DIPAC 1999 - List of Keywords

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

proton

Paper	Title	Other Keywords	Page
CT12	Preliminary Test of a Luminescence Profile Monitor in the CERN SPS	vacuum, ion, photon, injection	95
	J. Camas, R.J. Colchester, G. Ferioli, R. Jung, J. Koopman CERN, Geneva, Switzerland
	In order to satisfy the tight emittance requirements of LHC, a non-intercepting beam profile monitor is needed in the SPS to follow the beam emittance evolution during the acceleration cycle from 26 to 450 GeV. Beyond 300 GeV, the synchrotron light monitor can be used. To cover the energy range from injection at 26 GeV to 300 GeV, a monitor based on the luminescence of gas injected in the vacuum chamber has been tested and has given interesting results. This monitor could also be used in LHC, where the same problem arises. Design and results are presented for the SPS monitor.

PS02	Chromaticity Measurements at HERA-P Using the Head-Tail Technique with Chirp Excitation	betatron, synchrotron, pick-up, kicker	103
	M. Wendt, F. Willeke DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany A. Boudsko TRIUMF, Vancouver, Canada O.R. Jones, H. Schmickler CERN, Geneva, Switzerland
	Experiments have been performed in the HERA proton ring (HERA-p) to test a quasi non-destructive method of chromaticity measurements for protons. The method is based on the detection of the head-tail phase shift of coherend betatron oscillations using a broadband beam position pickup and a commercial “fast-frame” oscilloscope. Previous experiments have relied on a single kick for transverse excitation, whereas the results presented here were carried out using swept frequency “chirp” excitation. The tests proved to be successful, and the method seems to be a good candidate for chromaticity measurement in new large hadron accelerators, such as LHC.

PS10	Ionisation losses and wire scanner heating: evaluation, possible solutions, application to the LHC.	electron, lepton, ion, vacuum	120
	C. Fischer CERN, Geneva, Switzerland
	Harmful heating mechanisms, resulting in wire breakage, limit the utilisation of wire scanner monitors to below a given beam intensity. This threshold depends on the accelerator design parameters. In lepton colliders, the short beam bunches generate strong wake-fields inside the vacuum pipe which are sensed by the wire and are the predominant current limit. These effects can be minimised by a smooth design of the monitor cross section and by choosing a wire made of an insulating material. A second source of energy deposition inside the wire, also present in hadron machines, and even when the wire material is insulating, results from collision and ionisation of the wire material atoms by the incident beam particles. Calculations are presented to evaluate the efficiency of this process and a possible solution is suggested which may reduce this limitation. An example is given for the case of the LHC.

PS11	Ionisation profile monitor tests in the SPS	electron, ion, space-charge, insertion	123
	C. Fischer, J. Koopman CERN, Geneva, Switzerland
	A beam profile monitor, from DESY, based on the ionisation of the rest gas, was installed in the SPS in 1997. Horizontal beam profiles obtained from the extracted positive ions are presented. It is known that in this case some broadening affects the signal, which limits the monitor resolution. This broadening results from the transverse momentum that the ions gain within the space charge field of the circulating beam. In order to improve the resolution for LHC applications, the monitor was modified during the 1998/99 winter stop. A magnetic focusing was incorporated. The aim is to analyse the signal provided by collecting the electrons, rather than the ions, of the ionised rest gas. The details of this new set-up and the expectations for the resolution limit will be compared to the measurement results.

