DIPAC 2007 - List of Keywords (photon)

A B C D E F G H I K L M O P Q R S T U V

photon

Paper	Title	Other Keywords	Page
MOO1A02	High Resolution Transverse Profile Measurement	laser, electron, synchrotron, emittance	1
	E. Bravin CERN, Geneva
	In many cases the performance of a particle accelerator is in large part defined by the transverse emittance of the beams. In most cases, like colliders and light sources (Synchrotrons or Free Electron Lasers), the quality of the final product, i.e. luminosity and brilliance, is directly linked to this parameter. For this reason many techniques and devices have been developed over the years for monitoring the transverse distribution of particles along accelerator chains or over machine cycles. Moreover modern designs of accelerators allow smaller size and/or higher current beams. New, more demanding, emittance measurement techniques have to be introduced and existing ones expanded. This presentation will review the different methods and the different instruments developed so far.

MOO3A02	Beam Induced Fluorescence (BIF) Monitor for Transverse Profile Determination of 5 to 750 MeV/u Heavy Ion Beams	ion, background, vacuum, electron	33
	F. Becker, C. A. Andre, P. Forck GSI, Darmstadt D. Hoffmann TU Darmstadt, Darmstadt
	In the frame of the FAIR-project (facility for antiproton and ion research) at GSI, high intensity beams from protons to Uranium ions in the energy range from 100 MeV/u to 30 GeV/u are foreseen. In transport lines between the synchrotrons and in front of production targets a precise beam alignment is mandatory. Since the beam energy will increase from 90 Joule to about 10⁴ Joule per ion pulse, conventional intercepting beam diagnostics may not be used. For transverse profile determination we investigated a non-intercepting Beam Induced Fluorescence (BIF) monitor in residual nitrogen. An image intensified CCD camera was used to record the fluorescence images representing the beam profile. The photon yield and background contribution were determined for different ion species, beam energies and N2 pressures. Applying narrowband 10 nm interference filters we mapped the spectral response and associated it with the N2 transitions. Profile distortions were compared to simulations taking into account effects as momentum transfer, gas dynamics and the electrical field of the ion beam. Additionally the feasibility and appropriate layout for different diagnostic tasks is discussed.
	Slides

MOO3A03	First Vibrating Wire Monitor Measurements of a Hard X-ray Undulator Beam at the Advanced Photon Source	radiation, resonance, vacuum, insertion	36
	G. Decker ANL, Argonne, Illinois S. G. Arutunian, M. R. Mailian YerPhI, Yerevan G. Rosenbaum UGA, Athens, Georgia
	The first hard x-ray flux measurements with a vibrating wire monitor (VWM) using the acoustic resonance frequencies of two vertically-offset horizontal stainless steel wires as temperature diagnostics were conducted at APS beamline 19-ID. Due to the high sensitivity of this technique, the studies were performed at extremely low power levels using radiation from a 3.3-cm-period permanent magnet hybrid undulator with a 5-mA electron beam at an energy of 7 GeV. The x-ray beam was filtered by transmission through 7 mm of beryllium placed in the photon beam path, assuring that only hard x-rays were detected. The particle beam was scanned through a range of 400 microradians using an asymmetric closed-orbit angle bump, producing two vertical photon beam profiles. The difference between processed wire signals provides a very sensitive measure of photon beam position. Details of the measurements will be given, along with a discussion of the limitations of the method and possible future research directions.
	Slides

