Paper | Title | Other Keywords | Page |
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MOPG01 | Design, Production and Tests of Button Type BPM for TAC-TARLA IR FEL Facility | electron, FEL, radiation, impedance | 27 |
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Funding: Ankara University Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) facility is proposed as an IR FEL and Bremsstrahlung facility as the first facility of Turkish Accelerator Center (TAC) in Golbasi Campus of Ankara University. TARLA is proposed to generate oscillator mode FEL in 3-250 microns wavelengths range and Bremsstrahlung radiation. It will consist of normal conducting injector system with 250 keV beam energy and two superconducting RF accelerating modules in order to accelerate the beam 15-40 MeV. The electron beam will be in both continuous wave (CW) and macro pulse (MP) modes. The bunch charge will be limited by 77pC and the average beam current will be 1 mA. To detect electron beam position inside beam line, BPM (Beam Position Monitor) has to use through beam line. Wall current monitor based systems button type TARLA BPM are briefly mentioned. In this study, simulation results of the calculations in CST, production and test studies for button type TARLA BPMs are presented. Mechanical and electronic designs, antenna simulations, and the latest testing procedures are determined for button type BPMs. |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG01 | ||
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MOPG03 | Investigation of Transverse Beam Instability Induced by an In-vacuum Undulator at SPEAR3 | coupling, operation, vacuum, insertion-device | 31 |
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Funding: Work supported by U.S. Department of Energy Contract No. DE-AC02-76SF00515 Vertical beam instabilities have been observed at SPEAR3 when a newly installed in-vacuum undulator (IVUN) is operated at a set of narrow gap settings. The source of the instabilities is believed to be vertically deflecting trapped modes inside the IVUN tank that are excited by the beam. We have used beam-based measurements to characterize the frequencies and strengths of the excited modes using both our bunch-by-bunch feedback system and a spectrum analyzer. Using numerical simulations of our IVUN structure, we have found modes with high shunt impedance near the measured frequencies. Recently, we have successfully measured these IVUN modes during our current downtime. In this paper, we will report on the measurements, simulations, and plans to damp these modes. |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG03 | ||
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MOPG05 | Transient Studies of the Stripline Kicker for Beam Extraction from CLIC Damping Rings | flattop, impedance, extraction, kicker | 35 |
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Stripline kickers are generally assumed to have equal contributions from the electric and magnetic field to the total deflection angle, for ultra-relativistic beams. Hence parameters of the striplines, such as the characteristic impedance, the field homogeneity and the deflection angle are typically determined by simulating the striplines from an electrostatic perspective. However recent studies show that, when exciting the striplines with a trapezoidal current pulse, the magnetic field changes during the flat-top of the pulse, and this can have a significant effect upon the striplines performances. The transient solver of Opera2D has been used to study the magnetic field, for the striplines to be used for beam extraction from the CLIC damping rings, when exciting the electrodes with a pulse of 1 us flat-top and 100 ns rise and fall times. The time dependence of the characteristic impedance, field homogeneity and deflection angle are presented in this paper. In addition, two solutions are proposed to improve the flatness of the magnitude of the magnetic field throughout the flat-top of the pulse, and the predicted results are reported. | |||
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Poster MOPG05 [1.557 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG05 | ||
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MOPG25 | Industrialisation of Cavity BPMs | cavity, electronics, FPGA, controls | 98 |
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The industrialisation project of a cavity beam position monitor (CBPM) has been commissioned aiming at providing reliable and economical CBPM systems for future Free Electron Lasers (FEL) and similar linac-based facilities. The first prototype of a CBPM system was built at Versatile Electron Linear Accelerator (VELA) in Daresbury Laboratory. We report on the measurement results from the first prototype of our system at VELA and current developments of CBPMs, down-converter electronics and DAQ system. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG25 | ||
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MOPG36 | Timing Window and Optimization for Position Resolution and Energy Calibration of Scintillation Detector | detector, timing, radiation, photon | 123 |
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The real event selection, timing resolution, position resolution and energy response of the EJ-200 plastic scintillation detector have been analyzed using timing window coincidence measurement. The detector was simulated based on Monte Carlo, including its geometry, energy deposition, photon collection and signal generation. The detection efficiency and the real events selection have been obtained while the background noise has been reduced by using two-end readout timing window coincidence. We developed an off-line analysis code, which is suitable for massive data from the digitizer. We set different coincidence timing windows, and did the off-line data processing respectively. We find the detection efficiency increases as the width of the timing window increases, and when the width of timing window is more than 10ns, the detection efficiency will slowly grow until it reaches saturation. Time, position and energy response have been measured by exposing to radioactive sources. The best timing window parameter as 16ns is obtained for on-line coincidence measurement, and the position resolution is up to 12cm. Energy response of the detector was linear within the experimental energy range*.
