A. Villano - University of Minnesota

A. Villano
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A. Villano
University of Minnesota
United States

Pubs By Year

Pub Categories

High Energy Physics - Experiment (15)
Cosmology and Nongalactic Astrophysics (11)
Physics - Instrumentation and Detectors (9)
Nuclear Experiment (5)
Instrumentation and Methods for Astrophysics (4)
High Energy Physics - Phenomenology (2)
Astrophysics of Galaxies (1)
High Energy Astrophysical Phenomena (1)

Publications Authored By A. Villano

SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass (< 10 GeV/c$^2$) particles that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~ 1 x 10$^{-43}$ cm$^2$ for a dark matter particle mass of 1 GeV/c$^2$, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark matter. Read More

The proposed Mitchell Institute Neutrino Experiment at Reactor (MINER) experiment at the Nuclear Science Center at Texas A&M University will search for coherent elastic neutrino-nucleus scattering within close proximity (about 2 meters) of a 1 MW TRIGA nuclear reactor core using low threshold, cryogenic germanium and silicon detectors. Given the Standard Model cross section of the scattering process and the proposed experimental proximity to the reactor, as many as 5 to 20 events/kg/day are expected. We discuss the status of preliminary measurements to characterize the main backgrounds for the proposed experiment. Read More

Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the quark dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available for the longitudinal structure function in particular. Here we present separated structure functions for hydrogen and deuterium at low four--momentum transfer squared, Q^2< 1 GeV^2, and compare these with parton distribution parameterizations and a k_T factorization approach. Read More

The CDMS low ionization threshold experiment (CDMSlite) uses cryogenic germanium detectors operated at a relatively high bias voltage to amplify the phonon signal in the search for weakly interacting massive particles (WIMPs). Results are presented from the second CDMSlite run with an exposure of 70 kg days, which reached an energy threshold for electron recoils as low as 56 eV. A fiducialization cut reduces backgrounds below those previously reported by CDMSlite. Read More

CDMS II data from the 5-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector WIMP-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to $\sim$5 keV, to increase sensitivity near a WIMP mass of 8 GeV/$c^2$. Read More

We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. Read More

We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search (CDMS~II) experiment using a maximum likelihood analysis. A background model is constructed using GEANT4 to simulate the surface-event background from $^{210}$Pb decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. Read More

While the Standard Model of particle physics does not include free particles with fractional charge, experimental searches have not ruled out their existence. We report results from the Cryogenic Dark Matter Search (CDMS II) experiment that give the first direct-detection limits for cosmogenically-produced relativistic particles with electric charge lower than $e$/6. A search for tracks in the six stacked detectors of each of two of the CDMS II towers found no candidates, thereby excluding new parameter space for particles with electric charges between $e$/6 and $e$/200. Read More

We report a first search for weakly interacting massive particles (WIMPs) using the background rejection capabilities of SuperCDMS. An exposure of 577 kg-days was analyzed for WIMPs with mass < 30 GeV/c2, with the signal region blinded. Eleven events were observed after unblinding. Read More

The extraction of detailed nuclear structure information from transfer reactions requires reliable, well-normalized data as well as optical potentials and a theoretical framework demonstrated to work well in the relevant mass and beam energy ranges. It is rare that the theoretical ingredients can be tested well for exotic nuclei owing to the paucity of data. The halo nucleus Be-11 has been examined through the 10Be(d,p) reaction in inverse kinematics at equivalent deuteron energies of 12,15,18, and 21. Read More

SuperCDMS is an experiment designed to directly detect Weakly Interacting Massive Particles (WIMPs), a favored candidate for dark matter ubiquitous in the Universe. In this paper, we present WIMP-search results using a calorimetric technique we call CDMSlite, which relies on voltage- assisted Luke-Neganov amplification of the ionization energy deposited by particle interactions. The data were collected with a single 0. Read More

The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Surface event rejection capabilities were tested with two $^{210}$Pb sources producing $\sim$130 beta decays/hr. Read More

