You are here

Publications

PandaX-xT—A deep underground multi-ten-tonne liquid xenon observatory

Sci. China Phys. Mech. Astron., Vol.68, 221011(2024)

We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory. The new experiment, PandaX-xT, will be a multi-ten-tonne liquid xenon, ultra-low background, and general-purpose observatory. The full-scaled PandaX-xT contains a 43-t liquid xenon active target. Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics. The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits, approaching the so-called “neutrino floor” for a dark matter mass above 10 GeV/c2, providing a key test to the Weakly Interacting Massive Particle paradigm. By searching for the neutrinoless double beta decay of 136Xe isotope in the detector, the effective Majorana neutrino mass can be measured to a 10–41 meV/c2 sensitivity, providing a key test to the Dirac/Majorana nature of neutrinos. Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level, opening up new windows of discovery. Depending on the findings, PandaX-xT will seek the next stage upgrade utilizing isotopic separation of natural xenon.

DOI:10.1007/s11433-024-2539-y

First Indication of Solar 8^B Neutrinos through Coherent Elastic Neutrino-Nucleus Scattering in PandaX-4T

Phys. Rev. Lett., Vol.133, 191001(2024)

The PandaX-4T liquid xenon detector at the China Jinping Underground Laboratory is used to measure the solar 8B neutrino flux by detecting neutrinos through coherent scattering with xenon nuclei. Data samples requiring the coincidence of scintillation and ionization signals (paired), as well as unpaired ionization-only signals (US2), are selected with energy threshold of approximately 1.1 keV (0.33 keV) nuclear recoil energy. Combining the commissioning run and the first science run of PandaX-4T, a total exposure of 1.20 and 1.04 tonne·year are collected for the paired and US2, respectively. After unblinding, 3 and 332 events are observed with an expectation of 2.8±0.5 and 251±32 background events, for the paired and US2 data, respectively. A combined analysis yields a best-fit 8B neutrino signal of 3.5 (75) events from the paired (US2) data sample, with ∼37% uncertainty, and the background-only hypothesis is disfavored at 2.64σ significance. This gives a solar  8B neutrino flux of (8.4±3.1)×106 cm-2 s-1, consistent with the standard solar model prediction. It is also the first indication of solar B8 neutrino “fog” in a dark matter direct detection experiment.

DOI:10.1103/PhysRevLett.133.191001

Search for cosmic-ray boosted sub-MeV dark matter-electron scatterings in PandaX-4T

Phys. Rev. Lett. , Vol.133, 101805 (2024)

We report the first search for the elastic scatterings between cosmic-ray boosted sub-MeV dark matter (DM) and electrons in the PandaX-4T liquid xenon experiment. Sub-MeV DM particles can be accelerated by scattering with electrons in the cosmic rays and produce detectable electron recoil signals in the detector. Using the commissioning data from PandaX-4T of 0.63  tonne·year exposure, we set new constraints on DM-electron scattering cross sections for DM masses ranging from 10  eV/c2 to 3  keV/c2.

DOI:10.1103/PhysRevLett.133.101805

Signal response model in PandaX-4T

Phys. Rev. D, Vol.110, 023029(2024)

PandaX-4T experiment is a deep-underground dark matter direct search experiment that employs a dual-phase time projection chamber with a sensitive volume containing 3.7 tonne of liquid xenon. The detector of PandaX-4T is capable of simultaneously collecting the primary scintillation and ionization signals, utilizing their ratio to discriminate dark matter signals from background sources such as gamma rays and beta particles. The signal response model plays a crucial role in interpreting the data obtained by PandaX-4T. It describes the conversion from the deposited energy by dark matter interactions to the detectable signals within the detector. The signal response model is utilized in various PandaX-4T results. This work provides a comprehensive description of the procedures involved in constructing and parameter-fitting the signal response model for the energy range of approximately 1 keV to 25 keV for electronic recoils and 6 keV to 90 keV for nuclear recoils. It also covers the signal reconstruction, selection, and correction methods, which are crucial components integrated into the signal response model.