* L. Karsch, A. Bohm et al, "Design and Test of A Large-area Scintillation Detector for Fast Neutrons", Nuclear Instruments and Methods in Physics Research A, vol.460, pp.362-367, 2001. |
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Poster MOPG36 [5.665 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG36 | ||
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MOPG40 | Performance Studies of a Single Vertical Beam Halo Collimation System at ATF2 | background, collimation, wakefield, optics | 139 |
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Funding: Work supported by IDC-20101074, FPA2013-47883-C2-1-P and ANR-11-IDEX-0003-02 In order to reduce the background that could limit the precision of the diagnostics located in the ATF2 post-IP beamline, a single vertical beam halo collimation system was installed in March 2016. In this paper we present the measurements done in March and May 2016 in order to characterize the collimation system performance. Furthermore, the collimator wakefield impact has also been measured and compared with theoretical calculations and numerical simulations in order to determine the most efficient operation mode of the collimation system in terms of halo cleaning and negligible wakefield impact. |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG40 | ||
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MOPG41 | A New Wall Current Monitor for the CERN Proton Synchrotron | impedance, vacuum, proton, synchrotron | 143 |
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Wall Current Monitors are the devices of choice to observe the instantaneous beam current in proton accelerators. These entirely passive transformers deliver a high-fidelity image of the beam intensity in a bandwidth spanning from about 100kHz up to several GHz. They serve as a signal source for a diverse set of applications including Low Level RF feedback and longitudinal diagnostics such as bunch shape measurements and phase-space tomography. They are appreciated for their excellent reliability, large bandwidth and unsurpassed dynamic range. We describe the design of a new Wall Current Monitor for the CERN Proton Synchrotron with a useful bandwidth of 100kHz to 4GHz. Two such devices have been installed in the PS machine and are now used in regular operation. Some usage examples will be shown. | |||
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Poster MOPG41 [1.728 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG41 | ||
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MOPG50 | Deflecting Cavity Dynamics for Time-Resolved Machine Studies of SXFEL User Facility | electron, FEL, cavity, diagnostics | 169 |
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Radio frequency deflectors are widely used for time-resolved beam energy, emittance and radiation profile measurements in modern free electron laser facilities. Here, we present the beam dynamics aspects of the deflecting cavity of SXFEL user facility. With a targeted time resolution around 10 fs, it is expected to be an important tool for time-resolved machine studies for SXFEL user facility. | |||
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Poster MOPG50 [1.676 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG50 | ||
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MOPG52 | Simulation of THz Streak Camera Performance for Femtosecond FEL Pulse Length Measurement | FEL, electron, photon, laser | 176 |
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Measurement of the temporal duration of FEL pulses is important both for the operators to monitor the performance of the machine and the users performing pump-probe measurements with FEL beam. The light-field streak camera is a promising methods for the photon pulse length measurement that uses the electric field of an IR/THz laser to streak the photoelectrons*. This contribution presents a simulation of the performance of a streak camera using a single-cycle THz pulse**. The simulation recreates the photoionization process and generates electron spectra in presence of the THz field and without it. Using these spectra the photon pulse lengths are calculated and compared to the initial values. Most of the parameters used in the simulation are chosen based on experiments performed earlier.*** This contribution presents the simulation method and the obtained results. It validates the pulse length calculation analysis method and estimates the expected measurement accuracy and precision for the THz streak camera measurement technique. The simulations were done for different FEL pulse lengths ranging from about 1 fs to 40 fs both in soft and hard X-ray range.
