low energy momentum measurements was established to reduce artefacts in the phase space. This paper will explain the proof-of-principle simulations highlighting the key aspects to obtain accurate results. Reconstructed LPS for different experimental cases will be presented to demonstrate the diagnostic capability.
Paper: THPL073
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL073
About: Received: 29 Mar 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL074
4D Transverse Phase Space characterization of high brightness electron beams at PITZ
4605
The Photo Injector Test facility at DESY in Zeuthen (PITZ) utilizes slit scan technique as a standard tool for reconstruction of horizontal and vertical phase spaces of its space charge dominated electron beams. A novel method for 4-dimensional transverse phase space characterization, known as Virtual Pepper Pot, is proposed at PITZ, that can give insight to transverse beam phase space coupling. It utilizes the horizontal and vertical single slit scans to form pepper pot-like beamlets by careful crossing and post-processing of the slit scan data. All the elements of the 4D transverse beam matrix are calculated and used to obtain the 4D transverse emittance and coupling factor. The proposed technique has been applied to the experimental data with coupled beam phase space in order to demonstrate the diagnostic capability. The loss of signal at tails of the beamlets due to low signal-to- noise (SNR) ratio is considered in the algorithm and the systematic error resulting from crossing of the beamlets is also explored.
Paper: THPL074
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL074
About: Received: 03 May 2023 — Revised: 05 Jun 2023 — Accepted: 05 Jun 2023 — Issue date: 26 Sep 2023
THPL075
A compact dielectric grating-based charged particle bunch length diagnostic device at ARES
4609
Dielectric gratings are used in Dielectric Laser Acceleration due to their high damage thresholds in high acceleration gradients. When an electron bunch passes close to these gratings, it emits radiation, and the features of this radiation will be dependent on the beam position relative to the grating, the bunch charge, and the bunch length. A compact high-resolution diagnostic device will be developed that consists of multiple dielectric gratings with different periodicities; these types of devices are required for the accurate operation of future compact accelerators which are currently undergoing development and testing. The ARES linac at DESY is able to provide sub-fs electron bunches and has a range of high-resolution diagnostic devices installed, such as the PolariX Transverse Deflecting Structure, which will allow for performance verification of a new diagnostic. The electron bunches can be altered, allowing for the measurement and analysis of the emitted radiation for different bunch lengths and charges. This work will present the current progress in this area, including the presentation and discussion of simulations, and a discussion of the planned experiments at ARES.
Paper: THPL075
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL075
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL076
Operation improvements of the actual booster-injector for Elettra 2.0
4612
The current injector system, composed by a linac and a synchrotron booster, will be used to inject into the new storage ring. After 15 years of operation, some upgrade of the instrumentation devices are required to well characterize the beam parameters extracted from the booster, before and after the implementations in action to reduce the beam emittance.
Paper: THPL076
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL076
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL077
Elettra 2.0 eBPM: Complete System Overview
4615
Beam position monitors (BPMs) are fundamental diagnostic tools for lightsources: thanks to their data readout, machine orbit can be stabilized and corrected by control systems. New generation machines need better performances on these diagnostic devices due to increased demands, such as smaller photon beam size and long-term stability. This article outlines all the devices that will make up the future Elettra 2.0 BPM system, based on pilot tone compensation. The entire signal acquisition chain will be described, from the pickups to data delivery to the control system. After a brief introduction about the electronics (analog signal conditioning, digital conversion and processing), more emphasis will be given to the description of timing and synchronization functionalities, machine protection system integration and machine feedback
Paper: THPL077
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL077
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL078
Towards Elettra 2.0: Beam diagnostics overview
4618
Diffraction Limited Storage Rings, the 4th generation machines, provide transversely coherent beams with uniform phase, maintaining high photons flux and stability. Diagnostic systems play an essential role for both commissioning and operating tasks of Elettra 2.0. The small beam dimensions make measurements of both position and size challenging. Elettra 2.0 diagnostics will rely mainly on Beam Position Monitors and Synchrotron Radiation Profile Measurements. In this paper, an overview of all the beam diagnostics that will equip the new storage ring will be given, along with the diagnostic systems involved in the main machine control.
Paper: THPL078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL078
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL079
Button Type Beam Position Monitor Design for the Elettra 2.0 Storage Ring
4621
In order to fulfill the target performance of Elettra 2.0 light source, a brand new button type beam position monitor detector has been developed. From a theoretical point of view, the transfer function which relates beam position information to electromagnetic signal intensity induced on pick up electrodes is well known. In practice, due to a number of constraints, a real device implementing this transfer function is difficult to manufacture. In this paper, a series of practical design considerations involving electromagnetic, mechanical, vacuum, maintenance, and cost issues are reported to illustrate the advantages and disadvantages of the conceived constructive solutions.
Paper: THPL079
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL079
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL080
Review of CERN beam instrumentation for fixed target experiments
4625
Measuring beam parameters in the vicinity of fixed target experiments or interceptive devices like beam dumps is essential to ensure efficient fixed target physics and safe beam operation. At the same time the beam diagnostic reach is very often challenging in terms of robustness and performance. This paper reviews the CERN instruments exploited to measure protons at different CERN fixed target facilities (ISOLDE, PS East Area, AD, SPS North Area, HIRADMAT) and beam dumps (SPS, LHC), focusing on recent developments/results, limitations and future plans. Emphasis will be given to beam size and beam position monitors systems and their response to high power and/or density proton beams at target locations, thus involving radiation hardness, background and power deposition issues. The discussion will also refer to new materials studies and modern machine learning techniques developed to enhance the monitors overall accuracy and reliability.
Paper: THPL080
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL080
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL082
Radiation levels produced by the operation of the Beam Gas Vertex monitor in the LHC tunnel at IR4
4629
The Large Hadron Collider at CERN is equipped with instruments that exploit collisions between beam particles and gas targets, one of them being the Beam Gas Vertex monitor. By design, its operation generates secondary particle showers used to measure beam properties, that also result in radiation levels in the tunnel proportional to the beam intensity and gas pressure. In this work, the radiation showers are characterised using measured data from LHC Run 2 operation and Monte Carlo simulations with the FLUKA code, and predictions are made for the operation of these devices in the HL-LHC era.
Paper: THPL082
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL082
About: Received: 03 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL084
Cherenkov diffraction radiation dielectric button characterization via a slab-line
4637
The generation of Cherenkov diffraction radiation when a charged particle beam passes in close proximity to a dielectric target is being studied and developed for various non-invasive beam instrumentation applications. One such instrument is a beam position monitor (BPM) composed of four cylindrical dielectric inserts. A challenge of using the conventional stretched wire technique to characterize the BPM is the coupling of higher order modes (HOMs) into the inserts that are dielectric-loaded circular waveguides. To minimize the generation of HOMs and excite mainly the transverse electromagnetic (TEM) mode as a model of the beam field, a set-up comprising a dielectric insert mounted on a slab line with 50 Ohms characteristic impedance was tested. The results and comparison with numerical simulations in CST are presented.
Paper: THPL084
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL084
About: Received: 06 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL085
Calibration of the LHC Diamond beam loss monitors for LHC Run 3
4641
A set of twelve Polycrystalline Chemical Vapour Deposition (pCVD) diamond detectors are installed in the beam injection, extraction and betatron collimation areas of the Large Hadron Collider (LHC) as fast beam loss monitoring detectors. Their high-radiation tolerance and time resolution in the order of a few ns makes them an ideal candidate to monitor bunch-by-bunch losses in the LHC beams, which have a nominal bunch separation of 25 ns. Considering their location in some of the most critical areas for beam loss studies, a signal-to-lost-particle calibration of these detectors provides a useful insight of the various LHC bunch-by-bunch beam loss mechanisms. This contribution shows the principle of the calibration of the LHC diamond Beam Loss Monitors (dBLMs) as well as a description of the machine tests run to study and perform this calibration.
Paper: THPL085
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL085
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL086
Beam lifetime monitoring using beam loss monitors during LHC Run 3
4645
The Beam Loss Monitoring (BLM) system of the Large Hadron Collider (LHC) at CERN is essential for the protection of machine elements against energy deposition from beam losses. Employing around 4000 detectors placed around the 27-km LHC ring, the BLM system measures secondary particles continuously and can trigger beam extraction in less than 3 turns, in case the signals exceed certain predetermined thresholds. Thanks to its high dynamic range and sensitivity, a signal-to-lost-particle calibration of this system is suited to provide accurate information about the LHC beam loss patterns. This includes online monitoring of the beam lifetime and even the identification of the plane of losses, making it an asset to follow up the performance of the accelerator. In this contribution the principle of the monitor calibration is explained, as well as a description of the machine tests used to acquire the calibration data. Finally, an analysis of the beam lifetime during the first year of the LHC Run 3 is presented together with examples of selected LHC fills.
