YerPhI, Yerevan
Thermal sensors based on the vibrating wire principle are distinguished by high accuracy and stability. An important advantage of these sensors is that they produce a frequency signal that can be transferred large distances without disturbance. Original vibrating wire sensors and monitors for the measurement of beam transversal characteristics of charged-particle and photon beams are described. By means of these devices, measurements of an electron beam in the Yerevan synchrotron, a proton beam at PETRA (DESY), and a hard x-ray undulator beam at the APS (ANL) have been performed.
ANL, Argonne
YerPhI, Yerevan
A 5-wire vibrating wire monitor (VWM005) was developed and tested at the Advanced Photon Source (APS). The sensor was mounted on the outboard side of a bending-magnet synchrotron radiation terminating flange in sector 37 of the APS storage ring. The parallel wires were separated vertically by 0.5 mm; however, due to the possibility of rotation about a horizontal axis, the effective distance between the wires was reduced by 30%. To increase the response speed, the sensor was installed in air, resulting in a step response time of less than one second. Due to the extreme sensitivity of the detector, the very hard x-ray component of synchrotron radiation was successfully measured after its passage through the terminating flange.
Royal Holloway, University of London, Surrey
Lasers are increasingly being employed in particle beam diagnostics. Laser-based techniques are attractive because they are essentially non-invasive to the beam under test and can not be destroyed by it. They also have the potential to be extremely fast. Uses include transverse beam profile measurement at electron machines using the Compton effect,and at proton machines using laser-ionization of H- beams. An introduction is provided to Gaussian beam propagation and how this affects the laser properties and final focus optics needed for the various applications. Recent applications and results from ongoing research projects will be reviewed, with particular emphasis on the "laser-wire" systems recently employed at the PETRA and ATF machines.
ANL, Argonne
There are two parallel feedback systems to correct the transverse orbit at the Advanced Photon Source (APS) storage ring: a real-time feedback system that runs at 1.5 kHz using 38 fast correctors and up to 160 beam position monitors (BPMs), and a DC feedback system that runs at 10 Hz using up to 317 correctors and over 500 BPMs. An algorithm that uses the open- and closed-loop beam motion data to spatially locate strong noise sources in the storage ring is described. A simulation code has been developed to predict the ideal closed-loop beam motion data from measured open-loop beam motion data assuming no steering corrector noise. With the difference between predicted and measured closed-loop beam motion data and the full inverse response matrix, we compute the source candidate locations and infer their relative strengths for narrowband sources. The simulation process and experimental results with beam will be presented.
INFN/LNF, Frascati (Roma)
INFN-Roma, Roma
The DAΦNE Beam Test Facility (BTF), initially optimized to produce single electrons and positrons in the 25-750 MeV energy range, can now provide beam in a wider range of intensity, up to 1010 electrons/pulse. The facility has been also equipped with a system for the production of tagged photons, and the possibility of photo-production of neutron is under study. Different diagnostic tools have been developed and are available for high-energy users and accelerator community to monitor and check beam and device under test performance. The main results obtained, the performance and the most significant characteristics of the facility diagnostics and operation are presented, as well as the users experience collected during these years of operation.
Fermilab, Batavia
INFN/LNF, Frascati (Roma)
Università di Roma II Tor Vergata, Roma
ANL, Argonne
We have previously experimentally observed and modeled the near-field optical diffraction radiation (ODR) generated by a 3-nC micropulse of a 7-GeV electron beam at the Advanced Photon Source (APS). Due to the high gamma of ~14,000, the scaling factor of γλ/2π was about 1.4 mm for 0.628 um radiation. Thus, a standard CCD camera was sufficient for imaging at an impact parameter of 1.25 mm. The extension of this technique to γ 1000 is challenged by the ·1014 reduction in visible light photon production compared to the APS case. We discuss the feasibility of monitoring at a new Fermilab facility a high average current linac beam of 3000 times more charge in a video frame time and with a more sensitive 12- to 16-bit camera. Numerical integrations of our base model show beam size sensitivity for ±20% level changes at 200- and 400-um base beam sizes. We also evaluated impact parameters of 5 σy and 12 σy for both 800-nm and 10-um observation wavelengths. The latter examples are also related to a proposal to apply the technique to an ~ 0.94 TeV proton beam, but there are trades on photon intensity and beam size sensitivity to be considered at such gammas.
BNL, Upton, Long Island, New York
NSLS-II Storage Ring will provide ultrabright radiation sources with extra small sizes of the circulating electron beam. The beam dimensions will be monitored with a pinhole camera. In this paper we discuss possible design and ultimate achievable resolution of the system. The modeling is based on the SRW code as well as numerical calculations using MATLAB.
UMD, College Park, Maryland
I review the state of the art of diagnostics based on transition, diffraction and Smith Purcell radiation in the optical to millimeter wave band, which are currently being used to measure the transverse and longitudinal parameters of charged particle beams. The properties and diagnostic capabilities of both the incoherent and coherent forms of each type of radiation are described. Examples of TR, DR and SPR diagnostics for electron and proton beams are presented.
LBNL, Berkeley, California
The Advanced Light Source (ALS) in Berkeley was the first third generation light source ever built, and since 1993 has been in continuous and successful operation serving a large community of users in the VUV and soft x-ray community. During these years the storage ring underwent through several important upgrades that allowed to maintain the performances of this veteran facility at the forefront. The ALS beam diagnostics and instrumentation have followed a similar path of innovation and upgrade and nowadays include most of the modern and last generation devices and technologies that are commercially available and used in the recently constructed third generation light sources. In this talk we will not focus on such already widely known systems, but we will concentrate in the description of some measurements techniques, instrumentation and diagnostic system specifically developed at the ALS and used during the last few years.