DOI:10.1103/PhysRevD.110.023029

Radon removal commissioning of the PandaX-4T cryogenic distillation system

JINST, Vol.19, 07010(2024)

The PandaX-4T distillation system, designed for the removal of krypton and radon from xenon, is evaluated for its radon removal efficiency using a 222Rn source during the online distillation process. The PandaX-4T dark matter detector is employed to monitor the temporal evolution of radon activity. To determine the radon reduction factor, the experimental data of radon atoms introduced into and bypassed the distillation system is compared. The results indicate that the PandaX-4T distillation system achieves a radon reduction factor exceeding 190 at the flow rate of 10 slpm and the reflux ratio of 1.44. Gas-only online distillation process of a flow rate of 20 slpm is also conducted without observing significant reduction of radon levels in the detector. This observation suggests that the migration flow of radon atoms from the liquid phase to the gas phase is limited, and the flow rate of gas circulation and duration of the process are insignificant compared to the total xenon mass of 5.6 tons in the detector. This study provides the experimental data to support the efficient removal of radon at  ∼Bq level using the PandaX-4T distillation system, which is the prerequisite of the radon background control in the detector. The further operation with higher flow rate will be applied for the upcoming science run in PandaX-4T.

DOI:10.1088/1748-0221/19/07/P07010

Search for solar pp neutrinos using PandaX-4T electron recoil data

Chin. Phys. C, Vol.48, 091001(2024)

The proton-proton (pp) fusion chain dominates the neutrino production in the Sun. The uncertainty of the predicted pp neutrino flux is at the sub-percent level, whereas that of the best measurement is O(10%). In this study, for the first time, we measure solar pp neutrinos in the electron recoil energy range from 24 to 144 keV using the PandaX-4T commissioning data with 0.63 tonne × year exposure. The pp neutrino flux is determined as (8.0 ± 3.9 (stat) ± 10.0 (syst)) × 1010 s-1 cm-2 , which is consistent with the Standard Solar Model and existing measurements, corresponding to an upper flux limit of 23.3×1010 s-1cm-2 at 90% C.L..

DOI:10.1088/1674-1137/ad582a

Data reduction strategy in the PandaX-4T experiment

JINST, Vol.19, 05029(2024)

The PandaX-4T experiment is designed for multiple purposes, including searches for solar neutrinos, weakly interacting massive particles, and rare double beta decays of xenon isotopes. The experiment produces a huge amount of raw data that needs to be stored for related physical analyses in a wide energy range. With the upgrading of the PandaX-4T experiment, the doubled sampling rate resulted in a larger data size, which challenges both the cost and the data processing speed. To address this issue, we propose a data reduction strategy by removing the noise tail of large signals and downsampling the remaining parts of them. This strategy reduces the requirement for storage by 65% while increasing data processing speed. The influences on physical analyses on different topics at different energy regions are negligible.

DOI:10.1088/1748-0221/19/05/P05029

Improvement on the linearity response of PandaX-4T with new photomultiplier tubes bases

JINST, Vol.19, 05021(2024)

With the expanding reach of physics, xenon-based detectors such as PandaX-4T in the China Jinping Underground Laboratory aim to cover an energy range from sub-keV to multi-MeV. A linear response of the photomultiplier tubes (PMTs) is required for both scintillation and electroluminescence signals. Through a dedicated bench test, we investigated the cause of the non-linear response in the Hamamatsu R11410-23 PMTs used in PandaX-4T. The saturation and suppression of the PMT waveform observed during the commissioning of PandaX-4T were caused by the high-voltage divider base. The bench test data validated the de-saturation algorithm used in the PandaX-4T data analysis. We also confirmed the improvement in linearity of a new PMT base design with three more low radioactivity capacitors at later dynodes, which will be used to upgrade the PMT readout system in PandaX-4T.

DOI:10.1088/1748-0221/19/05/P05021

Detecting Neutrinos from Supernova Bursts in PandaX-4T

Chinese Physics C, Vol.48, 7(2024)

Neutrinos from core-collapse supernovae are essential for understanding neutrino physics and stellar evolution. Dual-phase xenon dark matter detectors can be used to track explosions of galactic supernovae by detecting neutrinos through coherent elastic neutrino-nucleus scatterings. In this study, a variation of progenitor masses and explosion models are assumed to predict neutrino fluxes and spectra, which result in the number of expected neutrino events ranging from 6.6 to 13.7 at a distance of 10 kpc over a 10-s duration with negligible backgrounds at PandaX-4T. Two specialized triggering alarms for monitoring supernova burst neutrinos are built. The efficiency of detecting supernova explosions at various distances in the Milky Way is estimated. These alarms will be implemented in the real-time supernova monitoring system at PandaX-4T in the near future, which will provide supernova early warnings for the astronomical community.

