DIPAC2011 - List of Keywords (photon)

Paper	Title	Other Keywords	Page
MOOB01	An Aperture Backscatter X-ray Beam Position Monitor at Diamond	vacuum, polarization, scattering, undulator	6
	C. Bloomer, G. Rehm, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	This paper presents the design and first results of a new XBPM developed at Diamond that images the backscatter from an aperture in the Front End to measure the beam centre of mass. This is of particular interest for monitoring the emission from elliptically polarizing undulators where the profile of the beam varies strongly with change of beam polarization. Traditional four-blade Front End XBPMs struggle to resolve a beam centre of mass for EPUs because of this. We have developed an XBPM that observes the backscattered photons from a copper aperture through a pinhole. This solution is capable of operating with the full white beam, and has been designed to fit into the same physical space as the standard front end XBPMs in use at Diamond. This offers the potential to easily replace traditional XBPMs where beneficial and required.
	Slides MOOB01 [7.211 MB]

MOPD23	Photon BPM Electronics Development at Taiwan Light Source	injection, feedback, controls, diagnostics	95
	P.C. Chiu, J. Chen, Y.K. Chen, K.T. Hsu, K.H. Hu, C.H. Kuo NSRRC, Hsinchu, Taiwan
	Photon BPMs are very useful for photon beam position and stability observation. There are several kinds of photon BPMs and electronics with different design installed at beamline front-ends at the Taiwan Light Source. To provide a better integration and efficient usage of the photon BPM, a commercial BPM electronics - Libera Photon was chosen for an integral solution and has showed at least one micron performance for several months of testing. In this report, the installation process and testing results of the photon BPM will be presented.
	Poster MOPD23 [0.595 MB]

MOPD28	Loss Factor Measurement using Time Correlated Single Photon Counting of Synchrotron Radiation	cavity, storage-ring, synchrotron, vacuum	110
	G. Rehm, C. Bloomer, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	A method to derive the total loss factor from the variation of SR photon arrival times with bunch charge has been developed. A time correlated single photon counting system is used operationally for fill pattern and bunch purity measurements. By fitting the individual peaks in the photon arrival time histogram, their relative timing can be retrieved with ps resolution and reproducibility. For a measurement of the loss factor, a fill pattern comprising a range of different bunch charges is stored and then their timing relative to the RF buckets is charted against charge. Examples of measurements illustrate the variation of loss factor with RF voltage and change in Insertion Device gap.

MOPD48	Optical Electron Beam Diagnostics for Relativistic Electron Cooling Devices	electron, laser, scattering, diagnostics	158
	T. Weilbach HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany J. Dietrich FZJ, Jülich, Germany
	New magnetized high energy coolers like the one proposed for the High Energy Storage Ring (HESR) at the Facility for Antiproton and Ion Research (FAIR) have specific demands on the diagnostic of the electron beam. Due to high voltage breakdowns they only allow a very small beam loss so non-invasive beam diagnostic methods are necessary. For beam profile measurement a system based on beam induced fluorescence (BIF) was designed and is under installation at the 100 keV polarized test setup at the Mainzer Mikrotron (MAMI) at the moment. For the diagnostic of other observables of the cooling beam, like the electron beam energy or the electron temperature, a Thomson scattering experiment is planned at the same setup. The planned experiments for the beam profile measurement are presented and the challenges of the Thomson scattering method are discussed.

MOPD60	Beam Induced Fluorescence (BIF) Monitors as a Standard Operating Tool	controls, ion, diagnostics, heavy-ion	185
	C.A. Andre, F. Becker, H. Bräuning, P. Forck, R. Haseitl, R. Lonsing, B. Walasek-Höhne GSI, Darmstadt, Germany
	For high current operation at the GSI Heavy Ion UNILAC non intercepting methods for transverse beam profile determination are required. The Beam Induced Fluorescence (BIF) Monitor, an optical measurement device based on the observation of fluorescent light emitted by excited gas molecules was brought to routine operation. Detailed investigations were conducted for various beam parameters to improve the electronics and the optical setup. Up to now, four BIF monitor stations (for detection of both, horizontal and vertical beam profiles) were installed at UNILAC and two additional setups are planned. This contribution reports on first upgrades of the BIF monitors with a Siemens PLC for FESA-based slow controls and hardware protection procedures. The versatile control and display software ProfileView is presented as an easy-to-use and stable beam diagnostic tool for the GSI operating team.
	Poster MOPD60 [3.060 MB]

MOPD61	Vertical Emittance Measurement at the ESRF	emittance, radiation, synchrotron, dipole	188
	F. Ewald, P. Elleaume, L. Farvacque, A. Franchi, D. Robinson, K.B. Scheidt, A. Snigirev, I. Snigireva ESRF, Grenoble, France
	In the short term the ESRF aims to reach emittances of less than 2 pm. We review the existing emittance diagnostics – X-ray projection monitors and pinhole cameras – and evaluate their ability to resolve such ultra-small vertical emittances. Even though these devices are reliable and show good agreement between measurements and theoretical predictions down to vertical emittance values of less than 10 pm, they will reach their limit of resolution for emittances decreasing below a few picometers. In addition to the existing emittance diagnostics, a new device was installed that images bending magnet radiation using compound refractive lenses (CRLs).

