The University of Texas at Austin, Austin, Texas, USA
Fermilab, Batavia, USA
For future experiments at the intensity frontier, precise and accurate knowledge of beam time structure will be critical to understanding backgrounds. The proposed Mu2e experiment will utilize ~150nsec (FWHM) bunches of 107 protons at 8 GeV with a bunch-to-bunch period of 1.7 microseconds. The out-of-bunch beam must be suppressed by a factor of 10-9 relative to in-bunch beam and continuously monitored. I propose a Cerenkov based particle telescope to measure secondary production from beam interactions in a several tens of microns thick foil. Correlating timing information with beam passage allows the determination of relative beam intensity to arbitrary precision given a sufficiently long integration time. The goal is to verify out-of-bunch extinction to the level 10-6 in the span of several seconds. This allows near real-time monitoring of the initial extinction of the beam slow extracted from Fermilab's Debuncher before a system of AC dipoles and collimators, which will provide the final extinction. The effect on beam emittance is minimal, allowing the necessary continuous measurement. I will present the detector design and results of a test in Fermilab's MI-12 beamline.
JLAB, Newport News, Virginia, USA
UMD, College Park, Maryland, USA
High average current and high brightness electron beams are needed for many applications. At the Jefferson Lab FEL facility, the search for dark matter with the FEL laser beam has produced interesting results*, and a second very promising method for dark matter search using JLab Energy-recovery-linac (ERL) machine has been put forward**. Although the required beam current has been achieved on this machine, one key challenge is the management of beam halo. UMD has demonstrated a high dynamic range halo measurement method using a digital micro-mirror array device. A similar system has been established at JLab FEL facility as a joint effort by UMD and JLab to measure the beam halo on the high current ERL machine***. The experiment and characterization are being performed while the new UV FEL is running for optimization. In this paper, the limitations of the current system will be analyzed and study of other approaches (such as an optimized coronagraph) for further extending measuring dynamic range will be presented. In particular, we will discuss in detail the possibility of performing both longitudinal and transverse (3D) halo measurement altogether on one single system.
* A. Afanasev, et al., PRL. 101 120401 (2008).
** J. Thale, Searching for a New Gauge Boson at JLab, Newport News, VA, September 20-21, 2010
*** H. Zhang, et al., this conference.
LNLS, Campinas, Brazil
ELSA, Bonn, Germany
The Electron Stretcher Facility ELSA consists of several accelerator stages, the last one being a storage ring providing a beam of polarized electrons of up to 3.5 GeV. At ELSA various diagnostic devices based on synchrotron radiation are installed or planned. A new beamline at the storage ring designed for high resolution diagnostics in the transversal plane will be presented. The measurement setup is sensitive at the UV range of the synchrotron light spectrum. Upgrade measures aiming to extend the diagnostic possibilities to the longitudinal direction will be detailed. In the external beamlines beam currents below 1 nA are delivered to photo production experiments. Beam profiles are detected using dedicated synchrotron light monitors optimized for low intensities. The characteristics of the monitors will be described. In addition, beam parameters derived from the measured profiles at different resonance extraction setups will be shown.
DELTA, Dortmund, Germany
SSRF, Shanghai, People's Republic of China
SINAP, Shanghai, People's Republic of China
USTC/NSRL, Hefei, Anhui, People's Republic of China
Traditional ways to get beam emittance of linacs, such as multi-slits method, are destructive and then not able to be used in on-line beam diagnostics. To meet the requirements of XFEL equipments and improve the quality of electron beam, non-destructive on-line beam emittance measurement methods basing on getting the quadrupole moment of a beam non-destructively are then required. An advanced way to pick up beam information non-destructively with great precision is making use of eigenmodes of resonant cavities. High brightness injector at Hefei light source is used to study FEL based on photocathode RF electron gun. Cavity beam quadrupole moment monitor system designed for the high brightness injector consists of a square pill-box cavity used to pick up quadrupole signal, a cylindrical pill-box reference cavity, a waveguide coupling network that can suppress monopole and dipole signal, and a superheterodyne receiver used as front-end signal processing system. The whole system works at 5.712 GHz. Strength of quadupole magnets is adjust to construct a matrix which can be used to work out beam parameters.
