Measurements on the low-intensity beams of LEAR and the antiproton accumulator

This report is complementary to that written by H. Koziol entitled 'Diagnostics for Low Intensity Beams' (CERN/PS 95-23 BD). Within this framework, we present and comment upon measurements made on some of the detectors already in use on the LEAR, AC and AA accelerators. Emphasis is placed on low-intensity beams and on the processing of weak signals, resulting from special diagnostics

Review of recent work on electron cooling at LEAR

The Low-Energy Antiproton Ring (LEAR) is expected to be used as an accumulator in the frame work of the LHC lead-ion project. This implies at first that the electron-cooled ions have a lifetime which is longer than the stacking time. On the other hand, in order to improve the electron-cooling time we expect to make use of large electron beam intensities, of the order of 0.5 A, at relativistic parameter b = v/c = 0.09. With such constraints the electron beam density is rather large so the induced space-charge forces become detrimental to the cooling process itself. A neutralization of the electron beam, which aims to reduce the effects of the space-charge forces, is therefore desirable. This paper describes the measurements made on the cooling and lifetimes and on the neutralization technique implemented on the LEAR electron cooler

Diffraction Radiation Angular Spectral Distributions

In a previous paper we have shown that, when applied to CLIC type beams, diffraction radiation (DR) should provide enough photons in the visible range to allow diagnostics measurements of the particle beam. In the present note we analyze in detail the horizontal and vertical polarization component distributions. Special emphasis is given to the influence of the electron beam r.m.s width and divergence

Comparative test results of various beam loss monitors in preparation for LHC

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

N2_2 and Xe Gas Scintillation Cross-Section, Spectrum, and Lifetime Measurements from 50 MeV to 26 GeV at the CERN PS and Booster

Beam parameters in CERN's Proton Synchrotron (PS) accelerator must be controlled (and measured) with tighter precision than ever before to meet the stringent requirements of the Large Hadron Collider (LHC) programme. A non-destructive beam profile measurement system would be a valuable diagnostic tool. To this end, we measured N2 and Xe gas scintillation absolute cross-sections and lifetimes for proton beam energies from 1.4 to 25 GeV, which should prove valuable in the design and construction of a gas scintillation profile measurement system. We also measured relative cross-sections for proton beam energies between 0.05 and 1.4 GeV

Transverse Profile Monitor using Ion Probe Beams

A profile monitor is described that makes use of a low-intensity and low-energy ion beam to measure the transverse profile of a dense proton beam of small dimensions. Three tehcniques are considered based on the use of ion beams having a pencil, curtain, or cylindrical shape. The detector is almost non-interceptive for the proton beam and does not introduce disturbances in the machine environment. The theroretical aspects of the techniques used, together with experimental results obtained at the CERN SPS and Linac, are presented

Test of a dispersion sweep correction system using a centroid in the DIRAC beam line

A new proton beam position detector named "centroid" is placed in the DIRAC target situation and is aligned with respect to the beam. Behind it there is a set of various targets used for the DIRAC experiment. The "centroid" itself collects the secondary electrons, which are emitted by the target when hit by the proton beam. This provides an on-line verification of the beam position without obstructing the beam path by a screen, and without perturbing the experiment. A computer application then calculates the corrections needed to centre the beam in both planes as a function of time. This report will explain how this is done

On the Optimum Dispersion of a Storage Ring for Electron Cooling with High Space Charge

With the intense electron beams used for cooling, matching of the ion and electron velocity over the largest possible fraction of the beam profile becomes important. In this situation, a finite dispersion from the ring in the cooling section can lead to an appreciable gain in the transverse cooling speed. Based on a simple model of the cooling force, an expression for the "optimum" dispersion as a function of the electron beam intensity, the momentum spread and other properties of the ion beam will be derived. This simple theory will be compared to measurements made on the Low Energy Ion Ring (LEIR) at CERN during 1997

LHC Beam Instrumentation Conceptual Design Report

The instruments and diagnostic systems considered for the LHC are presented and their specifications and expected performance discussed. Their task will be to measure the essential beam properties, establish diagnosis, and give information on beam behaviour. The diagnostic systems will be essential during the running-in period. Precise and reliable information from them are a prerequisite for operational optimization.During the last years, basic design and parameters of the LHC have evolved continuously. The present description of beam instrumentation and diagnostics is based on the most recent set of nominal LHC parameters