CERN, Geneva
The diamond beam monitor is a solid-state ionization chamber that stands out due to its fast and efficient charge collection and its high radiation tolerance. The diamond technology gives a charge collection time of less than 1 ns and lifetime studies made at CERN with 24 GeV protons showed a decrease in performance of only 50% at 10 MGy, which make this device particularly well adapted to applications in particle accelerators. A poly-crystalline CVD diamond beam monitor has been evaluated as a beam halo loss monitor for the CERN LHC accelerator. Despite the read-out being made through 250 m of cable, the tests showed a good signal-to-noise ratio of 6.8, an excellent double-pulse resolution of less than 5 ns and a high dynamic range basically unlimited except by the electronics. A single-crystalline CVD diamond beam monitor was built and tested in cooperation with Bergoz Instrumentation for ISOLDE at CERN for the HIE-REX upgrade. This device was used to measure the beam intensity for particle counting and for measuring the beam energy spectrum. An energy resolution of 0.6% and a time resolution of 39 ps were measured for a carbon ion energy of 22.8 MeV.
BNL, Upton, Long Island, New York
A residual gas x-ray beam position monitor (RGXBPM) was developed for PETRA-III storage ring. This type of x-ray beam position monitors (XBMP) tend to overcome some deficiencies of the blade type XBPMs, which are currently employed at the third generation synchrotron facilities as "white" undulator beam XBPMs. While blade XBPMs provide micron-accuracy resolution, the signal depends on the undulator gap and is also affected by stray radiation from bending magnets and focusing optics. The residual gas XBPM detects position of the centre of gravity of the undulator radiation; it has no elements that are hit by the x-ray beam, and complies with the windowless concept of the PETRA-III beamlines. Residual gas beam profile monitors were first developed to provide beam profile measurements at charged particles accelerators. The spatial resolution of RGXBPM was substantially improved in order to comply with the requirements at the PETRA III storage ring. Due to limited space, a thorough electrostatic optimization of RGXBPM was needed to achieve required electrical field quality. Test results obtained at the ESRF and commissioning of the RGXBPMs at PETRA-III will be reported.
UniDo/IBS, Dortmund
iThemba LABS, Somerset West
FZJ, Jülich
DELTA, Dortmund
The interaction of an ion beam with the residual gas might lead to a photon emission of the excited residual gas molecule. These photons can be used to monitor the beam profile. Therefore a multichannel photomultiplier is used together with an optical system. Measurements at the COSY synchrotron are presented. The usability of the method is discussed by comparing to measurements at the iThemba Labs beam line and the JESSICA experiment, a spallation source prearrangement at COSY.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Royal Holloway, University of London, Surrey
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The front end test stand FETS is an R&D project hosted at Rutherford Appleton Laboratory RAL with its aim to demonstrate a high power, fast chopped H- ion beam and will consist in final stage of ion source, low energy beam transport LEBT, RFQ and a transport line including a chopper system at 3MeV output energy. Possible candidates of applications are Isis upgrade (RAL neutron source), future spallation sources or the Neutrino factory. The high beam power may cause problems due to its thermal power deposition on diagnostics parts introduced into the beam so non-interceptive beam instruments are highly preferred to avoid those problems. Diagnostics for H- beams can benefit of laser light where photons with suitable energy are able to detach the additional electron. This method is applied to a beam profile monitor close to the ion source of the FETS beam line and the paper gives a status report of the ongoing process of commissioning and provides a detailed discussion of problems and recent changes including first "proof-of-principle" measurements.
BNL, Upton, Long Island, New York
Four ionization profile monitors (IPMs) in RHIC measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. In 2007 a prototype of a new design was installed in the yellow ring. During the 2007-2008 run it proved to be almost completely free from backgrounds from rf coupling, electron clouds and x-rays from upstream beam loss. In 2009 two more IPMs of this new design were installed and in the 2010 shutdown we will complete installation of four identical IPMs. This paper describes the new IPMs and shows data from the 2010 beam run. The new IPMs have been extremely important in the commissioning of the RHIC stochastic cooling system.
