Low-threshold analysis of CDMS shallow-site data

Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four ~224 g germanium and two ~105 g silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of ~1 and ~2 keV, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below 9 GeV/c^2. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments’ data as WIMP signals, and exclude new parameter space for WIMP masses between 3 and 4 GeV/c^2

Particle Astrophysics and Cosmology: Cosmic Laboratories for New Physics (Summary of the Snowmass 2001 P4 Working Group)

The past few years have seen dramatic breakthroughs and spectacular and puzzling discoveries in astrophysics and cosmology. In many cases, the new observations can only be explained with the introduction of new fundamental physics. Here we summarize some of these recent advances. We then describe several problem in astrophysics and cosmology, ripe for major advances, whose resolution will likely require new physics.Comment: 27 pages, 14 figure

Expected Performance of CryoArray

WIMP-nucleon cross sections below 10^(-9) pb may be probed by ton-scale experiments with low thresholds and background rates ~20 events per year. An array of cryogenic detectors ("CryoArray") could perform well enough to reach this goal. Sufficient discrimination and background suppression of photons has already been demonstrated. Reduction of neutron backgrounds may be achieved by siting the experiment deep enough. Removal of the surface-electron backgrounds alone has not yet been demonstrated, but the reductions required even for this troublesome background are quite modest and appear achieveable.Comment: 4 pages, 2 figures. Talk at DM2002 Conference, Marina del Rey, CA, Feb 20-22, 200

Dark Matter as Dense Color Superconductor

We discuss a novel cold dark matter candidate which is formed from the ordinary quarks during the QCD phase transition when the axion domain wall undergoes an unchecked collapse due to the tension in the wall. If a large number of quarks is trapped inside the bulk of a closed axion domain wall, the collapse stops due to the internal Fermi pressure. In this case the system in the bulk, may reach the critical density when it undergoes a phase transition to a color superconducting phase with the ground state being the quark condensate, similar to BCS theory. If this happens, the new state of matter representing the diquark condensate with a large baryon number B > 10^{20} becomes a stable soliton-like configuration. Consequently, it may serve as a novel cold dark matter candidate.Comment: To appear in the Proceedings "Dark Matter 2002

Status of the EDELWEISS-II experiment

EDELWEISS is a direct dark matter search experiment situated in the low radioactivity environment of the Modane Underground Laboratory. The experiment uses Ge detectors at very low temperature in order to identify eventual rare nuclear recoils induced by elastic scattering of WIMPs from our Galactic halo. We present results of the commissioning of the second phase of the experiment, involving more than 7 kg of Ge, that has been completed in 2007. We describe two new types of detectors with active rejection of events due to surface contamination. This active rejection is required in order to achieve the physics goals of 10-8 pb cross-section measurement for the current phase

Light Neutralinos and WIMP direct searches

The predictions of our previous analyses about possible low-mass (lower than 50 GeV) relic neutralinos are discussed in the light of the most recent results from WIMP direct detection experiments. It is proved that these light neutralinos are quite compatible with the new annual-modulation data of the DAMA Collaboration; our theoretical predictions are also compared with the upper bounds of the CDMS and EDELWEISS Collaborations.Comment: 4 pages, 1 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/note.ps.gz or through http://www.to.infn.it/astropart/index.htm

Dark Matter Candidates: What Cold, ..and What's Not

In this brief review of recent theoretical developments associated with the search for dark matter I describe the following: why baryons are now ruled out as dark matter candidates; SUSY WIMPS and signatures in the MSSM and NMSSM why claimed indirect signatures are probably not WIMP related, why axions may be of new interest, how WIMP detection might tell us about the galactic halo, and how theorists are preparing to avoid the next generation of experimental constraints.Comment: 6 pages, Invited Review talk, Neutrino 2006. To appear in Proceeding

Arguments for a "U.S. Kamioka": SNOLab and its Implications for North American Underground Science Planning

We argue for a cost-effective, long-term North American underground science strategy based on partnership with Canada and initial construction of a modest U.S. Stage I laboratory designed to complement SNOLab. We show, by reviewing the requirements of detectors now in the R&D phase, that SNOLab and a properly designed U.S. Stage I facility would be capable of meeting the needs of North America's next wave of underground experiments. We discuss one opportunity for creating a Stage I laboratory, the Pioneer tunnel in Washington State, a site that could be developed to provide dedicated, clean, horizontal access. This unused tunnel, part of the deepest (1040 m) tunnel system in the U.S., would allow the U.S. to establish, at low risk and low cost, a laboratory at a depth (2.12 km.w.e., or kilometers of water equivalent) quite similar to that of the Japanese laboratory Kamioka (2.04 km.w.e.). We describe studies of cosmic ray attenuation important to properly locating such a laboratory, and the tunnel improvements that would be required to produce an optimal Stage I facility. We also discuss possibilities for far-future Stage II (3.62 km.w.e.) and Stage III (5.00 km.w.e.) developments at the Pioneer tunnel, should future North American needs for deep space exceed that available at SNOLab.Comment: 23 pages, 10 figures; revised version includes discusion about neutrino-factory magic baseline