*J. Itatani et al, PRL 88,2002 *U. Fruhling et al, N. Phot. 3,2009 **I. Gorgisyan et al, JSR 3,2016 ***P. N. Juranic et al, Opt. Exp. 22,2014 ***P. N. Juranic et al, J. Inst. 9,2014 |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG52 | ||
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MOPG53 | Electron Beam Probe Diagnostic for BESSY II Storage Ring | electron, diagnostics, synchrotron, gun | 179 |
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A low energy electron beam can be used to characterize the high energy ultra-relativistic bunches. This technique allows one to obtain the bunch transverse profiles as well as the bunch length within a non-destructive single shot measurement. In this paper the bunch length measurement technique based on the interaction of the low energy electron beam with an ultra-relativistic bunch is described. Results of numerical simulations of measurements related to BESSY II are presented. A possible setup of such diagnostic system for BESSY II and in future for BESSY VSR is proposed. | |||
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Poster MOPG53 [0.868 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG53 | ||
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MOPG58 | Coherent Diffraction Radiation Imaging Methods to Measure RMS Bunch | electron, radiation, experiment, detector | 198 |
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The measurement of the RMS bunch length with high resolution is very important for latest generation light sources and also a key parameter for the optimization of the final beam quality in high gradient plasma accelerators. In this contribution we present progress in the development of novel single shot, RMS bunch length diagnostic techniques based on imaging the near and far fields of coherent THz diffraction radiation (CTHzDR) that is produced as a charged particle beam interacts with a solid foil or an aperture. Recent simulation results show that the profile of a THz image of the coherent point spread function (CSF) of a beam whose radius is less than the PSF, i.e. the image produced by a single electron, is sensitive to bunch length and can thus be used as a diagnostic. The advantages and disadvantages of near field and far field imaging are examined and the results of a recent high energy (20 GeV) CTHzDR experiments at SLAC/FACET are presented. Plans for experiments to further validate and compare these imaging methods for both moderate and high energy charged particle beams are also discussed. | |||
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Poster MOPG58 [1.067 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG58 | ||
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MOPG69 | Study of YAG Exposure Time for LEReC RF Diagnostic Beamline | electron, diagnostics, radiation, kicker | 233 |
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The LEReC RF diagnostic beamline is supposed to ac-cept 250 us long bunch trains of 1.6 MeV ' 2.6 MeV (kinetic energy) electrons. This beamline is equipped with a YAG profile monitor. Since we are interested in observ-ing only the last bunch in the train, one of the possibilities is to install a fast kicker and a dedicated dump upstream of the YAG screen and related diagnostic equipment. This approach is expensive and challenging from an engineer-ing point of view. Another possibility is to send the whole bunch train to the YAG screen and to use a fast gated camera to observe the image from the last bunch only. In this paper we demonstrate the feasibility of the last ap-proach, which significantly simplifies the overall design of the RF diagnostic beamline. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG69 | ||
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TUAL02 | A New Beam Loss Monitor Concept Based on Fast Neutron Detection and Very Low Photon Sensitivity | neutron, detector, photon, electron | 277 |
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Superconductive accelerators may emit X-rays and Gammas mainly due to high electric fields applied on the superconductive cavity surfaces. Indeed, electron emissions will generate photons when electrons impinge on some material. Their energies depend on electron energies, which can be strongly increased by the cavity radio frequency power when it is phase-correlated with the electrons. Such photons present a real problem for Beam Loss Monitor (BLM) systems since no discrimination can be made between cavity contributions and beam loss contributions. Therefore, a new BLM is proposed which is based on gaseous Micromegas detectors, highly sensitive to fast neutrons, not to thermal ones and mostly insensitive to X-rays and Gammas. This detector uses Polyethylene for neutron moderation and the detection is achieved using a 10B or 10B4C converter film with a Micromegas gaseous amplification. Simulations show that detection efficiencies > 8 % are achievable for neutrons with energies between 1 eV and 10 MeV. | |||
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Slides TUAL02 [1.248 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUAL02 | ||
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TUPG05 | Simulation of Bunch Length and Velocity Dependence of Button BPMs for Linacs Using CST Particle Studio® | pick-up, linac, wakefield, proton | 319 |
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At non-relativistic velocities at a proton LINAC, the electromagnetic field generated by the beam has a significant longitudinal component, and thus the time evolution of the signal coupled to the BPM electrodes depends on bunch length and beam velocity. Extensive simulations with the electromagnetic simulation tool CST Studio® were executed to investigate the dependence of the induced BPM signal on different bunch lengths and velocities. Related to the application, the simulations are executed for the button BPM arrangement as foreseen for the FAIR Proton LINAC. These investigations provide the required inputs for the BPM system and its related technical layout such as analogue bandwidth and signal processing electronics. For the BPM electronics, it is important to estimate the contribution of the harmonic used for the data processing. Additionally, the analogue bandwidth of the BPM system is determined from studying the output signal of the button BPM as a function of bunch length at different beam velocities. This contribution presents the results of the simulations and comments on general findings relevant for a BPM layout and the operation of a hadron LINAC. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG05 | ||
