摘要:

Four ionization beam profile monitors (IPM’s) are in RHIC to measure vertical and horizontal profiles in the two rings. Each IPM collects and measures the distribution of electrons in the beamline resulting from residual gas ionization during bunch passage. The ionized electron signal provides an accurate beam profile and the detectors are capable of measuring individual gold bunches. However the detectors are extremely sensitive and their performance has been limited by backgrounds from radiation spray, rf coupling to the beam, and secondary electrons. In 2002 two IPM’s were rebuilt using design changes which greatly reduced the backgrounds. During the summer 2003 shutdown another rebuild will increase the sweep electric field, make the electric field more uniform, and add a calibration system. The improvements in the electric field will increase the sensitivity to beam without increasing backgrounds and the calibration system will allow channel‐channel gain variations to be removed. These improvements should increase the detectors sensitivity to a level where the IPM can be considered as a beam halo monitor. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638341

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

To study CP violation, the HERA‐B experiment uses an internal wire target in the transverse halo of the stored HERA proton beam. Operational experience shows that the resulting interaction rates are extremely sensitive to tiny orbit jitter amplitudes. Various methods have been studied to stabilize these interaction rates by increasing diffusion in the transverse proton beam tails without affecting the luminosity at the electron‐proton collider experiments ZEUS and H1. Tune modulation was found to be a promising method for this task. Experiments performed in recent years will be reported. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638342

出版商:AIP    

年代:1903

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.1638343

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The ISIS 800 MeV proton synchrotron presently provides 2.5×1013protons per pulse at 50 Hz, corresponding to a mean power of 160 kW. A dual harmonic RF system upgrade, now being installed, is expected to increase the intensity and power to about 3.75×1013ppp and 240 kW respectively. This paper describes work presently underway to understand and optimise beam loss control, which is a dominant factor determining operational performance. The main features of the collimation system are described, and Monte Carlo simulations of the loss control process are used to understand variations of efficiency with beam loss mode (growth rate, plane). Results of simulations are compared with measurements and operational data. Improvements to measurements are also outlined. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638344

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

MARS14 Monte Carlo simulations were performed for collimation and shielding studies of the J‐PARC 3 GeV ring. A 400 MeV proton beam loss distribution, calculated with the STRUCT code, was used as a source term. The module locations in the ring and the curved tunnel sections were described by the MAD‐MARS beam line builder and a deep penetration calculation with good statistics was carried out using a 3‐dimensional multi‐layer technique. Prompt dose‐rate distributions were calculated inside and outside the concrete and soil shield, and an effective shielding design was made. The residual dose rates for various beam line materials were also calculated to estimate the external‐exposures during maintenance. In this paper, the calculation results are exemplified for the region from the injection through the collimator. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638345

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The collimating system in the accumulator ring and transfer lines of the Spallation Neutron Source (SNS) project is responsible for stopping 0.1&percent; of the 2 MW beam of 1.0 GeV protons that are in the beam halo. The collimating structures are a combination of movable beam scrapers and stationary absorbers. Specifically, pairs of charge‐exchange foils or scrapers moving in‐and‐out of the beam in the vertical and horizontal directions help guide the halo protons into respective absorbers which consist of an intricate design of a double wall beam tube, a water‐cooled particle bed and radial shielding. Off‐momentum protons, with the help of respective charge exchange foils and a dipole magnet, are directed to a momentum dump consisting of a cooled particle bed downstream of a double‐walled window separating it from the vacuum space. Addressed in this paper is the thermo‐mechanical response and survivability of key components of the collimating system (such as the collimating beam tube in the absorbers, the beam windows and the primary element of the bean scraper structure) in the event of intercept of the full beam under accident conditions. While the potential for the full beam to be intercepted by these components is remote, still special attention will be paid in assessing the amount of full beam (or number of pulses) they can tolerate. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638346

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The collimation system in the SNS ring includes a two‐stage collimator consisting of a halo scraper and an appropriate fixed aperture collimator. This unit is placed between the first quadru‐pole and the first doublet in the collimation straight section of the ring. The entire structure is surrounded by an outer shield structure. The downstream dose to the doublet and the attached corrector magnet will be estimated for normal operating conditions. In addition, the activities of cooling water, tunnel air, and dose to cables will be estimated. The dose at the flange locations will be estimated following machine shutdown. Finally, the implied dose to surroundings during the removal of an exposed collimator will be made. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638347

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The Spallation Neutron Source accelerator will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The expected highest doses to components are in the collimation regions. This paper presents the mechanical engineering design of a typical collimator highlighting the features incorporated to assist with collimator removal once it is activated. These features include modular shielding, integrated crane mounting, remote water fittings and vacuum clamps. Also presented is the design work in progress at present to validate the remote vacuum clamp design. This includes a test rig that mimics an active handling scenario where vacuum bellows can be compressed and clamps removed/replaced from a safe distance. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638348

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The Fermilab Collider Run I (1994–1996) experienced limitations in the Tevatron halo removal system that motivated upgrades for the halo removal system for the Collider Run II. The upgrade provided a new 2 stage collimator design, new designs for collimators and collimator motion control incorporating loss monitor and beam intensity feedback. A central process is used to coordinate the 12 collimator microprocessors that utilize local feedback to produce an automated halo removal system. The halo removal system and experiences for the Tevatron Collider Run II will be described. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638349

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

After a short review of past collimation work at LHC, the conception and baseline of the LHC collimation system are described. Abort‐gap cleaning and beam loss monitoring are also discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638350

出版商:AIP    

年代:1903

数据来源: AIP