MOPD78	Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage	cavity, electron, feedback, controls	227
	G. Rehm, M.G. Abbott, C. Bloomer, I. Uzun Diamond, Oxfordshire, United Kingdom
	We have developed hardware and software that allows continuous and synchronous recording of electron and X-Ray beam position as well as cavity voltage and ground vibrations at a rate of about 10kS/s for periods of many days. To this end, additional nodes have been added to our existing fast network that feeds the Fast Orbit Feedback System, namely tungsten vane type front end XBPMs, RF cavity pickups and accelerometers. The synchronous nature of these measurements shows the correlation between electron beam motion through an insertion device and observed X-ray beam motion in the frontend or orbit distortions caused by fluctuations of the RF cavity voltage. While the additional channels currently are only observed, the potential of including these in the fast orbit feedback will be discussed.

TUPD15	Technology Selection for the Beam Position Tuning System in Hadrontherapy Facilities	electron, high-voltage, controls, proton	332
	C. Belver-Aguilar, C. Blanch Gutierrez, A. Faus-Golfe, J.J. García-Garrigós IFIC, Valencia, Spain E. Benveniste, M. Haguenauer, P. Poilleux LLR, Palaiseau, France
	Funding: CYCIT – IN2P3: AIC10-D-000518 The Beam Delivery System of some hadrontherapy facilities is characterized by having scanning magnets, which move the beam in order to irradiate all the tumor volume. To control the beam position, a Beam Position Monitor (BPM) is needed. The BPM described in this paper is a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam. We present here the study of the possible photodiodes able to read the light emitted by the scintillating fiber, and the tests performed in order to find the most suitable photodiode to measure the beam position from the variations in the beam current. The setup used for the tests comprises a Sr-90 source, which emits electrons, a scintillating fiber, converting these electrons into photons, and a photodiode, which detects the photons leaving the fiber. The photodiodes studied have been of two types: Avalanche Photodiode (APD) and Multi Pixel Photon Counter (MPPC). In this paper both photodiodes are compared and the results are presented.

TUPD19	Initial Tests of New Electron and Photon Beam Position Monitor Electronics at the Advanced Photon Source	brilliance, injection, electron, controls	344
	P. Leban I-Tech, Solkan, Slovenia G. Decker ANL, Argonne, USA
	Funding: Use of the APS, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by ANL, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 Measurements were done at the Advanced Photon Source (APS) with Libera Brilliance+, connected to the small-aperture insertion device vacuum chamber pickup electrodes near the beamline 35-ID source point. A photoemission-based photon beam position monitor located 16.35 meters downstream of the center of the ID straight section was also monitored using Libera Photon electronics in horizontal/vertical configuration. Top-up injection transients were recorded simultaneously on both units, providing details about the electron and photon beam motions before, during, and after injection in the storage ring and beamline front end. FFT spectra from the APS-developed BSP-100 broadband BPM data acquisition electronics were compared with the Libera instruments. This article discusses the calibration procedure for electron and photon beam position monitors along with results of these measurements.

TUPD52	First Measurements with the Test Stand for Optical Beam Tomography	ion, vacuum, luminosity, beam-transport	422
	C. Wagner, O. Meusel, U. Ratzinger, H. Reichau IAP, Frankfurt am Main, Germany
	A test stand for optical beam tomography was developed. As a new non-destructive beam-diagnostic system for high current ion beams, the test stand will be installed in the low energy beam transport section (LEBT) of the Frankfurt Neutron Source (FRANZ) behind the chopper system. The test stand consists of a rotatable vacuum chamber with a mounted CCD camera. The maximum rotation angle amounts to 270°. In a first phase the optical beam profile measurement and 3D density reconstruction is tested with a time independent 10 keV He beam. The measurements and performance of data processing algorithms are compared with the beam transport simulations. In a later phase the performance with time dependent beams (120 keV, 200 mA) at a repetition rate of 250 kHz and a duty cycle of 2.5% has to be evaluated. An overview of the first phase results is shown.
	Poster TUPD52 [13.501 MB]