Paper: THPL086
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL086
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL087
Emittance tuning bumps for the main linac of CLIC 380 GeV
4649
The high luminosity specifications for future linear colliders, such as the Compact Linear Collider (CLIC) require extremely small vertical beam emittance at the interaction point. This relies on minimizing the emittance growth in the collider sub-systems. One major source of emittance growth is the Main Linac, mainly caused by misaligned quadrupoles and accelerating structures. The current budget for the normalized emittance growth is 5 nm due to the static misalignments and another 5 nm due to the dynamic imperfections. The budget for the static imperfections is achieved through the use of beam-based alignment, such as one-to-one correction, dispersion-free steering, and the realignment of accelerating structures. This paper explores the use of additional emittance tuning bumps to further decrease the emittance growth, thereby increasing the luminosity.
Paper: THPL087
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL087
About: Received: 03 May 2023 — Revised: 16 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL088
CERN’s beam instrumentation R&D study for FCC-ee
4653
The Future Circular Collider (FCC) R&D study was started in 2021 as a comprehensive feasibility analysis of CERN’s future accelerator project encompassing technical, administrative and financial aspects. As part of the study, Beam Instrumentation (BI) is a key technical infrastructure that will have to face unprecedented challenges. In the case of electron-positron FCC-ee, these are represented, among others, by the size of the accelerator, the amount of radiation produced along the ring and in machine-detector interaction region, the presence of the top-up booster and collider ring in the same tunnel. In this contribution we will present the current FCC-ee BI study and discuss its status and perspectives.
Paper: THPL088
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL088
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL089
HL-LHC BPM electronics development as a case study for direct digitization and integrated processing techniques in accelerator instrumentation
4657
The technological evolution of analog-to-digital and digital-to-analog converters increases the amount of data that can be processed in the digital domain. Therefore, direct digitization enables many advanced signal processing techniques and is attracting more and more attention in the field of accelerator instrumentation. The future HL-LHC Beam Position Monitor (BPM) data acquisition system to be installed near the ATLAS and CMS experiments is a clear example of an application with demanding signal processing requirements that could greatly benefit from this trend. The investigated architecture is based on an RF System-on-Chip from Xilinx, which allows fast RF conversion and high-performance digital processing to be integrated in a single chip for multiple channels. This paper compares the estimated performance and cost of such an integrated solution with an architecture based on discrete components.
Paper: THPL089
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL089
About: Received: 03 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL090
Improvements on the LHC Interlock BPM system
4661
The LHC interlock BPM system is used as part of the beam abort system to insure that beam trajectories in those regions are conform with a safe extraction of the beams from the main ring to the dump lines. After more than 10 years of operation, the system has shown some limitations in bandwidth and dynamic range and a study was initiated to look for improvements. Nowadays, with the availability of multi giga sample per second sampling rate ADC converters, there is poten-tial to greatly improve the performance of the system. In this paper a wideband architecture with direct acqui-sition of the BPM electrode signals, time interleaved on the same read-out channel is presented with emphasis on the design and construction of the critical components, and on the measured performance of a prototype system tested in the LHC during the 2022 run.
Paper: THPL090
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL090
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL091
Commissioning of ESS normal-conducting linac instrumentation and implications for future hadron linacs
4665
To support commissioning and early operation of the ESS normal-conducting linac, a variety of beam instrumentation systems have been deployed. These include beam chopping systems, Faraday cups, beam current monitors, and beam position and phase monitors as well as specialised systems such at wire scanners, emittance measurement units and neutron beam loss monitors. Commissioning has proceeded in three campaigns: proton beam through the Radio-Frequency Quadrupole to 3.6 MeV in 2021, through the first Drift Tube Linac (DTL) tank to 21 MeV in 2022 and through the first four DTL tanks to 74 MeV in 2023. In preparation for each campaign, the diagnostics team verified the measurement and protection functions of this instrumentation suite without beam. These functions were then verified with a low duty factor beam before finally declaring the systems operational. Throughout these verification activities and the succeeding commissioning stages, a rich data set was archived and analyzed. This paper describes the early experience with the ESS NCL instrumentation and, with a focus on lessons for future facilities, summarizes the data analysis techniques and results.
Paper: THPL091
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL091
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPL093
The ionization profile monitors in the recycler ring
4669
Ion profile monitors (IPM) are used to measure the beam size in synchrotrons. Both the Fermilab Recycler and Main Injector (MI) machines have IPMs. However, they were not well understood enough to provide confidence in their measurements. Accurately measuring beam size through the IPMs was crucial to recognize the loss mechanisms for accelerators and to keep the beam loss to a minimum. Thus, performing measurements with different parameters using the IPMs led to a better analysis on how changes in conditions affect the beam size. The IPM measurements are compared with that of multi-wires in the upstream transfer line after applying corrections. The results were compared with other diagnostics and the change in the beam size for different parameters are presented in this paper.
Paper: THPL093
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL093
About: Received: 04 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
THPL094
Beam loss monitoring with fixed and translating scintillation detectors along the Fermilab drift-tube linac
4673
The Fermilab Linac is a roughly 145 meter linear accelerator that accelerates H- beam from 750 keV to 400 MeV and provides beam for the Booster and the rest of the accelerator chain. The first section of the Linac is a Drift-Tube Linac (DTL), which in its current state, suffers from a lack of instrumentation along its length. As a result, operational staff do not have access to the diagnostic information needed to tune the critical components of this accelerator, such as the quadrupole magnets within the drift tubes. This work presents an effort to utilize both fixed and translating scintillation detectors to investigate beam loss along the first two tanks of the Drift-Tube Linac.
Paper: THPL094
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL094
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
THPL095
Measurement of beam energy in the Fermilab's Linac taken at the transfer line
4676
Linac is the first machine in the accelerator chain at Fermilab where H$^{-}$ ions are accelerated from 35 keV to 401.5\,MeV and then injected into a synchronton known as Booster where they are stripped of their electrons to become protons. One of the tools used during tuning of the Linac extraction energy is two beam pickups known as Griffin Detectors. Our goal is to control the output energy using machine learning techniques to increase the reliability and quality of the beam delivered from Linac. The first step is to understand the data from the diagnostics to develop reliable and accurate energy measurement, and control methods before implementing machine learning techniques. Two methods of energy measurement were studied, and their results are compared. The first method was the time of flight measurement using Beam Position Monitors that provide beam phase measurement. The second method used the relation between beam transverse positions and dispersion values to calculate momentum variation. The results of these two measurement methods are found to be consistent.
Paper: THPL095
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL095
About: Received: 12 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
THPL097
Cryogenic Current Comparator (CCC): absolute beam current measurement in the order of nA
4680
The Cryogenic Current Comparator (CCC) is able to provide a calibrated non-destructive measurement of beam current with a resolution of 10 nA or better. The non-interceptive, absolute intensity measurement of weak exotic ion beams (< 1 µA) is essential in heavy-ion storage rings and in transfer lines, as the ones in FAIR. With traditional diagnostics this measurement is challenging for bunched beams and virtually impossible for coasting beams. The CCC is able to provide reliable values of beam intensity for current of this order of magnitude or lower, independently of beam bunching, ion species and without tedious calibration procedures. The test of the CCC in the heavy-ion storage ring CRYRING@ESR at GSI confirmed its viability, and suggested several improvements to the detector hardware. Therefore, an upgrade of the CCC system was performed and tested in laboratory environment. A review of these improvements will be presented, with a deeper discussion of the improvements and of the next steps for the development of the final version of the CCC for FAIR.
Paper: THPL097
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL097
About: Received: 03 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
THPL098
Opendigitizer: digitizer modernisation using openCMW and GNU radio 4.0 for FAIR
4684
OpenDigitizer* is an open-source modernisation of FAIR's modular digitizer infrastructure and graphical user interface based on OpenCMW, WebAssembly, and the GNU Radio 4.0 frameworks. Already used to provide generic monitoring and first-line diagnostics for accelerator-related devices, it further supports equipment experts, operation, and FAIR users in developing basic to advanced top-level measurement and control loops. Supporting hundreds of industrial digitizers with sampling frequencies ranging from a few MS/s to GS/s, the core relies on directed signal flow graphs to express arbitrary post-processing and feedback control loop logics that are both numerically highly efficient as well as provide an intuitive high-level yet detailed nuts-and-bolts representation to inspect and/or to reconfigure existing systems by accelerator-, control- or other system domain-experts alike with little to no prior required programming experience. The diagnostics UI tools are compatible with WebAssembly (WASM) allowing their native deployment, on mobile as well as on any browser-based platform, facilitating their flexible use both in the accelerator tunnel during commissioning, trouble-shooting, as well as in the control room.