TUPB05	A Tagged Photon Source at the Frascati Beam-Test Facility (BTF)	electron, target, dipole, luminosity	63
	B. Buonomo, G. Mazzitelli, F. Murtas, L. Quintieri INFN/LNF, Frascati (Roma) L. G. Foggetta, S. Hasan, A. Mozzanica, M. Prest Univ. Insubria and INFN Milano, Como P. Valente INFN-Roma, Roma E. Vallazza INFN-Trieste, Trieste
	The DAΦNE Beam Test Facility, operating at the Frascati National Laboratory of INFN, provides electron or positron beams with tunable energy from 25 MeV to 750 MeV, while the intensity can be varied from 10¹⁰/pulse@ 0-50Hz down to a single particle per pulse. Recently a tagged photon source has been designed, built and tested. The photons are produced by bremsstrahlung of electrons with a maximum momentum of 750 MeV/c on a pair of x-y silicon micro-strip chambers(1), placed before the last bending magnet of the BTF transfer line. The photons are tagged in energy using the same bending dipole, whose internal walls have been covered by 10 modules of silicon micro-strip detectors. Depending on the energy loss in the photon production, the electrons impinge on a different strip once the dipole current has been set to the nominal value. The correlation between the directions on the electron measured by silicon chambers and the impinging position on the tagging module inside the magnet allows the tagging on the photons. In this paper the configuration of the system is presented with some results obtained during the latest test-beams. (1)Profile monitors for wide multiplicity range electron beams. Proceeding DIPAC 2005 Lyon, France,pp166-168.

TUPB08	Measurement of Vertical Emittance with a system of Six -In-Air-X-Ray- Projection Monitors at the ESRF	emittance, electron, controls, shielding	72
	K. B. Scheidt ESRF, Grenoble
	The ESRF Storage Ring is now equiped with a system of 5 independent imaging monitors that measure the vertical emittance of the electron beam in the middle of the bending magnet through the very hard X-rays that fully traverse the 40mm thick Copper dipole absorbers and enter the free air space behind it. The tiny power that leaks through the absorber, and carried by X-rays of ~160KeV of very narrow vertical divergence, is simply projected onto a scintillator screen at ~1.8m from the source-point and imaged by optics & camera. These inexpensive and compact detectors are fully operated in free air and can be easily installed and maintained without any vacuum intervention. They now work reliably in routine fashion and have demonstrated their high precision and resolution of the ESRF’s vertical emittance. These results will be presented in this paper together with the underlying principles of the projection detector, aswell as the practical design solutions applied to obtain the high spatial resolution, to make the system resistant to the hostile radiation environment behind the absorber, and to reduce its sensitivity to stray signals generated at this point.

TUPB14	Test of a Silicon Photomultiplier for Ionization Profile Monitor Applications	synchrotron, controls, simulation, permanent-magnet	90
	D. A. Liakin, S. V. Barabin, A. Y. Orlov ITEP, Moscow P. Forck, T. Giacomini GSI, Darmstadt
	A sample of SiPM (silicon photomultiplier) has been tested as an elementary light detector for accelerated beam fast profile evolution observation by using it in residual gas ionization profile monitors. A noise, sensitivity, dynamic range and timing parameters tests of SiPM were performed. A procedure of the data acquisition and following signal reconstruction is discussed. A special attention has been paid to the fine time resolution counting mode with single photon detection. A dedicated signal normalizing and time-to-digit converter design was prototyped and tested. In addition some different modes of operation and optical schemes are discussed in this paper. It is shown that fast optical detectors like SiPMs also could be used for high performance profile measurements with spatial resolution compatible with CCD sensors.

TUPB26	Characterisation of the Systematic Effects of the Insertion Devices with Photon Beam Position Monitors	polarization, undulator, insertion, insertion-device	126
	E. D. van Garderen, M. Böge, J. T.M. Chrin, J. Krempasky, V. Schlott, T. Schmidt, A. Streun PSI, Villigen
	The X-ray photon monitors at Swiss Light Source are used for beam-position stabilisation down to sub-micron level. The beam position changes are mainly induced by changing the insertion device (ID) settings. An ID correction scheme involves both digital beam-position monitors (DBPM) located inside the storage ring and analog photon monitors (XBPM) located inside beamline front-ends. However, a beam-position correction scheme optimised for the electron beam is not automatically optimal for the photon beam. A sub-micron stability of the photon beam by changing the ID-settings is possible only if the XBPM readouts are well characterised for each considered ID-setting. We account for some limitations of the XBPM readouts as well as for examples where a sub-micron stability for all considered ID-settings is achieved.