BNL, Upton, Long Island, New York
A beam profile and energy monitor for H- beams which measures electrons stripped from the beam by a laser has been installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. Also electrons are stripped by the residual gas at a rate of ~1.5 x 10-8/cm at 1 x 10-7torr. Beam electrons have the same velocity as the beam and so have an energy of 1/1836 of the beam protons. There is a chamber in which the laser light passes through the ion beam followed by a dipole magnet which deflects the electrons by 90° through a biased retarding grid (V<125kV) into a Faraday cup detector. To measure beam profiles, a narrow laser beam is stepped across the ion beam removing electrons from the portion of the H- beam intercepted by the laser. To measure the energy spectrum of the electrons, we use either the gas-stripped or laser-stripped signal. The total current is measured as the voltage on the grid is raised in small steps. We deduce the energy spread of the H- beam by deconvolving the electron spectrum into components from beam energy and from space-charge fields.
GSI, Darmstadt
Technical University Darmstadt, Darmstadt
TU Darmstadt, Darmstadt
Scintillating screens are widely used for transverse beam profile monitoring and pepper-pot emittance measuring instruments at accelerator facilities. For high current beam operations at the GSI heavy ion UNILAC, several inorganic scintillators were investigated under different ion beam conditions in the energy range from 4.8 to 11.4 MeV/u and currents up to some mA. The imaging properties of various scintillating screens were studied with respect to light yield and imaged beam width, i.e. important parameters for precise beam profile measurements. The measured light yield and beam width show a strong dependence on the scintillating material and change significantly with screen temperature. The spectral response of the materials was mapped for different temperature levels, using a spectrometer in the visible and near UV range. The results clearly demonstrate that the scintillating properties of the materials, and their temperature, are critical issues for high current operations and have to be taken into account for correct beam profile reading.
GSI, Darmstadt
LBNL, Berkeley, California
TU Darmstadt, Darmstadt
As conventional intercepting diagnostics will not withstand high intensity ion beams, Beam Induced Fluorescence (BIF) profile monitors constitute a preeminent alternative for non-intercepting profile measurements. This diagnostic technique makes use of optical emission of beam-excited gases. Recently BIF became an important diagnostic technique for beam profile measurement with applicability in beam tuning over a wide range of beams and accelerator conditions. Beam induced fluorescence spectra in the range of 300 - 800 nm were recorded with an imaging spectrograph for 5 MeV/u proton, S(6+) and Ta(24+) beams in nitrogen, Xe, Kr, Ar, Ne and He at 10-3 mbar gas pressure. Optical transitions were identified and associated with corresponding beam profiles. Effective light yields, normalized to the differential energy loss, are presented for all gas-species investigated. Since residual gas ionization is the basic process for BIF-monitors as well as for Ionization Profile Monitors (IPM), BIF-results are compared to IPM measurement data.
DESY, Hamburg
To control the beam position at the entrance of the FLASH dump a position monitor is required outside of the vacuum. When a charged particle travels through a gas it will ionize the atoms. Therefore the signal from a capacitive button monitor is caused not only by the electric field of the beam but also by the ionized atoms which add high background to the usable signal. To avoid the ionization signal a magnetic coupled monitor is designed. The monitor consists of four longitudinal loops symmetrically arranged at the tube wall. An analytical expression of the signal for this monitor is derived and compared with simulation. Raw data are compared with the expectation.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
For beam profile monitoring applications where low beam perturbation together with bi-dimensional imaging is required, ionization monitors based on neutral gas-jet targets shaped into a thin curtain are an interesting option. When integrated in ultra-high vacuum systems, such as in the Ultra-low energy Storage Ring (USR), where local vacuum preservation is of primary concern, such systems present severe difficulties linked to the creation and proper shaping of a high quality gas-jet curtain. In this contribution, investigations into the generation and evolution of the jet with the Gas Dynamics Tool (GDT) software and purpose-written C++ analysis modules are presented. By means of extensive numerical analysis, the advantages of a novel nozzle-skimmer system in terms of curtain quality are summarized as compared to traditional axisymmetric gas-jet creation and curtain shaping by means of scrapers. It is also shown that variable nozzle-skimmer geometries allow for modifying the gas-jet characteristics in a wide range, including jet splitting and local density modulation. Finally, the layout of a test stand that will be used for an experimental benchmark of these studies is shown.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
For destructive beam intensity measurements, electrostatic Faraday cups will be incorporated into the Ultra-low energy Storage Ring (USR) and its transfer lines at the Facility for Low-energy Antiproton and Ion Research (FLAIR). This multipurpose machine will offer both slow and fast extracted beams resulting in a wide range of intensities and varying time structure of the beam. In this contribution we present the particular challenges of measuring the beam intensity in the USR, results from numerical optimization studies, as well as the design of the cup.
