Overview

In electron-positron colliders, precision monitoring of beam-beam relative position, size, and orientation is essential to achieving and maintaining high luminosity. The case has been made for using large angle beamstrahlung detection as an effective means to more closely monitor the many degrees of freedom of the beam-beam collision at current and future colliders. Beamstrahlung is produced at every bunch crossing when charged particles in one beam are deflected by the electromagnetic field of the second, causing them to emit 'short magnet' synchrotron radiation. Beamstrahlung light is distinct from the more plentiful synchrotron light produced as the beam is bent by the dipoles and quadrupoles in the interaction region. Important distinguishing characteristics include wider angular spread and broader spectrum. Despite the comparatively small amount of beamstrahlung power available, by carefully choosing both a large enough angle and a low enough frequency range to observe, the signal-to-noise ratio can be made favorable. Since the ratio of vertically polarized to horizontally polarized light (relative to the plane of the storage ring) for a given azimuthal location depends on beam-beam offset and other luminosity wasting pathologies, extracting the polarization information is critical to the operation. A prototype large angle beamstrahlung detector has been constructed at the Cornell Electron Storage Ring (CESR) and is now in operation. This thesis focuses on the investigation of the expected signal for the current CESR conditions, which are quite different from when the detector was initially 68 proposed. The model incorporates the physics of beamstrahlung, detector optics, and PMT quantum efficiencies. Important parameters required for the model were calculated using measurements obtained from the CESR and CLEO timelines databases. The detector still requires some fine-tuning, but overall the prognosis looks good for detection of beamstrahlung at CESR in the near future.

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