We report results of a search for Weakly Interacting Massive Particles (WIMPS) with the silicon detectors of the CDMS II experiment. This blind analysis of 140.2 kg-days of data taken between July 2007 and September 2008 revealed three WIMP-candidate events with a surface-event background estimate of 0. Read More

Affiliations: 1University of Florida, Gainesville, 2California Institute of Technology, 3Massachusetts Institute of Technology, 4University of Zurich, 5University of Florida, Gainesville, 6Fermi National Accelerator Laboratory, 7Fermi National Accelerator Laboratory, 8SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 9SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 10SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 11University of Zurich, 12Syracuse University, 13Stanford University, 14University of California, Santa Barbara, 15Universidad Autonoma de Madrid, 16University of Minnesota, 17Southern Methodist University, 18California Institute of Technology, 19Queen's University, 20University of Minnesota, 21University of California, Berkeley, 22Fermi National Accelerator Laboratory, 23Queen's University, 24SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 25University of California, Berkeley, 26Universidad Autonoma de Madrid, 27University of Minnesota, 28Massachusetts Institute of Technology, 29California Institute of Technology, 30Queen's University, 31University of Minnesota, 32SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 33California Institute of Technology, 34Pacific Northwest National Laboratory, 35Texas A & M University, 36Massachusetts Institute of Technology, 37University of Minnesota, 38Fermi National Accelerator Laboratory, 39Fermi National Accelerator Laboratory, 40University of Colorado, Denver, 41Texas A & M University, 42Queen's University, 43Southern Methodist University, 44SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 45University of Minnesota, 46SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 47Syracuse University, 48University of Minnesota, 49Syracuse University, 50Massachusetts Institute of Technology, 51Universidad Autonoma de Madrid, 52Texas A & M University, 53University of Minnesota, 54Queen's University, 55Massachusetts Institute of Technology, 56University of California, Berkeley, 57Stanford University, 58California Institute of Technology, 59Queen's University, 60California Institute of Technology, 61Queen's University, 62SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 63University of Minnesota, 64University of California, Berkeley, 65Texas A & M University, 66University of California, Berkeley, 67Southern Methodist University, 68Queen's University, 69Stanford University, 70University of Evansville, 71Queen's University, 72University of Florida, Gainesville, 73University of California, Berkeley, 74Texas A & M University, 75SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 76Syracuse University, 77Southern Methodist University, 78University of California, Berkeley, 79Stanford University, 80University of California, Berkeley, 81University of California, Berkeley, 82University of Minnesota, 83University of Florida, Gainesville, 84SLAC National Accelerator Laboratory / Kavli Institute for Particle Astrophysics and Cosmology, 85Stanford University, 86Stanford University, 87Fermi National Accelerator Laboratory, 88Santa Clara University, 89University of Minnesota

We report results of a search for Weakly Interacting Massive Particles (WIMPs) with the Si detectors of the CDMS II experiment. This report describes a blind analysis of the first data taken with CDMS II's full complement of detectors in 2006-2007; results from this exposure using the Ge detectors have already been presented. We observed no candidate WIMP-scattering events in an exposure of 55. Read More

The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly-bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus Be-11, the spectroscopic factors for the two bound states remain poorly constrained. Read More

We report limits on annual modulation of the low-energy event rate from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Such a modulation could be produced by interactions from Weakly Interacting Massive Particles (WIMPs) with masses ~10 GeV/c^2. We find no evidence for annual modulation in the event rate of veto-anticoincident single-detector interactions consistent with nuclear recoils, and constrain the magnitude of any modulation to <0. Read More

A large set of cross sections for semi-inclusive electroproduction of charged pions ($\pi^\pm$) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared $W^2$ > 4 GeV$^2$ and range in four-momentum transfer squared $2 < Q^2 < 4$ (GeV/c)$^2$, and cover a range in the Bjorken scaling variable 0.2 < x < 0. Read More