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TUPG07 | Commisioning of Beam Position and Phase Monitors for LIPAc | pick-up, coupling, vacuum, electronics | 326 |
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Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project AIC-A-2011-0654 and FIS2013-40860-R The LIPAc accelerator will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. Several types of Beam Position Monitors BPMs- are placed in each section of the accelerator to ensure a good beam transport and minimize beam losses. LIPAc is presently under installation and commissioning of the second acceleration stage at 5 MeV. In this stage two types of BPMs are used: four striplines to control the position at the Medium Energy Beam Transport line (MEBT), and three striplines to precisely measure the mean beam energy at the Diagnostics Plate. The seven pickups have been installed and assembled in the beamlines after characterization in a wire test bench, and are presently been commissioned in the facility. In addition, the in-house acquisition system has been fully developed and tested in the wire test bench at CIEMAT. In this contribution, the results of the beam position monitors characterization, the tests carried out during the assembly and the first measurements with the electronics system will be reported. |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG07 | ||
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TUPG08 | Design of the Transverse Feedback Kicker for ThomX | impedance, kicker, feedback, dipole | 329 |
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ThomX is a Compton source project in the range of the hard X rays to be installed in 2017. The machine is composed of an injector Linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a FabryPerot resonator. The final goal is to provide an X-rays average flux of 1011÷1013 ph/s. To achieve this target, it is required to install a transverse feedback system to suppress instabilities generated by injection position jitter sources, resistive wall impedance or collective effects. This paper describes the design and simulation studies of the stripline kicker that will be used for the transverse feedback system. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG08 | ||
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TUPG09 | Novel Electrostatic Beam Position Monitors With Enhanced Sensitivity | instrumentation, quadrupole, linac, monitoring | 333 |
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Beam Position Monitors (BPM) measure the beam transverse position, the beam phase with respect to the radiofrequency voltage, and give an indication on beam transverse shape. Electrostatic BPMs are composed of four electrodes that transduce the associated electromagnetic field to the beam into electrical signal allowing the calculation of the beam parameters mentioned above. During commissioning and/or experiences phases that needs very low beam current; the precision of the BPM measurements is reduced due to the low sensitivity of electrostatic BPM to beam current. This paper addresses the design, the realization and the testing of a new set of electrostatic BPMs with large electrodes. It emphasizes the strong points of these BPMs in comparison with BPMs present in SPIRAL2 facility | |||
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Poster TUPG09 [0.770 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG09 | ||
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TUPG18 | Design Optimization of Button-Type BPM Electrode for the SPring-8 Upgrade | resonance, impedance, storage-ring, vacuum | 360 |
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The requirements for a BPM system for the SPring-8 upgrade are long-term stability, sufficient signal intensity and high accuracy*. The design of a button-type electrode for the BPM has been optimized from the perspectives of 1) mechanical structure, 2) rf characteristics, 3) thermal issue. We have adopted the electrode structure without a sleeve enclosing the button to maximize the button diameter for the narrow aperture of the vacuum chamber. The absence of an annular slot around the sleeve in a lodging hole for the electrode eliminates the associated beam impedance. To minimize the beam impedance and the trapped mode heating of the electrode, the rf structure has been optimized by 3D electro-magnetic simulations. To suppress the ohmic loss on the button and center pin thermally isolated from the water cooled BPM block, we have selected molybdenum as a material with high electric and thermal conductivities. The reduction of the heating suppresses thermal deformation of the electrode and the BPM block, and improves thermal stability of the BPM system. The mechanical tolerance of the electrode was defined to fit the error budget for the total BPM offset error of 0.1 mm rms.
* H. Maesaka et al., in this conference. |
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Poster TUPG18 [1.104 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG18 | ||
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TUPG22 | Timing Window and Optimization for Position Resolution and Energy Calibration of Scintillation Detector | detector, timing, radiation, photon | 372 |
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The real event selection, timing resolution, position resolution and energy response of the EJ-200 plastic scintillation detector have been analyzed using timing window coincidence measurement. The detector was simulated based on Monte Carlo, including its geometry, energy deposition, photon collection and signal generation. The detection efficiency and the real events selection have been obtained while the background noise has been reduced by using two-end readout timing window coincidence. We developed an off-line analysis code, which is suitable for massive data from the digitizer. We set different coincidence timing windows, and did the off-line data processing respectively. We find the detection efficiency increases as the width of the timing window increases, and when the width of timing window is more than 10ns, the detection efficiency will slowly grow until it reaches saturation. Time, position and energy response have been measured by exposing to radioactive sources. The best timing window parameter as 16ns is obtained for on-line coincidence measurement, and the position resolution is up to 12cm. Energy response of the detector was linear within the experimental energy range*.
