Development of Shashlyk calorimeter for KOPIO

Abstract

A Shashlyk calorimeter prototype for the KOPIO experiment has been constructed and experimentally tested. The energy resolution of about 4%/ E(GeV) for 0.5 ÷ 2.0 GeV/c positrons was obtained. Based on this results as well as on the results of special measurements, a Monte-Carlo model of the Shashlyk module response was developed. This model, including the effects of shower evolution, light collection in scintillator plates, light attenuation in fibers, quantum efficiency of the photodetector, thresholds and noises in the readout system is consistent with experimental results. Possible improvment of the Shashlyk energy resolution up to 3%/ E(GeV), the level required by KOPIO experiment, are discussed.

An improved Shashlyk calorimeter

“…As shown in Fig. 5, the parametric dependence of the light collection efficiency on the attenuation length, calculated from our model of module optics [3], is in a good agreement with the experimental results.…”

“…This paper describes the design and construction of the module, as well as the unit's performance in prototype tests. It is further development of the work described in Ref [3].…”

“…Analyzing the performance of the prototype Shashlyk module with energy resolution of about 4%/ E(GeV) 1 we found, that energy resolution of about 3.0%/ E(GeV) could be reached after some optimization of the module's mechanical and optical properties (see details in Ref. [3]). …”

“…At the outset of improving the module a detailed simulation model was developed [3]. This model is based on a GEANT3 [8] description of electromagnetic shower and a special optical simulation of the light collection in the scintillator plates.…”

“…Nevertheless, by removing the paper between the lead and scintillator tiles, both the sampling could be improved and the length of the module could be shortened. Compared to the design of the previous module [3], the sampling ratio was improved by a factor of 1.25.…”