TUPD76	Vibration and Beam Motion Diagnostics in TLS	electron, status, diagnostics, monitoring	485
	Y.K. Chen, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Kuo NSRRC, Hsinchu, Taiwan
	High beam stability is essential in a modern synchrotron light source due to small emittance. Beam motion caused by various factors should be remedy by various approaches to achieve high beam stability. Vibration will deteriorate beam stability and need considered as a part of beam diagnostic. An integrated environment for beam orbit and vibration monitoring systems were set up for various studies. Implementation details and some beam observation will be presented in this report.
	Poster TUPD76 [2.750 MB]

TUPD78	SOLEIL Beam Orbit Stability Improvements	feedback, kicker, synchrotron, electron	488
	N. Hubert, L. Cassinari, J.-C. Denard, P. Lebasque, L.S. Nadolski, D. Pédeau SOLEIL, Gif-sur-Yvette, France
	SOLEIL beam orbit stability is being significantly improved. A first effort was set on long term stability for specific beamlines (new 160 m long Nanoscopium and Hard X-rays beamlines). BPM and XBPM steel supports will be replaced for reducing their sensitiveness to temperature drift. Thermal expansion of INVAR and fused Silica stands has been measured. INVAR has been selected for the new BPM supports. A second effort aimed at improving the orbit stability of beamlines based on bending magnets. We plan to use their first XBPM in the global orbit feedback loops (slow and fast). For that purpose new XBPM electronics called Libera photons will be used. Soleil, having contributed to the development, tested extensively the first series. A third effort focused on noise source location. An application developed in-house has identified localized orbit perturbation sources introducing spurious spectrum lines at 46, 50 and 54 Hz on the orbit. They originate from fans rotating close to ceramics chambers of kickers, FCT and shaker. Their suppression decreases the vertical integrated noise down to 300 nm in the DC-500Hz frequency range.

TUPD83	Photodiode Calibration using an Electrical Substitution Radiometer in the Hard X-ray Region	simulation, alignment, radiation, cryogenics	500
	N.I. Bolibruch, R. Igarashi, J.M. Vogt CLS, Saskatoon, Saskatchewan, Canada
	Funding: Work supported by NSERC, NRC, CIHR, WEDC. An electrical substitution radiometer under development at the Canadian Light Source (CLS) has been used to calibrate a photodiode (AXUV100) from International Radiation Detectors Inc. within an energy range of 8 keV to 30 keV. These measurements were made using monochromatic X-rays on the Biomedical Imaging and Therapy bend magnet beam line and the Hard X-Ray Microanalysis beam line at the CLS. The results were then compared with silicon absorption calculations using data from the NIST mass absorption coefficient tables. Good agreement has been found between the diode calibration obtained from the radiometer and the theoretical calculation of the diode response.

TUPD89	Polarimetry of 0.1 – 130 MeV Electron Beams at the S-DALINAC*	electron, laser, polarization, linac	515
	C. Eckardt, P. Bangert, R. Barday, U. Bonnes, R. Eichhorn, J. Enders, C. Ingenhaag, Y. Poltoratska, M. Wagner TU Darmstadt, Darmstadt, Germany
	Funding: * Work supported by DFG through SFB 634 and by the state of Hesse through the Helmholtz International Center for FAIR in the framework of the LOEWE program. A source of polarized electrons[1] has been installed at the superconducting 130 MeV Darmstadt electron linear accelerator S-DALINAC[2], augmenting the experimental program for nuclear structure studies and fundamental experiments. Polarized electrons from a strained-superlattice GaAs cathode are electrostatically accelerated to 100 keV. In the low-energy beam line the beam parameters are measured using diagnostic elements like wire scanners and RF-monitors, a Wien filter for spin manipulation and a 100 keV Mott polarimeter for polarization measurement. Following a superconducting accelerator section, electron beams with 5-10 MeV energy are used for bremsstrahlung experiments. Here, the absolute degree of polarization will be measured using a Mott polarimeter, while monitoring the beam polarization during the experiment with a Compton transmission polarimeter. Alternatively, the electron beam can be further accelerated in the recirculating superconducting main linac. For beam energies of 50-130 MeV a Moeller polarimeter as well as two Compton transmission polarimeter are foreseen. We report on the performance of the polarized source and the polarimeter design and installation. [1] C. Eckardt et al., IPAC 10, Kyoto, _{_}THPEC019_{_}, p 4083. [2] A. Richter, Proc. EPAC 96, Sitges, _{_}WEX02A_{_}, p.110.

