Kevin Chalut, Albion College / NSCL Michigan State University

Title: Preparation and Testing of the CsI(Tl) Detectors for LASSA

Authors: K. Chalut (Albion College); W.G. Lynch, W. Tan (NSCL, Michigan State University)

Abstract: The LASSA (Large Array Silicon Strip detector Array) is a device designed for the reconstruction of the excitation energies of fragments emitted in multifragmentation reactions. Such information allows a determination of the yields of fragments in specific excited 
states and,through comparisons with statistical models,  a determination of the temperature of the multifragmenting system. This requires the measurement of the angles, energies, charges and mass of the detected particles with high accuracy. The energy information is obtained primarily from the CsI(Tl) detectors of LASSA. Since the light output of the CsI(Tl) crystals is sensitive to the thallium doping, the necessary resolution was ensured by carefully monitoring the thallium doping and selecting uniform crystals. The sensitivity to the surface preparation wrapping are also important. These issues were carefully tested and the resulting good energy resolution of the ASSA detectors reflects these choices as well.