Paper: THPL098
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL098
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPL100
Raspberry Pi cameras as beam induced fluorescence monitors for low and high energy beams
4692
Miniature single-board cameras have been used for several years to monitor beam-induced residual gas fluorescence. This work gives an overview of the use of so-called Raspberry Pi cameras in accelerator experiments. These devices are installed in vacuum at hard-to-reach locations. They have been tested in strong magnetic fields with low energy proton beams from 2 keV to 60 keV. They have also been tested in the high energy range with 4.8 MeV/u, $^{48}Ca^{10+}$ beams. Nitrogen and argon were used as residual gas and the pressure was varied from $1\cdot10^{-5}mbar$ to $1 mbar$.
Paper: THPL100
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL100
About: Received: 03 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL101
Advancements in the scintillation fibre beam monitor for low-intensity ion beams at HIT
4696
The Heidelberg Ion-Beam Therapy Centre (HIT) provides proton, helium, and carbon-ion beams with different energies and intensities for cancer treatment and oxygen-ion beams for experiments. For several experiments and possible future applications, such as helium ion beam radiography, a low-intensity ion beam monitor integrated into the dose delivery feedback system for the accelerator control is a necessary pre-requisite. The updated 2D prototype for this purpose consists of scintillating fibres with enhanced radiation hardness, silicon photomultipliers (SiPMs) to amplify the emitted light, and a dedicated front-end readout system (FERS) to process and record the generated signals. This setup was tested successfully on monitoring ion-beam position and profile horizontally and vertically, as well as the beam intensity, for all four ion types with energies from 50 to 430 MeV/u and intensities from 1E2 to 1E7 ions/s. Additionally, time-of-arrival (ToA) measurements on single ions have been successfully performed for a limited intensity range, allowing for ion tracking in a further update. This will reduce noise, and will also improve the accuracy and usability of ion radiography.
Paper: THPL101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL101
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL102
Reconstruction of the transverse electron beam profile using an interferometric beam size monitor
4699
The transverse size of the electron beam in a storage ring can be measured using the synchrotron radiation of a bending magnet. Due to the diffraction limit, many facilities exploit beam size monitors in the X-ray regime. On the other hand, the visible part of the emitted radiation delivers spatial information via an interference pattern after passing through a double slit. Assuming a Gaussian beam distribution the size of the beam can be easily obtained with an analytical formula. If this assumption is not fulfilled, the calculated beam shape will vary from the real distribution. This can appear for instance in case of exotic beam optics settings or complicated filling patterns, that are widely used in modern storage-ring-based light sources. In this paper the idea to reconstruct the electron beam distribution by measuring the absolute visibility and its phase with a spectral-resolved set-up is introduced.
Paper: THPL102
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL102
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL103
Instrumentation and operation modes for the commissioning phase of the SEALab SRF photoinjector
4703
Superconducting radio-frequency (SRF) photoinjectors offer a broad range of electron beam parameters and are therefore suitable for many applications such as energy recovery linac (ERL) driven lightsources, particle colliders, or for ultrafast electron scattering experiments. We are now nearing completion of the setup a SRF photoinjector with a SRF gun and SRF booster linac at the SEALAb accelerator test facility at HZB. The goal here is to realize an electron source with high brightness and high average current. In this work, the general planning for the commissioning phase, the operation modes and investigations into the diagnostic tools for achieving the expected beam parameters will be presented. The focus of the instrumentation is to provide information on the beam parameters at large dynamic range and on mechanisms for beam loss generation.
Paper: THPL103
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL103
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
THPL104
Recovery and check of the switching relay in the BPMs in the J-PARC MR
4706
The present BPMs of the J-PARC Main Ring have adopted mechanical relays in its processing circuits. Frequency range is limited less than 10 MHz by LPFs. Mechanical relay is chosen due to its good isolation. But the drawback is contact failures due to insulating materials after long suspension period of months. Methods of recovery and checking are reported. Recovery of contacts are performed with injecting dummy pulses. Contact is checked examining consistency comparing four independent position pairs (x, y) calculated from 3 electrodes out of four electrodes. The hermetically seal reed relays will be implemented in the new processing circuits under development.
Paper: THPL104
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL104
About: Received: 09 May 2023 — Revised: 19 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPL105
Improvement of the longitudinal phase space tomography at the J-PARC synchrotrons
4710
The longitudinal phase space tomography, which reconstructs the phase space distribution from the one-dimensional bunch profiles, is used in various accelerators to measure longitudinal beam parameters. At the J-PARC, an implementation of the phase space tomography based on the convolution back projection method has been used to measure the momentum spread of the injected beam. The method assumes that the beam distribution rotates without significant deformation during the synchrotron oscillation. Because of the nonlinearity of synchrotron motion with sinusoidal RF voltage, the method can be used only in limited situations such as small amplitude synchrotron oscillation. Algebraic Reconstruction Techniques (ART) in conjunction with particle tracking, which is implemented in CERN's tomography code, allows accurate reconstructions even for nonlinear large amplitude synchrotron oscillations. We present the overview of the application of CERN's tomography code to the J-PARC synchrotrons. The results of benchmarking are also reported.
Paper: THPL105
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL105
About: Received: 29 Mar 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL106
Three-stage simulation for the development of an ion-acoustic dose-deposition mapping system for LhARA
4714
LhARA, the Laser-hybrid Accelerator for Radiobiological Applications*, is a proposed facility for the study of proton and ion radiation biology. The accelerator is designed to deliver a variety of ion species over a wide range of spatial and temporal profiles at ultra-high dose rates. The facility requires that the deposited dose distribution be measured in real-time. For this purpose, an ion-acoustic dose mapping system has been developed that, exploits the ultrasound waves generated by the ion beam**. The feasibility of this approach is being evaluated using a two-stage simulation. A water phantom modelled in Geant4 with beam energies up to 250 MeV is used to calculate the energy deposited by the beam as a function of position and time. The time-dependent 3D energy distribution is then used as the source in k-Wave to simulate the ion energy generation of acoustic (pressure) waves and their propagation in the three-dimensional space. A hemispherical acoustic sensor array is also simulated and its ability to reconstruct the generated pressure distribution is evaluated. The results show that the 3D deposited-energy distribution can be reconstructed with sub-millimetre accuracy and suggest, that further development of the system can lead to real-time, non-invasive Bragg peak localization and dose deposition profile measurement during ion-beam therapy.
Paper: THPL106
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL106
About: Received: 03 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL107
Influence of vibratory effects on the beam parameters of SuperKEKB
4718
SuperKEKB is an asymmetrical lepton collider with a circumference of 3 016 meters, which collides 7 GeV electrons with 4 GeV positrons. To optimize the luminosity, which recently reached a world record of 4.71 10^34 cm-2 s-1, all the undesirable effects on beam parameters must be analyzed in detail, especially close to the interaction point where the Belle II detector is operated. The presented study investigates the influence of mechanical vibration on the luminosity. For this purpose, four seismic sensors (Guralp 6T) were installed and collect data 24 hours a day, two on the ground and another two located on the supports of the two cantilevered cryostats, inside which the last focusing magnets on both sides of the interaction point (the most critical for vibrations) are mounted. The luminosity is measured thanks to the LumiBelle2 fast luminosity monitor, which is based on diamond detectors installed in both beam lines. Vibration-induced disturbances in the luminosity frequency spectrum are investigated for several types of perturbations, in particular the ones resulting from ground motion amplified by the dynamical behavior of the cryostat, as well as also from external vibrations sources.
Paper: THPL107
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL107
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPL110
A consecutive double-slit emittance meter for high-brightness electron source
4721
High-brightness photoinjector has been an indispensable electron source driving X-ray free electron lasers (FEL). To improve the performance of the next-generation FEL, a high-quality electron beam with a small emittance, e.g, 0.1 micrometers for 100 pC bunch charge, will be of vital importance. A consecutive double-slit emittance meter has been proposed to measure such a small-emittance beam accurately. Analytical evaluations have been performed based upon the beam parameters of a C-band photocathode RF gun being constructed in the China Spallation Neutron Source.
Paper: THPL110
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL110
About: Received: 02 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
THPL112
Capacitive BPM electromagnetic design optimisation
4725
Capacitive beam position monitors (BPM) are widely used as diagnostics tools in particle accelerators. Typically due to a large number of BPM in an accelerator, their contribution to the beam coupling impedance cannot be neglected. In addition to the broadband part at low frequencies, the impedance exhibits resonant peaks at higher frequencies due to electromagnetic fields trapped around the BPM button and in the feedthrough assembly. Coupling of these peaks with beam spectrum lines can result in the BPM overheating. In this paper, we discuss the BPM design optimization aimed at the beam coupling impedance minimization while keeping/improving the BPM signal sensitivity (transfer impedance).