WEOA04	Synchrotron Radiation Measurements at the CERN LHC	ion, proton, emittance, booster	550
	F. Roncarolo, S. Bart Pedersen, A. Boccardi, E. Bravin, A. Guerrero, A. Jeff, T. Lefèvre, A. Rabiller CERN, Geneva, Switzerland A.S. Fisher SLAC, Menlo Park, California, USA
	The CERN LHC is equipped with two systems (one for each beam) designed to image the synchrotron radiation emitted by protons and heavy ions. After their commissioning in 2009, the detectors were extensively used and studied during the 2010 run. This allowed preliminary limits in terms of sensitivity, accuracy and resolution to be established. The upgrade to an intensified video camera capable of gating down to 25ns permitted the acquisition of single bunch profiles even with an LHC proton pilot bunch (~5·10⁹ protons) at 450 GeV or a single lead ion bunch (~10⁸ ions) from about 2 TeV. Plans for the optimization and upgrade of the system will be discussed. Since few months, part of the extracted light is deviated to the novel Longitudinal Density Monitor (LDM), consisting in an avalanche photo-diode detector providing a resolution better than 100 ps. The LDM system description will be complemented with the promising first measurement results.
	Slides WEOA04 [6.398 MB]

WEOB01	Scintillating Screen Applications in Beam Diagnostics	electron, ion, diagnostics, scattering	553
	B. Walasek-Höhne GSI, Darmstadt, Germany G. Kube DESY, Hamburg, Germany
	Scintillation screens are widely used for transverse beam profile diagnostics at particle accelerators. The monitor principle relies on the fact that a charged particle crossing the screen material will deposit a part of its energy which is converted to visible light. The resulting light spot is a direct image of the two-dimensional beam distribution and can be measured with standard optical techniques. Scintillating screen monitors were mainly deployed in hadron and low energy electron machines where the intensity of optical transition radiation (OTR) is rather low. The experience from modern linac based light sources showed that OTR diagnostics might fail even for high energetic electron beams, thus making the use of scintillators again very attractive. This contribution summarizes results and trends from "Scintillating Screen Applications in Beam Diagnostics" workshop recently held in Darmstadt. In the first part an introduction to the scintillation mechanism will be given, including demands and limitations as e.g. the dynamic range and saturation. Thereafter a brief overview on actual screen monitor applications at electron and hadron accelerators will be presented.
	Slides WEOB01 [14.721 MB]

WEOB03	Single-shot Resolution of X-ray Monitor using Coded Aperture Imaging	emittance, synchrotron, synchrotron-radiation, optics	561
	J.W. Flanagan, A. Arinaga, H. Fukuma, H. Ikeda, T.M. Mitsuhashi KEK, Ibaraki, Japan J.P. Alexander, M.A. Palmer, D.P. Peterson, N.T. Rider CLASSE, Ithaca, New York, USA G.S. Varner UH, Honolulu, HI, USA
	We report on tests of an x-ray beam size monitor based on coded aperture imaging. This technique uses a mask pattern to modulate incoming light, with the resulting image being deconvolved through the mask and detector responses, including the effects of diffraction and attenuation materials in the path, over the spectral and angular distribution of the synchrotron radiation generated by the beam. We have tested mask patterns called URA masks, which have relatively flat spatial frequency response, and an open aperture of 50% for high-flux throughput, enabling single-shot (bunch-by-bunch, turn-by-turn) measurements without the need for heat-sensitive mirrors. Bunch size measurements of ~10 micron bunches with single-shot (statistics-dominated) resolutions of ~2.5 microns have been demonstrated at CesrTA, and single-shot measurements with similar or better resolution of beams in the ~5 micron range are being aimed for at the ATF2. A beam-size monitor based on these principles is also being designed for the SuperKEKB low-emittance rings. We will present estimated single-shot resolutions, along with a comparison to single-shot resolution measurements made at CesrTA.
	Slides WEOB03 [1.694 MB]

WEOD01	Beam Induced Fluorescence Monitors	ion, diagnostics, electron, proton	575
	F. Becker GSI, Darmstadt, Germany
	Non-intercepting diagnostic devices in hadron accelerators offer continuous online monitoring capability. They also avoid the problem of potential thermal damage in high-current applications. Taking advantage of the residual gas as active material, the Beam Induced Fluorescence (BIF) monitor exploits gas fluorescence in the visible range for transversal profile measurements. Depending on beam parameters and vacuum-constraints, BIF monitors can be operated at base-pressure or in dedicated local pressure bumps up to the mbar range. Nowadays, BIF monitors are investigated in many accelerator laboratories for hadron energies from about 100 keV up to several 100 GeV. This talk gives an introduction to the measurement principle and typical operating conditions. It summarises recent investigations, e.g. on different working gases, and it compares various technical realisations.
	Slides WEOD01 [12.701 MB]

