We present the first results of the search for sub-MeV fermionic dark matter absorbed by electron targets of germanium using the 205.4 kg . day data collected by the CDEX-10 experiment, with the analysis threshold of 160 eVee. No significant dark matter (DM) signals over the background are observed. Results are presented as limits on the cross section of DM-electron interaction. We present new constraints of cross section in the DM range of 0.1-10 keV/c(2) for vector and axial-vector interaction. The upper limit on the cross section is set to be 6.8 x 10(-46) cm(2) for vector interaction, and 2.3 x 10(-46) cm(2) for axial-vector interaction at DM mass of 5 keV/c(2).

The WAG-H5-2 atom gravimeter is an upgraded version of the WAG-H5-1.Compared with previous work,a highly integrated and stable optical system has been developed for the new gravimeter,based on the principle of matter-wave interferometry.The Comparison of Absolute Gravimeters for the CMONOC(Crustal Movement Observation Network of China)project was organized by the China Earthquake Networks Center from January 30 to March 30,2026,in Wuhan.Our atom gravimeter(WAG-H5-2#2508)was invited to participate in this comparison.Absolute gravity at the indicated four sites was measured as requested by the organizer.Comparison results showed that no significant deviation existed between the WAG-H5-2#2508 atom gravimeter and laser interferometry absolute gravimeters,with deviations all within-4.3 to 6.1 μGal(1 μGal=10-8 m/s2).The performance of our instrument in terms of sensitivity,precision,repeatability,stability,and accuracy were evaluated.The WAG-H5-2#2508 exhibited a short-term sensitivity of 16.2 μGal/Hz1/2 and achieved an observation precision of～1.0 μGal over 1000 s.The measurement precision was better than 0.4 μGal,based on one-day observation data.The repeatability was approximately 1.5 μGal.Long-term gravity monitoring over half a month at a sampling interval of 88 s showed that the residual was within 10 μGal.The deviation of 1.4 μGal during the comparison represents the accuracy of the instrument compared with several other gravimeters(FG5X,A10,and IGG-03B).

We present the results of a search for gravitational-wave transients associated with core-collapse supernova SN 2023ixf, which was observed in the galaxy Messier 101 via optical emission on 2023 May 19, during the LIGO–Virgo–KAGRA 15th Engineering Run. We define a five-day on-source window during which an accompanying gravitational-wave signal may have occurred. No gravitational waves have been identified in data when at least two gravitational-wave observatories were operating, which covered ∼14% of this five-day window. We report the search detection efficiency for various possible gravitational-wave emission models. Considering the distance to M101 (6.7 Mpc), we derive constraints on the gravitational-wave emission mechanism of core-collapse supernovae across a broad frequency spectrum, ranging from 50 Hz to 2 kHz, where we assume the gravitational-wave emission occurred when coincident data are available in the on-source window. Considering an ellipsoid model for a rotating proto-neutron star, our search is sensitive to gravitational-wave energy 1 × 10 −4 M ⊙ c 2 and luminosity 2.6 × 10 −4 M ⊙ c 2 s −1 for a source emitting at 82 Hz. These constraints are around an order of magnitude more stringent than those obtained so far with gravitational-wave data. The constraint on the ellipticity of the proto-neutron star that is formed is as low as 1.08, at frequencies above 1200 Hz, surpassing past results.

We present Fermi Gamma-ray Burst Monitor (Fermi-GBM) and Swift Burst Alert Telescope (Swift-BAT) searches for gamma-ray/X-ray counterparts to gravitational wave (GW) candidate events identified during the third observing run of the Advanced LIGO and Advanced Virgo detectors. Using Fermi-GBM on-board triggers and sub-threshold gamma-ray burst (GRB) candidates found in the Fermi-GBM ground analyses, the Targeted Search and the Untargeted Search, we investigate whether there are any coincident GRBs associated with the GWs. We also search the Swift-BAT rate data around the GW times to determine whether a GRB counterpart is present. No counterparts are found. Using both the Fermi-GBM Targeted Search and the Swift-BAT search, we calculate flux upper limits and present joint upper limits on the gamma-ray luminosity of each GW. Given these limits, we constrain theoretical models for the emission of gamma-rays from binary black hole mergers.

We operated a p-type point contact high purity germanium (PPCGe) detector (CDEX-1B, 1.008 kg) in the China Jinping Underground Laboratory (CJPL) for 500.3 days to search for neutrinoless double beta ($\bb$) decay of $^{76}$Ge. A total of 504.3 kg$\cdot$day effective exposure data was accumulated. The anti-coincidence and the multi/single-site event (MSE/SSE) discrimination methods were used to suppress the background in the energy region of interest (ROI, 1989--2089 keV for this work) with a factor of 23. A background level of 0.33 counts/(keV$\cdot$kg$\cdot$yr) was achieved. The lower limit on the half life of $^{76}$Ge $\bb$ decay was constrained as $T_{1/2}^{0\nu}\ > \ {1.0}\times 10^{23}\ \rm yr\ (90\% \ C.L.)$, corresponding to the upper limits on the effective Majorana neutrino mass: $\langle m_{\beta\beta}\rangle < $ 3.2--7.5$\ \mathrm{eV}$.