Paper: THPL112
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL112
About: Received: 28 Mar 2023 — Revised: 18 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL113
Non-destructive definition of emittance using the compton back-scattering and AI machine learning
4729
The work goal is to present the concept and the model for the reconstruction of the beam emittance from the spectrum of the scattered photons. The Compton process is a back-scattering of a laser pulse on the relativistic electron beam and is at the base of X-ray sources, as for instance, the project STAR. In the scattering process, the scattered photons get energy boost. The energy boosted photons carry also informations about the transverse momentum of the initial electron bunch. In this work we present the theory and the model implementation on how the beam emittance can be reconstructed from the spectrum of the scattered photons.
Paper: THPL113
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL113
About: Received: 28 Apr 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL115
Beam loss monitors characterization for SPES proton beam line
4736
Beam Loss Monitors will be installed along the primary SPES beam line to detect proton beam losses in the cyclotron area. They will be connected to the cyclotron Machine Protection System (MPS), as it is significant for the proper management of the accelerator during the operation. This report shows the work of characterization of such devices. Preliminarily, the characteristics of models used in other facilities with features similar to SPES (Proton beam energy= 40-70 MeV and current= 200-500 μA) were analyzed. Instrumentation Technologies-Libera, a company that makes potentially suitable devices for the SPES facility, was contacted as a possible supplier. They offer a system designed for beam loss measurements based on scintillators integrated on Photomultiplier, flash ADC and data acquisition. The gain is controlled by dc voltage managed by the system. Detectors and electronics have been tested in two steps: 1. Irradiation with gamma and neutrons static sources; 2. Irradiation with the CN accelerator beam (zero-degree line). From the tests, the detectors resulted very reactive to gamma and neutron radiation, so they could be suitable to be implemented at SPES as beam loss monitor purposes. Moreover, to characterize the detector on the operational conditions is fundamental. For these reasons, testing the detector’s behavior at the SPES cyclotron in normal operation (current= 200 μA and proton energy= 40 MeV) is mandatory and is planned for the next future.
Paper: THPL115
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL115
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL116
Observation of beam emittance reduction due to gas sheet injection for beam profile measurement
4739
To realize more stable operation of a high-intensity ion beam accelerator with a minimum beam loss, we have developed a non-destructive beam profile monitor detecting photons produced by interaction between the beam and a gas sheet injected into the beam line. The gas-injection-type profile monitor should induce scattering of the beam particles, and the beam emittance is considered to become larger. On the other hand, the beam-gas interaction may also induce space-charge neutralization of the beam. The plasma produced by the beam-gas interaction cancels the electric potential of the beam, and emittance growth due to the beam space-charge force is inhibited; the emittance relatively becomes small. To evaluate the effect of gas sheet injection on the beam, we have measured the phase space distribution of the 3 MeV, 60 mA H- ion beam with/without the gas sheet injection. As the result, the root mean square value of the beam emittance was constant or decreased against the increase in the amount of the injected gas-sheet flux.
Paper: THPL116
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL116
About: Received: 09 Mar 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
THPL117
Beam profile measurement using the highly-oriented pyrolytic graphite
4743
The mitigation of heat loading is one of the important issues for beam instrumentation to measure the high-power proton beam. Recently, the highly-oriented pyrolytic graphite (HOPG) material was used for the target probe of the bunch-shape monitor at the front-end in the Japan Proton Accelerator Research Complex (J-PARC). Since the thermal conductivity of the HOPG is high, it is suitable to measure the beam profile under the condition of high heat loading. As an application of the HOPG, for example, the thin HOPG may be used as a substitutive material of the target wire for the transverse profile monitor such as the wire scanner monitor. The possibility of the HOPG target for the beam profile monitor is discussed from some results of the test experiment using the 3-MeV negative hydrogen ion beam at the test stand.
Paper: THPL117
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL117
About: Received: 28 Mar 2023 — Revised: 11 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL118
Beam diagnostics and instrumentation for MESA
4746
The Mainz Energy recovering Superconducting Accelerator (MESA) is currently being installed in the final area of the Institute for Nuclear Physics at Johannes Gutenberg-University in Mainz. To optimize and operate the accelerator reliably luminescence screens, wire scanners and RF cavity monitors are used. In this paper we will present the ongoing development of the beam diagnostics foreseen at MESA.
Paper: THPL118
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL118
About: Received: 03 May 2023 — Revised: 30 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
THPL119
Recording two-beam LHC BPM signals to validate a technique for extracting individual beam positions
4749
As part of the High Luminosity upgrade for the Large Hadron Collider, several new directive-coupler (stripline) BPMs will be installed near the ATLAS and CMS detectors where the two counter-rotating beams exist within a single beampipe. In the worst case scenario, the bunches of the second beam arrive at the BPM location just 4 ns after those of the first and the BPM signals from the two beams overlap significantly. Using simulations of the expected BPM output, a novel scheme for digitally processing these two-beam signals in order to extract the true position of each beam has been developed. The offline validation of this technique requires genuine two-beam signals. In October 2022, suitable signals were gathered using an early proof-of-concept digital BPM processor connected to an existing room-temperature stripline BPM close to the CMS detector. During this period of data acquisition, RF cogging was used to vary the difference in arrival time of the two beam at the BPM location and orbit bumps were used to vary the beam-beam displacement in order to ultimately be able to determine the performance of the digital processing scheme.
Paper: THPL119
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL119
About: Received: 02 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL120
Enhancing the sensitivity of the electro-optical far-field experiment for measuring CSR at KARA
4753
At the KIT storage ring KARA (Karlsruhe Research Accelerator), a far-field electro-optical (EO) experimental setup to measure the temporal profile of the coherent synchrotron radiation (CSR) is implemented. Here, the EOSD (electro-optical spectral decoding) technique will be used to obtain single-shot measurements of the temporal CSR profile in the terahertz frequency domain. To keep the crucial high signal-to-noise ratio a setup based on balanced detection is under commission. Therefore, simulations are performed for an optimized beam path and the setup is characterized. In this contribution, the upgraded setup and first measurements are presented.
Paper: THPL120
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL120
About: Received: 02 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL121
First two-bunch measurements using the electro-optical near-field monitor at KARA
4756
The Karlsruhe Research Accelerator (KARA) is an electron storage ring, which features an electro-optical near-field monitor within the beam pipe in vacuum as a tool for longitudinal bunch profile measurements. The device performs very well in single-shot turn-by-turn measurements during single-bunch operation and over the years. The design has been optimized to be prepared for measurements in multi-bunch operation. The ability to work with multiple bunches and short bunch spacing is an important step to make the device suitable for more application purposes such as a diagnostics tool for the Future Ciruclar Collider for electrons and positrons (FCC-ee). This contribution provides first tests of the monitor during two-bunch operation with minimum 2 ns bunch spacing. Challenges like crystal heating due to an increased beam current are discussed and strategies for mitigation are presented.
Paper: THPL121
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL121
About: Received: 02 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL122
Split-ring resonator experiments and data analysis at FLUTE
4760
FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact linac-based test facility for accelerator and diagnostics R&D located at the Karlsruher Institute of Technology (KIT). A new accelerator diagnostics tool, called the split-ring resonator (SRR), was tested at FLUTE, which aims at measuring the longitudinal bunch profile of fs-scale electron bunches. Laser-generated THz radiation is used to excite a high frequency oscillating electromagnetic field in the SRR. Electrons passing through the 20 µm x 20 µm SRR gap are time-dependently deflected in the vertical plane, leading to a vertical streaking of the electron bunch. During the commissioning of the SRR at FLUTE, large series of streaking attempts with varying machine parameters and set-ups were investigated in an automatized way. The recorded beam screen images during this experiment have been analyzed and evaluated. This contribution motivates and presents the automatized experiment and discusses the data analysis.
Paper: THPL122
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL122
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL123
Status and upgrade of the visible light diagnostics port for energy spread measurements at KARA
4764
At the visible light diagnostic (VLD) port at the Karlsruhe Research Accelerator (KARA), it is possible to measure the energy spread of electron bunches by measuring the horizontal bunch profile of the incoherent synchrotron radiation. KALYPSO, a MHz-rate line-array detector has been used to measure the bunch profile. Recently, the KALYPSO system has been upgraded to a version incorporating a microstrip sensor based on TI-LGAD. The performed measurements have shown that the overall sensitivity of the system was significantly improved, which enables measurements at low bunch charges. In this contribution, a brief overview of the upgraded setup and preliminary measurement results will be presented.