Paper

Title

Other Keywords

Page

MOOB01

An Aperture Backscatter X-ray Beam Position Monitor at Diamond

vacuum, polarization, scattering, undulator

6

C. Bloomer, G. Rehm, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

This paper presents the design and first results of a new XBPM developed at Diamond that images the backscatter from an aperture in the Front End to measure the beam centre of mass. This is of particular interest for monitoring the emission from elliptically polarizing undulators where the profile of the beam varies strongly with change of beam polarization. Traditional four-blade Front End XBPMs struggle to resolve a beam centre of mass for EPUs because of this. We have developed an XBPM that observes the backscattered photons from a copper aperture through a pinhole. This solution is capable of operating with the full white beam, and has been designed to fit into the same physical space as the standard front end XBPMs in use at Diamond. This offers the potential to easily replace traditional XBPMs where beneficial and required.

Slides MOOB01 [7.211 MB]

MOPD23

Photon BPM Electronics Development at Taiwan Light Source

injection, feedback, controls, diagnostics

95

P.C. Chiu, J. Chen, Y.K. Chen, K.T. Hsu, K.H. Hu, C.H. Kuo
NSRRC, Hsinchu, Taiwan

Photon BPMs are very useful for photon beam position and stability observation. There are several kinds of photon BPMs and electronics with different design installed at beamline front-ends at the Taiwan Light Source. To provide a better integration and efficient usage of the photon BPM, a commercial BPM electronics - Libera Photon was chosen for an integral solution and has showed at least one micron performance for several months of testing. In this report, the installation process and testing results of the photon BPM will be presented.

Poster MOPD23 [0.595 MB]

MOPD28

Loss Factor Measurement using Time Correlated Single Photon Counting of Synchrotron Radiation

cavity, storage-ring, synchrotron, vacuum

110

G. Rehm, C. Bloomer, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

A method to derive the total loss factor from the variation of SR photon arrival times with bunch charge has been developed. A time correlated single photon counting system is used operationally for fill pattern and bunch purity measurements. By fitting the individual peaks in the photon arrival time histogram, their relative timing can be retrieved with ps resolution and reproducibility. For a measurement of the loss factor, a fill pattern comprising a range of different bunch charges is stored and then their timing relative to the RF buckets is charted against charge. Examples of measurements illustrate the variation of loss factor with RF voltage and change in Insertion Device gap.

MOPD48

Optical Electron Beam Diagnostics for Relativistic Electron Cooling Devices

electron, laser, scattering, diagnostics

158

T. Weilbach
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany
J. Dietrich
FZJ, Jülich, Germany

New magnetized high energy coolers like the one proposed for the High Energy Storage Ring (HESR) at the Facility for Antiproton and Ion Research (FAIR) have specific demands on the diagnostic of the electron beam. Due to high voltage breakdowns they only allow a very small beam loss so non-invasive beam diagnostic methods are necessary. For beam profile measurement a system based on beam induced fluorescence (BIF) was designed and is under installation at the 100 keV polarized test setup at the Mainzer Mikrotron (MAMI) at the moment. For the diagnostic of other observables of the cooling beam, like the electron beam energy or the electron temperature, a Thomson scattering experiment is planned at the same setup. The planned experiments for the beam profile measurement are presented and the challenges of the Thomson scattering method are discussed.

MOPD60

Beam Induced Fluorescence (BIF) Monitors as a Standard Operating Tool

controls, ion, diagnostics, heavy-ion

185

C.A. Andre, F. Becker, H. Bräuning, P. Forck, R. Haseitl, R. Lonsing, B. Walasek-Höhne
GSI, Darmstadt, Germany

For high current operation at the GSI Heavy Ion UNILAC non intercepting methods for transverse beam profile determination are required. The Beam Induced Fluorescence (BIF) Monitor, an optical measurement device based on the observation of fluorescent light emitted by excited gas molecules was brought to routine operation. Detailed investigations were conducted for various beam parameters to improve the electronics and the optical setup. Up to now, four BIF monitor stations (for detection of both, horizontal and vertical beam profiles) were installed at UNILAC and two additional setups are planned. This contribution reports on first upgrades of the BIF monitors with a Siemens PLC for FESA-based slow controls and hardware protection procedures. The versatile control and display software ProfileView is presented as an easy-to-use and stable beam diagnostic tool for the GSI operating team.