LBNL, Berkeley, California
LLNL, Livermore, California
The versatility of the beams that ECR ion sources can provide make them the injector of choice for many heavy ion accelerators. However, the design of the LEBT* systems for these devices is challenging because the LEBT has to be matched for a wide variety of ions. In addition, due to the magnetic confinement fields, the ion density distribution across the extraction aperture is inhomogeneous and charge state dependent, and the ion beam is extracted from a region of high axial magnetic field, which adds a rotational component to the beam. In this presentation a simulation model for ECR ion source beams is described. The initial conditions (i.e., spatial and velocity distribution of the ions prior to extraction from the ion source) are obtained semi-empirically. Extraction from the plasma is then simulated with the particle-in-cell code WARP. The same code is used for the actual simulation of ion transport through the beam line. Simulations of a beam containing uranium ions of charge state 18+ to 42+, as well as other ions due to the use of support gases, extracted from VENUS**, are presented and compared to emittance measurements.
IAP, Frankfurt am Main
In beam diagnostics optical techniques had become increasingly important as they provide information with the advantage to have only minimal effect on the beam. The planned Frankfurt Neutron Source will consist of a proton driver LINAC providing beam energies up to 2.0 MeV. The rotatable diagnosis tank hybrid ion beam tomography tank HIBTT will be placed at the end of the low energy beam transport section (LEBT) to provide beam tomography based on the visible radiation of the ion beam in front of the RFQ. The beam energy in this section will be 120keV and the current 200 mA. Additional to the CCD camera that takes optical data for the tomography, other non-interceptive devices could be used to gain additional information. The question behind this hybrid approach on non invasive beam diagnostics is: which and how much information can be extracted from an ion beam without disturbing or destroying it. The actual contribution deals with the information of profile width in beam profile measurements. The presentation introduces a definition and an information sensitive method for profile width determination and verifies them using experimental and numerical data.
HIT, Heidelberg
GSI, Darmstadt
The transverse emittance of the ion beam at the Heidelberg Ion Therapy Center (HIT) will be measured within the Low Energy Beam Transport (LEBT) using a pepper-pot measurement system. At HIT, two ECR sources produce ions (H, He, C and O) at an energy of 8keV/u with different beam currents from about 80 μA to 2mA. The functionality and components of the pepper-pot device is reviewed as well as the final design and the choice of the scintillator. For that, results from recent beam test at the Max Planck Institute für Kernphysik at Heidelberg are presented. The material investigation was focused on inorganic doped crystal, inorganic undoped crystal, borosilicate glass and quartz glass with the following characteristics: availability, prior use in beam diagnostics, radiation hardness, fast response, spectral matching to CCD detectors.
LBNL, Berkeley, California
University of Applied Sciences Karlsruhe, Karlsruhe
Two ECR* ion sources are currently available to inject beams into the 88-Inch Cyclotron at LBNL.** The recently commissioned pepper-pot emittance scanner at LBNL was used to measure the beam emittance for various ion species of both sources. A pepper-pot scanner is capable of extracting the full four-dimensional transverse phase space of the beam, allowing for the calculation of the cross coupled emittances xy' and yx'. This is especially of interest for ECR ion sources where asymmetric beams are extracted in the presence of a strong solenoid field. The axial field adds a rotational momentum to the extracted beam, resulting in a transverse emittance growth, which depends on the magnetic stiffness of the extracted species. In this paper, the pepper-pot setup is described and emittance data from both LBNL ECR sources are presented and compared. The data confirm a strong mass dependence of the normalized emittance for ions with the same mass to charge state ratio as previously also measured by other groups. This dependence indicates a different particle distribution at the extraction aperture for different ion species.
