122516190
SuperCDMS status from Soudan and plans for SNOLab
Matter, as we know it, makes up less than 5% of the Universe. Various astrophysical observations have confirmed that one quarter of the Universe and most of the matter content in the Universe is made up of Dark Matter. The nature of Dark Matter is yet to be discovered and is one of the biggest questions in Physics. Particle Physics combined with astrophysical measurements of the abundance gives rise to a Dark Matter candidate called Weakly Interacting Massive Particle (WIMP). The low density of WIMPs in the galaxies and the extremely weak nature of the interaction with ordinary matter make detection of the WIMP an extraordinarily challenging task, with abundant fakes from various radioactive and cosmogenic backgrounds with much stronger electromagnetic interaction. The extremely weak nature of the WIMP interaction dictates detectors that have extremely low naturally occurring radioactive background, a large active volume (mass) of sensitive detector material to maximize statistics, a highly efficient detector based rejection mechanism for the dominant electromagnetic background and sophisticated analysis techniques to reject any residual background. This paper describes the status of the SuperCDMS experiment.
118538422
Titanium nitride films for ultrasensitive microresonator detectors
Titanium nitride (TiNx) films are ideal for use in superconducting microresonator detectors for the following reasons: (a) the critical temperature varies with composition (0 107) and have noise properties similar to resonators made using other materials, while the quasiparticle lifetimes are reasonably long, 10–200 μs. TiN microresonators should therefore reach sensitivities well below 10−19 W Hz−1/2.
6851820
The Effect of Reduced Spatial Symmetries on Lattice States: Results for Non-zero Linear Momentum
The irreducible representations of the cubic space group are described and used to determine the mapping of continuum states to lattice states with non-zero linear momentum. The Clebsch-Gordan decomposition is calculated from the character table for the cubic space group. These results are used to identify multiparticle states which appear in the hadron spectrum on the lattice.
12246338
Position and energy-resolved particle detection using phonon-mediated microwave kinetic inductance detectors
We demonstrate position and energy-resolved phonon-mediated detection of particle interactions in a silicon substrate instrumented with an array of microwave kinetic inductance detectors (MKIDs). The relative magnitude and delay of the signal received in each sensor allow the location of the interaction to be determined with ≲ 1mm resolution at 30 keV. Using this position information, variations in the detector response with position can be removed, and an energy resolution of σ_E = 0.55 keV at 30 keV was measured. Since MKIDs can be fabricated from a single deposited film and are naturally multiplexed in the frequency domain, this technology can be extended to provide highly pixelized athermal phonon sensors for ∼1 kg scale detector elements. Such high-resolution, massive particle detectors would be applicable to rare-event searches such as the direct detection of dark matter, neutrinoless double-beta decay, or coherent neutrino-nucleus scattering.
7535151
Search for low-mass weakly interacting massive particles using voltage-assisted calorimetric ionization detection in the SuperCDMS experiment.
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 Letter, 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 0.6 kg germanium detector running for ten live days at the Soudan Underground Laboratory. A low energy threshold of 170  eVee (electron equivalent) was obtained, which allows us to constrain new WIMP-nucleon spin-independent parameter space for WIMP masses below 6  GeV/c2.
119378198
Multiparticle States and the Hadron Spectrum on the Lattice
The Clebsch-Gordan decomposition is calculated for direct products of the irreducible representations of the cubic space group. These results are used to identify multiparticle states which appear in the hadron spectrum on the lattice. Consideration of the cubic space group indicates how combinations of both zero momentum and non-zero momentum multiparticle states contribute to the spectrum.