* L. Karsch, A. Bohm et al,"Design and Test of A Large-area Scintillation Detector for Fast Neutrons", Nuclear Instruments and Methods in Physics Research A, vol.460, pp.362-367, 2001. |
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Poster TUPG22 [5.665 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG22 | ||
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TUPG30 | Testing the Untestable: A Realistic Vision of Fearlessly Testing (Almost) Every Single Accelerator Component Without Beam and Continuous Deployment Thereof | hardware, software, operation, luminosity | 399 |
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Whenever a bug of some piece of software or hardware stops beam operation, loss of time is rarely negligible and the cost (either in lost luminosity or real financial one) might be significant. Optimization of the accelerator availability is a strong motivation to avoid such kind of issues. Still, even at large accelerator labs like CERN, release cycles of many accelerator components are managed in a "deploy and pray" manner. In this paper we will give a short general overview on testing strategies used commonly in software development projects and illustrate their application on accelerator components, both hardware and software. Finally, several examples of CERN systems will be shown on which these techniques were or will be applied (LHC Beam-Based Feedbacks and LHC Luminosity Server) and describe why it is worth doing so. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG30 | ||
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TUPG49 | Review of Chromaticity Measurement Approaches Using Head-Tail Phase Shift Method at RHIC | synchrotron, betatron, emittance, operation | 457 |
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Funding: Work supported the URA., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy We review tests of the head-tail phase shift method using various approaches at BNL's RHIC. Both the standard and some more exotic approaches to measure the phase differential between the head and tail of a bunched beam has been attempted at RHIC. The standard kick beam and measured phase evolution of the head and tail of a given bunch has been tried at RHIC. Additionally a more exotic approach to measure the head versus tail phase difference has been tried. In this approach we used a BBQ pickup and kicker with the input stripline signal to the BBQ mixed with a nano second pulse timed to the head and tail of the bunch. In this way we hoped to force the BBQ to sample the head or tail of the bunch depending on the pulse timing. We report on the results and challenges which each approach presented. |
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Poster TUPG49 [0.957 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG49 | ||
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TUPG56 | Design of a Time-resolved Electron Diagnostics Using THz Fields Excited in a Split Ring Resonator at FLUTE | electron, diagnostics, laser, gun | 475 |
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Time-resolved electron diagnostics with ultra-high temporal resolution is increasingly required by the state-of-the-art accelerators. Strong terahertz (THz) fields, excited in a split ring resonator (SRR), have been recently proposed to streak electron bunches for their temporal characterisation. Thanks to the high amplitude and frequency of the THz field, temporal resolution down to the sub-femtosecond range can be expected. We are planning a proof-of-principle experiment of the SRR time-resolved diagnostics at the accelerator test-facility FLUTE (Ferninfrarot Linac und Test Experiment) at the Karlsruhe Institute of Technology. The design of the experimental chamber has been finished and integrated into the design layout of the FLUTE accelerator. Beam dynamics simulations have been conducted to investigate and optimise the performance of the SRR diagnostics. In this paper, we present the design layout of the experimental setup and discuss the simulation results for the optimised parameters of the accelerator and the SRR structure. | |||
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Poster TUPG56 [6.961 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG56 | ||
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TUPG71 | Ionization Profile Monitor Simulations - Status and Future Plans | electron, ion, detector, space-charge | 520 |
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Nonuniformities of the extraction fields, the velocity distribution of electrons from ionization processes and strong bunch fields are just a few of the effects affecting Ionization Profile Monitor measurements and operation. Careful analysis of these phenomena require specialized simulation programs. A handful of such codes has been written independently by various researchers over the recent years, showing an important demand for this type of study. In this paper we describe the available codes and discuss various approaches to Ionization Profile Monitor simulations. We propose benchmark conditions to compare these codes between themselves and we collect data from various devices to benchmark codes against the measurements. Finally we present a community effort with a goal to discuss the codes, exchange simulation results and to develop and maintain a new, common codebase. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG71 | ||
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TUPG75 | Thermal Simulations for Optical Transition Radiation Screen for ELI-NP Compton Gamma Source | target, radiation, electron, linac | 536 |
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The Gamma Beam Source (ELI-GBS) is a high brightness electron LINAC that is being built at the ELI Nuclear Physics (ELI-NP) facility in Romania. The ELI-GBS aims to produce high quality gamma beam through Compton Backscattering. A train of 32 bunches at 100Hz with a nominal charge of 250pC is accelerated up to 740 MeV. Two interaction points with an IR Laser beam produces the gamma beam at two different energies. In order to measure the electron beam spot size and the beam properties, the LINAC is equipped with several optical transition radiation (OTR) profile monitors. Those OTR screens must sustain the thermal and mechanical stress due to the energy deposited by the bunches. We present a numerical (ANSYS) study of the thermo-mechanical issues due to beam energy deposition in the screens; our analysis will cover both the steady state and transient regime. | |||