We present the first limit on g_Aγ coupling constant using the Bragg-Primakoff conversion based on an exposure of 1107.5 kg days of data from the CDEX-1B experiment at the China Jinping Underground Laboratory. The data are consistent with the null signal hypothesis, and no excess signals are observed. Limits of the coupling g_Aγ<2.08×10^-9 GeV^-1 (95% C.L.) are derived for axions with mass up to 100 eV/c^2. Within the hadronic model of KSVZ, our results exclude axion mass >5.3 eV/c^2 at 95% C.L.

Inertial sensors utilizing cold atom interferometry are advancing toward real-world applications, necessitating optical systems with superior integration and stability. We have developed a highly integrated and stable optical system for a fountain-type 85Rb atom gravimeter, utilizing dual fiber laser outputs to generate all the laser beams. The optical system design involves bonding miniaturized optical components onto quartz glass plates, significantly reducing the volume of the optical module while maintaining high spatial laser utilization efficiency. This enables the system to be integrated into a chassis with the dimension of 43 cm x 42 cm x 13 cm. Remarkably, the system maintains its functionality without the need for adjustments even after being transported over 14,000 km. It achieves a gravity measurement sensitivity of 14.5 mu Gal/Hz1/2 and a long-term stability of 0.4 mu Gal over 2560 seconds. This versatile optical system also supports various atom interferometry-based sensors, facilitating their deployment in practical settings.

The magnetar SGR 1935+2154 is the only known Galactic source of fast radio bursts (FRBs). FRBs from SGR 1935+2154 were first detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB and the Survey for Transient Astronomical Radio Emission 2 in 2020 April, after the conclusion of the LIGO, Virgo, and KAGRA Collaborations' O3 observing run. Here, we analyze four periods of gravitational wave (GW) data from the GEO600 detector coincident with four periods of FRB activity detected by CHIME/FRB, as well as X-ray glitches and X-ray bursts detected by NICER and NuSTAR close to the time of one of the FRBs. We do not detect any significant GW emission from any of the events. Instead, using a short-duration GW search (for bursts <= 1 s) we derive 50% (90%) upper limits of 10(48) (10(49)) erg for GWs at 300 Hz and 10(49) (10(50)) erg at 2 kHz, and constrain the GW-to-radio energy ratio to <= 10(14)-10(16). We also derive upper limits from a long-duration search for bursts with durations between 1 and 10 s. These represent the strictest upper limits on concurrent GW emission from FRBs.

CDEX-50 is a next-generation project of the China Dark Matter Experiment (CDEX) that aims to search for dark matter using a 50-kg germanium detector array. This paper comprises a thorough summary of the CDEX-50 dark matter experiment, including an investigation of potential background sources and the development of a background model. Based on the baseline model, the projected sensitivity of weakly interacting massive particle (WIMP) is also presented. The expected background level within the energy region of interest, set to 2–2.5 keVee, is ∼0.01 counts keVee^-1 kg^-1 day^-1. At 90% confidence level, the expected sensitivity to spin-independent WIMP-nucleon couplings is estimated to reach a cross-section of 5.1 × 10^-45 cm^2 for a WIMP mass of 5 GeV/c^2 with an exposure objective of 150 kg·year and an analysis threshold of 160 eVee. This science goal will correspond to the most sensitive results for WIMPs with a mass of 2.2–8 GeV/c^2.

Recently a dark matter-electron (DM-electron) paradigm has drawn much attention. Models beyond the standard halo model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this Letter, a velocity components analysis (VCA) method dedicated to swift analysis of accelerated DM-electron interactions via semiconductor detectors is proposed and the first HPGe detector-based accelerated DM-electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV solar reflected DM-electron interaction is presented with the 205.4  kg·day dataset from the CDEX-10 experiment. In the heavy mediator scenario, our result excels in the mass range of 5-15  keV/c^{2}, achieving a 3 orders of magnitude improvement comparing with previous semiconductor experiments. In the light mediator scenario, the strongest laboratory constraint for DM lighter than 0.1  MeV/c^{2} is presented. The result proves the feasibility and demonstrates the vast potential of the VCA technique in future accelerated DM-electron analyses with semiconductor detectors.

