We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below 10 GeV/c2. This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c2 and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.
We report results from a blind analysis of the final data taken with the Cryogenic Dark Matter Search experiment (CDMS II) at the Soudan Underground Laboratory, Minnesota, USA. A total raw exposure of 612 kg-days was analyzed for this work. We observed two events in the signal region; based on our background estimate, the probability of observing two or more background events is 23%. These data set an upper limit on the Weakly Interacting Massive Particle (WIMP)-nucleon elastic-scattering spin-independent cross-section of 7.0 × 10 −44 cm 2 for a WIMP of mass 70 GeV/c 2 at the 90% confidence level. Combining this result with all previous CDMS II data gives an upper limit on the WIMP-nucleon spin-independent cross-section of 3.8 × 10 −44 cm 2 for a WIMP of mass 70 GeV/c 2 . We also exclude new parameter space in recently proposed inelastic dark matter models. Cosmological observations [1] have led to a concordance model of the universe where ∼85% of matter is non-baryonic, non-luminous and non-relativistic at the time of structure formation. Weakly Interacting Massive Particles (WIMPs) [2] are a class of candidates for this dark matter which are particularly well motivated by proposed extensions to the Standard Model of particle physics and by thermal production models for dark matter in the early universe [3,4,5,6]. WIMPs, distributed in a halo surrounding our galaxy, would coherently scatter off nuclei in terrestrial detectors [7,8,9] with a mean recoil energy of ∼ tens of keV, presently limited by observation to a rate of less than 0.1 event 5,6,10]. Direct search experiments seek recoil signatures of these interactions and have achieved the sensitivity to begin testing the most interesting classes of WIMP models [11,12,13,14].The Cryogenic Dark Matter Search (CDMS II) experiment, located at the Soudan Underground Laboratory, uses 19 Ge (∼230 g) and 11 Si (∼100 g) particle detectors operated at cryogenic temperatures (< 50 mK) [11,15]. Each detector is a disk ∼10 mm thick and 76 mm in diameter. Particle interactions in the detectors deposit energy in the form of phonons and ionization. Phonon sensors on the top of each detector are connected to four phonon readout channels to allow measurement of the recoil enarXiv:0912.3592v1 [astro-ph.CO]
We report on the first axion search results from the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a search for possible solar axion conversion into photons or local galactic axion conversion into electrons in the germanium crystal detectors. The solar axion search sets an upper limit on the Primakov coupling g(agammagamma) of 2.4x10(-9) GeV-1 at the 95% confidence level for an axion mass less than 0.1 keV/c2. This limit benefits from the first precise measurement of the absolute crystal plane orientations in this type of experiment. The galactic axion search analysis sets a world-leading experimental upper limit on the axioelectric coupling g(aee) of 1.4x10(-12) at the 90% confidence level for an axion mass of 2.5 keV/c2.
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)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.