GSI, Darmstadt
To avoid beam losses of intense beams stored at the GSI heavy ion synchrotron SIS-18 a precise tune measurement during a whole acceleration cycle is required. This contribution presents a sensitive method of tune determination using data of Beam Position Monitor (BPM) measured in bunch-by-bunch manner. The signals induced in the BPM electrodes were digitized by 125 MS/s and integrated for each individual bunch. The tune was determined by Fourier transformation of the position data for typically 512 subsequent turns. Coherent betatron oscillations were excited with bandwidth-limited white noise. The presented method allows for tune measurements with satisfactory signal-to-noise ratio already at relatively low beam excitation i.e. without a significant increase of transverse beam emittance. In parallel the evolution of transverse beam emittance was monitored by means of Ionization Profile Monitor. The system for online tune measurement is an integral part of the new digital BPM System, presently under commissioning.
Fermilab, Batavia
The Fermi National Accelerator Laboratory (FNAL) High Intensity Neutrino Sources (HINS) is a research project to address accelerator physics and technology questions for a new concept, low-energy, high-intensity long pulse H- superconducting linac. HINS will consist of a 50 keV ion source, a 2.5 MeV Radiofrequency Quadrupole (RFQ), and a 10 MeV room temperature spoke resonator acceleration section followed by superconducting spoke resonator acceleration sections. At this time a proton ion source and the RFQ module have operated with beam. This paper will present the results of first beam measurements through the HINS RFQ.
GSI, Darmstadt
TUD, Darmstadt
In this paper, a method for measuring the absolute signal delays of active optical transmission lines will be presented. This measurement method is an essential part of the timing system for FAIR (Facility for Antiproton and Ion Research). To prevent interference of the timing signals whose delays are to be measured with the measurement signal sequence, the latter is transmitted on a separate optical carrier in the same fibre. By using a wavelength selective mirror at the end of the transmission line, the optical measurement signals are reflected and lead back to the measurement unit. The measurement sequence consists of a number of sinusoidal signals with different frequencies that are modulated one by one on the optical carrier. For each frequency a phase comparison of the outgoing and returning signal is performed. In the last step, the absolute delay is calculated from the obtained phase values by using an algorithm. It will be shown that this method enables cost efficient delay measurements with an accuracy of better than 100 fs.
LBNL, Berkeley, California
Laboratory high energy density experiments using ion beam drivers rely upon the delivery of high-current, high-brightness ion beams with high peak intensity onto planar targets. Solid-state optical scintillators are typically used to measure the ion beam spatial profile but they display dose-dependent degradation and aging effects. These effects produce uncertainties and limit the accuracy of measuring peak beam intensities delivered to the target. For beam tuning and benchmarking the incident beam intensity, we have developed a cross-calibrating diagnostic suite that both places a lower limit on intensity and extends the upper limit of measurable peak intensity dynamic range. Absolute intensity calibration is obtained with a 3 um thick tungsten foil calorimeter. We present experimental evidence for peak intensity measures in excess of 200 kW/cm2 using a 300 kV, 25 mA, 5-20 usec K+ beam driver. Radiative models and thermal diffusion effects are discussed as they affect temporal and spatial resolution of beam intensity profiles.
Fermilab, Batavia
A linear accelerator test facility called HINS has been operating at Fermilab. The goal of this program is to test new technology for the front end of an intensity frontier linac. Some of the new technologies that will be tested include: operation of multiple cavities from a single RF source using high-power vector modulators, round beam transport using superconducting solenoidal focusing, accelerating beam with spoke cavities, and a transition to superconducting RF cavities at 10 MeV. The testing has been split into four different stages: 2.5 MeV beam out of the RFQ only, acceleration through 6 room temperature cavities with quadrupole focusing, acceleration through 18 room temperature cavities with solenoidal focusing, and acceleration through the room temperature section plus one cryomodule of superconducting spoke cavities. Each stage focuses on testing the beam quality with a particular new technology. This paper describes the instrumentation necessary to verify the specified beam quality for each stage of the program.