Magnetars are neutron stars with exceptionally strong dipole magnetic fields which are observed to display a range of x-ray flaring behavior, but the flaring mechanism is not well understood. The third observing run of Advanced LIGO and Virgo extended from April 1, 2019 to March 27, 2020, and contained x-ray flares from known magnetar SGR 1935+2154, as well as the newly-discovered magnetar, Swift J1818-1607. We search for gravitational waves coincident with these magnetar flares with minimally modeled, coherent searches which specifically target both short-duration gravitational waves produced by excited f-modes in the magnetar's core, as well as long-duration gravitational waves motivated by the Quasi-Periodic Oscillations observed in the tails of giant flares. In this paper, we report on the methods and sensitivity estimates of these searches, and the astrophysical implications.

The second Gravitational-Wave Transient Catalog reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15:00 UTC and 1 October 2019 15:00 UTC. We present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the astrophysical probability for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have an astrophysical probability greater than 0.5. Of these candidates, 36 have been reported in GWTC-2. If the 8 additional high-significance candidates presented here are astrophysical, the mass range of events that are unambiguously identified as binary black holes (both objects $\geq 3M_\odot$) is increased compared to GWTC-2, with total masses from $\sim 14 M_\odot$ for GW190924_021846 to $\sim 182 M_\odot$ for GW190426_190642. The primary components of two new candidate events (GW190403_051519 and GW190426_190642) fall in the mass gap predicted by pair instability supernova theory. We also expand the population of binaries with significantly asymmetric mass ratios reported in GWTC-2 by an additional two events (the mass ratio is less than $0.65$ and $0.44$ at $90\%$ probability for GW190403_051519 and GW190917_114630 respectively), and find that 2 of the 8 new events have effective inspiral spins $\chi_\mathrm{eff} > 0$ (at $90\%$ credibility), while no binary is consistent with $\chi_\mathrm{eff} < 0$ at the same significance.

We report new constraints on light dark matter (DM) boosted by blazars using the 205.4 kg day data from the CDEX-10 experiment located at the China Jinping Underground Laboratory. Two representative blazars, TXS 0506+56 and BL Lacertae are studied. The results derived from TXS 0506+56 exclude DM-nucleon elastic scattering cross sections from 4.6× 10^-33 cm^2 to 1×10^-26 cm^2 for DM masses between 10 keV and 1 GeV, and the results derived from BL Lacertae exclude DM-nucleon elastic scattering cross sections from 2.4× 10^-34 cm^2 to 1×10^-26 cm^2 for the same range of DM masses. The constraints correspond to the best sensitivities among solid-state detector experiments in the sub-MeV mass range.

We investigate exotic neutrino interactions using the 205.4 kg$\cdot$day dataset from the CDEX-10 experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings of new gauge bosons are presented. Two nonstandard neutrino interactions are considered: a $U(1)_{B-L}$ gauge-boson-induced interaction between an active neutrino and electron/nucleus, and a dark-photon-induced interaction between a sterile neutrino and electron/nucleus via kinetic mixing with a photon. This work probes an unexplored parameter space involving sterile neutrino coupling with a dark photon. New laboratory limits are derived on dark photon masses below $1~{\rm eV}/c^{2}$ at some benchmark values of $\Delta m_{41}^{2}$ and $g^{\prime2}{\rm{sin}}^{2}2\theta_{14}$.

We present novel constraints on boosted light dark matter particles (denoted as ``$\chi$'') from evaporating primordial black holes (PBHs) using 205.4 kg$\cdot$day data from the China Jinping Underground Laboratory's CDEX-10 p-type point contact germanium detector with a 160 eVee analysis threshold. $\chi$ from PBHs with masses ranging from 1$\times$10$^{15}$ g to 7$\times$10$^{16}$ g are searched in this work. In the presence of PBH abundance compatible with present bounds, our result excludes the $\chi$-nucleon elastic-scattering cross section region from 3.4$\times$10$^{-32}$ cm$^{2}$ to 2.3$\times$10$^{-29}$ cm$^{2}$ for $\chi$ of 1 keV to 24 MeV from PBHs with masses of 5$\times$10$^{15}$ g, as well as from 1.1$\times$10$^{-28}$ cm$^{2}$ to 7.6$\times$10$^{-28}$ cm$^{2}$ for $\chi$ of 1 keV to 0.6 MeV from PBHs with masses of 7$\times$10$^{16}$ g. If the $\chi$-nucleon elastic-scattering cross section can be determined in the future, the abundance of PBHs may be severely constrained by $\chi$ evaporation. With the lower threshold (160 eVee) of the CDEX-10 experiment compared to the previously used experiments, this work allows for a better reach at soft spectra produced by heavier PBHs, which demonstrates the vast potential of such a technical route to pursue $\chi$ from larger PBHs with a low threshold.