Poster MOPD60 [3.060 MB]

MOPD61

Vertical Emittance Measurement at the ESRF

emittance, radiation, synchrotron, dipole

188

F. Ewald, P. Elleaume, L. Farvacque, A. Franchi, D. Robinson, K.B. Scheidt, A. Snigirev, I. Snigireva
ESRF, Grenoble, France

In the short term the ESRF aims to reach emittances of less than 2 pm. We review the existing emittance diagnostics – X-ray projection monitors and pinhole cameras – and evaluate their ability to resolve such ultra-small vertical emittances. Even though these devices are reliable and show good agreement between measurements and theoretical predictions down to vertical emittance values of less than 10 pm, they will reach their limit of resolution for emittances decreasing below a few picometers. In addition to the existing emittance diagnostics, a new device was installed that images bending magnet radiation using compound refractive lenses (CRLs).

MOPD78

Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage

cavity, electron, feedback, controls

227

G. Rehm, M.G. Abbott, C. Bloomer, I. Uzun
Diamond, Oxfordshire, United Kingdom

We have developed hardware and software that allows continuous and synchronous recording of electron and X-Ray beam position as well as cavity voltage and ground vibrations at a rate of about 10kS/s for periods of many days. To this end, additional nodes have been added to our existing fast network that feeds the Fast Orbit Feedback System, namely tungsten vane type front end XBPMs, RF cavity pickups and accelerometers. The synchronous nature of these measurements shows the correlation between electron beam motion through an insertion device and observed X-ray beam motion in the frontend or orbit distortions caused by fluctuations of the RF cavity voltage. While the additional channels currently are only observed, the potential of including these in the fast orbit feedback will be discussed.

TUPD15

Technology Selection for the Beam Position Tuning System in Hadrontherapy Facilities

electron, high-voltage, controls, proton

332

C. Belver-Aguilar, C. Blanch Gutierrez, A. Faus-Golfe, J.J. García-Garrigós
IFIC, Valencia, Spain
E. Benveniste, M. Haguenauer, P. Poilleux
LLR, Palaiseau, France

Funding: CYCIT – IN2P3: AIC10-D-000518
The Beam Delivery System of some hadrontherapy facilities is characterized by having scanning magnets, which move the beam in order to irradiate all the tumor volume. To control the beam position, a Beam Position Monitor (BPM) is needed. The BPM described in this paper is a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam. We present here the study of the possible photodiodes able to read the light emitted by the scintillating fiber, and the tests performed in order to find the most suitable photodiode to measure the beam position from the variations in the beam current. The setup used for the tests comprises a Sr-90 source, which emits electrons, a scintillating fiber, converting these electrons into photons, and a photodiode, which detects the photons leaving the fiber. The photodiodes studied have been of two types: Avalanche Photodiode (APD) and Multi Pixel Photon Counter (MPPC). In this paper both photodiodes are compared and the results are presented.

TUPD19

Initial Tests of New Electron and Photon Beam Position Monitor Electronics at the Advanced Photon Source

brilliance, injection, electron, controls

344

P. Leban
I-Tech, Solkan, Slovenia
G. Decker
ANL, Argonne, USA

Funding: Use of the APS, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by ANL, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357
Measurements were done at the Advanced Photon Source (APS) with Libera Brilliance+, connected to the small-aperture insertion device vacuum chamber pickup electrodes near the beamline 35-ID source point. A photoemission-based photon beam position monitor located 16.35 meters downstream of the center of the ID straight section was also monitored using Libera Photon electronics in horizontal/vertical configuration. Top-up injection transients were recorded simultaneously on both units, providing details about the electron and photon beam motions before, during, and after injection in the storage ring and beamline front end. FFT spectra from the APS-developed BSP-100 broadband BPM data acquisition electronics were compared with the Libera instruments. This article discusses the calibration procedure for electron and photon beam position monitors along with results of these measurements.

TUPD52

First Measurements with the Test Stand for Optical Beam Tomography

ion, vacuum, luminosity, beam-transport

422

C. Wagner, O. Meusel, U. Ratzinger, H. Reichau
IAP, Frankfurt am Main, Germany

A test stand for optical beam tomography was developed. As a new non-destructive beam-diagnostic system for high current ion beams, the test stand will be installed in the low energy beam transport section (LEBT) of the Frankfurt Neutron Source (FRANZ) behind the chopper system. The test stand consists of a rotatable vacuum chamber with a mounted CCD camera. The maximum rotation angle amounts to 270°. In a first phase the optical beam profile measurement and 3D density reconstruction is tested with a time independent 10 keV He beam. The measurements and performance of data processing algorithms are compared with the beam transport simulations. In a later phase the performance with time dependent beams (120 keV, 200 mA) at a repetition rate of 250 kHz and a duty cycle of 2.5% has to be evaluated. An overview of the first phase results is shown.

