Fabrication of silica aerogel with n=1.08 for e+/μ+ separation in a threshold Cherenkov counter of the J-PARC TREK/E36 experiment

• DOI: 10.1016/j.nima.2015.06.002
• Publication Date: 2015-06-12T04:04:13Z
• Authors: Makoto Tabata; Akihisa Toyoda; Hideyuki Kawai; Youichi Igarashi; Jun Imazato; Suguru Shimizu; Hirohito Yamazaki
• Keywords: High Energy Physics - Experiment (hep-ex); Physics - Instrumentation and Detectors; 0103 physical sciences; FOS: Physical sciences; Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex); Nuclear Experiment; 01 natural sciences; High Energy Physics - Experiment

This study presents the development of hydrophobic silica aerogel for use as a radiator in threshold-type Cherenkov counters. These counters are to be used for separating positrons and positive muons produced by kaon decay in the J-PARC TREK/E36 experiment. We chose to employ aerogel with a refractive index of 1.08 to identify charged particles with momenta of approximately 240 MeV/$c$, and the radiator block shape was designed with a trapezoidal cross-section to fit the barrel region surrounding the kaon stopping target in the center of the TREK/E36 detector system. Including spares, we obtained 30 crack-free aerogel blocks segmented into two layers, each layer having a thickness of 2 cm and a length of 18 cm, to fill 12 counter modules. Optical measurements showed that the produced aerogel tiles had the required refractive indices and transparency.<br/>To be published in Nucl. Instrum. Methods A,, 9 pages, 14 figures<br/>