A. Juillard

Improved exclusion limits from the edelweiss wimp search

Abstract The EDELWEISS experiment has improved its sensitivity for the direct search for WIMP dark matter. In the recoil energy range relevant for WIMP masses below 10xa0TeV/ c 2 , no nuclear recoils were observed in the fiducial volume of a heat-and-ionization cryogenic Ge detector operated in the low-background environment of the Laboratoire Souterrain de Modane in the Frejus Tunnel, during an effective exposure ofxa07.4xa0kgxa0d. This result is combined with the previous EDELWEISS data to derive a limit on the cross-section for spin-independent interaction of WIMPs and nucleons as a function of WIMP mass, using standard nuclear physics and astrophysical assumptions. This limit excludes at more than 99.8%xa0CL a WIMP candidate with a mass of 44xa0GeV/ c 2 and a cross-section of 5.4×10 −6 xa0pb, as reported by the DAMA Collaboration. A first sample of supersymmetric models are also excluded atxa090% CL.

First results of the EDELWEISS WIMP search using a 320 g heat-and-ionization Ge detector

The EDELWEISS collaboration has performed a direct search for WIMP dark matter using a 320 g heat-and-ionization cryogenic Ge detector operated in a low-background environment in the Laboratoire Souterrain de Modane. No nuclear recoils are observed in the fiducial volume in the 30-200 keV energy range during an effective exposure of 4.53 kg.days. Limits for the cross-section for the spin-independent interaction of WIMPs and nucleons are set in the framework of the Minimal Supersymmetric Standard Model (MSSM). The central value of the signal reported by the experiment DAMA is excluded at 90% CL.

SICANE: A Detector array for the measurement of nuclear recoil quenching factors using a monoenergetic neutron beam

Abstract SICANE is a neutron scattering multidetector facility for the determination of the quenching factor (ratio of the response to nuclear recoils and to electrons) of cryogenic detectors used in direct WIMP searches. Well-collimated monoenergetic neutron beams are obtained with inverse (p,n) reactions. The facility is described, and results obtained for the quenching factors of scintillation in NaI(Tl) and of heat and ionization in Ge are presented.

Calibration of the EDELWEISS cryogenic heat-and-ionization germanium detectors for dark matter search

Several aspects of the analysis of the data obtained with the cryogenic heat-and-ionization Ge detectors used by the EDELWEISS dark matter search experiment are presented. Their calibration, the determination of their energy threshold, fiducial volume and nuclear recoil acceptance are detailed.

Sensitivity of the EDELWEISS WIMP search to spin-dependent interactions

The EDELWEISS collaboration is searching for WIMP dark matter using natural Ge cryogenic detectors. The whole data set of the first phase of the experiment contains a fiducial exposure of 4.8 kg.day on Ge-73, the naturally present (7.8%), high-spin Ge isotope. The sensitivity of the experiment to the spin-dependent WIMP-nucleon interactions is evaluated using the model-independent framework proposed by Tovey et al.

Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils

Abstract The heat quenching factor Q ′ (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDELWEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q / Q ′ , where Q is the quenching factor of the ionization yield. To measure Q ′ , a precise EDELWEISS measurement of Q / Q ′ is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q ′ are discussed in detail. For recoil energies between 20 and 100xa0keV, the resulting heat quenching factor is Q ′ = 0.91 ± 0.03 ± 0.04 , where the two errors are the contributions from the Q and Q / Q ′ measurements, respectively. The present compilation of Q values and evaluation of Q ′ represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for WIMP dark matter.

320 g ionization-heat cryogenic detector for dark matter search in the EDEL WEISS experiment

The EDEL WEISS experiment is presently using for direct WIMP detection a 320g heat-and-ionization cryogenic Ge detector operated in a low-background environment in the Laboratoire Souterrain de Modane (LSM). This detector presents an increase of more than 4 times the mass of previous detectors. Calibrations of this detector are used to determine its energy resolution and fiducial volume, and to optimize the detector design for the 1 kg phase of the EDEL WEISS-I experiment. Analysis of the calibrations and characteristics of a first series of 320g-detectors are presented.

Status and Outlook of the EDELWEISS Experiment

EDELWEISS is a direct search for WIMPs using cryogenic germanium ionizationphonon detectors and located in the Modane underground laboratory. We summarize the final results of the EDELWEISS I experiment obtained with up to nearly a kilogram of detectors. The increased exposure confirms previous results. We also report on the preparations for EDELWEISS II. Preliminary results are expected in 2006; the experiment could ultimately deploy up to 40 kg of detectors. Goals are to gain two orders of magnitude in sensitivity and to serve as a testbed for an even larger, tonne-scale, experiment.

Dark Matter Search in the EDELWEISS Experiment

Abstract The EDELWEISS collaboration is performing a direct search for WIMP dark matter in a low-background environment in the Laboratoire Souterrain de Modane. Two series of results obtained with 320 g heat-and-ionization detectors are presented. During the 4.53 effective exposure of the year 2000 run, no nuclear events are observed in the fiducial volume in the 30–200 keV energy range. The central value of the signal reported by the DAMA experiment NaI1–4 is thus excluded at 90% CL. The present 2002 setup with three detectors is described and improved calibration performances are presented. The R&D program and the EDELWEISS-II stage of the experiment are also briefly described.

Dark matter search in the EDELWEISS experiment using a 320 g ionization-heat Ge-detector

The EDELWEISS collaboration has performed a direct search for WIMPs using a 320g ionization-heat Ge-cryogenic detector operated in a low-background environment in the Laboratoire Souterrain de Modane. No nuclear recoils events are observed in the fiducial volume in the 30-200 keV energy range during an effective exposure of 4.53 kg.days. A limit on the cross-section of the WIMP-proton spin-independent interaction as a function of the WIMP mass is deduced. The central value of the signal reported by the DAMA experiment is excluded at 90% CL.