Studies of the Earth shielding effect to direct dark matter searches at the China Jinping Underground Laboratory

Q. Wang,Y. L. Li ,Chih-Hsiang Yeh ,Jianfeng Yue ,H. J. Yu ,Juan Hu ,Jie Ren ,T. Xue,H. T. Jia ,Y. Y. Liu ,Y. Mao ,X. P. Geng ,R. M. J. Li ,Hui Ma ,Y. X. Wang ,H. T. Wong ,Y. D. Liu ,M. G. Zhao ,Longzhuang He ,Z. Y. Zhang ,S. K. Liu ,Qian Yue ,Zhi Deng ,Tuchen Huang ,K. K. Zhang ,Z. Y. Zhou ,J. M. Li ,Shou-De Lin ,C. X. Yu ,Ming Zeng ,Z. H. Zhang ,H. Gong,Y. L. Yan ,Ningchun Qi ,K. Kang ,L. Wang,G. F. Wang ,J. Li,Haipeng An ,Z. Z. Liu ,Y. Xu,Z. Wang,J. Cheng ,Haoyang Xing ,Bin Liao ,Jinhua Ning ,Y. H. Chen ,Y. Liu,Xuyuan Guo ,F. K. Lin ,Z. She,J. J. Zhu ,J. H. Chen ,M. K. Singh ,Jifang Zhou ,Tao Sun ,Jianping Cheng ,B. T. Zhang ,Yang Tian ,C. H. Fang ,Y. J. Li ,Hanxiong Huang ,X. Q. Li ,Q. Guo ,Kapil Saraswat ,V. Sharma,S. He ,W. Y. Tang ,Xichao Ruan ,Q. Y. Nie ,Yi Nan ,F. S. Zhang ,Y. Wang,H. Pan,L. T. Yang ,Wenhan Dai ,Xi Jiang ,X. Li ,M. Ağartıoğlu ,Y. C. Wu ,C. J. Tang ,H. B. Li ,Shiyong Wu ,Zhi Zeng ,H. Li

doi:10.1103/physrevd.105.052005

Abstract

Dark matter direct detection experiments mostly operate at deep underground laboratories. It is necessary to consider shielding effect of the Earth, especially for dark matter particles interacting with a large cross section. We analyzed and simulated the Earth shielding effect for dark matter at the China Jinping Underground Laboratory (CJPL) with a simulation package, CJPL Earth Shielding Simulation code (CJPL\_ESS), which is applicable to other underground locations. The further constraints on the $\chi$-N cross section exclusion regions are derived based on the studies with CDEX experiment data.

Highlights

Interacting massive particles (WIMPs, denoted as χ) as a dark matter candidate, have not been observed in direct detection experiments, which provided exclusion limits [1–5]
Direct detection experiments are usually located in deep underground laboratories such as China Jinping Underground Laboratory (CJPL) [6], SNOLab [7], and LNGS [8], which means that the dark matter particle will go through a few kilometers of rock before reaching the laboratory
We have introduced a Monte Carlo simulation package for Earth shielding effect

Summary

INTRODUCTION

Interacting massive particles (WIMPs, denoted as χ) as a dark matter candidate, have not been observed in direct detection experiments, which provided exclusion limits [1–5]. Direct detection experiments are usually located in deep underground laboratories such as China Jinping Underground Laboratory (CJPL) [6], SNOLab [7], and LNGS [8], which means that the dark matter particle will go through a few kilometers of rock before reaching the laboratory. References [9–12] have studied the shielding effect in detail, but the geometric model was the entire Earth with the laboratory placed on a spherical shell a few kilometers deep, where the undulating terrain above the laboratory has been ignored. In this way, these works may not be completely suitable for laboratories at traffic tunnel whose overburden are mountains, such as CJPL, LNGS. We analyze and simulate the Earth shielding effect for dark matter searches at CJPL, and we calculated the exclusion region of χ-N cross section with CDEX [1,13–20] experiment data

THEORY

SIMULATION

RESULT

Findings

DISCUSSION