Showing papers by "Pengwei Xie published in 2020"
TL;DR: In this article, the results obtained using the full 132 ton·day exposure of the PandaX-II experiment, including all data from March 2016 to August 2018, were reported.
Abstract: We report the dark matter search results obtained using the full 132 ton·day exposure of the PandaX-II experiment, including all data from March 2016 to August 2018. No significant excess of events is identified above the expected background. Upper limits are set on the spin-independent dark matter-nucleon interactions. The lowest 90% confidence level exclusion on the spin-independent cross section is 2.2 × 10−46 cm2 at a WIMP mass of 30 GeV/c2.
100 citations
TL;DR: In this paper, the authors report the results obtained using the full 132 ton$\cdot$day exposure of the PandaX-II experiment, including all data from March 2016 to August 2018.
Abstract: We report the dark matter search results obtained using the full 132 ton$\cdot$day exposure of the PandaX-II experiment, including all data from March 2016 to August 2018. No significant excess of events is identified above the expected background. Upper limits are set on the spin-independent dark matter-nucleon interactions. The lowest 90% confidence level exclusion on the spin-independent cross section is $2.2\times 10^{-46}$ cm$^2$ at a WIMP mass of 30 GeV/$c^2$.
49 citations
TL;DR: In this paper, a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-II, in light of the recent event excess reported by XENON1T, is reported.
Abstract: We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-II, in light of the recent event excess reported by XENON1T. The data correspond to a total exposure of 100.7 ton-day with liquid xenon. With robust estimates of the dominant background spectra, we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment. We find that the axion-electron coupling $g_{Ae}<4.6\times 10^{-12}$ for an axion mass less than $\rm 0.1~keV/c^2$ and the neutrino magnetic moment $\mu_{
u}<4.9\times 10^{-11}\mu_{B}$ at 90\% confidence level. The observed excess from XENON1T is within our experimental constraints.
26 citations
TL;DR: In this article, the authors presented an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach, instead of fully relying on the Monte Carlo simulation, the overall neutron background is determined from the neutron-induced high energy signals in the data.
Abstract: In dark matter direct detection experiments, neutron is a serious source of background, which can mimic the dark matter-nucleus scattering signals. In this paper, we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach. Instead of fully relying on the Monte Carlo simulation, the overall neutron background is determined from the neutron-induced high energy signals in the data. In addition, the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator, where the correlated emission of neutron(s) and γ(s) in the (α, n) reactions and spontaneous fissions is taken into consideration. With this method, the neutron backgrounds in the Run 9 (26-ton-day) and Run 10 (28-ton-day) data sets of PandaX-II are estimated to be (0.66±0.24) and (0.47±0.25) events, respectively.
15 citations
TL;DR: In this article, a low-energy electron recoil (ER) calibration method with $^{220}$Rn was developed for the PandaX-II detector through the xenon purification system.
Abstract: We have developed a low-energy electron recoil (ER) calibration method with $^{220}$Rn for the PandaX-II detector. $^{220}$Rn, emanated from natural thorium compounds, was fed into the detector through the xenon purification system. From 2017 to 2019, we performed three dedicated calibration campaigns with different radon sources. We studied the detector response to $\alpha$, $\beta$, and $\gamma$ particles with focus on low energy ER events. During the runs in 2017 and 2018, the amount of radioactivity of $^{222}$Rn were on the order of 1\% of that of $^{220}$Rn and thorium particulate contamination was negligible, especially in 2018. We also measured the background contribution from $^{214}$Pb for the first time in PandaX-II with the help from a $^{222}$Rn injection. Calibration strategy with $^{220}$Rn and $^{222}$Rn will be implemented in the upcoming PandaX-4T experiment and can be useful for other xenon-based detectors as well.
11 citations
TL;DR: In this article, a low-energy electron recoil (ER) calibration method with 220Rn was developed for the PandaX-II detector, which can be used for other xenon-based detectors as well.
Abstract: We have developed a low-energy electron recoil (ER) calibration method with 220Rn for the PandaX-II detector. 220Rn, emanated from natural thorium compounds, was fed into the detector through the xenon purification system. From 2017 to 2019, we performed three dedicated calibration campaigns with different radon sources. We studied the detector response to α, β, and γ particles with focus on low energy ER events. During the runs in 2017 and 2018, the amount of radioactivity of 222Rn were on the order of 1% of that of 220Rn and thorium particulate contamination was negligible, especially in 2018. We also measured the background contribution from 214Pb for the first time in PandaX-II with the help from a 222Rn injection. Calibration strategy with 220Rn and 222Rn will be implemented in the upcoming PandaX-4T experiment and can be useful for other xenon-based detectors as well.
5 citations