Spatial and temporal beam profile monitor with nanosecond resolution for CERN's Linac4 and Superconducting Proton Linac

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• 作者：M. Hori ; K. Hanke
• 关键词：Beam profile monitor ; Halo monitor ; Secondary electron emission ; Beam chopper
• 刊名：Nuclear Instruments and Methods in Physics Research Section A ; Accelerators ; Spectrometers ; Detectors and Associated Equipment
• 出版年：2008
• 期刊代码：41_01689002
• 类别：ph
• 出版时间：11 April 2008
• 卷：588
• 期：3
• 页码：359-374
• 文件大小：1058 K

摘要

The Linac4, now being developed at CERN, will provide 160-MeV H^- beams of high intensity . Before this beam can be injected into the CERN Proton Synchrotron Booster or future Superconducting Proton Linac for further acceleration, some sequences of 500-ps-long micro-bunches must be removed from it, using a beam chopper. These bunches, if left in the beam, would fall outside the longitudinal acceptance of the accelerators and make them radioactive. We developed a monitor to measure the time structure and spatial profile of this chopped beam, with respective resolutions and . Its large active area and dynamic range also allows investigations of beam halos. The ion beam first struck a carbon foil, and secondary electrons emerging from the foil were accelerated by a series of parallel grid electrodes. These electrons struck a phosphor screen, and the resulting image of the scintillation light was guided to a thermoelectrically cooled, charge-coupled device camera. The time resolution was attained by applying high-voltage pulses of sub-nanosecond rise and fall times to the grids. The monitor has been tested with 700-ps-long UV laser pulses, and a 3-MeV proton beam. Its response over a wide range of beam intensities between N_e5 and 4×10⁸ electrons emitted from the foil per pulse was studied. The monitor can also be used to measure the profiles of antiproton beams in the future facilities of Facility for Low-energy Antiproton Ion Research (FLAIR) or Extra Low Energy Antiproton Ring (ELENA).