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Poster TUPG75 [41.161 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG75 | ||
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TUPG81 | Space Charge Studies for the Ionisation Profile Monitors for the ESS Cold Linac | proton, space-charge, electron, linac | 555 |
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In this paper, we present the results from a numerical code developed to study the effect of space charge on the performance of Ionisation Profile Monitors. The code has been developed from the analytical expression of the electromagnetic field generated by a 3D bunch of charged particles moving along one axis. This transient field is evaluated to calculate the momentum gained by a test moving particle, but not necessary co-moving with the bunch, and included in a non-linear ordinary differential equation solver (Runge-Kutta) to track the 3D motion of the test particle. The model of the IPM is complete when an additional constant electric field is included to project the test particle onto a screen. The results from this code, modelling the IPM to be developed for the ESS Cold Linac, are presented here, and the impact of the space charge on the measurement of the beam profile is discussed. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG81 | ||
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WEAL01 | Longitudinal Diagnostics Methods and Limits for Hadron Linacs | linac, cavity, diagnostics, space-charge | 563 |
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Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The United States Govern-ment retains and the publisher, A summary of the longitudinal diagnostics for linacs is presented based on the Spallation Neutron Source (SNS) linac example. It includes acceptance phase scans, Bunch Shape Monitors (BSM), and a method based on the analysis of the stripline Beam Position Monitors (BPM) signals. The last method can deliver the longitudinal Twiss parameters of the beam. The accuracy, applicability, and limitations of this method are presented and discussed. |
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Slides WEAL01 [2.256 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEAL01 | ||
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WEBL03 | Beam Shape Reconstruction Using Synchrotron Radiation Interferometry | radiation, synchrotron, synchrotron-radiation, coupling | 589 |
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Synchrotron Radiation Interferometry (SRI) through a double-aperture system is a well known technique to measure the transverse beam size using visible light. In many machines the beam is tilted in the transverse plane, but the SRI technique only allows to directly measure the size of the projection of the beam shape along the axis connecting the two apertures. A method to fully reconstruct the beam in the transverse plane using SRI has been developed and successfully tested at the ALBA synchrotron light source. This report shows the full beam reconstruction technique and presents the results at ALBA. Moreover, we also discuss how this technique could improve the measurement of very small beam sizes, improving the resolution of standard SRI. | |||
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Slides WEBL03 [20.443 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEBL03 | ||
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WEPG01 | Numerical Comparative Study of BPM Designs for the HESR at FAIR | pick-up, emittance, monitoring, software | 608 |
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The institute of Nuclear Physics 4(IKP-4) of the Research Center Jülich (FZJ) is in charge of building and commissioning the High Energy Storage Ring (HESR) within the international Facility for Antiproton and Ion Research (FAIR) at Darmstadt. Simulations and numerical calculations were performed to characterize the BPM pickup design that is currently envisaged for the HESR, i.e. a diagonally cut cylindrical pickup. The equivalent circuit has been studied with emphasis on capacitive cross coupling. Based on our findings, performance increasing changes could be introduced. A prototype BPM was constructed and tested on a test bench. A comparison of results is presented. Another proposed design was characterized, as a symmetric coupling behavior is expected. That is a symmetrical straight four-strip geometry. Additionally an extensive study was conducted to see effects due to manufacturing tolerances. Driven by curiosity an eight-strip design was considered, which would allow for beam size measurements. First results for this configuration are shown. Used methodology, tools and results of expected signal level and sensitivity distributions are presented as well. | |||
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Poster WEPG01 [2.172 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG01 | ||
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WEPG05 | Design of Stripline Beam Position Monitors for the ESS MEBT | impedance, electronics, quadrupole, coupling | 620 |
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There will be overall 8 Beam Position Monitors (BPM) installed in MEBT of ESS. Seven of them will be used for the measurement of beam position, phase and intensity. One BPM will be used for the fast timing characterization of the chopped beam. The design is based on shortened stripline to accommodate the signal level for low velocity proton beam within MEBT read by electronics. Due to mechanical space limits, all the BPMs are embedded inside quadrupoles; which requires special care on the magnetic properties of the materials within BPM sets and in particular the feedthroughs. The prototype electromagnetic and mechanical design is finished and its fabrication is underway. This paper gives an overview of the electromagnetic and mechanical design and related analysis including position signal sensitivity of the BPMs. | |||
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Poster WEPG05 [1.107 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG05 | ||
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WEPG35 | Design of an Electron Cloud Detector in a Quadrupole Magnet at CesrTA | detector, electron, quadrupole, vacuum | 704 |
