Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
The CESR Test Accelerator (CesrTA) program targets the study of beam physics issues relevant to linear collider damping rings and other low emittance storage rings. This endeavor requires new instrumentation to study the beam dynamics along trains of ultra-low emittance bunches. A key element of the program has been the design, commissioning and operation of an x-ray beam size monitor capable, on a turn by turn basis, of collecting single pass measurements of each individual bunch in a train over many thousands of turns. The x-ray beam size monitor development has matured to include the design of a new instrument which has been permanently integrated into the storage ring. A new beam line has been designed and constructed which allows for the extraction of x-rays from the positron beam using a newly developed electro magnet pair. This new instrument utilizes custom, high bandwidth amplifiers and digitization hardware and firmware to collect signals from a linear InGaAs diode array. This paper reports on the development of this new instrument and its integration into storage ring operation including vacuum component design, electromagnet design, electronics and capabilities.
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
We have designed a detector that measures the electron cloud density in a quadrupole magnet using two independent techniques. Stripline electrodes collect electrons that would otherwise impact the beam-pipe surface. The striplines are placed behind an array of small holes in the beam-pipe wall in order to shield them from the beam-induced electromagnetic pulse. There are three striplines placed near one of the pole tips so that they cover a roughly 0.43 radian azimuth. The beam-pipe chamber has also been designed so that microwave measurements of the electron cloud density can be performed. Beam position monitor buttons have been included for excitation and reception of microwaves and the chamber has been designed so that the resonant microwaves are confined to be within the 56 cm length of the quadrupole field. This paper provides some details of the design including CST Microwave Studio time domain simulation of the stripline detectors and eigenmode simulation of the resonant chamber. The detector is installed in the Cornell Electron Storage Ring and is part of the test accelerator program for the study of electron cloud using electron and positron beams from 2 to 5 GeV.