CERN, Geneva
The protection of the LHC equipment against beam-induced destruction is given by losses lasting up to three revolutions and longer losses. For the fast losses a passive system consisting of collimators, absorbers and masks is used. For the others an active system consists of beam loss monitors, a beam interlock system and the beam dump. The LHC protection requirements are different to other accelerators. The differences are mainly due to its energy, its stored beam intensity and its dimension. At the LHC top energy the beam intensity is about 3 orders of magnitude above the destruction limit of the superconducting magnet coils and 11 orders above their fast loss quench limit. These extreme conditions require a very reliable damage protection and quench prevention with a high mean time between failures. The numerous amounts of loss locations require an appropriate amount of detectors. In such a fail safe system the false dump probability has to be kept low to keep high operation efficiency. A balance was found between a reliable protection and operational efficiency. The main protection systems and beam instrumentation aspects of the measurement systems will be discussed.
IHEP Beijing, Beijing
As the upgrade project of Beijing Electron Positron Collider (BEPC), BEPCII will still serve both high energy physics experiments and synchrotron radiation applications. The storage ring of BEPCII consists of electron ring (BER), positron ring (BPR) and synchrotron radiation ring (BSR). Up to now, we have completed two stages run. The first stage run started on Nov. 13, 2006 by using conventional magnets instead of superconducting (SC) magnets in the interaction region (IR). The second stage operation started on Oct. 24, 2007 by using SC magnets and without BESIII detector. In this paper, we will present the progress of the BEPCII storage ring diagnostics system along with the BEPCII commissioning, such as how Libera BPM has been used for the BPR first turn measurement and the injection residual orbit research of BER; COD measurement can satisfy the resolution requirement for the beam-beam scan in the IR and for the slow orbit feedback; BCM can help us on the different injection pattern; and the TFB system is important to suppress the strong multibunch instabilities when the higher beam current run. The tune meters and the beam-loss monitors are also described in this paper.
JLAB, Newport News, Virginia
CNU, Newport News, Virginia
Beamline components used for diagnostic elements often rely on thermal stabilization, continual physical maintenance (ie. tuning), and frequent beam-based calibrations to maintain specified performance. Direct-sequence spread spectrum (DSSS) pilot tones injected into a particular element and combined with the beam-derived signal can subsequently be separated and used to assess performance degradation. In addition, the DSSS tone can be used as a real-time calibration signal, without interference to the intended diagnostic signal. This paper demonstrates such a technique in the design of a Beam Current Monitor downconverter system, as an intended upgrade to the CEBAF Beam Loss Accounting system. A brief spread-spectrum primer is included, as well as a description of appropriate spreading codes and their generation.
GSI, Darmstadt
HIT, Heidelberg
The Heidelberg Ion Therapy Center (HIT) for tumor treatment is presently being commissioned using the beam diagnostic devices designed and produced by the GSI beam diagnostic department. To fulfil the requirements for hadron therapy a high-resolution analysis of the particle distribution within the slowly extracted beam is necessary. We present spill-structure measurements for carbon ion beams at energies from 88 MeV up to 430 MeV, also with respect to the spill-pause and abort functionality of the rf-knock-out extraction method. The spill-structure, as measured by internal intercepting ionization chambers (IC) is compared to data recorded with external beam loss monitors (BLM). The high-resolution data acquisition system with sampling rates up to 10 kSa/s and the connected detectors are described and the achievements during the commissioning phase are discussed.
ORNL, Oak Ridge, Tennessee
The original wire-scanner software was written by one of the Spallation Neutron Source (SNS) partners, Los Alamos National Laboratory. This software was designed for the types of wire-scanners initially planned and their planned usage at that time. New variations in the wire-scanner hardware added gearing, different position read-back methods, and a timing card. The new software handles these additional hardware variations in a flexible manner through configuration files. The software upgrade allows the user to synchronize the stepping of the fork with external applications, such as loss monitors to study the losses caused by the wire. Another new functionality allows you to change what part of the beam pulse is used to determine the transverse profile after the data has been taken. This avoids having to do time consuming rescans if the timing was not perfectly setup. The new software, also a LabVIEW program, is structured around a state-machine with sequence capability to manage the complexities of stepping through a scan and interacting with the user. This paper discusses the features of the new software, the implementation, and the obtained results.