Estimation of Neutron dose during the Irradiation test of p-type Silicon Sensor for ALICE FoCal detector

¹ Nara Women’s University, Kitauoyahigashimachi, Nara, Nara, Japan
² Tsukuba University of Technology, Amakubo, Tsukuba, Ibaraki, Japan
³ University of Tsukuba, Tennodai, Tsukuba, Ibaraki, Japan
⁴ RIKEN, Hirosawa, Wako, Saitama, Japan
⁵ Xi’an Jiaotong University, Xi’an, Shaanxi, China
⁶ Juntendo University, Hongo, Bunkyo-ku, Tokyo, Japan

Published online: 7 March 2025

Abstract

What is unknown about Quark-Gluon Plasma (QGP) in heavy ion collisions is that it reaches thermal equilibrium much earlier than theoretically expected. And the Color Glass Condensate (CGC) is a strong candidate to explain this. The future forward calorimeter (FoCal), consisting of an electromagnetic calorimeter and a hadron calorimeter, is being developed to detect CGC experimentally. Since this calorimeter will be installed in the forward region from collision point, where it will be exposed to a large neutron dose, so we plan to use a p-type silicon sensor, known for its high neutron tolerance. And we need to investigate this radiation tolerance. To evaluate this, a neutron irradiation test was conducted at RIKEN (RANS) in July 2023. In this test, indium foil with highly sensitive to the amount of neutron irradiation was placed around the silicon sensor and irradiated with a neutron beam of about 10¹⁴ n_eq/cm² at the maximum, as assumed in the ALICE experiment. Since the neutron dose depends on the distance from the beam, then estimated the dose of the silicon sensor by analyzing the indium foil dose. As a result of this estimation, it was found that the silicon sensor with the highest neutron dose reached about 5 × 10¹³n_eq/cm².