PS12	Performance of the new SPS beam position orbit system (MOPOS)	ion, pick-up, heavy-ion, extraction	126
	C. Boccard, T. Bogey, J. de Vries, S. Jackson, R. Jones, J.P. Papis, W. Rawnsley, K. Rybaltchenko, H. Schmickler CERN, Geneva, Switzerland
	The orbit and trajectory measurement system COPOS of the CERN SPS accelerator has been in operation since the construction of the machine in 1976. Over the years the system has been slightly modified in order to follow the evolving demands of the machine, in particular for its operation as a p-pbar collider and, since 1991, for the acceleration of heavy ions. In 1995 the performance of the system was reviewed and the following shortcomings were identified: lack of turn-by-turn position measurements due to the 1ms integration time of the voltage to frequency converters used for the analogue to digital conversion (to be compared with a revolution time of 23 ms), ageing effects on the 200 MHz resonating input filters, which had over the years drifted out of tolerance. As a consequence the signal to noise ratio, the linearity and the absolute precision were affected. the calibration system based on electromechanical relays had become very unreliable, such that frequent calibrations were no longer possible, a remote diagnostic for the observation of timing signals relative to the beam signals was missing. For the above reasons a large-scale upgrade program was launched, the results of which are described in the following sections.

PS13	Analysis of the proton beam in the DESY transport lines by video readout	emittance, background, luminosity, vacuum	129
	F. Solodovnik, T. Limberg, K. Wittenburg IHEP, Institute for High Energy Physics, Protvino, Russia
	Injection efficiency, beam optic matching and emittance preservation are very important parameters in achieving a high luminosity in large proton accelerators. We improved the analysing system of the phosphor screen readout of the proton transport lines in the accelerator chain of HERA with respect to the parameters above. The screens are read out by simple CCD video cameras. The signals are stored in local frame grabbers. An analogue output of the stored image is multiplexed and read-out by a fast PCI frame grabber card in a PC. The beam orbit and the beam emittance can be measured from each screen. A Visual Basic program is used to displays the trajectory and the envelope of the beam from a single transfer. The same program helps to drive bumps to achieve a proper steering through the line. The beam width can be measured from selected screens to calculate the emittance and other beam parameters including their errors. The read out and analysing system will be described and measurements will be shown.

PS14	Comparative test results of various beam loss monitors in preparation for LHC	ion, beam-losses, simulation, electron	132
	J. Bosser, G. Ferioli CERN, Geneva, Switzerland
	Beam loss detectors will play an important role in the protection of the superconducting LHC magnets. Different types of detectors have been tested in the SPS ring and secondary beam lines with a view to their possible use for this application. This paper describes the measurements made with: microcalorimeters at cryogenic temperatures, PIN diodes, ionisation chambers, scintillators, and ACEMs. Measurements made using proton beams showing their relative sensitivities, linearities in counting or analog mode and minimum detection level will be presented.

PS15	Beam profile measurements at 40 MHz in the PS to SPS transfer channel	injection, ion, radiation, kicker	135
	G. Ferioli, J.J. Gras, H. Hiller, R. Jung CERN, Geneva, Switzerland
	Bunch to bunch beam profile measurements provide a valuable tool to control the injection lines to the SPS. A fast profile monitor based on a 2.5μm Mylar coated with Aluminium Optical Transition Radiation (OTR) radiator, has been developed, installed and tested in the transfer line between the PS and SPS. The OTR beam image is focused onto a fast Linear Multianode Photo Multiplier Tube and the associated electronics sample and store profiles every 25ns. The paper describes the detector design, the electronic processing, and presents the results of different measurements made with bunches of 10⁹-10¹¹ protons at 26 GeV, and bunches of 10⁶ Pb⁸²⁺ ions at 5.11 GeV/u.

PS17	Beam Profile Detectors at the new fermilab injector and associated beamlines	instrumentation, booster, target, controls	141
	G. Tassotto, J. Zagel FNAL, Fermi National Accelerator Laboratory, Batavia, IL, USA
	Transition radiation (TR) is nowadays intensively exploited by a number of techniques to characterize different beam parameters. These methods are based, sometimes implicitly, on standard formulae, and used often without paying due attention to their applicability. In particular, standard expressions are only first-order asymptotic, i.e., strictly speaking, valid at infinity. In this paper TR is examined in a spatial domain where conventional results are no more exact and variations in radiation properties are observed. Under certain conditions, for example, at long wavelengths or very high energies the effect is so considerable that should be taken into account in accurate beam measurements.