USTC/NSRL, Hefei, Anhui, People's Republic of China
An S-band cavity BPM is designed for a new injector in National Synchrotron Radiation Laboratory. A re-entrant position cavity is tuned to TM110 mode as position cavity. Theoretical resolution of the BPM is 31 nm. A prototype cavity BPM system is manufactured for cold test. Wire scanning method is used to calibrate the BPM and estimate the performance of the on-line BPM system. Cold test results showed that position resolution of prototype BPM is better than 3 μm. Cross-talk has been detected during the cold test. Racetrack cavity can be used to suppress cross-talk. Ignoring nonlinear effect, transformation matrix is a way to correct cross-talk.
POSTECH, Pohang, Kyungbuk, Republic of Korea
PAL, Pohang, Kyungbuk, Republic of Korea
The X-ray is focused by two zone plates in 1B2 beamline to image electron beam in PLS. From numerical study, we can determine the optical limit of resolution with the same specifications of Fresnel zone plates in 1B2 beamline. The width of Airy pattern and the outmost width of zone plates are turned out to be not good parameters to determine the resolution of the imaging system with a zone plate. The resolution of the entire imaging system 1B2 beamline will be revealed as 682 nm.
BINP SB RAS, Novosibirsk, Russia
I-Tech, Solkan, Slovenia
NSRRC, Hsinchu, Taiwan
ESS, Lund, Sweden
Cockcroft Institute, Warrington, Cheshire, United Kingdom
The University of Liverpool, Liverpool, United Kingdom
The exact determination of the time structure of ever shorter bunches in accelerators and light sources such as for example the X-FEL, the ILC or CLIC is of high importance for the successful operation of these next-generation machines. It is also a key to the optimization of existing scientific infrastructures. The exact measurement of the time structure poses a number of challenges to the beam diagnostics system: The monitors should be non-destructive, easy to maintain and provide time resolutions down to the femtosecond regime. Several DITANET partners are active in this field. This contribution gives examples of the network’s research activities in this area with a focus on the LHC longitudinal density monitor, beam profile monitoring using electro-optics techniques and the exploitation of diffraction radiation for non-invasive diagnostics.
Cockcroft Institute, Warrington, Cheshire, United Kingdom
The University of Liverpool, Liverpool, United Kingdom
Low energetic ion beam are very attractive for a large number of fundamental physics experiments. The development of beam instrumentation for such beams poses many challenges due to the very low currents down to only a few thousands of particles per second and the resulting very low signal levels. Within DITANET, several institutions aim at pushing low energy, low intensity diagnostics beyond the present state-of-the-art. This contribution gives examples from the progress across the DITANET network in this research area.
On behalf of the DITANET consortium.
ANL, Argonne, USA
Recently, a grazing-incidence insertion device x-ray beam position monitor (GRID-XBPM) was proposed for the intense x-ray beam from the future APS undulators [*]. By combining the function of limiting aperture with the XBPM, it increases the power-bearing capacity of the XBPM and, at the same time, eliminates the problem of relative alignment of the two critical components in the beamline. Furthermore, by imaging the hard x-ray fluorescence footprint on the collimator, the XBPM is immune to the soft x-ray background, and its accuracy is improved at larger gap settings. In addition to these advantages, the GRID-XBPM can also be implemented to measure center-of-mass of the x-ray fluorescence footprint when pinhole-camera-like optics are used for position readout*. This offers a solution for long-standing XBPM design issues for elliptical undulators, which have a donut-shaped power distribution. In this work, we report design progress for the GRID-XBPM for the high-power elliptically polarized undulator planned for the APS intermediate energy x-ray (IEX) beamline. Computer simulation of its performance and experimental tests from a scale model system will also be presented.
* B.X. Yang, G. Decker, S. H. Lee, and P. Den Hartog, Beam Instrumentation Workshop, Santa Fe, 2010, to be published.
