LAT CU Heavy Ion Beam Test at GSI - Run Plan
Motivations
The CU Beam Test at GSI is part of the general beam test program of the GLAST LAT CU.
The main goal of the program is to support the LAT Instrument Calibration by providing direct measurements of the physical processes taking place in the CU detector when exposed to different beams, by comparing the obtained measurements with Monte Carlo predictions and by eventually validating the full LAT MC code used to provide instrument calibrations and background rejection strategies.
The first part of the program took place at CERN using a variety of different particle beams (e, e+, p, pions, photons) and ranging in energies from tens of MeV up to hundreds of GeV.
The second part of the program exploits the high energy heavy ion beams available at GSI to measure the response of the CU to such radiation. Heavy ions are an important component of primary cosmic rays, and the LAT plans to use them to calibrate the CAL and ACD subsystems during flight operations. Therefore the GSI test is primarily meant to verify the on-orbit calibration procedure for the CAL, which uses also the ACD and TKR subsystems for triggering and tracking.
The CU beam test at GSI is also a first test with heavy ions for the TKR subsystem.
List of topics
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Below is a list of specific topics of intereset for the subsystems
TKR: saturation effects from heavy ions on ToT signal, tracking performance, instrument deadtime
CAL: verification of quenching factors (measured at GSI 2003), test on-orbit calibration procedure and code
ACD: verification of CNO trigger, verify ACD dynamic range