138 research outputs found
Limits on Axion Couplings from the first 80-day data of PandaX-II Experiment
We report new searches for the solar axions and galactic axion-like dark
matter particles, using the first low-background data from PandaX-II experiment
at China Jinping Underground Laboratory, corresponding to a total exposure of
about kgday. No solar axion or galactic axion-like dark
matter particle candidate has been identified. The upper limit on the
axion-electron coupling () from the solar flux is found to be about
in mass range from to 1 keV/ with 90\%
confidence level, similar to the recent LUX result. We also report a new best
limit from the Fe de-excitation. On the other hand, the upper limit from
the galactic axions is on the order of in the mass range from 1
keV/ to 10 keV/ with 90\% confidence level, slightly improved
compared with the LUX.Comment: 5 pages, 4 figure
Exploring the dark matter inelastic frontier with 79.6 days of PandaX-II data
We report here the results of searching for inelastic scattering of dark
matter (initial and final state dark matter particles differ by a small mass
splitting) with nucleon with the first 79.6-day of PandaX-II data (Run 9). We
set the upper limits for the spin independent WIMP-nucleon scattering cross
section up to a mass splitting of 300 keV/c at two benchmark dark matter
masses of 1 and 10 TeV/c.Comment: 5 pages, 6 figure
Dark Matter Search Results from the Commissioning Run of PandaX-II
We present the results of a search for WIMPs from the commissioning run of
the PandaX-II experiment located at the China Jinping underground Laboratory. A
WIMP search data set with an exposure of 30619.1 kg-day was taken,
while its dominant Kr background was used as the electron recoil
calibration. No WIMP candidates are identified, and a 90\% upper limit is set
on the spin-independent elastic WIMP-nucleon cross section with a lowest
excluded cross section of 2.9710~cm at a WIMP mass of
44.7~GeV/c.Comment: 7 pages, 6 figures, v2 as accepted by PR
Dark Matter Results From 54-Ton-Day Exposure of PandaX-II Experiment
We report a new search of weakly interacting massive particles (WIMPs) using
the combined low background data sets in 2016 and 2017 from the PandaX-II
experiment in China. The latest data set contains a new exposure of 77.1 live
day, with the background reduced to a level of 0.8 evt/kg/day,
improved by a factor of 2.5 in comparison to the previous run in 2016. No
excess events were found above the expected background. With a total exposure
of 5.4 kg day, the most stringent upper limit on spin-independent
WIMP-nucleon cross section was set for a WIMP with mass larger than 100
GeV/c, with the lowest exclusion at 8.6 cm at 40
GeV/c.Comment: Supplementary materials at
https://pandax.sjtu.edu.cn/articles/2nd/supplemental.pdf version 2 as
accepted by PR
Constraining Dark Matter Models with a Light Mediator from PandaX-II Experiment
We search for nuclear recoil signals of dark matter models with a light
mediator in PandaX-II, a direct detection experiment in China Jinping
underground Laboratory. Using data collected in 2016 and 2017 runs,
corresponding to a total exposure of 54 ton day, we set upper limits on the
zero-momentum dark matter-nucleon cross section. These limits have a strong
dependence on the mediator mass when it is comparable to or below the typical
momentum transfer. We apply our results to constrain self-interacting dark
matter models with a light mediator mixing with standard model particles, and
set strong limits on the model parameter space for the dark matter mass ranging
from to .Comment: Version accepted by PRL, new figures (Fig.2 ) adde
Dark matter direct search sensitivity of the PandaX-4T experiment
The PandaX-4T experiment, a four-ton scale dark matter direct detection
experiment, is being planned at the China Jinping Underground Laboratory. In
this paper we present a simulation study of the expected background in this
experiment. In a 2.8-ton fiducial mass and the signal region between 1 to 10
keV electron equivalent energy, the total electron recoil background is found
to be 4.9x10^{-5} /(kg day keV). The nuclear recoil background in the same
region is 2.8x10^{-7}/(kg day keV). With an exposure of 5.6 ton-years, the
sensitivity of PandaX-4T could reach a minimum spin-independent dark
matter-nucleon cross section of 6x10^{-48} cm^{2} at a dark matter mass of 40
GeV/c^{2}.Comment: 11 pages, 13 figure
An Improved Evaluation of the Neutron Background in the PandaX-II Experiment
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 (s) in the (, 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 0.660.24 and 0.470.25 events, respectively.Comment: 9 pages, 9 figures, 7 tables; version2 accepted by Sci. China Phys.
Mech. Astro
Results of Dark Matter Search using the Full PandaX-II Exposure
We report the dark matter search results obtained using the full 132
tonday 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 cm at a WIMP mass of
30 GeV/.Comment: 23 pages, 19 figures, 6 tables, version published in Chinese Physics
A search for solar axions and anomalous neutrino magnetic moment with the complete PandaX-II data
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
for an axion mass less than and
the neutrino magnetic moment at 90%
confidence level. The observed excess from XENON1T is within our experimental
constraints.Comment: updated with an erratum CHIN. PHYS. LETT. Vol. 38, No. 10 (2021)
10990
Internal Calibration of the PandaX-II Detector with Radon Gaseous Sources
We have developed a low-energy electron recoil (ER) calibration method with
Rn for the PandaX-II detector. 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 ,
, and particles with focus on low energy ER events. During the
runs in 2017 and 2018, the amount of radioactivity of Rn were on the
order of 1\% of that of Rn and thorium particulate contamination was
negligible, especially in 2018. We also measured the background contribution
from Pb for the first time in PandaX-II with the help from a Rn
injection. Calibration strategy with Rn and Rn will be
implemented in the upcoming PandaX-4T experiment and can be useful for other
xenon-based detectors as well.Comment: 14 pages, 8 figures. published in JINS
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