TUPB28	A Large Scintillating Screen for the LHC Dump Line	proton, radiation, kicker, controls	132
	T. Lefèvre, C. B. Bal, E. Bravin, S. Burger, B. Goddard, S. C. Hutchins, T. Renaglia CERN, Geneva
	7 TeV proton beam from the LHC is ejected through a long transfer line to a beam dump block. Approximately 100 m downstream of the ejection septa, a series of dilution kicker magnets provide a sweeping deflection spreading the extracted beam over a 40 cm diameter area on the face of the beam dump core. During normal operation, the quality of each dump event must be recorded and verified. The so called “Post-Mortem” data-set will include information from the beam dumping system as well as from the beam diagnostics along the extraction line. For this purpose, a profile monitor in front of the dump block is permanently available during machine operation. With more than 10¹⁴ protons stored in LHC, the thermal properties of the screen have to be considered as beam energy deposition becomes an issue. This paper presents the design of this device, which is original due to its very large size. We introduce the different technical considerations involved in the design of the system and present the complete layout of its installation with a special emphasis on the mechanical design, the screen assembly and the choice of the radiation-hard video camera used to capture the image.

TUPC16	Ultimate Resolution of Soleil X-Ray Pinhole Camera	radiation, coupling, synchrotron, synchrotron-radiation	180
	M.-A. Tordeux, L. Cassinari, O. V. Chubar, J.-C. Denard, D. Pédeau, B. Pottin SOLEIL, Gif-sur-Yvette
	During the commissioning of the SOLEIL Storage Ring, beam emittances have been measured with an X-ray pinhole camera system. The evolution of the system and its performances are presented here. As a result of the excellent alignment of the ring magnets, the vertical beam size is smaller than expected, that led us to an effort towards improving the initial resolution of the instrument. A high sensitivity CCD camera allows us to select the harder X-ray part of the radiation which is a key element for resolution improvement. Finally an evaluation of the ultimate pinhole resolution is made for SOLEIL.

WEPB06	Direct Comparison of the Methods of Beam Energy Spread Determination in the VEPP-4M Collider	collider, betatron, diagnostics, electron	244
	O. I. Meshkov, V. A. Kiselev, N. Yu. Muchnoi, S. V. Sinyatkin, V. V. Smaluk, V. N. Zhilich, A. N. Zhuravlev BINP SB RAS, Novosibirsk
	The VEPP-4M electron-positron collider is now operating with the KEDR detector for the experiment of precise measurement of tau-lepton mass. The nearest experimental program of the accelerator includes scan of the energy area below J/psi meson to search narrow resonances. The monitoring of beam energy spread is important to know the energy spread contribution into the total systematic error. In this report we discuss the application of several diagnostics for beam energy spread measurement. The data obtained with Compton BackScattering (CBS) technique* are compared with the value of the spread derived from the betatron motion of the beam. The measurements by all the methods were done at the same accelerator run, i.e. the different diagnostics can be compared directly. The value of the energy spread was determined for a set of collider operating modes, covering the energy area from 1200 MeV up to 1843 MeV. Width of the J/psi and psi' resonance measured with the KEDR detector is used as a reference. ReferencesN. Muchnoi et al. //Proceed. of EPAC 2006, Edinburg, Scotland, TUPCH074T. Nakamura et al. // Proceed. of the 2001 Particle Accelerator Conference, Chicago, p. 1972-1974.*

WEPB20	Optical System for Measuring Electron Bunch Length and Longitudinal Phase Space at Pitz: Extension and Methodical Investigations	electron, optics, booster, gun	274
	J. W. Bähr, H. L. Luedecke DESY Zeuthen, Zeuthen J. Rönsch Uni HH, Hamburg
	An extended optical system* for the measurement of the electron bunch length and the longitudinal phase space** using a streak camera is installed at PITZ. This system will be extended by two new branches in 2007, one in the straight section behind the booster cavity and another one in the first magnet spectrometer behind the booster cavity. The physics design of the chambers containing the radiators and of the optical system are presented. The results of optical calculations of the whole system will be given. Results of methodical investigations will be shown as well, especially concerning transversal optical resolution and time dispersion. * J. Baehr et al., DIPAC ‘03, Mainz, Germany 2003** J. Roensch et al. FEL ’05, SLAC, Stanford, USA, 2005