DOI:10.1088/1674-1137/ad3efe

Waveform simulation in PandaX-4T

Chin. Phys. C, Vol.48, 073001(2024)

Signal reconstruction through software processing is a crucial component of the background and signal models in the PandaX-4T experiment, which is a multi-tonne dark matter direct search experiment. The accuracy of signal reconstruction is influenced by various detector artifacts, including noise, dark count of photomultiplier, photoionization of impurities in the detector, and other relevant considerations. In this study, we presented a detailed description of a semi-data-driven approach designed to simulate a signal waveform. This work provides a reliable model for the efficiency and bias of the signal reconstruction in the data analysis of PandaX-4T. By comparing critical variables that relate to the temporal shape and hit pattern of the signals, we found good agreement between the simulation and data.

DOI:10.1088/1674-1137/ad380f

Search for Light Dark Matter with Ionization Signals in the PandaX-4T Experiment

Phys. Rev. Lett., Vol.130, 261001 (2023)

We report the search results of light dark matter through its interactions with shell electrons and nuclei, using the commissioning data from the PandaX-4T liquid xenon detector. Low energy events are selected to have an ionization-only signal between 60 to 200 photoelectrons, corresponding to a mean nuclear recoil energy from 0.77 to 2.54 $keV$ and electronic recoil energy from 0.07 to 0.23 $keV$. With an effective exposure of 0.55 tonne · year, we set the most stringent limits within a mass range from 40 $MeV/c^2$ to 10 $GeV/c^2$ for pointlike dark matter-electron interaction, 100 $MeV/c^2$ to 10 $GeV/c^2$ for dark matter-electron interaction via a light mediator, and 3.2 to 4 $GeV/c^2$ for dark matter-nucleon spin-independent interaction. For DM interaction with electrons, our limits are closing in on the parameter space predicted by the freeze-in and freeze-out mechanisms in the early Universe.

DOI:10.1103/PhysRevLett.130.261001

Limits on the luminance of dark matter from xenon recoil data

Nature(2023)

It is commonly conjectured that dark matter is a charge neutral fundamental particle. However, it may still have minute photon-mediated interactions through millicharge or higher-order multipole interactions, resulting from new physics at a high energy scale. Here we report a direct search for effective electromagnetic interactions between dark matter and xenon nuclei that produce a recoil of the latter from the PandaX-4T xenon-based detector. Using this technique, the first constraint on the charge radius of dark matter is derived with the lowest excluded value of $1.9 \times 10^{-10} fm^{2}$ for a dark matter mass of 40 giga electron volts per speed of light in a vaccum ($GeV / c^{2}$) more stringent than that for neutrinos by four orders of magnitude. Constraints on the magnitudes of millicharge, magnetic dipole moment, electric dipole moment and anapole moment are also improved substantially from previous searches, with corresponding tightest upper limits of $2.6 \times 10^{-11}e$, $4.8 \times 10^{-10}$ Bohr magnetons, $1.2 \times 10^{-23}$ ecm and $1.6 \times 10 ^{-33} cm^{2}$, respectively, for a dark matter mass of 20–40 $GeV / c^{2}$.

DOI:10.1038/s41586-023-05982-0

Search for Solar 8^B Neutrinos in the PandaX-4T Experiment Using Neutrino-Nucleus Coherent Scattering

Phys. Rev. Lett., Vol.130, 021802(2023)

A search for interactions from solar $^8B$ neutrinos elastically scattering off xenon nuclei using PandaX-4T commissioning data is reported. The energy threshold of this search is further lowered compared with the previous search for dark matter, with various techniques utilized to suppress the background that emerges from data with the lowered threshold. A blind analysis is performed on the data with an effective exposure of 0.48 tonne year, and no significant excess of events is observed. Among the results obtained using the neutrino-nucleus coherent scattering, our results give the best constraint on the solar $^8B$ neutrino flux. We further provide a more stringent limit on the cross section between dark matter and nucleon in the mass range from 3 to 9 $GeV/c^2$.

DOI:https://doi.org/10.1103/PhysRevLett.130.021802

Measurement of double beta decay half-life of 136Xe with the PandaX-4T detector

(2022)

Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double-beta decay. We report the measurement of DBD half-life of ${}^{136}Xe$ using the PandaX-4T dual-phase Time Projection Chamber (TPC) with 3.7-tonne natural xenon and the first 94.9-day physics data release. The background model in the fiducial volume is well constrained in situ by events in the outer active region. With a ${}^{136}Xe$ exposure of 15.5 kg-year, we establish the half-life as 2.27±0.03(stat.)±0.10(syst.) $\times 10^{21}$ year. This is the first DBD half-life measurement with natural xenon and demonstrates the physics capability of a large-scale liquid xenon TPC in the field of rare event searches.

