DAMIC's results on the search for low-mass weakly interacting massive particles (WIMPs) was posted yesterday on the arXiv! Link.
We probed with the same nuclear target, and with an order-of-magnitude improvement in energy threshold, the parameter space that corresponds to the WIMP-signal interpretation of the excess of nuclear-recoil events recorded by the CDMS silicon experiment in 2013.
We observed an excess of ionization events above threshold that is inconsistent with the standard WIMP-signal interpretation of the CDMS result and demands further investigation. Although this excess leads to a weaker-than-expected exclusion limit at small mχ, our data still provide the most stringent exclusion limit from a silicon target experiment for WIMPs with mχ < 9 GeV c−2.
|Upper limit (90% CL) on the spin-independent WIMP-nucleon elastic scattering cross section σχ−n as a function of WIMP mass mχ obtained from the 11 kg-day exposure of DAMIC (solid red line). The expectation ±1σ band if only known backgrounds are present in our data set is shown by the red band. For comparison, we also include 90% CL exclusion limits from our 2016 result with a 0.6 kg-day exposure, other experiments, and the 90% CL contours for the WIMP-signal interpretation of the CDMS silicon result.|