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Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. We have designed a detector that measures the electron cloud density in a quadrupole magnet using two independent techniques. Stripline electrodes collect electrons that would otherwise impact the beam-pipe surface. The striplines are placed behind an array of small holes in the beam-pipe wall in order to shield them from the beam-induced electromagnetic pulse. There are three striplines placed near one of the pole tips so that they cover a roughly 0.43 radian azimuth. The beam-pipe chamber has also been designed so that microwave measurements of the electron cloud density can be performed. Beam position monitor buttons have been included for excitation and reception of microwaves and the chamber has been designed so that the resonant microwaves are confined to be within the 56 cm length of the quadrupole field. This paper provides some details of the design including CST Microwave Studio time domain simulation of the stripline detectors and eigenmode simulation of the resonant chamber. The detector is installed in the Cornell Electron Storage Ring and is part of the test accelerator program for the study of electron cloud using electron and positron beams from 2 to 5 GeV. |
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Poster WEPG35 [2.166 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG35 | ||
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WEPG40 | Optimization Studies for an Advanced Cryogenic Current Comparator (CCC) System for FAIR | cryogenics, shielding, pick-up, synchrotron | 715 |
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Funding: The work is supported by BMBF (Contract number: 05P15SJRBA) After successful tests with the GSI-CCC prototype, measuring beam intensities down to 2nA at a bandwidth of 10 kHz, a new advanced Cryogenic Current Comparator system with extended geometry (CCC-XD) is under development. This system will be installed in the upcoming Cryring facility for further optimization, beam diagnostics and as an additional instrument for physics experiments. After the test phase in Cryring it is foreseen to build four additional CCC units for FAIR, where they will be installed in the HEBT lines and in the Collector Ring (CR). A universal cryostat has been designed to cope with the various boundary conditions at FAIR and at the same time to allow for uncomplicated access to the inner components. To realize this compact cryostat, the size of the superconducting magnetic shielding has to be minimized as well, without affecting its field attenuation properties. Hence detailed FEM simulations were performed to optimize the attenuation factor by variation of geometrical parameters of the shield. The beam tests results with the GSI-CCC prototype, and the developments for FAIR, as well as the results of simulation for magnetic shield optimization will be presented. |
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DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG40 | ||
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WEPG41 | Measurement of Coupling Impedances using a Goubau Line | impedance, resonance, coupling, scattering | 719 |
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Longitudinal coupling impedances can be deduced from S-Parameter measurements performed on a Goubau Line. The Goubau Line, also known as single wire line, is a variant of the coaxial wire method. Both setups use a wire for mimicking the particle beam. Coaxial tapers at the wire ends adapt wave impedance to the 50ohm impedance of coaxial cables, sources and receivers. But for guiding the electromagnetic wave, the Goubau Line relies on the realistic boundary conditions imposed by an insulated wire instead of using a coaxial shield. Equations for the deduction of longitudinal coupling impedances are reviewed and applied to Goubau Line measurements. Goubau Line measurements and CST Studio simulations are compared, showing good agreement. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG41 | ||
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WEPG47 | Progress on the PITZ TDS | emittance, electron, laser, space-charge | 744 |
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A transverse deflecting system (TDS) is under commissioning at the Photo Injector Test Facility at DESY, Zeuthen site (PITZ). The structure was designed and manufactured by the Institute for Nuclear Research (INR RAS, Moscow, Russia) as prototype for the TDS in the injector part of the European XFEL. Last year the deflection voltage was limited for safety reasons, but after thorough investigations of the waveguide system we are now able to operate the cavity close to design specifications. The PITZ TDS streaks the electron beam vertically, allowing measurements of the longitudinal bunch profile, and, in combination with a subsequent horizontal bending magnet, also of the longitudinal phase space and slice energy spread. Furthermore, several quadrupole magnets and screen stations can be employed for slice emittance measurements using the TDS. This paper describes the progress in commissioning of the hardware, measurement techniques and simulations, and outlines the prospects of reliable slice emittance measurements at 20 MeV/c, where space charge forces complicate the determination of transfer matrices. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG47 | ||
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WEPG50 | Non-Invasive Bunch Length Diagnostics of Sub-Picosecond Beams | detector, pick-up, vacuum, real-time | 756 |
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Funding: This work was partially supported by the Russian Scientific Foundation (grant #16-19-10448). We propose a non-invasive bunch length measurement system based on RF pickup interferometry. A device performs interferometry between two broadband wake signals generated by a single short particle bunch. The mentioned wakes are excited by two consequent small gaps in beam channel. A field pattern formed by interference of the mentioned two coherent wake signals is registered by means of detector arrays placed at outer side of beam channel. The detectors are assumed to be low-cost integrating detectors (pyro-detectors or bolometers) so that integration time is assumed to be much bigger than bunch length. Because RF signals come from gaps to any detector with different time delays which depend on particular detector coordinate, the array allows to substitute measurements in time by measurements in space. Simulations with a 1 ps beam and a set of two 200 micron wide vacuum breaks separated by 0.5 mm were done using CST Particle Studio. These simulations show good accuracy. Moreover, one can recover the detailed temporal structure of the measured pulse using a new developed synthesis procedure. |