DOI:10.48550/arXiv.2205.12809

Search for light fermionic dark matter absorption on electrons in PandaX-4T

Physical Review Letters, Vol.129, 161804(2022)

We report a search on sub-MeV fermionic dark matter absorbed by electrons with an outgoing active neutrino using the $0.63$ tonne year exposure collected by the PandaX-4T liquid xenon experiment. No significant signals are observed over the expected background. The data are interpreted into limits to the effective couplings between such dark matter and the electron. For axial-vector or vector interactions, our sensitivity is competitive in comparison to existing astrophysical bounds on the decay of such a dark matter candidate into photon final states. In particular, we present the first direct detection limits for a vector (axial-vector) interaction which are the strongest in the mass range from $35$ to $55$ ($25$ to $45$) $keV/c^2$ in comparison to other astrophysical and cosmological constraints.

DOI:10.1103/PhysRevLett.129.161804

First search for the absorption of fermionic dark matter with the PandaX-4T experiment

Physical Review Letters, Vol.129, 161803(2022)

Compared to the signature of dark matter elastic scattering off nuclei, absorption of fermionic dark matter by nuclei opens up a new searching channel for light dark matter with a characteristic mono-energetic signal. In this letter, we explore the 95.0-day data from PandaX-4T commissioning run and report the first dedicated searching results of the fermionic dark matter absorption signal through neutral current process. No significant signal was found and the lowest limit on the dark matter-nucleon interaction cross section is set to be $ 1.5 \times 10^{-50} cm^{2} $ for a fermionic dark matter mass of $40 MeV / c^{2}$ with 90% confidence level.

DOI:10.1103/PhysRevLett.129.161803
arXiv:2205.15771

Constraints on the axial-vector and pseudo-scalar mediated WIMP-nucleus interactions from PandaX-4T experiment

Physics Letters B(2022)

We present the constraints on the axial-vector and pseudo-scalar mediated WIMP-nucleus interactions from the PandaX-4T experiment, using the data set corresponding to a total exposure of 0.63 tonne⋅year. No significant signal excess is observed, and the most stringent upper limits to date on the spin-dependent WIMP-neutron scattering cross section are set at 90% confidence level with the minimum WIMP-neutron scattering cross section of $5.8\times 10^{-42}cm^{2}$ for WIMP mass of 40 $GeV/c^{2}$. Exclusion limits on the axial-vector and pseudo-scalar simplified models are also derived.

arXiv:2208.03626

A search for two-component Majorana dark matter in a simplified model using the full exposure data of PandaX-II experiment

Physics Letters B, Vol.832, 137254(2022)

In the two-component Majorana dark matter model, one dark matter particle can scatter off the target nuclei, and turn into a slightly heavier component. In the framework of a simplified model with a vector boson mediator, both the tree-level and loop-level processes contribute to the signal in direct detection experiment. In this paper, we report the search results for such dark matter from PandaX-II experiment, using total data of the full 100.7 tonne⋅day exposure. No significant excess is observed, so strong constraints on the combined parameter space of mediator mass and dark matter mass are derived. With the complementary search results from collider experiments, a large range of parameter space can be excluded.

DOI:10.1016/j.physletb.2022.137254
arXiv:2205.08066

Study of background from accidental coincidence signals in the PandaX-II experiment

Chinese Physics C, Vol.46, 103001(2022)

Study of background from accidental coincidence signals in the PandaX-II experiment

DOI: 10.1088/1674-1137/ac7cd8

Neutron-induced nuclear recoil background in the PandaX-4T experiment

Chinese Physics C(2022)

Neutron-induced nuclear recoil background is critical to the dark matter searches in the PandaX-4T liquid xenon experiment. This paper studies the feature of neutron background in liquid xenon and evaluates their contribution in the single scattering nuclear recoil events through three methods. The first method is fully Monte Carlo simulation based. The last two are data-driven methods that also use the multiple scattering signals and high energy signals in the data, respectively. In the PandaX-4T commissioning data with an exposure of 0.63 tonne⋅year, all these methods give a consistent result that there are 1.15±0.57 neutron-induced background in dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.