BNL, Upton, Long Island, New York, USA
MEPhI, Moscow, Russia
IUCF, Bloomington, Indiana, USA
A new polarimeter for absolute proton beam polarization measurements at 200 MeV to accuracy better than ±0.5% has been developed as a part of the RHIC polarized source upgrade. The polarimeter is based on the elastic proton-carbon scattering at 16.2 degree angle, where the analyzing power is close to 100% and was measured with high accuracy. The elastically and in-elastically scattered protons are clearly identified by the difference in the propagation through variable copper absorber and energy deposition of the protons in the detectors. The 16.2 degree elastic scattering polarimeter was used for calibration of a high rate inclusive 12 degree polarimeter for the on-line polarization tuning and monitoring. This technique can be used for accurate polarization measurements in energy range of at least 160-250 MeV.
BNL, Upton, Long Island, New York, USA
The commissioning of the RHIC spin flipper in the RHIC Blue ring during the RHIC polarized proton run in 2009 showed the detrimental effects of global vertical coherent betatron oscillation induced by the 2-AC dipole plus 4-DC dipole configuration *. Additional three AC dipoles were added to the RHIC spin flipper in the RHIC Blue ring during the summer of 2010 to eliminate the vertical coherent betatron oscillations outside the spin flipper [2]. This new design is scheduled to be commissioned during the RHIC polarized proton run in 2011. This paper presents the status of the system as well as latest simulation results.
* M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010
BNL, Upton, Long Island, New York, USA
Rogue mode RF shielding has been successfully designed and implemented into the production multipole vacuum chambers. In order to avoid systematic errors in the NSLS-II BPM system we introduced frequency shift of HOM's by using RF metal shielding located in the antechamber slot of each multipole vacuum chamber. To satisfy the pumping requirement the face of the shielding has been perforated with roughly 50 percent transparency. It stays clear of synchrotron radiation in each chamber.
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H− beam by background gas. Electrons are stripped by the 1.7x10-7torr residual gas at a rate of ~2.4x10-8/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by mp/me=1836. A 183.6MeV H− beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. The chamber in which the laser light passes through the ion beam is upstream of a dipole magnet which deflects the electrons into a biased retarding-grid (V<125kV) 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. The laser also gives us energy measurements on the 0.2mA polarized proton beam.
BNL, Upton, Long Island, New York, USA
Relativistic Heavy Ion Collider (RHIC) beams are subject to Intra-Beam Scattering (IBS) that causes an emittance growth in all three-phase space planes. The only way to increase integrated luminosity is to counteract IBS with cooling during RHIC stores. A stochastic cooling system [1] for this purpose has been developed, it includes moveable pick-ups and kickers in the collider that require precise motion control mechanics, drives and controllers. Since these moving parts can limit the beam path aperture, accuracy and reliability is important. Servo, stepper, and DC motors are used to provide actuation solutions for position control. The choice of motion stage, drive motor type, and controls are based on needs defined by the variety of mechanical specifications, the unique performance requirements, and the special needs required for remote operations in an accelerator environment. In this report we will describe the remote motion control related beam line hardware, position transducers, rack electronics, and software developed for the RHIC stochastic cooling pick-ups and kickers.
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
LBNL, Berkeley, California, USA
BNL, Upton, Long Island, New York, USA
Heidelberg University, Heidelberg, Germany
We have constructed two pairs of fast ionization chambers (BRAN) for measurement and optimization of luminosity at IR1 and IR5 of the LHC. These devices are capable of monitoring the performance of the LHC at low luminosity 1028 cm-2s−1 during beam commissioning all the way up to the expected full luminosity of 1034 cm-2s−1 at 7.0 TeV. The ionization chambers measure the intensity of hadronic/electromagnetic showers produced by the forward neutral particles of LHC collisions. To predict and improve the understanding of the BRAN performance, we created a detailed FLUKA model of the detector and its surroundings. In this paper, we describe the model and the results of our simulations including the detector’s estimated response to pp collisions at beam energies of 3.5, 5.0, and 7.0 TeV per beam. In addition, these simulations show the sensitivity of the BRAN to the crossing angle of the two LHC beams. It is shown that the BRAN sensitivity to crossing angle is proportional to the measurement of crossing angle by the LHC beam position monitors.
BNL, Upton, Long Island, New York, USA
The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to control and dynamically tune the magnets. The current implementation and results will be presented.
