118323618
Search for An Annual Modulation in Three Years of CoGeNT Dark Matter Detector Data
Weakly Interacting Massive Particles (WIMPs) are well-established dark matter candidates. WIMP interactions with sensitive detectors are expected to display a characteristic annual modulation in rate. We release a dataset spanning 3.4 years of operation from a low-background germanium detector, designed to search for this signature. A previously reported modulation persists, concentrated in a region of the energy spectrum populated by an exponential excess of unknown origin. Its phase and period agree with phenomenological expectations, but its amplitude is a factor �4-7 larger than predicted for a standard WIMP galactic halo. We consider the possibility of a non-Maxwellian local halo velocity distribution as a plausible explanation, able to help reconcile recently reported WIMP search anomalies.
16108826
Validation of spallation neutron production and propagation within Geant4
Using simulations to understand backgrounds from muon-induced neutrons is important in designing next-generation low-background underground experiments. Validation of relevant physics within the Geant4 simulation package has been completed by comparing to data from two recent experiments. Verification focused on the production and propagation of neutrons at energies important to underground experiments. Discrepancies were observed between experimental data and the simulation. Techniques were explored to correct for these discrepancies.
22349078
Development of a data acquisition system for the MALBEK Low-Background BEGe detector
The Majorana collaboration is currently building the Majorana Demonstrator, an array of natural and en­riched high purity germanium (HPGe) detectors that will search for the neutrinoless double-beta decay of the 76Ge isotope. As part of the Demonstrator research and development effort we have deployed a prototype 450 g modified broad energy germanium (BEGe) detector at the Kimballton Underground Research Facility (KURF) in Ripplemeade, VA. This detector, the Majorana Low-Background BEGe Detector at KURF (MAL-BEK), will examine detector performance and background in the double-beta decay region of interest as well as explore the sub-keV energy spectrum in a search for light weakly interacting massive particles (WIMPs). In order to achieve this goal we have implemented a modular and highly automated data acquisition system (DAQ) capable of digitizing sub-keV signals and running autonomously in an underground environment. The DAQ is built using the Object-oriented Real-time Control and Acquisition (ORCA) application. ORCA enables the remote monitoring and control of all DAQ electronics, hardware, and slow control systems. A built in scripting language, ORCAScript, allows for the automation of run-time experimental parameters, real-time event building and data filtering, and system monitoring with email notification and alarms. The implemented MALBEK DAQ is currently operating at KURF in a production data taking mode.
121657706
A Pulse Shape Analysis Technique for the MAJORANA Experiment
Abstract In order to achieve background count rates sufficiently low so as to allow the observation of rare events such as neutrinoless double beta (0νββ) decay, background suppression techniques are routinely employed. In this paper we present details of a novel Pulse Shape Analysis algorithm, which allows single-site events such as 0νββ decay to be distinguished from multi-site background events in germanium detectors. The algorithm, which is based on the event-by-event χ 2 fitting of experimental signals to a basis data set of unique single-site pulse shapes, has been developed through simulation studies and tested experimentally using a Broad Energy Germanium detector. It is found experimentally that the technique is able to successfully identify and reject 99% of multi-site events in the single escape peak associated with the gamma decay of 208 Tl, whilst maintaining a survival probability of 98% for neutrinoless double-beta-decay-like double escape peak events.
7696495
Search for an annual modulation in a p-type Point Contact germanium dark matter detector.
Fifteen months of cumulative CoGeNT data are examined for indications of an annual modulation, a predicted signature of weakly interacting massive particle (WIMP) interactions. Presently available data support the presence of a modulated component of unknown origin, with parameters prima facie compatible with a galactic halo composed of light-mass WIMPs. Unoptimized estimators yield a statistical significance for a modulation of ∼2.8σ, limited by the short exposure.
35493425
A magnetically shielded room with ultra low residual field and gradient.
A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements.