DOI:10.1088/1674-1137/ac8539
arXiv:2206.06087

Low radioactive material screening and background control for the PandaX-4T experiment

Journal of High Energy Physics, Vol.06, 147(2022)

PandaX-4T is a ton-scale dark matter direct detection experiment using a dual-phase TPC technique at the China Jinping Underground Laboratory. Various ultra-low background technologies have been developed and applied to material screening for PandaX·4T, including HPGe gamma spectroscopy, ICP-MS, NAA, radon emanation measurement system, krypton assay station, and alpha detection system. Low background materials were selected to assemble the detector. Surface treatment procedures were investigated to further suppress radioactive background. Combining measured results and Monte Carlo simulation, the total material background rates of PandaX-4T in the energy region of $1–25$ $keV_{ee}$ are estimated to be $(9.9 ± 1.9)$ $\times$ $10^{−3} $mDRU$ for electron recoil and $(2.8 ± 0.6)$ $\times$ $10^{−4}$ $mDRU$ for nuclear recoil. In addition, ${}^{nat}Kr$ in the detector is estimated to be < $8$ $ppt$.

DOI:10.1007/JHEP06(2022)147

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter at the PandaX-II Experiment

Physical Review Letters, Vol.128, 171801(2022)

We report a novel search for the cosmic-ray boosted dark matter using the 100 tonne · day full dataset of the PandaX-II detector located at the China Jinping Underground Laboratory. With the extra energy gained from the cosmic rays, sub-GeV dark matter particles can produce visible recoil signals in the detector. The diurnal modulations in rate and energy spectrum are utilized to further enhance the signal sensitivity. Our result excludes the dark matter–nucleon elastic scattering cross section between 10−31 and 10−28 cm2 for dark matter masses from 0.1 MeV/c2 to 0.1 GeV/c2, with a large parameter space previously unexplored by experimental collaborations.

DOI:10.1103/PhysRevLett.128.171801
arXiv:2112.08957

Light yield and field dependence measurement in PandaX-II dual-phase xenon detector

Journal of Instrumentation, Vol.17, 01008(2022)

The dual-phase xenon detector is one of the most sensitive detectors for dark matter direct detection, where the energy deposition of incoming particles can be converted into light and electrons through xenon excitation and ionization. The detector response to signal energy deposition varies significantly with the electric field in liquid xenon . We study the detector light yield and its dependence on the electric field in PandaX-II dual-phase detector containing 580 kg liquid xenon in the sensitive volume. From measurement, the light yield at electric field from 0 V/cm to 317 V/cm is obtained for energy deposition up to 236 keV.

DOI:10.1088/1748-0221/17/01/P01008
arXiv:2111.01492

${}^{83}Rb$/$ {}^{83m}Kr$ production and cross-section measurement with 3.4 MeV and 20 MeV proton beams

Physical Review C, Vol.105, 014604(2022)

${}^{83m}Kr$ with a short lifetime is an ideal calibration source for liquid xenon or liquid argon detector. The ${}^{83m}Kr$ isomer can be generated through the decay of ${}^{83}Rb$ isotope, and ${}^{83}Rb$ is usually produced by proton beams bombarding natural krypton atoms. In this paper, we report a successful production of ${}^{83}Rb$/$ {}^{83m}Kr$ with $3.4$ $MeV$ proton beam energy and measure the production rate with such low proton energy for the first time. Another production attempt was performed with newly available 20 MeV proton beam in China, the production rate is consistent with our expectation. The produced ${}^{83m}Kr$ source has been successfully injected into PandaX-II liquid xenon detector and yielded enough statistics for detector calibration.

DOI:10.1103/PhysRevC.105.014604
arXiv:2102.02490

Dark Matter Search Results from the PandaX-4T Commissioning Run

Physical Review Letters, Vol.127(2021)

We report the first dark matter search results using the commissioning data from PandaX-4T. Using a time projection chamber with 3.7-tonne of liquid xenon target and an exposure of 0.63~tonne⋅year, 1058 candidate events are identified within an approximate electron equivalent energy window between 1 and 30 $keV$. No significant excess over background is observed. Our data set a stringent limit to the dark matter-nucleon spin-independent interactions, with a lowest excluded cross section (90% C.L.) of $3.3 \times 10^{−47}cm^2$ at a dark matter mass of 30 $GeV/c^2$.