WEPB25	Time Domain Measurements at Diamond	electron, single-bunch, synchrotron, diagnostics	289
	C. A. Thomas, G. Rehm Diamond, Oxfordshire
	We present a set of four complementary measurements of the synchrotron visible light to characterise the stored electron beam at Diamond in the time domain. The electron bunch profiles and its evolution is measured with picosecond accuracy using a dual sweep streak camera. The beam dynamics are also given by a fast photodiode connected to a fast oscilloscope. The fill pattern is measured using a time correlated single photon counting system which has a high dynamic range for bunch purity measurement, and a fast averaging card which gives the fill structure with high accuracy within a short integration time. We describe our set of instruments, discuss their performance and show first results from measurements of Diamond's properties.

WEPB26	Transition Thermal Processes In Vibrating Wire Monitors	vacuum, radiation, undulator, instrumentation	292
	S. G. Arutunian, M. R. Mailian YerPhI, Yerevan G. Decker ANL, Argonne, Illinois G. Rosenbaum UGA, Athens, Georgia
	Dynamic characteristics of vibrating wire monitors (VWM) strongly depend on the media where the wire oscillates, and also on the geometry and materials of the wire and VWM housing. On the basis of a one-dimensional model of heat transfer along the wire, the time characteristics of transition processes of thermal equilibrium profiles are defined for wires of different materials and geometry. To decrease the response time of the VWM, a new scheme of measurement with constant mean temperature is suggested. In addition to the flux of particles/radiation deposited on the wire, the additional DC current maintains a constant wire oscillation frequency. The value of DC current serves as measure of particles/radiation flux.

WEPC08	Fiberoptics-Based Instrumentation for Storage Ring Beam Diagnostics	coupling, synchrotron, diagnostics, synchrotron-radiation	325
	S. De Santis, J. M. Byrd LBNL, Berkeley, California Y. Yin Y. Y. Labs, Inc., Fremont, California
	We present the results of our experiments at the Advanced Light Source concerning the coupling of synchrotron radiation into optical fibers. Many beam diagnostic devices in today's synchrotron rings make use of the radiation emitted by the circulating particles. Such instruments are placed in close proximity of the accelerator, where in many instances they cannot be easily accessed for safety consideration, or at the end of a beamline, which, because of its cost, can only move the light port a few meters away from the ring. Our method, suitable for all those applications where the longitudinal properties of the beam are measured (i.e. bunch length, phase, etc.), allows placing the diagnostic instruments wherever is more convenient, up to several hundreds of meters away from the tunnel. This would make maintaining and replacing instruments, or switching between them, possible without any access to restricted areas. Additionally, one can use the vast array of optoelectronic devices, developed by the telecommunication industry, for signal analysis.

WEPC13	Jitter Reduced Pump-Probe Experiments	laser, electron, diagnostics, target	337
	A. Azima, S. Düsterer, J. Feldhaus, P. Radcliffe, H. Redlin, H. Schlarb DESY, Hamburg M. Meyer LIXAM, Orsay
	For two-colour pump-probe experiments carried out at the free electron laser FLASH@DESY, the FEL laser pulses in the XUV have to be synchronized with femtosecond precision to optical laser pulses (Ti:Sapphire). An electro-optical sampling diagnostic measures the arrival time jitter of the infrared pump-probe laser pulse in respect to the electron bunch of the FEL. Here, the electron arrival time is encoded spatially into the laser pulse profile and readout by an intensified camera. In this paper we report about the improvement of the temporal resolution of pump-probe experiments on gaseous and solid targets using the arrival time data acquired by the described EO-diagnostic.