The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors to search for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. CDMS data, accounting for the neutron background, give limits on the spin-independent WIMP-nucleon elastic-scattering cross section that exclude unexplored parameter space above 10 GeV͞c 2 WIMP mass and, at .75% C.L., the entire 3s allowed region for the WIMP signal reported by the DAMA experiment. Extensive evidence indicates that a large fraction of the matter in the universe is nonluminous, nonbaryonic, and "cold"-nonrelativistic at the time matter began to dominate the energy density of the universe [1][2][3]. Weakly interacting massive particles (WIMPs) are an excellent candidate for nonbaryonic, cold dark matter [2,4]. Minimal supersymmetry provides a natural WIMP candidate in the form of the lightest superpartner, with a typical mass M ϳ 100 GeV͞c 2 [5][6][7][8]. WIMPs are expected to have collapsed into a roughly isothermal, spherical halo within which the visible portion of our galaxy resides. WIMPs scatter off nuclei via the weak interaction, potentially allowing their direct detection [9,10]. The expected spectrum of recoil energies (energy given to the recoiling nucleus during the interaction) is exponential with a characteristic energy of a few to tens of keV [11]. The expected event rate is model dependent, but is generically 1 kg 21 d 21 or lower [10].This Letter reports new exclusion limits on the spinindependent WIMP-nucleon elastic-scattering cross section by the Cryogenic Dark Matter Search (CDMS). The rate of rare WIMP-nucleon interactions is constrained by extended exposure of detectors that discriminate WIMPinduced nuclear recoils from electron recoils caused by interactions of background particles [12,13].The ionization yield Y (the ratio of ionization production to recoil energy in a semiconductor) of a particle interaction differs greatly for nuclear and electron recoils. CDMS detectors measure phonon and electron-hole pair production to determine recoil energy and ionization yield for each event. The data discussed here were obtained with two types of detectors, Berkeley Large Ionization-and Phonon-mediated (BLIP) and Z-sensitive Ionization-and Phonon-mediated (ZIP) detectors [12][13][14][15][16][17][18]. For both types, the drift field for the ionization measurement is supplied by radially segmented electrodes on the faces of the disk-shaped crystals [19]. In BLIP detectors, phonon production is determined from the detector's calorimetric temperature change. In ZIP detectors, athermal phonons are collected to determine phonon production and xy position. Detector performance is discussed in detail elsewhere [14,[16][17][18][19][20].Photons cause most bulk electron recoils, while lowenergy electrons incident on the detector surfaces cause low-Y electron recoils in a thin surface layer ("surface events"). Neutron, photon, and electron sources ar...

The corresponding propagators are easily found to be ($ r fa)= [24w 2 (^2-m 2 )]~1{ (yp+m) ti'l(yp+m)T s (yp~m)T r 2+2(yp+m)l\ (yp-m)r r (yp+m)} +I72m^~1{yp tr[r s r^]+2 tr[ T^rs r-]+27^r 5 r--2r sT^r -+2r s r^}+[8w]-1 {tr[r ,r']+2r j*}. Similarly, for the spin-(^) field we may write and find for the propagators (rp r $ s ) + = [\2m 2 (p 2~m2 )']~l{ (yp+m) tr[(7^+w)r s (7^-w)r r ]-(yp+m)T s (yp-m)T r (yp+m)} -[36W 2 ]-1 {T^ tr[r s r^]-4 tr[ 7^rs r^+ 7^rs r'*+5r s 7^r'-+r s r^}+[4m]-1 {tr[r s r^-r s r'*}.The explicit evaluation of these propagators is straightforward but the result is not particularly illuminating, and we omit it. We note that the residues at the pole p 2 =m 2 are identical with those of SDS, but that the contact terms are different. The asymptotic behavior for large p is no worse than linear.Low-energy iT~-meson interactions in hydrogen are studied in the following channels: K~+p-*K-+p, K-+p-*2-+T + ,K~+p -• S+-T-7T-, and cross sections, as a function of momentum, are presented in the region of 60-300 MeV/c K~ laboratory momentum. These cross sections, combined with existing data, are used to fit the zero-effective-range theory of Dalitz and Tuan. Two possible solutions are obtained; the preferred one agrees with previous higher energy data. The favored solution also suggests an S-wave bound state at 1410 MeV, which could be associated with the Fo* at 1405 MeV whose spin is still undetermined. Various properties of the two solutions are presented for K~p interactions and K 2°p interactions.

The Cryogenic Dark Matter Search (CDMS) is an experiment to detect weakly interacting massive particles (WIMPs), which may constitute the universe's dark matter, based on their interactions with Ge and Si nuclei. We report the results of an analysis of data from the first two runs of CDMS at the Soudan Underground Laboratory in terms of spin-dependent WIMP-nucleon interactions on 73 Ge and 29 Si. These data exclude new regions of WIMP parameter space, including regions relevant to spin-dependent interpretations of the annual modulation signal reported by the DAMA/NaI experiment. DOI: 10.1103/PhysRevD.73.011102 PACS numbers: 95.35.+d, 14.80.Ly The nature of the dark matter which dominates structure formation in our universe is one of the most pressing questions of modern cosmology [1][2][3]. A promising class of candidates is weakly interacting massive particles (WIMPs) [4], particularly the lightest neutralino in supersymmetric (SUSY) extensions to the standard model [3]. Many groups have sought to detect WIMPs directly via their elastic scattering off atomic nuclei [5].The nucleon coupling of a slow-moving Majorana neutralino (or of any WIMP in the extreme nonrelativistic limit [6]) is characterized by two terms: spin-independent (e.g. scalar) and spin-dependent (e.g. axial vector). When coherence across the nucleus is taken into account [7], these two terms behave very differently. The neutralino has similar scalar couplings to the proton and neutron [3], and nucleon contributions interfere constructively to enhance the WIMP-nucleus elastic cross section. Thus, though neutralino-nucleon cross sections for such interactions are generally orders of magnitude smaller than in the axial case [8], scalar couplings dominate direct-detection event rates in most SUSY models for experiments using heavy target nuclides.In contrast, the axial couplings of nucleons with opposing spins interfere destructively, leaving WIMP scattering amplitudes determined roughly by the unpaired nucleons (if any) in the target nucleus. Spin-dependent WIMP couplings to nuclei thus do not benefit from a significant coherent enhancement, and sensitivity to such interactions requires the use of target nuclides with unpaired neutrons or protons. Spin-dependent interactions may nonetheless dominate direct-detection event rates in spin-sensitive experiments in regions of parameter space where the scalar coupling is strongly suppressed. This can provide a lower bound on the total WIMP-nucleus elastic cross section, since spin-dependent amplitudes are more robust against fine cancellations [9]. In general, consideration of such couplings when interpreting experimental results more fully constrains WIMP parameter space and allows exploration of alternative interpretations of possible signals [10,11]. In this work we explore the implications of recent results from the Cryogenic Dark Matter Search (CDMS) * Deceased PHYSICAL REVIEW D 73, 011102(R) (2006)

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