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Poster WEPG50 [2.780 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG50 | ||
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WEPG59 | Thermal Simulations of Wire Profile Monitors in ISIS Extracted Proton Beamline 1 | proton, neutron, target, electron | 785 |
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Wire scanners and secondary emission (SEM) grids are used for measurements of transverse beam profile at the ISIS neutron and muon source. Silicon carbide-coated carbon fibre wires are used in profile monitors throughout the ISIS accelerator. One such SEM grid is currently installed close to the target in EPB2 and is intercepted by the 800 MeV proton beam at a repetition rate of 10 Hz. Future profile measurements will require another of these monitors to be installed close to the target in EPB1; intercepted with a repetition rate of 40 Hz. Wires intercepting the ion beam are heated due to the deposition of beam-energy. Thermal simulations for the higher repetition rate were performed using ANSYS and a numerical code. The numerical code was then expanded to include various beam, wire and material properties. Assumptions for temperature dependent material emissivities and heat capacities were included in the simulation. Estimated temperatures due to the energy deposited by protons, and approximate values of deposited energy from the expected neutron flux are presented. The effects on wire-temperature of various beam and wire parameters are also discussed. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG59 | ||
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WEPG68 | An Investigation into the Behaviour of Residual Gas Ionisation Profile Monitors in the ISIS Extracted Beamline | ion, detector, synchrotron, proton | 807 |
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Non-destructive beam profile measurements at the ISIS neutron source are performed using Multi-Channel Profile Monitors (MCPMs). These use residual gas ionisation within the beam pipe, with the ions being guided to an array of 40 Channeltron electron multipliers by a high voltage drift field. Non-uniform transverse electric fields within these monitors are caused by the drift field and the beam's space charge. Longitudinally, a saddle point located between the drift field plate and the opposing compensating field plate introduces extra complexity into the ion motion. To allow for detailed studies of this behaviour, an MCPM has been placed in Extracted Proton Beamline 1 (EPB1) where the beam is well defined. Simulations of the profiles obtained by this monitor are performed using machine measurements, CST EM Studio and a simple C++ particle tracking code. This paper describes the process used to simulate MCPM profiles along with a comparison of simulated and measured results. Trajectories of detected ions from their creation to the Channeltrons are discussed, together with a study of Channeltron detection characteristics carried out in the ISIS diagnostics laboratory vacuum tank. | |||
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Poster WEPG68 [2.703 MB] | ||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG68 | ||
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WEPG69 | Profile Measurement by the Ionization Profile Monitor with 0.2T Magnet System in J-PARC MR | electron, ion, detector, injection | 811 |
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A nondestructive Ionization Profile Monitor (IPM) is widely used to measure transversal profile. At J-PARC Main Ring (MR), three IPM systems have been used not only to measure emittances but also to correct injection miss matchings. To measure injection 3GeV beam profiles, the high external E field of +50kV/130mm at the maximum is used to guide ionized positive ions to a position sensitive detector; transversal kick force originating from space charge E field of circulating beam is a main error source which deteriorates profile. The strong B field is also used to compensate the kick force. To measure 30GeV bunched beam at the flat top on the fast extraction mode in good resolution, the strong B field of about 0.2T is needed. One set of magnet system, which consists of a C-type and two H-type magnets, were developed and installed in one IPM system. The IPM chamber was inserted between the 2 poles of the C-type magnet. To make the line integral of B field along the beam axis zero, the H-type magnets have the opposite field polarity to that of the C-type magnet and were installed on both sides of the C-type magnet. Details of the magnet system and its first trials will be presented. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG69 | ||
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WEPG78 | BPM Based Optics Correction of the Solaris 1.5 GeV Storage Ring | storage-ring, closed-orbit, alignment, optics | 836 |
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The Solaris is a novel approach for the third generation synchrotron light sources. The machine consists of 600 MeV linear injector and 1.5 GeV storage ring based on 12 compact Double Bend Achromat (DBA) magnets designed in MAX-IV Laboratory in Sweden. After the commissioning phase of the Solaris storage ring the optimization phase has been started along with the commissioning of the first beamline. An essential part of the beam diagnostics and instrumentation system in the storage ring are Beam Position Monitors (BPMs) based on 36 quarter-wave button BPMs spread along the ring. Proper calibration allowed to measure and correct several beam parameters like closed orbit, tune, chromaticity, dispersion and orbit response matrix. The results of the latest machine optimization including the orbit correction, beam-based alignment and BPM phase advance will be presented. | |||
DOI • | reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG78 | ||
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