Poster TUPD52 [13.501 MB]

TUPD76

Vibration and Beam Motion Diagnostics in TLS

electron, status, diagnostics, monitoring

485

Y.K. Chen, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Kuo
NSRRC, Hsinchu, Taiwan

High beam stability is essential in a modern synchrotron light source due to small emittance. Beam motion caused by various factors should be remedy by various approaches to achieve high beam stability. Vibration will deteriorate beam stability and need considered as a part of beam diagnostic. An integrated environment for beam orbit and vibration monitoring systems were set up for various studies. Implementation details and some beam observation will be presented in this report.

Poster TUPD76 [2.750 MB]

TUPD78

SOLEIL Beam Orbit Stability Improvements

feedback, kicker, synchrotron, electron

488

N. Hubert, L. Cassinari, J.-C. Denard, P. Lebasque, L.S. Nadolski, D. Pédeau
SOLEIL, Gif-sur-Yvette, France

SOLEIL beam orbit stability is being significantly improved. A first effort was set on long term stability for specific beamlines (new 160 m long Nanoscopium and Hard X-rays beamlines). BPM and XBPM steel supports will be replaced for reducing their sensitiveness to temperature drift. Thermal expansion of INVAR and fused Silica stands has been measured. INVAR has been selected for the new BPM supports. A second effort aimed at improving the orbit stability of beamlines based on bending magnets. We plan to use their first XBPM in the global orbit feedback loops (slow and fast). For that purpose new XBPM electronics called Libera photons will be used. Soleil, having contributed to the development, tested extensively the first series. A third effort focused on noise source location. An application developed in-house has identified localized orbit perturbation sources introducing spurious spectrum lines at 46, 50 and 54 Hz on the orbit. They originate from fans rotating close to ceramics chambers of kickers, FCT and shaker. Their suppression decreases the vertical integrated noise down to 300 nm in the DC-500Hz frequency range.

TUPD83

Photodiode Calibration using an Electrical Substitution Radiometer in the Hard X-ray Region

simulation, alignment, radiation, cryogenics

500

N.I. Bolibruch, R. Igarashi, J.M. Vogt
CLS, Saskatoon, Saskatchewan, Canada

Funding: Work supported by NSERC, NRC, CIHR, WEDC.
An electrical substitution radiometer under development at the Canadian Light Source (CLS) has been used to calibrate a photodiode (AXUV100) from International Radiation Detectors Inc. within an energy range of 8 keV to 30 keV. These measurements were made using monochromatic X-rays on the Biomedical Imaging and Therapy bend magnet beam line and the Hard X-Ray Microanalysis beam line at the CLS. The results were then compared with silicon absorption calculations using data from the NIST mass absorption coefficient tables. Good agreement has been found between the diode calibration obtained from the radiometer and the theoretical calculation of the diode response.

TUPD89

Polarimetry of 0.1 – 130 MeV Electron Beams at the S-DALINAC*

electron, laser, polarization, linac

515

C. Eckardt, P. Bangert, R. Barday, U. Bonnes, R. Eichhorn, J. Enders, C. Ingenhaag, Y. Poltoratska, M. Wagner
TU Darmstadt, Darmstadt, Germany

Funding: * Work supported by DFG through SFB 634 and by the state of Hesse through the Helmholtz International Center for FAIR in the framework of the LOEWE program.
A source of polarized electrons[1] has been installed at the superconducting 130 MeV Darmstadt electron linear accelerator S-DALINAC[2], augmenting the experimental program for nuclear structure studies and fundamental experiments. Polarized electrons from a strained-superlattice GaAs cathode are electrostatically accelerated to 100 keV. In the low-energy beam line the beam parameters are measured using diagnostic elements like wire scanners and RF-monitors, a Wien filter for spin manipulation and a 100 keV Mott polarimeter for polarization measurement. Following a superconducting accelerator section, electron beams with 5-10 MeV energy are used for bremsstrahlung experiments. Here, the absolute degree of polarization will be measured using a Mott polarimeter, while monitoring the beam polarization during the experiment with a Compton transmission polarimeter. Alternatively, the electron beam can be further accelerated in the recirculating superconducting main linac. For beam energies of 50-130 MeV a Moeller polarimeter as well as two Compton transmission polarimeter are foreseen. We report on the performance of the polarized source and the polarimeter design and installation.
[1] C. Eckardt et al., IPAC 10, Kyoto, _{_}THPEC019_{_}, p 4083.
[2] A. Richter, Proc. EPAC 96, Sitges, _{_}WEX02A_{_}, p.110.