Paper: THPL123
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL123
About: Received: 07 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL126
Towards fiber optics-guided synchrotron radiation-based longitudinal beam diagnostics at the KARA booster synchrotron
4768
Before injection into the Karlsruhe Research Accelerator (KARA), the electron storage ring of the KIT Light Source, the beam energy is ramped up from 53 MeV to 500 MeV by a booster synchrotron. The whole booster is located in a concrete enclosure inside the storage ring and thus not accessible during operation. For the study of longitudinal beam dynamics, a cost-effective solution to leverage the synchrotron radiation emitted at the booster bending magnets is desired. To ensure durability of the setup and to not obstruct the removable concrete ceiling of the booster enclosure, it is required to place the radiation-sensitive readout electronics outside of the booster enclosure and outside of the storage ring. In this contribution a fiber-optic setup consisting of commercially available optical components, such as collimators, optical fibers and high bandwidth photodetectors is used. As a proof-of-concept we present experimental results of different components characterized at the visible light diagnostics port of the storage ring KARA. In addition, we report on first booster measurements along with planned future experiments.
Paper: THPL126
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL126
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
Feasibility Study of the Real-time Proton Flux Monitoring System for Space Radiation Environment Test By Using a 100 MeV Proton Irradiation Facility
Protons are dominant radiation source in the space environment causing radiation effects such as SEE(Single Event Effects), DD(Displacement Damage) to EEE(electrical, electornics and Electromechanical) parts of spacecraft. Until now, radiation effect test for space EEE parts have been carried out by using a 100 MeV proton irradiation facility (BL102) at KOMAC(Korea Multi-purpose Accelerator Complex). For this kind of the accelerated ground test of such radiation effects on devices to predict their performance in space, the new space radiation environment simulation apparatus, which can simulate ultra high vacuum and thermal cylcling (-55 to +125 celcius degree) as well as 100 MeV proton irradiation, have been developing under way. For the new space environment test for space EEE parts, the Determination of dose or Fluence is the key parameter. Although the BL102 facility usually provide the the users the beam intensities range from 1E6 to 1E8 protons [cm-2 s-1], In order to match the demand of the space testing community of the South Korea, the new real-time beam flux monitoring system was developed by the combination of the high sensitivity in-air ACCT(AC current transformer) and the Bragg peak chamber detector which have the measurable range from 1E4 to 1E8 protons [cm-2 sec-1] and the beam flux can be measured by the pulse to pulse in real time. In this paper, new space radiation environment test apparatus and its beam flux monitoring system will be introduced.
THPL128
Diagnostics beamline development for ALS-U
4772
The Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory is currently undergoing an upgrade known as ALS-U. As part of this upgrade, the existing Triple-Bend Achromat (TBA) storage ring lattice is being replaced with a Multi-Bend Achromat (MBA) lattice, which allows for the tight focusing of electron beams to approximately 10 um, reaching the diffraction limit in the soft x-ray region. However, accurately measuring the beam size in such a tightly focused beam presents a challenge. This paper presents a diagnostics beamline design for ALS-U that utilizes a 2-slit interferometer technique to achieve a sub-micron resolution for beam size measurement. The impact of beam jitter, optics vibration as well as the incoherent depth-of-field effect on the measurement are also discussed.
Paper: THPL128
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL128
About: Received: 04 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL131
Time resolved measurements of DARHT-II multi-pulse beam
4776
Using a calibrated permanent magnet spectrometer and a streak camera, a time resolved measurement is made for a multi-pulse beam. These measurements are cross calibrated with cell voltage monitors to have a reliable online energy measurement. The Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) Axis-II produces a 16 MeV, 1.65 kA electron beam. Timing on the cell voltages is changed such that the beam has a varying kinetic energy spread. Multi-pulses are produced by a kicker at varying pulse lengths and selecting out different energies from the beam. This paper reports the results of these measurements.
Paper: THPL131
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL131
About: Received: 28 Apr 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL132
Improving the phase stability of the 201.25 MHz BPPM reference for the LANSCE 805 MHz LINAC
4779
The Los Alamos Neutron Science Center (LANSCE) employs the use of BPPMs (Beam Position and Phase Monitors) to track the position and phase of beam throughout the site. In the past, BPPMs in the 805MHz CCL (Coupled Cavity Linac) section of the site used a 201.25MHz reference over facility network fiber, using RF media converters. This fiber reference distribution gave rise to give a large diurnal phase & temperature dependency causing a large error in beam phase measurement. A system was devised to use the site’s temperature controlled 805MHz reference divided by 4 as a 201.25MHz reference, with the n*90˚ phase uncertainty eliminated though measurement of phase between 805MHz divided by 4 and fiber 201.25MHz alongside a switched hybrid coupler network. Deployment of 7 phase reference units in 2022 allowed for greatly reduced error in beam phase measurement.
Paper: THPL132
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL132
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL133
LANSCE's instrumentation and controls system modernization
4783
The Los Alamos Neutron Science Center (LANSCE) continues to invest into the future of its facility. In 2022 and after a 11-year effort the original and reliable RICE (Remote Instrumentation and Control Equipment) system was decommissioned. It was replaced with a modern customized control system in small stages during each annual 4-month outage. Since 1972 when the first proton beam was delivered through the near mile long accelerator, the control system was in a continuous state of modification. Thus, an extensive amount of non-RICE equipment was added over the years to expand the capabilities of the facility. Some of that equipment is now up to ~40 years old. Hence, the effort to replace the lingering obsolete and end-of-life equipment must continue to ensure reliable beam operations enabling scientific success in LANSCE’s five experimental areas. This paper discusses the scope of the designated Instrumentation and Controls Modernization project. We describe our technologies of choice and remaining challenges we face before we can implement them. The boundary condition for the whole project, as usual, is that we must implement these changes on a running accelerator.
Paper: THPL133
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL133
About: Received: 27 Apr 2023 — Revised: 08 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
Novel diagnostics for measuring 4D beam matrix
The widely used transverse parameters characterizing particle beams are the Twiss parameters. These parameters can be measured experimentally but they do not fully characterize the beam since they do not account for possible correlations in particle distribution between two transverse coordinates. These correlations may occur due to uncompensated magnetic field at the cathode or misalignment of focusing quadrupoles in the transport beamline. We propose a novel diagnostic for diagnosing full 4D beam matrix which may be used to identify such imperfections. The diagnostic is based on transporting the beam through the beamline which includes a quadrupole and a skew quadrupole magnets and measuring the resulting 2D beam distribution at the screen downstream. Such a measurement can be viewed as measuring a 2D projection of the 4D distribution. Different settings of the quads provide measurements of different slices of the phase space. The reconstruction of the original beam matrix from a number of measurements is done using machine learning algorithm, which provides a fast and reliable way of reconstruction for an arbitrary configuration of the scanning beamline. We study the performance of such a diagnostic, estimate its accuracy, and demonstrate that the uncertainty in the reconstructed sigma matrix can be smaller than the error of the measurements if the number of scans is large enough.
THPL136
Longitudinal Electron Beam Characterisation at the MAX IV Linac
4787
The MAX IV 3 GeV linac delivers electron beams to two synchrotron rings and to a dedicated undulator system for X-ray beam delivery in the Short Pulse Facility (SPF). In addition, there are plans to use the linac as an injector for a future Soft X-ray Laser (SXL). For both SPF and SXL operations, longitudinal beam characterisation with a high temporal resolution is essential. For this purpose, a transverse deflecting cavity (TDC) system has been developed and installed in a dedicated electron accelerator line located downstream of the 3 GeV linac. This accelerator line consists of two consecutive 3 m long transverse S-band RF structures, followed by a variable vertical deflector dipole magnet used as an energy spectrometer. This conference contribution presents the beam dynamics calculations for the beam transport along the TDC line, and in particular the optics configurations for slice emittance measurements. The operation of an analysis algorithm for use in the control room is presented. The aim is to provide 1 fs temporal measurement resolution to access the bunch duration of highly compressed bunches and slice parameters for sub-10-fs bunches.
Paper: THPL136
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL136
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL138
Electron gun for sheet electron probe for beam tomography
4791
In the novel device described in this presentation uses a simple, strip cathode provides a sheet beam probe for tomography instead of a scanning pencil beam that was used in previous electron probe bunch profile monitors. The apparatus with the strip cathode is smaller, has simpler design and less expensive manufacturing, has better magnetic shielding, has higher sensitivity, higher resolution, has better accuracy of measurement, and better time resolution. With this device it is possible to develop almost ideal tomography diagnostics of bunches in linear accelerators and in circular accelerators and storage rings. Currently we are planning to build a prototype tomography system will be built for testing in a proton or ion beam.
Paper: THPL138
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL138
About: Received: 04 May 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPL140
TPS fast orbit feedback upgrade
4794
Orbit feedback system of the Taiwan Photon Source (TPS) had been delivered since 2014. As long as more and more insertion devices installed, there are various wide-band disturbance produced. To further improve orbit stability, the fast orbit feedback (FOFB) system upgrade plan had been proposed in 2019. The upgrade plan includes both power supply controller revise and feedback computation rate increase from 10 kHz to 30 kHz. After upgrade, TPS fast orbit feedback bandwidth could be expanded from 250 Hz to 400 Hz in the vertical plane and from 200 Hz to 250 Hz in the horizontal plane. The integrated orbit power spectrum density could be effectively decreased around 20%.