10625598
UNIVERSALITY AND ASYMPTOTICS OF GRAPH COUNTING PROBLEMS IN UNORIENTED SURFACES
Bender-Canfield showed that a plethora of graph counting problems in oriented/unoriented surfaces involve two constants tg and pg for the oriented and the unoriented case respectively. T.T.Q. Le and the authors recently discovered a hidden relation between the sequence tg and a formal power series solution u(z) of the Painlevé I equation which, among other things, allows to give exact asymptotic expansion of tg to all orders in 1/g for large g. The paper introduces a formal power series solution v(z) of a Riccati equation, gives a nonlinear recursion for its coefficients and an exact asymptotic expansion to all orders in g for large g, using the theory of Borel transforms. In addition, we conjecture a precise relation between the sequence pg and v(z). Our conjecture is motivated by the enumerative aspects of a quartic matrix model for real symmetric matrices, and the analytic properties of its double scaling limit. In particular, the matrix model provides a computation of the number of rooted quadrangulations in the 2-dimensional projective plane. Our conjecture implies analyticity of the O(N) and Sp(N)-types of free energy of an arbitrary closed 3-manifold in a neighborhood of zero. Finally, we give a matrix model calculation of the Stokes constants, pose several problems that can be answered by the Riemann-Hilbert approach, and provide ample numerical evidence for our results.
55759997
ABJM theory as a Fermi gas
The partition function on the 3-sphere of many supersymmetric Chern?Simons-matter theories reduces, by localization, to a matrix model. We develop a new method to study these models in the M-theory limit, but at all orders in the 1/N expansion. The method is based on reformulating the matrix model as the partition function of an ideal Fermi gas with a non-trivial, one-particle quantum Hamiltonian. This new approach leads to a completely elementary derivation of the N3/2 behavior for ABJM theory and quiver Chern?Simons-matter theories. In addition, the full series of 1/N corrections to the original matrix integral can be simply determined by a next-to-leading calculation in the WKB or semiclassical expansion of the quantum gas, and we show that, for several quiver Chern?Simons-matter theories, it is given by an Airy function. This generalizes a recent result of Fuji, Hirano and Moriyama for ABJM theory. It turns out that the semiclassical expansion of the Fermi gas corresponds to a strong coupling expansion in type IIA theory, and it is dual to the genus expansion. This allows us to calculate explicitly non-perturbative effects due to D0-?and D2-brane instantons in the AdS background.
18733586
Remodeling the B-Model
We propose a complete, new formalism to compute unambiguously B-model open and closed amplitudes in local Calabi–Yau geometries, including the mirrors of toric manifolds. The formalism is based on the recursive solution of matrix models recently proposed by Eynard and Orantin. The resulting amplitudes are non-perturbative in both the closed and the open moduli. The formalism can then be used to study stringy phase transitions in the open/closed moduli space. At large radius, this formalism may be seen as a mirror formalism to the topological vertex, but it is also valid in other phases in the moduli space. We develop the formalism in general and provide an extensive number of checks, including a test at the orbifold point of Ap fibrations, where the amplitudes compute the ’t Hooft expansion of vevs of Wilson loops in Chern-Simons theory on lens spaces. We also use our formalism to predict the disk amplitude for the orbifold $${{mathbb {C}}^3 /{mathbb{Z}}_3}$$ .
119202302
A one-loop test of quantum supergravity
The partition function on the three-sphere of ABJM theory and its generalizations has, at large N, a universal, subleading logarithmic term. Inspired by the success of one-loop quantum gravity for computing the logarithmic corrections to black hole entropy, we try to reproduce this universal term by a one-loop calculation in Euclidean 11-dimensional supergravity on AdS4 × X7. We find perfect agreement between the results of ABJM theory and the 11-dimensional supergravity.
15021686
MORE ON SOFTLY BROKEN N = 2 QCD
We extend previous work on the soft breaking of N = 2 supersymmetric QCD. We present the formalism for the breaking due to a dilaton spurion for a general gauge group and obtain the exact effective potential. We obtain some general features of the vacuum structure in the pure SU(N) Yang–Mills theory and we also derive a general mass formula for this class of theories, in particular we present explicit results for the mass spectrum in the SU(2) case. Finally we analyze the vacuum structure of the SU(2) theory with one massless hypermultiplet. This theory presents dyon condensation and a first order phase transition in the supersymmetry breaking parameter driven by nonmutually local BPS states. This could be a hint of Argyres–Douglas-like phases in nonsupersymmetric gauge theories.