The NAIAD experiment (NaI Advanced Detector) for WIMP dark matter searches at Boulby mine (UK) is described. The detector consists of an array of encapsulated and unencapsulated NaI(Tl) crystals with high light yield. Six crystals are collecting data at present. Data accumulated by four of them (10.6 kg x year exposure) have been used to set upper limits on the WIMP-nucleon spin-independent and WIMP-proton spin-dependent cross-sections. Pulse shape analysis has been applied to discriminate between nuclear recoils, as may be caused by WIMP interactions, and electron recoils due to gamma background. Various calibrations of crystals are presented.
The neutron background at the underground laboratory at Boulby - a site for several dark matter experiments - is discussed. Special emphasis is put on the neutron background produced by cosmic-ray muons. The most rece
The CRESST experiment seeks hypothetical WIMP particles that could account for the bulk of dark matter in the Universe. The detectors are cryogenic calorimeters in which WIMPs would scatter elastically on nuclei, releasing phonons. The first phase of the experiment has successfully deployed several 262 g sapphire devices in the Gran Sasso underground laboratories. A main source of background has been identified as microscopic mechanical fracturing of the crystals, and has been eliminated, improving the background rate by up to three orders of magnitude at low energies, leaving a rate close to one count per day per kg and per keV above 10 keV recoil energy. This background now appears to be dominated by radioactivity, and future CRESST scintillating calorimeters which simultaneously measure light and phonons will allow rejection of a great part of it.
MINOS is an accelerator neutrino oscillation experiment at Fermilab. An intense high energy neutrino beam is produced at Fermilab and sent to a near detector on the Fermilab site and also to a 5 kTon far detector 735 km away in the Soudan mine in northern Minnesota. The experiment has now had several years of running with millions of events in the near detector and hundreds of events recorded in the far detector. I will report on the recent results from this experiment which include precise measurement of $|Delta m^2_{32}|$, ~analysis of neutral current data to limit the component of sterile neutrinos, and the search for $ u_mu to u_e$ conversion. The focus will be on the analysis of data for $ u_mu to u_e$ conversion. Using data from an exposure of $3.14times 10^{20}$ protons on target, we have selected electron type events in both the near and the far detector. The near detector is used to measure the background which is extrapolated to the far detector. We have found 35 events in the signal region with a background expectation of $27pm 5(stat)pm 2(syst)$. Using this observation we set a 90% C.L. limit of $sin^2 2 theta_{13} < 0.29$ for $delta_{cp} = 0$ and normal mass hierarchy. Further analysis is under way to reduce backgrounds and improve sensitivity.
DANSS is a one cubic meter highly segmented plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1GW reactor of the Kalinin Nuclear Power plant 350km NW from Moscow. The distance to the core ia varied on-line from 10.7m to 12.7m. Recent results on searches for a sterile neutrino are presented as well as measurements of the antineutrino spectrum dependence on the fuel composition. All results are preliminary. PACS: 14.60.Pq, 14.60.St
We present new results of the DANSS experiment on the searches for sterile neutrinos. They are based on 2.1 million of inverse beta decay events collected at 10.7, 11.7 and 12.7 meters from the reactor core of the 3.1 GW Kalinin Nuclear Power Plant in Russia. This data sample is 2.5 times larger than the data sample in the previous DANSS publication. The search for the sterile neutrinos is performed using the ratio of $bar u_e$ spectra at two distances. This method is very robust against systematic uncertainties in the $bar u_e$ spectrum and the detector efficiency. We do not see any statistically significant sign for the $bar u_e$ oscillations. This allows us to exclude further a large and interesting part of the sterile neutrino parameter space. All results are preliminary.