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
We report on a study of the behavior of a secondary emission chamber (SEC). We show the dependence of the SEC signal on the charge and velocity of the primary beam for beams of protons, and heavy ions including Helium, Neon, Chlorine and Iron. We fill the SEC with a selection of different gases including Hydrogen, Helium, Nitrogen, Argon, and air, studying the SEC response when it is acting as an ion chamber. We also investigate the behavior of the SEC at intermediate pressures between 10-8 torr and atmospheric pressure.
BNL, Upton, Long Island, New York, USA
ANL, Argonne, USA
Case Western Reserve University, Center for Synchrotron Biosciences, Upton, New York, USA
LANL, Los Alamos, New Mexico, USA
SBU, Stony Brook, New York, USA
Stony Brook University, Stony Brook, USA
Modern synchrotrons are capable of significant per-pulse x-ray flux, and time resolved pulse-probe experiments have become feasible. These experiments provide unique demands on x-ray monitors, as the beam position, flux and arrival time all potentially need to be recorded for each x-ray pulse. Further, monitoring of “white” x-ray beam position and flux upstream of beamline optics is desirable as a diagnostic of the electron source. We report on a diamond quadrant monitors which provide beam monitoring for a variety of applications, for both white and monochromatic beams. These monitors have a position resolution of 20 nm for a stable beam, are linear in flux over at least 11 orders of magnitude, and can resolve beam motion shot-by-shot at repetition rates up to 6.5 MHz.
BNL, Upton, Long Island, New York, USA
The use of fluorescent screens for beam profile monitors provides a simple and widely used way to obtain detailed two dimensional intensity maps. For high precision measurements many possible error contributions need to be considered that have to do with properties of the fluorescent screens and of the CCDs. Saturation effects, reflections within and outside the screen, non-linearities, radiation damage, etc are often mentioned. Here we concentrate on an error source less commonly described, namely erroneous baseline subtraction, which is particularly important when fitting projected images. We show computer simulations as well as measurement results having remarkable sensitivity of the fitted profile widths to even partial suppression of the profile baseline data, which often arises from large pixel-to-pixel variations at low intensity levels. Such inadvertent baseline data suppression is very easy to miss as it is usually not obvious when inspecting projected profiles. In this report we illustrate this effect and discuss possible algorithms to automate the detection of this problem as well as some possible corrective measures.
BNL, Upton, Long Island, New York, USA
An electron lens for head-on beam-beam compensation planned for RHIC requires precise overlap of the electron and proton beams which both can have down to 0.3 mm rms transverse radial widths along the 2m long interaction region. Here we describe a new diagnostic tool that is being considered to aid in the tuning and verification of this overlap. Some of ultra relativistic protons (100 or 250 GeV) colliding with low energy electrons (2 to 10 keV) will transfer sufficient transverse momentum to cause the electrons to spiral around the magnetic guiding field in a way that will make them detectable outside of the main solenoid. Time-of-flight of the halo electron signals will provide position-sensitive information along the overlap region. Scattering cross sections are calculated and counting rate estimates are presented as function of electron energy and detector position.
BNL, Upton, Long Island, New York, USA
A residual gas fluorescence beam profile monitor at the relativistic heavy ion collider (RHIC) has successfully recorded vertical beam sizes of Au-ion beams from 3.85 to 100 GeV/n during the 2010 beam runs. Although the fluorescence cross section of Au-ion is sufficiently large, the low residual gas in a typical vacuum chamber of <10-9 torr produces necessary weak fluorescence photons. However, with adequate CCD exposure time, the vertical beam profiles are captured to provide an independent measurement of the RHIC beam size and emittance. This beam diagnostic technique, utilizing the Au-ion beam induced fluorescence from residual gas where hydrogen is still the dominant constituent in nearly all vacuum system, represents a step towards the realization of a truly noninvasive beam monitor for high-energy particle beams.
BNL, Upton, Long Island, New York, USA
LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
An internal R&D program has been undertaken at BNL to develop a sub-micron RF Beam Position Monitor (BPM) for the NSLS-II 3rd generation light source that is currently under construction. The BPM R&D program started in August 2009. Successful beam tests were conducted 15 months from the start of the program. The NSLS-II RF BPM has been designed to meet all requirements for the NSLS-II Injection system and Storage Ring. Housing of the RF BPMs in ±0.1C thermally controlled racks provide sub-micron stabilization without active correction. An active pilot-tone has been incorporated to aid long-term (8hr min) stabilization to 200nm RMS.
