Diamond, Oxfordshire
JAI, Egham, Surrey
UCL, London
Royal Holloway, University of London, Surrey
This paper describes the design of a cavity BPM for use in single pass machines. The design was modelled using a number of different EM codes to allow cross comparison of the simulation results. Furthermore, in addition to existing designs, the geometry has been modified to introduce a frequency separation between the horizontal and vertical dipole signals, as well as a reduction of the sensitivity of the position monitor to the monopole sum signal. The next stage of this project will be the manufacture of a prototype for tests in the transfer path at Diamond Light Source.
SLAC, Menlo Park, California
ANL, Argonne
CERN, Geneva
The Linac Coherent Light Source (LCLS) is a free-electron laser (FEL) at SLAC producing coherent 1.5 angstrom x-rays. This requires precise and stable alignment of the electron and photon beams in the undulator. We describe construction and operational experience of the beam position monitor (BPM) system which allows the required alignment to be established and maintained. Each X-band cavity BPM employs a TM010 monopole reference cavity and a single TM110 dipole cavity detecting both horizontal and vertical beam position. The processing electronics feature low-noise single-stage three-channel heterodyne receivers with selectable gain and a phase-locked local oscillator. Sub-micron position resolution is required for a single-bunch beam of 200 pC. We discuss the specifications, commissioning and performance of 36 installed BPMs. Single shot resolutions have been measured to be about 200 nm rms at a beam charge of 200 pC.
Fermilab, Batavia
CERN, Geneva
In the context of the development of a high resolution BPM system for the CLIC Main Linac we present the design of a cavity BPM prototype. It consists of a waveguide loaded dipole mode resonator and a monopole mode reference cavity, both operating at 15 GHz, to be compatible with the bunch frequencies at the CLIC Test Facility. Requirements, design concept, numerical analysis, and practical considerations are discussed.
CEA, Gif-sur-Yvette
IPN, Orsay
The European XFEL is a research facility, currently under construction in Germany. It is based on a superconducting electron linac including about 100 cryomodules based on the TESLA technology. Each cryomodule is equipped with a beam position monitor connected to a quadrupole at the high-energy end of the cavity string. Around one third of cold BPMs will be re-entrant RF cavities. This contribution will describe the present status of the cold re-entrant cavity BPM, and will present measurements of the BPM pickup and electronics prototypes.
BNL, Upton, Long Island, New York
AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it’s beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore deliberately spoil the Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning the resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The ALBA Booster is a synchrotron designed to accelerate electron beam from 100 MeV to 3 GeV in a 3 Hz cycle. The maximum pulse coming from the ALBA Linac provides 4 mA in the Booster. In order to check all the Booster sub-systems, a Booster pre-commissioning took place during two weeks between December 2009 and January 2010. This paper presents the Diagnostics elements installed in the ALBA Booster and our experience during the Booster pre-commissioning.
LAL, Orsay
The PHIL (PhotoInjector at LAL: http://phil.lal.in2p3.fr/ ) accelerator is the new LAL (Orsay, France) facility dedicated to test state-of-the-art RF and beam sources technologies used for future electron accelerators. The machine based on 3 GHz RF gun triggered with a 262 nm wavelength laser, delivers a low energy ( E<10 MeV) single pulse electron beam at 5 Hz, with a low charge (0.1 nC) for now. The machine is about 5 meters long, with one direct and one deviated beam line (created after a 60° dipole). This paper describes the current status (first beam in november 2009) and the development of the diagnostics sections of the machine. At present, the machine is equipped by a transverse beam profile monitor based on «YAG:Ce» screen (30 mm diameter and 300 micrometers thick), two BPMs (one "button type" and one "reentrant resonators" type) and two Faraday cups (at the end of each line). The paper will present some preliminary results of the dimension and position of the beam at specific point for different charges and phase, and will present the expected development of the diagnostics of the machine (measurement of mean and energy dispersion, 2D emittance, beam length).