BNL, Upton, Long Island, New York
A diffraction-limited storage ring like NSLS2 sets more stringent beam stability requirements. Due to resistive wall impedance and fast-ion effect, transverse instabilities will happen at low current (~15 mA). An active transverse feedback system has been designed to cure the betatron oscillations. The system will have a <200 us damping rate at 50 0mA to suppress the fast-ion instability, which is severe in the vertical plane due to small beam size.
LBNL, Berkeley, California
Electron Cyclotron Resonance (ECR) ion sources are an essential component of heavy-ion accelerators due to their ability to produce wide range of ions as required by these facilities. The ever-increasing intensity demands have led to remarkable performance improvements of ECR injector systems, due to advances in magnet technology as well as an improved understanding of the ECR ion source plasma physics. At the same time, enhanced diagnostics and simulation capabilities have improved the understanding of the injector beam transport properties. However, the initial ion beam distribution at the extraction aperture is still a subject of research. Due to the magnetic confinement necessary to sustain the ECR plasma, the ion density distribution across the extraction aperture is inhomogeneous and charge-state-dependent. In addition, the ion beam is extracted from a region of high axial magnetic field, which adds a rotational component to the beam; this leads to emittance growth. This talk will review the ongoing simulation and diagnostics efforts at LBNL to develop a consistent modeling tool for the design of an optimized beam transport system for ECR ion sources.
RIKEN Nishina Center, Wako
A highly sensitive beam current (position) monitor with a high Tc (Critical Temperature) SQUID (Superconducting QUantum Interference Device) and current sensor – the HTc-SQUID monitor – has been developed for the RIBF (RI Beam Factory) in RIKEN. In the present work, the HTc-SQUID monitor allows us to measure the DC of high-energy heavy-ion beams nondestructively in such a way that the beams are diagnosed in real time and the beam current extracted from the cyclotron can be recorded without interrupting the beam user's experiments. Both the HTc magnetic shield and the HTc current sensor were dip-coated with a thin layer of Bi-Sr-Ca-Cu-O (2223-phase, Tc 106 K) on 99.9 % MgO ceramic substrates. Unlike other existing facilities, all these HTS fabrications are cooled by a low-vibration pulse-tube refrigerator. These technologies enable us to downsize the system. Last year, aiming at the practical use, the HTc-SQUID monitor was installed in the RIBF. As a result, a 1 uA Xe beam intensity (50 MeV/u) was successfully measured with a 100 nA resolution. We will report the present status of the facility, the details of the monitor system and the results of the beam measurement.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
DITANET is the largest-ever EU funded training network in beam diagnostics. The network members – universities, research centres and industry partners – are developing diagnostics methods for a wide range of existing or future particle accelerators, both for electron and for ion beams. This is achieved through a cohesive approach that allows for the exploitation of synergies, whilst promoting knowledge exchange between partners. In addition to its broad research program, the network organizes schools and topical workshops for the beam instrumentation community. This contribution gives an overview of the Network's research portfolio, summarizes the main research results from the first two years of DITANET and presents past and future training activities.
ORNL, Oak Ridge, Tennessee
Beam Loss Monitors are common devices used in hadron and lepton accelerators. Depending on accelerator specifics, BLMs could be just diagnostics or could play an essential role in the Machine Protection System (MPS). This tutorial discusses different types of BLMs and their applicability to different accelerators. It covers traditional BLMs like ionization chambers and scintillator-based devices, and also less common techniques like those based on fiber optics and avalanche diodes. The tutorial gives an overview of the underlying physics involved in beam loss detection, and recent advances in computer simulation of particle interaction with matter helpful for BLM modeling. Options for signal processing electronics are described, as well as interfaces to both the control system and the MPS.