119293103
THE FATE OF LORENTZ FRAME IN THE VICINITY OF BLACK HOLE SINGULARITY
General Relativity (GR) is known to break down at singularities. However, it is expected that quantum corrections become important when the curvature is of the order of Planck scale avoiding the singularity. By calculating the effect of tidal forces on a freely falling inertial frame, and assuming the least possible size of the frame to be of the Planck length, we show that the Lorentz frames cease to exist at a finite distance from the singularity. Within that characteristic radius, one cannot apply GR nor Quantum Field Theory (QFT) as we know them today. Additionally, we consider other quantum length scales and impose limits on the distances from the singularity at which those theories can conceivably be applied within a Lorentz frame.
118426859
SYSTEMATIC INVESTIGATIONS OF THE FREE FERMIONIC HETEROTIC STRING GAUGE GROUP STATISTICS: LAYER 1 RESULTS
Using software under development at Baylor University, we explicitly construct all layer 1 gauge, weakly coupled free fermionic heterotic string models up to order 22 in four large spacetime dimensions. The gauge models consist primarily of gauge content making a systematic construction process efficient. We present an overview of the model building procedure, redundancies in the process, methods used to reduce such redundancies and statistics regarding the occurrence of various combinations of gauge group factors and GUT groups. Statistics for both and models are presented.
118448597
NEW 145-MHZ SOURCE MEASUREMENTS BY PAPER IN THE SOUTHERN SKY
We present observations from the Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa, observed in May and September 2010. Using two nights of drift scanning with PAPER’s 60 ◦ FWHM beam we have made a map covering the entire sky below +10 degrees declination with an effective center frequency of 145 MHz, a 70-MHz bandwidth, and a resolution of 26 ′ . A 4800 square-degree region of this large map with the lowest Galactic emission reaches an RMS of 0.7 Jy. We establish an absolute flux scale using sources from the 160-MHz Culgoora catalog. Using the 408-MHz Molonglo Reference Catalog (MRC) as a finding survey, we identify counterparts to 480 sources in our maps, and compare our fluxes to the MRC and to 332 sources in the Culgoora catalog. For both catalogs, the ratio of PAPER to catalog flux averages to 1, with a standard deviation of 50%. This measured variation is consistent with comparisons between independent catalogs observed at different bands. The PAPER data represent new 145-MHz flux measurements for a large number of sources in the band expected to encompass cosmic reionization, and represents a significant step toward establishing a model for removing foregrounds to the reionization signal. Subject headings: dark ages, reionization, first stars — catalogs — instrumentation: interferometers
73360743
Initial Systematic Investigations of the Landscape of Low-Layer NAHE Variation Extensions
The discovery that the number of physically consistent string vacua is on the order of 10500 has prompted several statistical studies of string phenomenology. Focusing on the Weakly Coupled Free Fermionic String formalism, we present systematic extensions of a variation on the NAHE (Nanopoulos, Antoniadis, Hagelin, Ellis) set of basis vectors. This variation is more conducive to the production of “mirrored” models, in which the observable and hidden sector gauge groups (and possibly matter content) are identical. This study is parallel to the extensions of the NAHE set itself and presents statistics related to similar model properties. Statistical coupling between specific gauge groups and spacetime supersymmetry is also examined. Finally, a model with completely mirrored gauge groups is discussed. It is found that the region of the landscape explored generates no physically realistic models due to a lack of three net chiral generations.
67793460
Algorithm for determining U(1) charges in free fermionic heterotic string models
To assist in the search for phenomenologically realistic models in the string landscape, we must develop tools for investigating all gauge charges, including U(1) charges, in string models. We introduce the process for constructing fermionic string models and present an algorithm for determining the U(1) gauge states and U(1) charges in weakly-coupled free fermionic heterotic string (WCFFHS) models given their matter and non-Abelian gauge content. We determine the computational complexity of this algorithm and discuss a particular implementation that can be used in conjunction with a framework developed at Baylor University for building WCFFHS models. We also present preliminary results regarding matter state uniqueness for a run of 1.4 million gauge models and find that U(1) charges affect the number of unique matter states in a significant minority of models constructed. We conclude by considering future avenues of investigation to which this algorithm may be applied.