We search for gravitational-wave (GW) transients associated with fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project, during the first part of the third observing run of Advanced LIGO and Advanced Virgo (2019 April 1 15:00 UTC–2019 October 1 15:00 UTC). Triggers from 22 FRBs were analyzed with a search that targets both binary neutron star (BNS) and neutron star–black hole (NSBH) mergers. A targeted search for generic GW transients was conducted on 40 FRBs. We find no significant evidence for a GW association in either search. Given the large uncertainties in the distances of our FRB sample, we are unable to exclude the possibility of a GW association. Assessing the volumetric event rates of both FRB and binary mergers, an association is limited to 15% of the FRB population for BNS mergers or 1% for NSBH mergers. We report 90% confidence lower bounds on the distance to each FRB for a range of GW progenitor models and set upper limits on the energy emitted through GWs for a range of emission scenarios. We find values of order 10 51 –10 57 erg for models with central GW frequencies in the range 70–3560 Hz. At the sensitivity of this search, we find these limits to be above the predicted GW emissions for the models considered. We also find no significant coincident detection of GWs with the repeater, FRB 20200120E, which is the closest known extragalactic FRB.

KAGRA is a gravitational-wave (GW) detector constructed in Japan with two unique key features: It was constructed underground, and the test-mass mirrors are cooled to cryogenic temperatures. These features are not included in other kilometer-scale detectors but will be adopted in future detectors such as the Einstein Telescope. KAGRA performed its first joint observation run with GEO600 in 2020. In this observation, the sensitivity of KAGRA to GWs was inferior to that of other kilometer-scale detectors such as LIGO and Virgo. However, further upgrades to the detector are ongoing to reach the sensitivity for detecting GWs in the next observation run, which is scheduled for 2022. In this article, the current situation, sensitivity, and future perspectives are reviewed.

Z. Z. Liu, L. T. Yang, ∗ Q. Yue, † C. H. Yeh, ‡ K. J. Kang, Y. J. Li, M. Agartioglu, ‡ H. P. An, 3 J. P. Chang, J. H. Chen, ‡ Y. H. Chen, J. P. Cheng, 6 W. H. Dai, Z. Deng, C. H. Fang, X. P. Geng, H. Gong, X. Y. Guo, Q. J. Guo, L. He, S. M. He, J. W. Hu, H. X. Huang, T. C. Huang, H. T. Jia, X. Jiang, H. B. Li, ‡ J. M. Li, J. Li, R. M. J. Li, X. Q. Li, Y. L. Li, B. Liao, F. K. Lin, ‡ S. T. Lin, S. K. Liu, Y. Liu, Y. D. Liu, Y. Y. Liu, H. Ma, Y. C. Mao, Q. Y. Nie, J. H. Ning, H. Pan, N. C. Qi, J. Ren, X. C. Ruan, K. Saraswat, ‡ V. Sharma, 12, ‡ Z. She, M. K. Singh, 12, ‡ T. X. Sun, C. J. Tang, W. Y. Tang, Y. Tian, G. F. Wang, L. Wang, Q. Wang, 3 Y. Wang, 3 Y. X. Wang, Z. Wang, H. T. Wong, ‡ S. Y. Wu, Y. C. Wu, H. Y. Xing, Y. Xu, T. Xue, Y. L. Yan, N. Yi, C. X. Yu, H. J. Yu, J. F. Yue, M. Zeng, Z. Zeng, B. T. Zhang, F. S. Zhang, Z. H. Zhang, Z. Y. Zhang, K. K. Zhao, M. G. Zhao, J. F. Zhou, Z. Y. Zhou, and J. J. Zhu

We present new constraints on light dark matter boosted by cosmic rays (CRDM) using the 205.4 kg day data of the CDEX-10 experiment conducted at the China Jinping Underground Laboratory. The Monte Carlo simulation package CJPL ESS was employed to evaluate the Earth shielding effect. Several key factors have been introduced and discussed in our CRDM analysis, including the contributions from heavier CR nuclei than proton and helium, the inhomogeneity of CR distribution, and the impact of the form factor in the Earth attenuation calculation. Our result excludes the dark matter-nucleon elastic scattering cross section region from 1.7 x 10(-30) to 10(-26) cm(2) for dark matter of 10 keV/c(2) to 1 GeV/c(2).

We present directed searches for continuous gravitational waves from the neutron stars in the Cassiopeia A (Cas A) and Vela Jr. supernova remnants. We carry out the searches in the LIGO data from the first six months of the third Advanced LIGO and Virgo observing run, using the Weave semi-coherent method, which sums matched-filter detection-statistic values over many time segments spanning the observation period. No gravitational wave signal is detected in the search band of 20--976 Hz for assumed source ages greater than 300 years for Cas A and greater than 700 years for Vela Jr. Estimates from simulated continuous wave signals indicate we achieve the most sensitive results to date across the explored parameter space volume, probing to strain magnitudes as low as ~$6.3\times10^{-26}$ for Cas A and ~$5.6\times10^{-26}$ for Vela Jr. at frequencies near 166 Hz at 95% efficiency.