12,333 research outputs found
Neutron and muon-induced background studies for the AMoRE double-beta decay experiment
AMoRE (Advanced Mo-based Rare process Experiment) is an experiment to search
a neutrinoless double-beta decay of Mo in molybdate crystals. The
neutron and muon-induced backgrounds are crucial to obtain the zero-background
level (< counts/(keVkgyr)) for the AMoRE-II experiment,
which is the second phase of the AMoRE project, planned to run at YEMI
underground laboratory. To evaluate the effects of neutron and muon-induced
backgrounds, we performed Geant4 Monte Carlo simulations and studied a
shielding strategy for the AMORE-II experiment. Neutron-induced backgrounds
were also included in the study. In this paper, we estimated the background
level in the presence of possible shielding structures, which meet the
background requirement for the AMoRE-II experiment
Pseudo Wigner-Ville Distribution, Computer program and its Applications to Time-Frequency Domain Problems
Machinery operating in non-stationary mode generates a signature which at each instant of time has a distinct frequency. A time-frequency domain representation is needed to characterize such signature. Pseudo Wigner-Ville distribution is ideally suited for portraying non-stationary signal in the time- frequency domain and carried out by adapting the fast Fourier transform algorithm. The important parameters affecting the pseudo Wigner-Ville distribution are discussed and sensitivity analyses are also performed. Practical examples of an actual transient signal are used to illustrate its dynamic features jointly in time and frequency.Naval Sea Systems Commandhttp://archive.org/details/pseudowignervill00jeonNaval Sea Systems CommandApproved for public release; distribution is unlimited
Radiative and Collisional Jet Energy Loss in a Quark-Gluon Plasma
We calculate radiative and collisional energy loss of hard partons traversing
the quark-gluon plasma created at RHIC and compare the respective size of these
contributions. We employ the AMY formalism for radiative energy loss and
include additionally energy loss by elastic collisions. Our treatment of both
processes is complete at leading order in the coupling, and accounts for the
probabilistic nature of jet energy loss. We find that a solution of the
Fokker-Planck equation for the probability density distributions of partons is
necessary for a complete calculation of the nuclear modification factor
for pion production in heavy ion collisions. It is found that the
magnitude of is sensitive to the inclusion of both collisional and
radiative energy loss, while the average energy is less affected by the
addition of collisional contributions. We present a calculation of for
at RHIC, combining our energy loss formalism with a relativistic
(3+1)-dimensional hydrodynamic description of the thermalized medium.Comment: 4 pages, 4 figures, contributed to Quark Matter 2008, Jaipur, Indi
Performance of a prototype active veto system using liquid scintillator for a dark matter search experiment
We report the performance of an active veto system using a liquid
scintillator with NaI(Tl) crystals for use in a dark matter search experiment.
When a NaI(Tl) crystal is immersed in the prototype detector, the detector tags
48% of the internal K-40 background in the 0-10 keV energy region. We also
determined the tagging efficiency for events at 6-20 keV as 26.5 +/- 1.7% of
the total events, which corresponds to 0.76 +/- 0.04 events/keV/kg/day.
According to a simulation, approximately 60% of the background events from U,
Th, and K radioisotopes in photomultiplier tubes are tagged at energies of 0-10
keV. Full shielding with a 40-cm-thick liquid scintillator can increase the
tagging efficiency for both the internal K-40 and external background to
approximately 80%.Comment: Submitted to Nuclear Instruments and Methods in Physics Research
Section
Balance Functions, Correlations, Charge Fluctuations and Interferometry
Connections between charge balance functions, charge fluctuations and
correlations are presented. It is shown that charge fluctuations can be
directly expressed in terms of a balance functions under certain assumptions.
The distortion of charge balance functions due to experimental acceptance is
discussed and the effects of identical boson interference is illustrated with a
simple model.Comment: 1 eps figure included. 5 pages in revtex
Quantum and frustration effects on fluctuations of the inverse compressibility in two-dimensional Coulomb glasses
We consider interacting electrons in a two-dimensional quantum Coulomb glass
and investigate by means of the Hartree-Fock approximation the combined effects
of the electron-electron interaction and the transverse magnetic field on
fluctuations of the inverse compressibility. Preceding systematic study of the
system in the absence of the magnetic field identifies the source of the
fluctuations, interplay of disorder and interaction, and effects of hopping.
Revealed in sufficiently clean samples with strong interactions is an unusual
right-biased distribution of the inverse compressibility, which is neither of
the Gaussian nor of the Wigner-Dyson type. While in most cases weak magnetic
fields tend to suppress fluctuations, in relatively clean samples with weak
interactions fluctuations are found to grow with the magnetic field. This is
attributed to the localization properties of the electron states, which may be
measured by the participation ratio and the inverse participation number. It is
also observed that at the frustration where the Fermi level is degenerate,
localization or modulation of electrons is enhanced, raising fluctuations.
Strong frustration in general suppresses effects of the interaction on the
inverse compressibility and on the configuration of electrons.Comment: 15 pages, 18 figures, To appear in Phys. Rev.
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