Paper: THPL140
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL140
About: Received: 29 Mar 2023 — Revised: 10 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL141
TLS orbit feedback upgrade
4798
Orbit feedback system (OFB) of the Taiwan Light Source (TLS) had been deployed two decade ago and upgraded to improve performance several times. The loop bandwidth was limited by existed hardware. The system cannot remove perturbation form fast source. Therefore, to improve orbit feedback performance, the system have been upgraded in 2008 [1]. It included the BPM electronics upgraded from analogy type BPM to digital BPM and the corrector power supply was also replaced by high performance switching type power supply with wide bandwidth in the same time. Later after Taiwan Photon Source (TPS) commissioning in 2015, to share resources between TLS and TPS control system, it has been decided that TLS’s control system would be migrated gradually to the EPICS (Experimental Physics and Industrial Control System) control system which has been adopted by TPS [2][3]. Orbit feedback system is one of the rejuvenated subsystem with EPICS support. Besides, the feedback computation unit is also upgraded to FPGA and increase calculating cycle from 2.5 kHz to 10 kHz. The integration of BPM, power supply control and fast orbit feedback will be summarized in this report.
Paper: THPL141
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL141
About: Received: 29 Mar 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL142
Bunch-by-bunch transverse position measurement during injection
4802
Bunch-by-bunch systems are developed at the Taiwan Light source and the Taiwan Photon source to monitor the transverse position and filling pattern. This system consists four channels with 500 MHz sampling rate which synchronizes with the radio frequency of the accelerator. This system is used to diagnose the injection transition due to the kick mismatch and beam oscillation coming from the damped betatron oscillation and wake field.
Paper: THPL142
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL142
About: Received: 27 Apr 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
The Design of the Emittance Diagnostic for the Scorpius Accelerator
The planned multi-pulse linear induction accelerator, Scorpius, will be used in radiographic experiments at the NNSS U1A facility. One of the many diagnostics, the emittance diagnostics, will provide information on the quality of the beam emanating from the injector and therefore the quality of the beam in the accelerator. A Slit-Harp design was chosen for the emittance diagnostic. COMSOL multi-physics parameter space modeling using modeled Scorpius input beams tunes drove both the slit and harp designs to achieve the measurement of the emittance. Additional modeling for energy deposition/heat dissipation/x-ray reduction drove material choices for the slit (aperture) and harp wires. The signal chain is designed around constraints of signal extraction, biasing against secondary electrons which would cause errors in the emittance reconstruction calculation, and individual multi-pulse record capability. The ensemble of materials, electrical, and mechanical aspects of the design to reconstruct the emittance from the injector of the accelerator will be discussed.
THPL146
Electron beam studies on a beam position monitor based on Cherenkov diffraction radiation
4806
A beam position monitor based on Cherenkov diffraction radiation (ChDR BPM) is currently under investigation to disentangle the electromagnetic field of an electron bunch from that of a proton bunch travelling together in time and space in the beam-line of the AWAKE plasma acceleration experiment at CERN. The signals from a horizontal pair of ChDR BPM radiators have been studied under a variety of beam conditions at the CLEAR electron beam test facility. This paper summarizes the results using microwave signal processing at different frequency ranges.
Paper: THPL146
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL146
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL147
Developments and characterization of a gas jet ionization imaging optical column
4810
Standard methods of measuring the transverse beam profile are not adaptable for sufficiently high-intensity beams. Therefore, the development of non-invasive techniques for extracting beam parameters is necessary. Here we present experimental progress on developing a transverse profile diagnostic that reconstructs beam parameters based on images of an ion distribution generated by beam-induced ionization. Laser-based ionization is used as an initial step to validate the electrostatic column focusing characteristics, and different modalities, including velocity map imaging. This paper focuses on measurements of the ion imaging performance, as well as the dependence of Ion intensity on gas density and incident beam current for low-energy electron beams (<10 MeV).
Paper: THPL147
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL147
About: Received: 03 May 2023 — Revised: 19 May 2023 — Accepted: 19 May 2023 — Issue date: 26 Sep 2023
THPL148
Beam size measurement developments at SLS
4814
Advancements in low-emittance x-ray sources have required the exploration of various diagnostic techniques to push the resolution limit. Here we will present the two techniques to measure the size of the electron beam using X-rays: zone plate transmission microscope and a multi-crystal diffraction-based beam property analyzer. Both techniques have been tested at the Swiss Synchrotron Light Source (SLS), with encouraging results. With the zone plates, it is possible to measure the beam profile in 2D simultaneously. However, with the diffraction-based method, only the vertical beam size was measured. We have built and tested a diffraction-based system that is able to measure the beam size in both dimensions. This concept was also built to be compact and does not require long x-ray beamlines such that it could afford beam size monitoring for light sources with limited space.
Paper: THPL148
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL148
About: Received: 09 May 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL149
Fast kickers for bunch by bunch feedbacks at SLS 2.0 and ELETTRA
4817
The accelerator upgrades of SLS and Elettra will use newly designed kickers adapted for their small aperture beam pipes. The striplines of the transverse kickers conform closely to the aperture of the beam pipe with special grooves to avoid synchrotron light on the blades. The multitude of trapped higher order modes, caused by a high beam pipe cut-off frequency and dangerous in terms of stability and heat up, is suppressed by lossy silicon carbide dampers. The devices feature integrated pumping ports. The transverse shunt impedance improves by a factor of four compared to the current SLS/Elettra kicker. The longitudinal kicker is a heavily coupled cavity at 1.875 GHz (3.75 * RF) with four input and four output couplers for driver and loads. A nose cone design optimizes the shunt impedance resulting in a 20% improvement over the current SLS/Elettra kicker. Also here, the high cut-off frequency of the beam pipe caused problematic higher order modes, which needed to be damped by higher order mode couplers. A dedicated field sensor pickup will be used to synchronize the feedback to the bunch train.
Paper: THPL149
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL149
About: Received: 28 Apr 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL150
Dealing with thermionic emission in wire scanners based on secondary electron emission
4820
Measuring transverse beam profiles using thin wires is a very successful and widely used method. The signal is generated either by measuring scattered particles outside of the vacuum chamber or by measuring the current of the secondary electrons emitted from the wire. In high-brightness accelerators, the heating of the wire induced by the direct beam interaction or by coupling to RF fields can lead to the thermionic emission of electrons, which disturbs the measurement. The spectra of the electrons are different, but they overlap, therefore the typically used method of biasing the wire only partly reinstates the original beam profile. This study investigates the mixing of current signals from both phenomena and tries to address the question of the optimal bias voltage and potential reconstruction of the original beam profile. The estimations are compared to measurements performed on high-brightness beams of PSI HIPA machines.
Paper: THPL150
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL150
About: Received: 01 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL151
About the damage mechanisms of thin targets exposed to high-power particle beams
4824
Thin targets, in the form of wires, stripes, or foils, are often used in accelerators to measure the properties of particle beams. Motivation for a small thickness, typically between several and to hundred micrometers, is diverse and depends on a particular case. For instance, small diameters of wires allow for precision measurement because it is probing a small fraction of the beam transverse profile. In case of high-power beams, the critical argument is small energy deposits and good cooling because of the large surface-to-volume ratio. In certain beam conditions, the temperature of the target can be very high and lead to thermal damage. This paper attempts to give an overview of the conditions under which the breakage occurs and the damage mechanisms for various materials.
Paper: THPL151
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL151
About: Received: 29 Mar 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
Non-invasive bunch length reconstruction in linacs
The bunch length in linacs is an important parameter to characterize the beam as well as to tune and optimize the final accelerator performances. In linear machines this observable is typically determined from the bunch imaged on a screen located downstream of a Transverse Deflecting Structure (TDS) used to impinge a time dependent kick along the longitudinal coordinate of the beam. This kind of measurement is typically performed during the machine setup and only sporadically to check the beam duration, but it cannot be continuously repeated, because time consuming and invasive. A non-invasive method to determine the electron bunch length was already presented in the past [1]. This method is based on the analysis of the synchrotron radiation light spot emitted by the bunch passing through a magnetic chicane provided that the energy chirp impinged on the bunch by the upstream radiofrequency structures is known. In order to overcome a systematic discrepancy affecting the SRM based results compared to the absolute TDS based ones, we implemented and optimized a Machine Learning (ML) approach to predict the bunch length downstream of the two SwissFEL compression stages - from about 10 fs up to about 2 ps - as well as the beam longitudinal profile at the first one. [1] G. L. Orlandi, R. Xue, H. Brands, F. Frei, Z. Geng, V. Thominet, and S. Bettoni, Bunch length and energy measurements in the bunch compressor of a free-electron laser, Phys. Rev. Accel. Beams 22, 072803 (2019).
