## PandaX: Particle and Astrophysical Xenon Experiments

PandaX is a series of experimental projects that utilizes Xenon detectors to search for elusive dark matter particles and to understand the fundamental properties of neutrinos. The PandaX collaboration has now entered into the multi-ton stage of the project, PandaX-4T.

PandaX-II is a dark matter direct detection experiment equipped with a half-ton scale dual-phase time projection chamber (TPC), operated in CJPL between Oct. 2014 and June 2019. In 2016 and 2017, PandaX-II produced the world leading constraints to dark matter-nucleon interactions. See a list of scientific publications here.

With 6-ton of total Xenon and 4-ton sensitive target, PandaX-4T aims to improve the dark matter sensitivity by one order of magnitude in comparison to PandaX-II. PandaX-4T also plans to make sensitive searches on neutrinoless double beta decay of ${}^{136}Xe$ , and other signals from new physics. This project is expected to commence data taking in 2021.

PandaX-III searches for the possible neutrinoless double beta decay with 200 kg to one ton of 90% enriched ${}^{136}Xe$ in a high pressure gaseous Xenon TPC.

## News

• Recent result from PandaX-II was published on Physical Review Letter (Phys. Rev. Lett. 119, 181302, "Editor's Suggestion") on October 30, 2017, back-to-back with the first result from XENON1T experiment. The papers are highlighted by a Physics "Viewpoint" commentary by Dan Hooper from FNAL and Univ. of Chicago, commenting that “...

• The PandaX-II collaboration released the official WIMP search results using 54 ton-day exposure on Aug. 23, 2017. No excess events were found above the expected background. The most stringent upper limit on spin-independent WIMP-nucleon cross section was set for a WIMP mass greater than $100 GeV/c^{2}$, with the lowest exclusion at $8.6\times10^{-47} cm^{2}$ at $40 GeV/c^{2}$. The result reported here is more conservative than the preliminary result shown during the TeVPA2017 conference, due to the adoption of updated photon/electron detection efficiencies.

• Prof. Xiangdong Ji of Shanghai Jiao Tong University and University of Maryland, spokesperson of the PandaX Collaboration, announced new results on the dark matter (DM) search from the PandaX-II experiment on Monday Aug. 7, during the TeV Particle Astrophysics 2017 Conference at Columbus, Ohio, the United States. No DM candidate was identified within the data from an exposure of 54 ton-day, the largest reported DM direct detection data set to date.

• The PandaX observatory uses xenon as target and detector to search for WIMP particles as well as neutrinoless double beta decay ($0\nu\beta\beta$) in ${}^{136}Xe$. At present, the PandaX-II experiment is in operation in CJPL-I. The future PandaX program will pursue the following three main directions:

## Events

• Saturday, January 9, 2021 - 08:00
T. D. Lee Library

上海市物理学会粒子物理与核物理专委会及上海市核学会核物理专委会计划于2021年1月8日-10日在上海夏阳湖皇冠假日酒店举行2020年度联合学术交流会暨粒子物理与核物理上海研讨会，欢迎两个专委会的同事以及相关团队成员参会，开展学术交流；会议也将邀请国内有关专家参会交流。

• Saturday, January 4, 2020 - 08:00
Xichang
• Saturday, December 14, 2019 - 13:00
T. D. Lee Library