BNL, Upton, Long Island, New York, USA
JLAB, Newport News, Virginia, USA
Continued beam-based alignment (BBA) efforts have provided significant benefit to both heavy ion and polarized proton operations at RHIC. Recent studies demonstrated previously unknown systematic beam position monitor (BPM) offset errors and produced accurate measurements of individual BPM offsets in the experiment interaction regions. Here we describe the algorithm used to collect and analyze data during the 2010 and early 2011 RHIC runs and the results of these measurements.
CLASSE, Ithaca, New York, USA
LBNL, Berkeley, California, USA
ANL, Argonne, USA
Over the course of the CesrTA program at Cornell, over 30 Retarding Field Analyzers (RFAs) have been installed in the CESR storage ring, and a great deal of data has been taken with them. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. Obtaining a quantitative understanding of RFA data requires use of cloud simulation programs, as well as a detailed model of the detector itself. In a drift region, the RFA can be modeled by postprocessing the output of a simulation code, and one can obtain best fit values for important simulation parameters with a chi-square minimization method.
CLASSE, Ithaca, New York, USA
Numerous storage ring diagnostic operations require synchronous excitation of beam motion. An example is the lattice phase measurement, which involves synchronous detection of the driven betatron motion. In the CESR storage ring, the transverse tunes continuously vary by several times their natural width. Hence, synchronous beam excitation is impossible without active feedback control. The digital tune tracker consists of a direct digital frequency synthesizer which drives the beam through a transverse kicker, and is phase locked to the detected betatron signal from a quad button position detector. This ensures synchronous excitation, and by setting the correct locking phase, the excitation can be tuned to peak resonance. The fully digital signal detection allows a single bunch amid a long train to be synchronously driven, which allows lattice diagnostics to be performed which include collective effects. The collective effects potentially of interest in CESR include wakefield couplings within the train, and plasma effects such as ion trapping and electron cloud trapping.
Fermilab, Batavia, USA
CERN, Geneva, Switzerland
ESS, Lund, Sweden
SLAC, Menlo Park, California, USA
Fermilab, Batavia, USA
Beam-profile diagnostics are being developed for a superconducting (SC) radiofrequency (RF) Test Accelerator that is currently under construction at the New Muon Lab (NML) at Fermilab. The facility’s design goals include the replication of the pulse train proscribed for the International Linear Collider (ILC). An RF photoelectric gun based on the DESY design will generate the beam. In test-beam mode a low-power beam will be characterized with intercepting radiation converter screens: either a 100-micron thick YAG:Ce single crystal scintillator or a 1-micron thin Al optical transition radiation (OTR) foil. This prototype station was constructed by RadiaBeam Technologies under a contract with Fermilab. In both cases the screen surface was normal to the beam direction followed by a downstream 45-degree mirror that directed the radiation into the optical system. The optical system has better than 20 (10) micron rms spatial resolution when covering a vertical field of view of 18(5) mm. These initial tests were performed at the A0 Photoinjector at a beam energy of ~15 MeV and with micropulse charges from 25 to 500 pC for beam sizes of 45 to 250 microns. Example results will be presented.
Fermilab, Batavia, USA
SLAC, Menlo Park, California, USA
USC, Los Angeles, California, USA
ANL, Argonne, USA
Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam- size sensitivity at the 10- to 20- μm σ level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year.
Fermilab, Batavia, USA
A console application using the phasing of Turn-by-Turn signals from the different BPMs has been tested at the Fermilab Booster. This techinique allows the on-line detection of the beam tunes during the fast Booster ramp in conditions where other algorithms were unsuccessful. The application has been recently expanded to include the computation of the linear coupling coefficients. Algorithm and measurement results are presented.
Fermilab, Batavia, USA
Ionization profile monitors (IPMs) are used in the Fermilab Main Injector (MI) for injection lattice matching and to measure transverse emittance of the beam during acceleration. The IPMs provide a periodic, non-destructive means for emittance measurements where other techniques are not applicable. As Fermilab is refocusing its attention on the intensity frontier, non-intercepting diagnostics such as IPMs are expected to become even more important. This paper gives an overview of the operational use of IPMs for emittance measurements and injection lattice matching measurements at Fermilab, and summarizes the future plans.
