NRA-97-13-OSS-013 ABSTARCT

PI: Eun-Suk Seo

TITLE: Optimized Calorimeter for ACCESS Measurements of Z=1-26 Nuclei and Electrons

It is proposed to carry out extensive modeling and simulations relevant to assessing the performance of the ACCESS ionization calorimeter. The calculations will focus on the measurements necessary to achieve the primary objective to measure the elemental composition and energy spectra of Z=1 to 26 nuclei from about 10 GeV up to 1000 TeV, but they will also include studies relevant to measurements of cosmic ray electrons. Trade offs among different ACCESS configurations will be studied to optimize the calorimeter within the ISS constraints, taking into account the transition radiation and charge measuring detectors. Our experience in modeling and simulations for the ATIC (Advanced Thin Ionization Calorimeter) balloon experiment has already been used to develop the basic code for simulating the ACCESS baseline BGO calorimeter. However, calculations for only some representative energies below 100 TeV have been made, so it will be necessary to extend the calculations for the baseline instrument to the required higher energies. We also propose to simulate several different calorimeter configurations that could potentially facilitate electron measurements. Furthermore, we will simulate other absorber materials such as PbWO4, which is being considered for use in the CMS experiment for the LHC at CERN, and we will conduct laboratory studies of some critical properties of this new crystal. In addition, we propose to serve as the liaison between the ACCESS science community and Fermilab, Brookhaven National Laboratory, and CERN, in order to facilitate critical beam tests that would provide data to check the simulations and calibrate ACCESS prototypes.