Speaker
Description
In the Hadron Hall of J-PARC, we plan to measure the cross sections for exclusive Drell-Yan reaction ($π^- p→μ^+ μ^- n$) aiming to determine the generalized parton distribution functions (GPDs) of nucleons. The experiment will be conducted in the π20 beamline and MRPCs will be utilized for muon identification. An area of 1.8 m × 2.4 m will be covered by a MRPC that is designed to identify a muon pair from the Drell-Yan reaction. It is important to distinguish the desired muon pair from random combinatorial muons. For that purpose, we designed a MRPC that can measure timing and position simultaneously, which we call a TOF-tracker MRPC. We have designed 2-dimensional read-out strips for both zero-degree and 90-degree configurations. In the zero-degree read-out (X-direction), we utilize positive signals, while in the 90-degree configuration (Y-direction), we employ negative signals. The configuration is 1 stack, 0.26 mm $\times$ 5gaps, 500 mm $\times$ 1000 mm active area, and a 5 mm of strip pitch. We conducted a beam test at the LEPS2 beamline in the SPring-8 facility. We achieved more than 99 % efficiency, 65 ps time resolution, and 0.8 mm position resolution. The results satisfy the performance requirements, which are 99 % efficiency, 100 ps time resolution, and 1 mm position resolution. However, we are facing a shortage of carbon sheets that we have been using for the HV electrodes. As an alternative, we are exploring the possibility of utilizing several kinds of polymer-based conductive coatings. The performance of the prototype TOF-tracker and the test results of alternative electrodes will be presented in this report.
