Speaker
Description
Author
Kanato Matsutani$^{1,2}$ for the ePIC Japan Group
$^1$Graduate School of Advanced Science and Engineering, Hiroshima University, Japan
$^2$WPI-SKCM2, Hiroshima University, Japan
Abstract
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will collide polarized electrons with protons and nuclei to explore the partonic structure of matter. Hadron identification in the ePIC barrel relies on a time-of-flight layer (BTOF) of strip-type AC-coupled Low-Gain Avalanche Diodes (AC-LGADs) with 500 µm pitch and 1 cm long strips, with a per-hit timing requirement of 95 ps and a stretch goal of 40 ps. We evaluated strip AC-LGAD sensors through a beam test at KEK PF-AR with 2 GeV electrons and infrared laser TCT scans, and discuss how the measured time resolution maps onto the π/K separation reach. The beam test achieved about 60 ps per hit at -185 V, satisfying the requirement, after time-walk corrections using the pulse amplitude and the hit position reconstructed from signal sharing between neighboring strips. The TCT scans, which are free of ionization statistics, yield a per-channel resolution below 30 ps and characterize the signal propagation along the strip. The origin of the difference between the two measurements is under investigation, considering Landau fluctuations, the reference MCP-PMT contribution, and the smaller signal amplitude of the present sensors. We present these studies and the prospects toward the stretch goal.