Fermilab, Batavia, USA
A longitudinal beam properties, data acquisition system has been commissioned to operate in the Fermilab booster ring. This system captures real time information including beam synchronous phase, bunch length, and coupled bunch instability amplitudes as the beam is accelerated from 400MeV to 8GeV in 33ms. The system uses an off-the-shelf Tektronix oscilloscope running Labview software and a synchronous pulse generator. This paper describes the hardware configuration and the software configuration used to optimize the data processing rate.
Fermilab, Batavia, USA
ORNL, Oak Ridge, Tennessee, USA
Measuring the profile of a high intensity proton beam is problematic in that traditional invasive techniques such as flying wires don't survive the encounter with the beam. One alternative is the use of an electron beam as a probe of the charge distribution in the proton beam as was done at the Spallation Neutron Source at ORNL. Here we present an initial characterization of the beam from a commercial electron gun from Kimball Physics, intended for use in the Fermilab Main Injector for Project X.
Fermilab, Batavia, USA
The Fermilab A0 Photoinjector is a 16MeV high intensity, high brightness electron Linac developed for advanced accelerator R&D. One of the key parameters for the electron beam is the transverse beam emittance. Here we report on a newly developed MATLAB based GUI program used for transverse emittance measurements using the multi-slit technique. This program combines the image acquisition and post-processing tools for determining the transverse phase space parameters with uncertainties.
LBNL, Berkeley, California, USA
CLASSE, Ithaca, New York, USA
Harvard University, Cambridge, Massachusetts, USA
The TE wave propagation method has become a widely used technique for measuring electron cloud density in an accelerator beampipe. In most instances the wave very low power is not capable of affecting the low-energy electrons distribution. During experiments in the CESR Damping Ring Test Accelerator (Cesr-TA), we have observed a particular situation where a resonance between the wave and a dipole magnetic field produces a large modification in the electron cloud distribution that can be measured by other detectors. We believe this resonance is strongly dependent on the geometry of standing waves pattern that discontinuities in the beampipe generate. We present measurements in Cesr-TA, which describe the effect and are in support of our hypothesis.
LBNL, Berkeley, California, USA
A new single-shot diagnostic is presented for mapping THz spatiotemporal waveforms with high temporal resolu- tion for use in diagnostics of electron bunch temporal pro- files. The THz waveform is encoded using electro-optic sampling onto either the phase or amplitude of a broadband chirped probe pulse, and is recovered using linear spectral interferometry with a temporally-short reader pulse. The technique was used to measure waveforms of coherent, ultrashort THz pulses emitted by electron bunches from a laser-plasma accelerator with sub-50 fs resolution. The presence of strong spatiotemporal coupling in the THz waveforms and of complex temporal electron bunch structure was determined.
LBNL, Berkeley, California, USA
UCB, Berkeley, California, USA
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based mea- surement, and integrating current transformer. The diagnostics agreed within ±8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.
LBNL, Berkeley, California, USA
Cornell University, Ithaca, New York, USA
We report on an alternative way to measure beam fluence at NDCX-I, which is necessary for numerical simulation and planning of warm-dense-matter (WDM) experiments. So far the NDCX-I beam fluence has been characterized using a fast Faraday cup, radiation from a scintillator and tungsten foil calorimeter techniques. The present beam intensity is sufficient to melt and partially evaporate a 150 nm thick gold foil. Thermal emission (function of temperature) of the gold foil in the visible spectrum was measured during beam irradiation. A distinct shelf in the thermal emission intensity was observed after 600 ns, indicating that the sample reached the melting temperature. Using known heat capacity and latent heat of melting, the beam flux fully determines the duration of the melting shelf and the moment it appears. Using this technique we estimate an average 260 kW/cm2 beam flux over 10μs, which is consistent with values provided by the other methods.
