CERN, Geneva
IHEP Protvino, Protvino, Moscow Region
Due to rapid progress with the LHC commissioning in 2010 set-up beam intensities were soon surpassed and damage potential reached. One of the key systems for machine protection is the beam loss monitoring (BLM) system. Around 4000 monitors are installed at likely or critical loss locations. Each monitor has 384 associated beam abort thresholds (12 integrated loss durations from 40 us to 83 s for 32 energy intervals). A single integrated loss over threshold on a single monitor aborts the beam. Simulations of deposited energy, critical energy deposition for damage or quench and BLM signal response backed-up by control measurements determined the initial threshold settings. The commissioning and optimization of the BLM system is presented. Test procedures were used to verify the machine protection functionalities and optimize the system parameters. Dedicated beam tests and accidental magnet quenches were used to fine-tune threshold settings. The most significant changes to the BLM system during the 2010 run concerned the injection, the collimation and the beam dump region, where hardware changes and threshold increases became necessary to accommodate for increasing beam intensity.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Royal Holloway, University of London, Surrey
STFC/RAL, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
The Rutherford Appleton Laboratory (RAL) is developing a Linac front end suitable for High Power Proton Applications (HPPA). The main components are an H- ion source with up to 60mA current at 65keV, a transport section to match the beam to an RFQ with 3MeV output energy and a MEBT comprising a chopper system with severalbuncher cavities. Photo detachment can be used as a non-destructive diagnostics method. The paper reports on progress with a beam profile monitor that is placed in a pumping vessel right after the ion source at the intersection to the Low Energy Beam Transport (LEBT). This consists of mirrors inside the vacuum to scan the laser beam through the beam, the actual detector to measure photo detached electrons, laser and optics outside the vacuum and electronics to amplify and read out the signal. The paper summarises the experimental set-up and status, discusses problems and presents recent measurements.
GSI, Darmstadt
As conventional intercepting diagnostics will not withstand high intensity ion beams, the non-destructive Beam Induced Fluorescence (BIF) method for transverse profile monitoring was extensively developed during the last years at the GSI heavy ion facility. An overview of the general performance, technical realization, applications and limitations will be given. Detailed investigations required for the optimization of this method were performed. Fluorescence spectra for various working gases like nitrogen and rare gases were recorded using an imaging spectrograph and wavelength selected beam profiles were obtained. The recorded profile width coincides for all working gases with the exception of He showing a significantly broader beam image. Experiments concerning the background contribution by beam induced neutrons and gammas were performed and the consequences for a possible installation close to a target will be discussed.
CIEMAT, Madrid
CNA, Sevilla
In the frame of the IFMIF-EVEDA accelerator project (a 125 mA, 9 MeV, 175 MHz (CW) Deuteron accelerator) two different optical non-interceptive monitors based on gas fluorescence has been designed and tested. One prototype of profiler is based on a PMT linear array whereas the other is based on a custom intensified CID camera. Both monitors have been tested at CNA cyclotron using 9 MeV deuterons up to 40 uA and 18 MeV protons up to 10 uA. Preliminary results of vertical beam profiles for deuterons and protons measured under different beam conditions are presented. The performance of both monitors under significant gamma and neutron background will be discussed. This optical beam diagnostic technique offers a non-invasive beam profile characterization for medium to high current hadron beams.
J-PARC, KEK & JAEA, Ibaraki-ken
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
The overview and the present status of residual gas ionization profile monitors (IPMs) for J-PARC will be presented. Measured turn by turn profiles demonstrate clear contributions from dipole and quadupole injection mismatches. Injection tunings by using the IPMs are essential for painting injection tunings of 3 GeV Rapid Cycling Synchrotron (RCS) as well as to measure the emittance. As for the IPMs for RCS (RCS-IPMs), a magnetic guiding field (Bg) which is parallel to an external electric field (Eext) is also used, on the other hands, only the Eext is used for IPM for Main Ring synchrotron (MR-IPM); the Eext applied perpendicularly to the beam axis projects the ionized charged particles on the detector plane. Collecting the ionized ions with no Bg, the beam position at the RCS-IPMs calculated by using the BPMs (PosBPM) and the profile center (PosIPM) by the RCS-IPM suggests that PosIPM=PosBPM/2, and thus the measured beam size is shrink to a half size. Numerical analyses reveal that the fringe field of the electrodes to produce the Eext is the main source. The issue on the profile distortion due to the fringe fields will be discussed together with recovery plans.
Fermilab, Batavia
A number of high-intensity, multi-GeV superconducting proton or H- linacs are being developed or proposed throughout the world. The intensity frontier, having been identified as one leg of the future of particle physics, can be addressed by the development of such a linac. These accelerators will place strict demands on the required beam diagnostics, especially in the development of non-interacting monitors such as profile and halo monitors. Fermilab has started the High Intensity Neutrino Source (HINS) project as a research linac to address accelerator physics and technology questions for high-intensity, long pulse H- superconducting linacs. The paper will discuss the beam diagnostic needs for these high-intensity linacs as well as the role of HINS as a test facility for the development of beam diagnostic instrumentation required for the intensity frontier.