DOI:10.1103/PhysRevLett.127.261802
arXiv:2107.13438

PandaX-4T cryogenic distillation system for removing krypton from xenon

Review of Scientific Instruments, Vol.92, 123303(2021)

An efficient cryogenic distillation system was designed and constructed for the PandaX-4T dark matter detector based on the McCabe–Thiele method and the conservation of mass and energy. This distillation system is designed to reduce the concentration of krypton in commercial xenon from $5$ $\times$ $10^{−7}$ to $\sim$ $10^{−14}$ $mol/mol$ with $99\%$ xenon collection efficiency at a maximum flow rate of $10$ $kg/h$. The offline distillation operation has been completed and $5.75$ tons of ultra-high purity xenon was produced, which is used as the detection medium in the PandaX4T detector. The krypton concentration of the product xenon is measured with an upper limit of $8.0$ $ppt$. The construction, operation, and stable purification performance of the cryogenic distillation system are studied with the experimental data, which is important for theoretical research and distillation operation optimization.

DOI:10.1063/5.0065154

A 500 MS/s waveform digitizer for PandaX dark matter experiments

Journal of Instrumentation(2021)

Waveform digitizers are key readout instruments in particle physics experiments. In this paper, we present a waveform digitizer for the PandaX dark matter experiments. It supports both external-trigger readout and triggerless readout, accommodating the needs of low rate full-waveform readout and channel-independent low threshold acquisition, respectively. This digitizer is a 8-channel VME board with a sampling rate of 500 MS/s and 14-bit resolution for each channel. A digitizer system consisting of 72 channels has been tested in situ of the PandaX-4T experiment. We report the system performance with real data.

arXiv:2108.11804

Performance of cryogenic demountable indium seal at high pressures

Review of Scientific Instruments, Vol.92, 093905(2021)

An essential challenge in seal design is to provide an ultra-low leak rate at cryogenic temperatures and high pressures. In this paper, the performance of demountable indium seals under a charging pressure of 8.5 MPa A and at cryogenic temperatures down to −190 °C was investigated. Three indium seal structures with a diameter of 30 mm were specifically designed and tested. All three structures went through both room temperature and cryogenic temperature tests in cycles with a pressure of up to 8.5 MPa A. In addition, leak rate experiments regarding the creep relaxation effect of the indium ring were conducted. The results showed that the leak rates of all three structures were lower than $1 \times 10^{-10} Pa\thinspace m^{3} s^{-1}$ at both room temperature and cryogenic temperature with the pressure up to 8.5 MPa A when the torque was 8 or 12 N m. It was concluded that the linear loads for achieving a successful indium seal were 163, 171, and $220 N mm^{-1}$ alongside its circumference for the 2 mm indium M-T structure, the 3 mm indium M-T structure, and the Z-shaped seal structure, respectively. Furthermore, although the torque slightly dropped after the assembly due to the creep relaxation effect, the leak rates of the structure were still lower than $1 \times 10^{-10} Pa\thinspace m^{3} s^{-1}$ three days after the assembly. The present work is helpful for designing ultra-low leak rate demountable indium seals at cryogenic temperatures and high pressures.

DOI:10.1063/5.0051279

BambooMC -- A Geant4-based simulation program for the PandaX experiments

Journal of Instrumentation(2021)

The purpose of the PandaX experiments is to search for the possible events resulted from dark matter particles, neutrinoless double beta decay or other rare processes with xenon detectors. Understanding the energy depositions from backgrounds or calibration sources in these detectors is very important. The program of BambooMC is created to perform the Geant4-based Monte Carlo simulation, providing reference information for the experiments. We introduce the design and features of BambooMC in this report. The running of the program depends on a configuration file, which combines different detectors, event generators, physics lists and analysis packs together in one simulation. The program can be easily extended and applied to other experiments.

arXiv:2107.05935

Constraining self-interacting dark matter with the full dataset of PandaX-II

SCIENCE CHINA Physics, Mechanics & Astronomy, Vol.64, 111062(2021)

Self-interacting dark matter (SIDM) is a leading candidate proposed to solve discrepancies between predictions of the prevailing cold dark matter theory and observations of galaxies. Many SIDM models predict the existence of a light force carrier that mediates strong dark matter self-interactions. If the mediator couples to the standard model particles, it could produce characteristic signals in dark matter direct detection experiments. We report searches for signals of SIDM models with a light mediator using the full dataset of the PandaX-II experiment, basing on a total exposure of 132 tonne-days. No significant excess over background is found, and our likelihood analysis leads to a strong upper limit on the dark matter-nucleon coupling strength. We further combine the PandaX-II constraints and those from observations of the light element abundances in the early universe, and show that direct detection and cosmological probes can provide complementary constraints on dark matter models with a light mediator.

DOI:10.1007/s11433-021-1740-2
arXiv:2104.14724