URS, Albuquerque, New Mexico, USA
LANL, Los Alamos, New Mexico, USA
A new AFE is being developed for the new LANSCE-R wire-scanner systems. The new AFE is implemented in a National Instruments cRIO module installed a BiRa 4U BiRIO cRIO chassis specifically designed to accommodate the cRIO crate and all the wire-scanner interface, control and motor-drive electronics. A single AFE module provides interface to both X and Y wire sensors using true DC coupled transimpedance amplifiers providing collection of the wire charge signals, real-time wire integrity verification using the normal data-acquisition system, and wire bias of 0V to ±50V. The AFE system is designed to accommodate comparatively long macropulses (>1ms) with high PRF (>120Hz) without the need to provide timing signals. The basic AFE bandwidth is flat from true DC to 50kHz with a true first-order pole at 50kHz. Numeric integration in the cRIO FPGA provides real-time pulse-to-pulse numeric integration of the AFE signal to compute the total charge collected in each macropulse. This method of charge collection eliminates the need to provide synchronization signals to the wire-scanner AFE while providing the capability to accurately record the charge from long macropulses at high PRF.
URS, Albuquerque, New Mexico, USA
LANL, Los Alamos, New Mexico, USA
The National Instruments cRIO platform is used for the new LANSCE-R wire-scanner systems. All wire-scanner electronics are integrated into a single BiRa BiRIO 4U cRIO chassis specifically designed for the cRIO crate and all interface electronics. The BiRIO chassis, actuator and LabVIEW VIs provide a complete wire-scanner system integrated with EPICS. The new wire-scanner chassis includes an 8-slot cRIO crate with Virtex-5 LX 110 FPGA and Power-PC real-time controller, the LANL-developed cRIO 2-axis wire-sensor analog interface module (AFE), NI9222 cRIO 4-channel 16-bit digitizer, cRIO resolver demodulator, cRIO event receiver, front-panel touch panel display, motor driver, and all necessary software, interface wiring, connectors and ancillary components. This wire-scanner system provides a complete, turn-key, 2-axis wire-scanner system including 2-channel low-noise sense-wire interface with variable DC wire bias and wire-integrity monitor, 16-bit signal digitizers, actuator motor drive and control, actuator position sensing, limit-switch interfaces, event receiver, LabVIEW and EPICS interface, and both remote operation and full stand-alone operation using the touch panel.
LANL, Los Alamos, New Mexico, USA
New beam-position and phase monitors are under development for the linac at the Los Alamos Neutron Science Center. Transducers have been designed and are being fabricated. We are considering many options for the electronic instrumentation to process the signals and provide position and phase data with the necessary precision and flexibility to serve the various required functions. We’ll present the requirements of the system and the various options under consideration for instrumentation along with the advantages and shortcomings of these options.
LANL, Los Alamos, New Mexico, USA
LANL, Los Alamos, New Mexico, USA
URS, Albuquerque, New Mexico, USA
The Beam Diagnostics and Instrumentation Team at Los Alamos National Laboratory’s LANSCE facility is presently developing a new and improved wire scanner diagnostics system controlled by National Instrument’s cRIO platform. This report describes the current state of development of the control system along with the results gathered from the latest actuator motion performance and accelerator beam data acquisition tests.
ORNL, Oak Ridge, Tennessee, USA
Beam profile diagnostics with large dynamic range is an important tool for understanding origin and evolution of the beam halo in accelerators. Typical dynamic range for conventional wire scanners has been in the range of 100. In high power machines like SNS fractional losses of 1 to 100 part per million is of concern and, therefore, higher dynamic range of profile measurements is desirable. Our near term goal was set to achieve a dynamic range of at least 10000 for all profile measurements in the SNS linac and transport lines. We will discuss present status of this program, challenges, and solutions.
Private Address, Huntington, USA
* Arnold Stillman, in Proceedings of the 1995 Particle Accelerator Conference, 1995, p.2560
RadiaBeam, Santa Monica, USA
SLAC, Menlo Park, California, USA
FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23 GeV, 3 nC electron bunches compressed to ~20 μm long and focussed to ~10 μm wide. Characterization of the beam- plasma interaction requires complete knowledge of the incoming beam parameters on a pulse-to- pulse basis. FACET diagnostics include Beam Position Monitors, Toroidal current monitors, X-ray and Cerenkov based energy spectrometers, optical transition radiation (OTR) profile monitors and coherent transition radiation (CTR) bunch length measurement systems. The compliment of beam diagnostics and their expected performance are reviewed.