WEOA04

Synchrotron Radiation Measurements at the CERN LHC

ion, proton, emittance, booster

550

F. Roncarolo, S. Bart Pedersen, A. Boccardi, E. Bravin, A. Guerrero, A. Jeff, T. Lefèvre, A. Rabiller
CERN, Geneva, Switzerland
A.S. Fisher
SLAC, Menlo Park, California, USA

The CERN LHC is equipped with two systems (one for each beam) designed to image the synchrotron radiation emitted by protons and heavy ions. After their commissioning in 2009, the detectors were extensively used and studied during the 2010 run. This allowed preliminary limits in terms of sensitivity, accuracy and resolution to be established. The upgrade to an intensified video camera capable of gating down to 25ns permitted the acquisition of single bunch profiles even with an LHC proton pilot bunch (~5·10⁹ protons) at 450 GeV or a single lead ion bunch (~10⁸ ions) from about 2 TeV. Plans for the optimization and upgrade of the system will be discussed. Since few months, part of the extracted light is deviated to the novel Longitudinal Density Monitor (LDM), consisting in an avalanche photo-diode detector providing a resolution better than 100 ps. The LDM system description will be complemented with the promising first measurement results.

Slides WEOA04 [6.398 MB]

WEOB01

Scintillating Screen Applications in Beam Diagnostics

electron, ion, diagnostics, scattering

553

B. Walasek-Höhne
GSI, Darmstadt, Germany
G. Kube
DESY, Hamburg, Germany

Scintillation screens are widely used for transverse beam profile diagnostics at particle accelerators. The monitor principle relies on the fact that a charged particle crossing the screen material will deposit a part of its energy which is converted to visible light. The resulting light spot is a direct image of the two-dimensional beam distribution and can be measured with standard optical techniques. Scintillating screen monitors were mainly deployed in hadron and low energy electron machines where the intensity of optical transition radiation (OTR) is rather low. The experience from modern linac based light sources showed that OTR diagnostics might fail even for high energetic electron beams, thus making the use of scintillators again very attractive. This contribution summarizes results and trends from "Scintillating Screen Applications in Beam Diagnostics" workshop recently held in Darmstadt. In the first part an introduction to the scintillation mechanism will be given, including demands and limitations as e.g. the dynamic range and saturation. Thereafter a brief overview on actual screen monitor applications at electron and hadron accelerators will be presented.

Slides WEOB01 [14.721 MB]

WEOB03

Single-shot Resolution of X-ray Monitor using Coded Aperture Imaging

emittance, synchrotron, synchrotron-radiation, optics

561

J.W. Flanagan, A. Arinaga, H. Fukuma, H. Ikeda, T.M. Mitsuhashi
KEK, Ibaraki, Japan
J.P. Alexander, M.A. Palmer, D.P. Peterson, N.T. Rider
CLASSE, Ithaca, New York, USA
G.S. Varner
UH, Honolulu, HI, USA

We report on tests of an x-ray beam size monitor based on coded aperture imaging. This technique uses a mask pattern to modulate incoming light, with the resulting image being deconvolved through the mask and detector responses, including the effects of diffraction and attenuation materials in the path, over the spectral and angular distribution of the synchrotron radiation generated by the beam. We have tested mask patterns called URA masks, which have relatively flat spatial frequency response, and an open aperture of 50% for high-flux throughput, enabling single-shot (bunch-by-bunch, turn-by-turn) measurements without the need for heat-sensitive mirrors. Bunch size measurements of ~10 micron bunches with single-shot (statistics-dominated) resolutions of ~2.5 microns have been demonstrated at CesrTA, and single-shot measurements with similar or better resolution of beams in the ~5 micron range are being aimed for at the ATF2. A beam-size monitor based on these principles is also being designed for the SuperKEKB low-emittance rings. We will present estimated single-shot resolutions, along with a comparison to single-shot resolution measurements made at CesrTA.

Slides WEOB03 [1.694 MB]

WEOD01

Beam Induced Fluorescence Monitors

ion, diagnostics, electron, proton

575

F. Becker
GSI, Darmstadt, Germany

Non-intercepting diagnostic devices in hadron accelerators offer continuous online monitoring capability. They also avoid the problem of potential thermal damage in high-current applications. Taking advantage of the residual gas as active material, the Beam Induced Fluorescence (BIF) monitor exploits gas fluorescence in the visible range for transversal profile measurements. Depending on beam parameters and vacuum-constraints, BIF monitors can be operated at base-pressure or in dedicated local pressure bumps up to the mbar range. Nowadays, BIF monitors are investigated in many accelerator laboratories for hadron energies from about 100 keV up to several 100 GeV. This talk gives an introduction to the measurement principle and typical operating conditions. It summarises recent investigations, e.g. on different working gases, and it compares various technical realisations.

Slides WEOD01 [12.701 MB]