S. W. Yang

The ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}\ensuremath{-}{\mathrm{e}}^{\ensuremath{-}}$ elastic scattering cross section was measured with a CsI(Tl) scintillating crystal array having a total mass of 187 kg. The detector was exposed to an average reactor ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}$ flux of $6.4\ifmmode\times\else\texttimes\fi{}{10}^{12}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ at the Kuo-Sheng Nuclear Power Station. The experimental design, conceptual merits, detector hardware, data analysis, and background understanding of the experiment are presented. Using $29882/7369\text{ }\text{ }\mathrm{kg}$-days of Reactor ON/OFF data, the standard model (SM) electroweak interaction was probed at the squared 4-momentum transfer range of ${Q}^{2}\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\text{ }\text{ }{\mathrm{GeV}}^{2}$. The ratio of experimental to SM cross sections of $\ensuremath{\xi}=[1.08\ifmmode\pm\else\textpm\fi{}0.21(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.16(\mathrm{sys})]$ was measured. Constraints on the electroweak parameters (${g}_{V},{g}_{A}$) were placed, corresponding to a weak mixing angle measurement of ${sin}^{2}{\ensuremath{\theta}}_{\mathrm{W}}=0.251\ifmmode\pm\else\textpm\fi{}0.031(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.024(\mathrm{sys})$. Destructive interference in the SM ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}\ensuremath{-}\mathrm{e}$ process was verified. Bounds on anomalous neutrino electromagnetic properties were placed: neutrino magnetic moment at ${\ensuremath{\mu}}_{{\overline{\ensuremath{\nu}}}_{\mathrm{e}}}<2.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }\text{ }{\ensuremath{\mu}}_{\mathrm{B}}$ and the neutrino charge radius at $\ensuremath{-}2.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}\text{ }\text{ }{\mathrm{cm}}^{2}<⟨{\mathrm{r}}_{{\overline{\ensuremath{\nu}}}_{\mathrm{e}}}^{2}⟩<3.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}\text{ }\text{ }{\mathrm{cm}}^{2}$, both at 90% confidence level.

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.

The China Dark Matter Experiment Collaboration reports the first experimental limit on weakly interacting massive particles (WIMPs) dark matter from 14.6 kg-days of data taken with a 994 g p-type point-contact germanium detector at the China Jinping underground laboratory where the rock overburden is more than 2400 m. The energy threshold achieved was 400 eVee. According to the 14.6 kg-day live data, we placed the limit of ${\ensuremath{\sigma}}_{\ensuremath{\chi}N}=1.75\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}40}\text{ }\text{ }{\mathrm{cm}}^{2}$ at a 90% confidence level on the spin-independent cross section at a WIMP mass of 7 GeV before differentiating bulk signals from the surface backgrounds.