THPL153
Corrugated wakefield structures at SwissFEL
4828
Dedicated wakefield-generating structures are capable of measuring the electron beam current profile, and of removing residual energy chirps (dechirping). Furthermore, at Free-Electron Laser (FEL) facilities they can be used to measure* or shape the photon pulse power profile. We motivate and present the mechanical design of the rectangular, double-sided corrugated structures used at SwissFEL, and compare it to similar designs employed at other facilities.
Paper: THPL153
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL153
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL154
Development of beam position monitor for korea 4GSR project
4832
The emittance of fourth-generation storage ring(4GSR) will be built in Cheongju-Ochang, Korea, is expected to be 100 times smaller than the existing third-generation storage ring. As the emittance decreases, more precise beam stabilization is required. To satisfy this, the resolution of the Beam Position Monitor (BPM) should also be further improved. We have performed an optimization study of 4GSR BPM to minimize wake impedance and power dissipation in small size of 4GSR vacuum chamber. Moreover, The cut-off frequency of feed-through antenna was designed to be high by using a material with a low dielectric constant. As a result, the BPM output signal is fully decayed and supressed within a bunch interval of 2ns. In this presentation, we will describe that the more detailed current status of the design and development of the beam position monitor for Korea 4GSR.
Paper: THPL154
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL154
About: Received: 11 May 2023 — Revised: 15 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
A Simulation Study on Residual Gas Chamber Based Photon Beam Position Monitor
Contaminated photon beams which comes from upstream and downstream dipole magnet in between an Insertion Device (ID), the main light source, often cause a critical measurement error on blade-type Photon Beam Position Monitors (PBPMs). The reason of such misreading is that the center position of the beam is calculated by only with the weak photoelectric current generated from both ends of the blade. Instead of direct photoelectric effect on metal blades, we considered an ionization of residual gas as a main detecting principle of photon beam position to remove the measurement error caused by the contamination. Realistic photon beam profiles which comes from the ID and dipoles were generated, and they were used as a photon source of beam-gas interaction calculation in order to get a distribution of ionized electrons. The electrons were tracked inside a conceptually designed model that consisting of residual gas chamber, electrodes and uniformly distributed electric field. In this paper, we introduce a Monte Carlo simulation method of gaseous type PBPM and a preliminary result of the parameter optimization
THPL157
Study on transverse beam size measurement using Cherenkov diffraction radiation in low-energy electron accelerator
4836
Cherenkov Diffraction Radiation (ChDR), which is emitted when relativistic charged particles pass around dielectric materials, has recently been presented as non-invasive beam diagnostics in various studies. We intend to measure transverse beam size using ChDR in e-LABs, a 100 MeV electron experimental accelerator at the Pohang Accelerator Laboratory (PAL). The electron energy of e-LABs is low, so the intensity of photons generated by ChDR is absolutely small. Therefore, a cumulative dielectric radiator with a length of 157 mm was designed to increase the photons incident on the detector. This contribution shows the characteristics of ChDR simulated numerically at low energies. Furthermore, we present an experimental configuration for measuring transverse beam size with some considerations.
Paper: THPL157
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL157
About: Received: 11 May 2023 — Revised: 11 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL160
High-bandwidth Electro-Optic BPMs and an optical time-stretch technique
4839
An electro-optic beam position monitor is in development for the HL-LHC to enable high-bandwidth monitoring of crabbed bunch rotation and intra-bunch instabilities. Following in-air beam tests of a prototype at HiRadMat and the Clear facilities at CERN in 2021 and 2022, a new in-vacuum version is being prepared for operation in the SPS during LHC Run 3. We report on progress toward the design aims and investigate a novel method of readout of single shot pulsed bunch signals at high bandwidth, while acquiring data at lower bandwidths using an optical time-stretch technique.
Paper: THPL160
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL160
About: Received: 07 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
THPL161
Detector parametrisation for the front end test stand laserwire diagnostic using GEANT4
4843
Comprehensive simulations for the FETS laserwire have been made with the developed Geant4 laser package. Feasibility of the longitudinal mode laser to provide full 6D beam characterisation has been made. Simulation results have been used to outline minimum detector requirements. The detector necessary for measuring the 6D phase space requires a drift distance of at least 2.5m between interaction point and detection plane, a 1mm2 spatial resolution, across a total transverse area of 40mm2 for the transverse measurements. To include longitudinal data the time resolution of the detector would need to be 200ps or less. The Timepix4 is proposed as a candidate detector due to its tile structure enabling custom size detector, a <100 μm spatial resolution, and a 195 ps time resolution.
Paper: THPL161
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL161
About: Received: 03 May 2023 — Revised: 31 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
XH Detector integration with LImA
Many complex systems require the use of different detector devices. The detectors usually acquire 1D or 2D data, but as the manufacturers differ, they all have diverse controlling interfaces. When the API and interface differ, it can become complex to control multiple different devices. The Lima library was created to overcome those obstacles. It unifies the usage of 1D and 2D detectors by exposing an interface which can, later on, be customized to use different detectors' APIs. The XH detector designed by STFC and used at ESRF is one example. The data collected by XH is sent to the server named "DA" acting as an API proxy and answers the string commands. The commands can both set the attributes and trigger the acquisition. All those complex commands and logic are wrapped into the Lima interface allowing transparent control over the device without additional knowledge and personal training.
Detailed Phase Space Reconstruction from Accelerator Beam Measurements Using Differentiable Simulations
Characterizing the phase space distribution of particle beams in accelerators is a central part of accelerator understanding and performance optimization. However, conventional reconstruction-based techniques either use simplifying assumptions or require specialized diagnostics to infer high-dimensional (> 2D) beam properties. In this work, we introduce a general-purpose algorithm that combines neural networks with differentiable particle tracking to efficiently reconstruct high-dimensional phase space distributions without using specialized beam diagnostics or beam manipulations. We demonstrate that our algorithm reconstructs detailed 4D phase space distributions with corresponding confidence intervals in both simulation and experiment using a single focusing quadrupole and diagnostic screen. This technique allows for the measurement of multiple correlated phase spaces simultaneously, enabling simplified 6D phase space reconstruction diagnostics in the future.
THPL170
Transverse phase space tomography using machine learning at the CLARA accelerator test facility
4851
Phase space tomography is a powerful technique for characterising beams in particle accelerators and has found widespread use at many facilities. However, conventional tomography techniques require significant computational resources, particularly when reconstructing the charge distribution for two or more degrees of freedom. Here, we describe a novel technique that employs machine learning and image compression for transverse phase space tomography in two degrees of freedom. The use of machine learning allows the beam distribution in 4D phase space to be reconstructed more quickly than by conventional tomography techniques, while the application of image compression can dramatically reduce the size of the data sets involved in the analysis. The new method has been deployed on the CLARA accelerator at Daresbury laboratory to characterise electron bunches with moderate energy (35 MeV) and charges up to 100 pC. We compare the machine learning technique against a conventional tomography algorithm (algebraic reconstruction) applied to the same data set, and show that the results are at least as good in terms of predicting the observed beam profiles for a range of quadrupole strengths.
Paper: THPL170
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL170
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL171
Demonstration of an electro-optic spectral interferometry longitudinal profile monitor at Clara
4855
Electro-optic diagnostics are able to non-destructively resolve the longitudinal charge profile of highly relativistic bunches without complicated calibrations and ambiguous phase recovery techniques. The most implemented technique is EO spectral decoding as it is simple and reliable, and has an easy to interpret output. However, its resolution is limited to the geometric mean of the transform limited and stretched probe laser durations. Until very recently, efforts to improve on this have resulted in designs that lose the attractive properties of spectral decoding. On the CLARA accelerator at Daresbury Laboratory we have demonstrated a new EO system that exploits common-path spectral interferometry, 'EOSI', which removes the geometric mean limitation. The system was used to measure 35 MeV/c bunches live at 10 Hz, ranging from 150 pC down to 2 pC, and at a range of compressions from several ps down to ~300 fs rms. We explain the technique, describe the measurements, and outline issues and improvements. The technique differs from a spectral decoding system by only a single optical element, potentially allowing current EO systems to be upgraded.
Paper: THPL171
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL171
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL172
Bead-pull analysis of HOM in X-band linearizer linac on CLARA, with update on HOM measurement system
4859
The X-band lineariser linac planned to be installed on CLARA will be aligned using beam induced higher order modes (HOMs). Higher order modes in the cavity were studied using a bead-pull measurement technique. A software application was developed in LabVIEW to control the 3D motorised bead position scanning setup and VNA for S-parameter measurements. Propagation of HOM frequencies in the linac were verified, identifying the most suitable HOMs to use. Progress in development of HOM signal processing hardware system with dynamic control is also discussed in the paper.