SLAC, Menlo Park, California, USA
Three temporal diagnostic techniques are considered for use in the FACET facility at SLAC, which will incorporate a unique two-bunch beam for plasma wakefield acceleration experiments. The results of these experiments will depend strongly on the the inter-bunch spacing as well as the longitudinal profiles of the two bunches. A reliable, single-shot, high resolution measurement of the beam’s temporal profile is necessary to fully quantify the physical mechanisms underlying the beam driven plasma wakefield acceleration. In this study we show that a transverse deflecting cavity is the diagnostic which best meets our criteria.
UMD, College Park, Maryland, USA
Retarding-potential energy analyzers have long been used for energy spread measurements in low-energy beams. In addition to energy spread and energy profile measurements, a high-resolution analyzer can be used to reconstruct the longitudinal phase space. This is useful for our experimental studies of longitudinal physics topics, such as dispersion, space charge waves, and longitudinal focusing. A previous energy analyzer designed at the University of Maryland demonstrated high-resolution measurements of a 5 keV electron beam.* Motivated by the need to characterize the 10 keV electron beam of the University of Maryland Electron Ring, we have improved on the design of the earlier analyzer, increasing its high voltage breakdown threshold and vacuum performance. Results of high-voltage testing and particle optics simulations of the new design are presented.
*Y. Cui, Y. Zou, et al., "Design and Operation of a Retarding Field Energy Analyzer with Variable Focusing for Space-Charge Dominated Electron Beams," Review of Scientific Instruments 75(8), 2736 (2004).
CLASSE, Ithaca, New York, USA
KEK, Ibaraki, Japan
Fermilab, Batavia, USA
CERN, Geneva, Switzerland
ESS, Lund, Sweden
ORNL, Oak Ridge, Tennessee, USA
ORNL RAD, Oak Ridge, Tennessee, USA
In recent years, a number of laser based H- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser transverse emittance scanner at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of laser based diagnostics at accelerator facilities will be addressed.
ORNL, Oak Ridge, Tennessee, USA
A non-destructive profile monitor has been installed and commissioned in the accumulator ring of the Spallation Neutron Source (SNS). The SNS Ring accumulates high intensity proton bunches of up to 1.5·1014 protons with a typical peak current of over 50 A and a bunch length of about 0.7 us during a 1 ms cycle. The profile monitor consists of two systems, one for each plane, with electron guns, correctors, defectors, and quadrupoles to produce pulsed electron beams that scan through the proton bunch. The proton bunch EM fields alter the trajectory of the electrons and their projection on a fluorescent screen. The projection is analyzed to determine the transverse profile of the proton bunch. The speaker will describe the theory, hardware, software, analysis, results, and improvements to these electron scanners. The results include a comparison to wire scanner profiles of extracted ring beam.
BNL, Upton, Long Island, New York, USA
CERN, Geneva, Switzerland
LBNL, Berkeley, California, USA
The Luminosity Monitors for the high luminosity regions in the LHC have been operating to monitor and optimize the luminosity since the beginning of the 2009 run. The device is a gas ionization chamber, which has the ability to resolve bunch-by-bunch luminosity as well as survive the extreme levels of radiation at nominal high intensity LHC operations. The chambers are installed at the zero degree collision angle inside the neutral absorbers 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. A second device, a photo-multiplier based system (PMT) located directly behind the gas ionization chamber, has been also used at low luminosities. We will present operational results for the ionization chambers for both pp and Pb-Pb collisions. These measurements include signal, noise and background studies, and correlation between the gas ionization detector and the PMT. Also, comparison with ongoing modeling efforts will be included.
JLAB, Newport News, Virginia, USA
UMD, College Park, Maryland, USA
JLAB, Newport News, Virginia, USA
Beam halo is a challenging issue for intense beams since it can cause beam loss, emittance growth, nuclear activation and secondary electron emission. Because of the potentially low number of particles in the halo compared with beam core, traditional imaging methods may not have sufficient contrast to detect faint halos. We have developed a high dynamic range, adaptive masking method to measure halo using a digital micro-mirror array device and demonstrated its effectiveness experimentally on the University of Maryland Electron Ring (UMER). We also report on similar experiments currently in progress at the Jefferson Lab Free Electron Laser (FEL) using this method.
KEK, Ibaraki, Japan