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).

We search for nuclear recoil signals of dark matter(DM)models with a light mediator using data taken from a p-type point-contact germanium detector of the CDEX-10 experiment at the China Jinping Underground Laboratory.The 90％confidence level upper limits on the DM-nucleon interaction cross section from 205.4 kg-day exposure data are derived,excluding the new parameter space in 2-3 GeV DM mass when the mediator mass is comparable to or lower than the typical momentum transfer.We further interpret our results to constrain a specific self-interacting DM model with a light mediator coupling to the photon through kinetic mixing and set experimental limits on the model parameter region favored by astrophysical observations.

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.

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.

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 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).

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 improved germanium-based constraints on sub-GeV dark matter via dark matter-electron (χ-e) scattering using the 205.4  kg·day dataset from the CDEX-10 experiment. Using a novel calculation technique, we attain predicted χ-e scattering spectra observable in high-purity germanium detectors. In the heavy mediator scenario, our results achieve 3 orders of magnitude of improvement for m_{χ} larger than 80  MeV/c^{2} compared to previous germanium-based χ-e results. We also present the most stringent χ-e cross-section limit to date among experiments using solid-state detectors for m_{χ} larger than 90  MeV/c^{2} with heavy mediators and m_{χ} larger than 100  MeV/c^{2} with electric dipole coupling. The result proves the feasibility and demonstrates the vast potential of a new χ-e detection method with high-purity germanium detectors in ultralow radioactive background.

国家战略 我国的建国百年目标是实现社会主义现代化强国.2035年的阶段目标是基本实现社会主义现代化,具体包括进入创新型国家前列;建成现代化紧急体系;基本建成法治国家、法治政府、法治社会;建成文化、教育、人才、体育强国;2030年前实现碳达峰,之后稳中有降,生态环境根本好转等. 但同时,我国还存在许多有重大薄弱环节的领域,如能源、粮食、网信、科技、国防、健康、金融等,短板问题日益暴露和尖锐.

A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg day data taken from a p-type point contact germanium detector of the CDEX-10 experiment at China's Jinping underground laboratory. New low-mass dark matter searching channels, neutral current fermionic DM absorption (χ+A→ν+A) and DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), have been analyzed with an energy threshold of 160 eVee. No significant signal was found; thus new limits on the DM-nucleon interaction cross section are set for both models at the sub-GeV DM mass region. A cross section limit for the fermionic DM absorption is set to be 2.5×10^{-46}  cm^{2} (90% C.L.) at DM mass of 10  MeV/c^{2}. For the DM-nucleus 3→2 scattering scenario, limits are extended to DM mass of 5 and 14  MeV/c^{2} for the massless dark photon and bound DM final state, respectively.

A natural broad energy germanium detector is operated in the China Jinping Underground Laboratory for a feasibility study of building the next generation experiment of the neutrinoless double-beta (0 nu beta beta) decay of Ge-76. The setup of the prototype facility, characteristics of the broad energy germanium detector, background reduction methods, and data analysis are described in this paper. A background index of 6.4 x 10(-3) counts/(keV kg day) is achieved and 1.86 times lower than our previous result of the CDEX-1 detector. No signal is observed with an exposure of 186.4 kg day, thus a limit on the half life of Ge-76 0 nu beta beta decay is set at T-1/2(0 nu) > 5.62 x 10(22) yr at 90% C.L. The limit corresponds to an effective Majorana neutrino mass in the range of 4.6-10.3 eV, dependent on the nuclear matrix elements.

We present weakly interacting massive particles (WIMPs) search results performed using two approaches of effective field theory from the China Dark Matter Experiment (CDEX), based on the data from both CDEX-1B and CDEX-10 stages. In the nonrelativistic effective field theory approach, both time-integrated and annual modulation analyses were used to set new limits for the coupling of WIMP-nucleon effective operators at 90% confidence level (C.L.) and improve over the current bounds in the low mχregion. In the chiral effective field theory approach, data from CDEX-10 were used to set an upper limit on WIMP-pion coupling at 90% C.L. We for the first time extended the limit to the mχ < 6 GeV/c2 region.

We present the improved constraints on couplings of solar axions and more generic bosonic dark matter particles using 737.1 kg days of data from the CDEX-1B experiment. The CDEX-1B experiment, located at the China Jinping Underground Laboratory, primarily aims at the direct detection of weakly interacting massive particles using a p-type point-contact germanium detector. We adopt the profile likelihood ratio method for analysis of data in the presence of backgrounds. An energy threshold of 160 eV was achieved, much better than the 475 eV of CDEX-1A with an exposure of 335.6 kg days. This significantly improves the sensitivity for the bosonic dark matter below 0.8 keV among germanium detectors. Limits are also placed on the coupling g(Ae) < 2.48 x 10(-11) from Compton, bremsstrahlung, atomic-recombination, and deexcitation channels and g(AN)(eff) x g(Ae) < 4.14 x 10(-17) from a Fe-57 M1 transition at 90% confidence level.

We report constraints on the dark photon effective kinetic mixing parameter (κ) with data taken from two p-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90% confidence level upper limits on κ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (m_{V}) from 10 to 300  eV/c^{2} in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90% confidence level with m_{V} from 0.1 to 4.0  keV/c^{2} are set from 449.6 kg-day data, with a minimum of κ=1.3×10^{-15} at m_{V}=200  eV/c^{2}.

The China Dark Matter Experiment (CDEX) aims at direct searches of light Weakly Interacting Massive Particles (WIMPs) at the China Jinping Underground Laboratory (CJPL) with an overburden of about 2400m rock. Results from a prototype CDEX-1 994 g p-type Point Contact Germanium(pPCGe) detector are reported. Research programs are pursued to further reduce the physics threshold by improving hardware and data analysis. The CDEX-10 experiment with a pPCGe array of 10 kg target mass range is being tested. The evolution of CDEX program into "CDEX-1T Experiment" with ton-scale germanium detector arrays will also be introduced in this study.

Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.