Paper: THPL172
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL172
About: Received: 02 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
THPL174
Qualitative measurements of bunch length at CLARA using coherent transition radiation
4863
Bunch length is an important metric for user experiments at the Compact Linear Accelerator for Research and Applications (CLARA). A prototype Bunch Compression Monitor (BCM) based on Coherent Transition Ration (CTR) was recently installed and commissioned to support recent user experiments. The intensity of CTR is measured using a pyroelectric detector. A noise cancellation scheme based on a second detector offset from the focus of the CTR was used to reduce the noise caused by the broadband nature of pyroelectric detectors. Qualitative measurements of the bunch length as a function of RF phase are presented, along with an overview of the system design. Plans for an improved system are also presented.
Paper: THPL174
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL174
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
Update on the status of the uTCA Digitizer BPM design for SARAF Phase II
One of the crucial monitoring systems of any particle accelerator is the Beam Position Monitor (BPM). The purpose of a BPM is to provide information on the position, phase and current of the beam at different points along the accelerator line. The BPM is a subsystem of the CEA control domain for the SARAF-LINAC instrumentation and Orolia-Spain has designed, developed, manufactured and tested the system based on CEA technical specifications. A preliminary version of this system has been already installed in the SARAF accelerator in Israel at the beginning 2022 and the first results are going to be shown. The architecture, design and development as well as the performance of the BPM system will be presented in this paper. The benefits of the proposed architecture and the first results obtained under different conditions will be detailed
THPL177
BAM system and machine stability at SXFEL
4866
Beam arrival time is one of the key fundamental parameters for free-electron laser (FEL) facilities to ensure an accurate synchronization between an electron bunch and a seeded laser. Thus a high-performance beam arrival time/flight time measurement (BAM) system is indispensable for an FEL. A cavity-based BAM system has already been established at the Shanghai Soft-X-ray FEL test facility three years ago. To further optimize the system performance, the impacts of the local oscillator, signal processing window, and temperature around the electronic devices were analyzed, and the related subsystems were upgraded and optimized accordingly. Currently, the upgraded BAM system has been applied at the Shanghai Soft-X-ray FEL user facility. This report will focus on the evaluation of the upgraded BAM system performance and the analysis of the beam instability caused by the beam energy jitter by both analytic calculation and beam test. The beam test results show the deviation of beam flight time can reach 10 fs. Besides, a linear correlation between the beam energy and beam flight time is found and the energy jitter can contribute 33 fs to 65 fs to the beam flight time RMS jitter.
Paper: THPL177
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL177
About: Received: 03 May 2023 — Revised: 17 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPL178
Turn-by-turn beam size measurement based on spatial interferometer
4869
The transverse beam size is a key parameter of electron bunches in the storage ring for beam quality evaluation. High-precision beam size measurement will offer better performance for accelerator monitoring and will be beneficial to study beam instabilities and optimizing machine operation. The interferometer system is a commonly used diagnostic tool for beam size measurement. High accuracy measurement can be achieved with low variation of beam size. It can also be used for very small size measurements by altering slit spacing. For future research on the physics and key technologies of high-brightness electron accelerators, we will build a turn-by-turn and bunch-by-bunch beam size measurement system based on the Shanghai Synchrotron Radiation Facility (SSRF) platform for related research. It will realize high-speed and high-resolution beam size measurements with the help of a multi-slit spatial interferometer and photomultiplier array (PMT). In this paper, we will introduce the construction of the overall system, discuss related problems, and give preliminary experimental results.
Paper: THPL178
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL178
About: Received: 03 May 2023 — Revised: 08 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
THPL182
Direct RF sampling processor for cavity BPM system
4873
Digital beam signal processor is critical for the beam diagnostic resolution and on-line application performance. High speed & high precision ADC, high performance FPGA are the key devices for the evolution of the processor. At present, ADC technology has entered the era of RF direct sampling, which bandwidth is up to 9GHz, sampling rate is higher than 2GSPS, and sampling bits is up to 14 bits. If the beam signal is sampled directly and processed with an FPGA, the beam diagnostic system structure will be much more concise and stable. In this paper, a developed direct RF sampling processor for beam diagnostic in SXFEL and SSRF will be introduced, and the first application on cavity BPM system will be shown.
Paper: THPL182
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL182
About: Received: 17 May 2023 — Revised: 18 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
THPL183
Optimization and development of the CBPM system for the SHINE
4876
Beam-based alignment and feedback systems are essential for the operation of the Free Electron Lasers (FELs). Cavity BPMs having the advantage of high position resolution are widely used in the field of accelerators. Systematically analyze the impact of the key parameters of each subsystem on the performance of the whole system, so that the key technical indicators of each subsystem can achieve the optimal and balanced allocation, is the primary issue to be considered when designing a CBPM system. In this paper, the relationship between the relative amplitude extraction uncertainty of the CBPM system and the key parameters of each subsystem is proposed based on theoretical analysis. And this method has also been applied in the development of the CBPM system for the Shanghai High repetition rate X-ray Free Electron Laser and Extreme Light facility (SHINE). Based on the beam test bench in the Shanghai Soft X-ray FEL facility (SXFEL), the position measurement uncertainty of the CBPM system can reach 40 nm at the bunch charge of 100 pC, which is consistent with the theoretical analysis results and better than the requirements of the SHINE.
Paper: THPL183
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL183
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL190
Tolerance analysis of a bunch arrival-time monitor design with rod-shaped pickups on a printed circuit board for the European XFEL and FELBE
4879
For arrival-time monitors of the electro-optical synchronization system at the European XFEL, FELBE and other free-electron laser facilities, a novel concept based on rod-shaped pickups mounted on a printed circuit board is proposed. New simulation results show the huge potential for low charge applications foreseen at the European XFEL and FELBE for future operation modes. A theoretical jitter-charge product 𝜎t × 𝑄B of 9 fs pC was estimated for this pickup structure in combination with tailor-made ultra-wideband low-pi-voltage electro-optical modulators. The design meets the desired criteria for 1 pC operation, so it is planned to produce a prototype for first tests in FELBE. The structure is assumed to be sensitive to the production accuracy, manufacturing tolerances for different components of the pickup-structure are analyzed in this work. The results allow to identify critical dimensions and will help to predict the effect of inevitable geometric deviations.
Paper: THPL190
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL190
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL191
Absolute charge measurements with pick-ups
4883
Capacitive Pick-Ups (PUs) are typically used for monitoring the beam position and measuring the relative intensity of bunched beams. We explore the potential usage of capacitive PUs for measuring the absolute charge in a bunch over the full range of beam energies, transverse beam offsets and bunch lengths found at ion accelerators. The results suggest that absolute charge measurements can be performed, however a correction specific to the design and installation of PUs is required. In this contribution, the field simulation results for a typical PU design installed at GSI UNILAC and CRYRING@ESR for a standard beam parameter range are shown. Historical experimental data from comparative measurements between PUs and current transformers performed at CRYRING@ESR support the simulation results.
Paper: THPL191
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL191
About: Received: 03 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL192
Simulations of the compact transverse-deflecting system for ultra-short electron bunch diagnostic
4887
A compact TDS (transverse-deflecting system) has been proposed for diagnostics of extremely short electron bunches (up to single-digit femtosecond range). The main idea is to use terahertz radiation, produced from optical rectification of the facility’s electron gun laser pulse. This provides an intrinsic synchronization between the electron bunch and the laser pulse. The proposed system is to be constructed at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) at Karlsruher Institut für Technologie (KIT), which provides the opportunity to create electron bunches of variable length and at medium energy (7 MeV up to 90 MeV). Simulations in CST MICROWAVE STUDIO are carried out in parallel with the experimental activities to optimize the design of the system. In the present paper the simulation results for several possible designs will be presented.
Paper: THPL192
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL192
About: Received: 02 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPM136
Phase-space reconstruction based on severe undersampling for ultrafast electron beam
5183
In an Ultrafast Electron Diffraction (UED), high-brightness ultrafast electron beams are indispensable to capture critical ultrafast events on an atomic/molecular scale. For space-charge effects (SCE) dominated electron beams, the beam emittance increases significantly during propagation. Understanding the beam emittance evolution during its passage is critical for further improving the UED performance. To diagnose the in situ emittance of the beam at several certain positions, we use a multi-slit device with a low sampling rate to eliminate the SCE influence. Due to the fabrication technology limitation, only a few slits can be made, leading to a severe undersampling rate, creating challenges in reconstructing the original beam information. This paper introduces a method to reproduce beam from severely under-sampled data.
Paper: THPM136
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM136
About: Received: 03 May 2023 — Revised: 13 Jun 2023 — Accepted: 13 Jun 2023 — Issue date: 26 Sep 2023