Z. Y. Zhou

We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of $8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}42}$ and $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}36}\text{ }\text{ }{\mathrm{cm}}^{2}$ at a 90% confidence level on spin-independent and spin-dependent WIMP-nucleon cross sections, respectively, at a WIMP mass (${m}_{\ensuremath{\chi}}$) of $5\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ are achieved. The lower reach of ${m}_{\ensuremath{\chi}}$ is extended to $2\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

We report results of a search for light dark matter weakly interacting massive particles (WIMPs) with CDEX-1 experiment at the China Jinping Underground Laboratory, based on 53.9 kg-days of data from a $p$-type point-contact germanium detector enclosed by a NaI(Tl) crystal scintillator as anti-Compton detector. The event rate and spectrum above the analysis threshold of 475 eVee are consistent with the understood background model. Part of the allowed regions for WIMP-nucleus coherent elastic scattering at WIMP mass of 6--20 GeV are probed and excluded. Independent of interaction channels, this result contradicts the interpretation that the anomalous excesses of the CoGeNT experiment are induced by dark matter, since identical detector techniques are used in both experiments.

Back-streaming neutrons through the incoming proton channel at the spallation target station of China Spallation Neutron Source (CSNS) has been exploited as a white neutron beam line (so-called Back-n), and a number of spectrometers for nuclear data measurements have been planned. With a thick tungsten target and modest moderation by the cooling water through the target slices, the neutron beam is very intense which is in the order of 5.0×106 n/cm2/s at 80 m from the target and has an excellent energy spectrum spanning from 1 eV to 100 MeV. In addition, the time structure of the primary proton beam under different accelerator operation modes is fully applicable for time-of-flight measurements. Altogether, it makes the CSNS Back-n very much suitable for nuclear data measurements. The construction of the neutron beam line and five of the seven planned spectrometers are under way. It is expected that the first batch experiments be carried out from late 2017, when CSNS starts commissioning.

The CDEX-1 experiment conducted a search of low-mass ($<10\text{ }\text{ }\mathrm{GeV}/{c}^{2}$) weakly interacting massive particles dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware setup, detector characterization, data acquisition, and analysis procedures of this experiment. No excess of unidentified events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.

We report constraints on the dark photon effective kinetic mixing parameter ($\ensuremath{\kappa}$) 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 $\ensuremath{\kappa}$ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (${m}_{V}$) from 10 to $300\text{ }\text{ }\mathrm{eV}/{c}^{2}$ in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90% confidence level with ${m}_{V}$ from 0.1 to $4.0\text{ }\text{ }\mathrm{keV}/{c}^{2}$ are set from 449.6 kg-day data, with a minimum of $\ensuremath{\kappa}=1.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$ at ${\mathrm{m}}_{\mathrm{V}}=200\text{ }\text{ }\mathrm{eV}/{\mathrm{c}}^{2}$.