218 research outputs found
A Cryogenic Underground Observatory for Rare Events: Cuore, an Update
CUORE is a proposed tightly packed array of 1000 TeO_{2} bolometers, each
being a cube 5 cm on a side with a mass of 750 gms. The array consists of 25
vertical towers, arranged in a square, of 5 towers by 5 towers, each containing
10 layers of 4 crystals. The design of the detector is optimized for ultralow-
background searches for neutrinoless double beta decay of ^{130}Te (33.8%
abundance), cold dark matter, solar axions, and rare nuclear decays. A
preliminary experiment involving 20 crystals of various sizes (MIBETA) has been
completed, and a single CUORE tower is being constructed as a smaller scale
experiment called CUORICINO. The expected performance and sensitivity, based on
Monte Carlo simulations and extrapolations of present results, are reported.Comment: in press: Nucl. Phys. of Russian Academy of Sc
A New Limit on the Neutrinoless DBD of 130Te
We report the present results of CUORICINO a cryogenic experiment on
neutrinoless double beta decay (DBD) of 130Te consisting of an array of 62
crystals of TeO2 with a total active mass of 40.7 kg. The array is framed
inside of a dilution refrigerator, heavily shielded against environmental
radioactivity and high-energy neutrons, and operated at a temperature of ~8 mK
in the Gran Sasso Underground Laboratory. Temperature pulses induced by
particle interacting in the crystals are recorded and measured by means of
Neutron Transmutation Doped thermistors. The gain of each bolometer is
stabilized with voltage pulses developed by a high stability pulse generator
across heater resistors put in thermal contact with the absorber.
The calibration is performed by means of two thoriated wires routinely
inserted in the set-up. No evidence for a peak indicating neutrinoless DBD of
130Te is detected and a 90% C.L. lower limit of 1.8E24 years is set for the
lifetime of this process. Taking largely into account the uncertainties in the
theoretical values of nuclear matrix elements, this implies an upper boud on
the effective mass of the electron neutrino ranging from 0.2 to 1.1 eV. This
sensitivity is similar to those of the 76Ge experiments.Comment: 4 pages, 2 figure
First results from the CERN Axion Solar Telescope (CAST)
Hypothetical axion-like particles with a two-photon interaction would be
produced in the Sun by the Primakoff process. In a laboratory magnetic field
(``axion helioscope'') they would be transformed into X-rays with energies of a
few keV. Using a decommissioned LHC test magnet, CAST has been running for
about 6 months during 2003. The first results from the analysis of these data
are presented here. No signal above background was observed, implying an upper
limit to the axion-photon coupling < 1.16 10^{-10} GeV^-1 at 95% CL for m_a
<~0.02 eV. This limit is comparable to the limit from stellar energy-loss
arguments and considerably more restrictive than any previous experiment in
this axion mass range.Comment: 4 pages, accepted by PRL. Final version after the referees comment
Artificial Sequences and Complexity Measures
In this paper we exploit concepts of information theory to address the
fundamental problem of identifying and defining the most suitable tools to
extract, in a automatic and agnostic way, information from a generic string of
characters. We introduce in particular a class of methods which use in a
crucial way data compression techniques in order to define a measure of
remoteness and distance between pairs of sequences of characters (e.g. texts)
based on their relative information content. We also discuss in detail how
specific features of data compression techniques could be used to introduce the
notion of dictionary of a given sequence and of Artificial Text and we show how
these new tools can be used for information extraction purposes. We point out
the versatility and generality of our method that applies to any kind of
corpora of character strings independently of the type of coding behind them.
We consider as a case study linguistic motivated problems and we present
results for automatic language recognition, authorship attribution and self
consistent-classification.Comment: Revised version, with major changes, of previous "Data Compression
approach to Information Extraction and Classification" by A. Baronchelli and
V. Loreto. 15 pages; 5 figure
Faster Approximate String Matching for Short Patterns
We study the classical approximate string matching problem, that is, given
strings and and an error threshold , find all ending positions of
substrings of whose edit distance to is at most . Let and
have lengths and , respectively. On a standard unit-cost word RAM with
word size we present an algorithm using time When is
short, namely, or this
improves the previously best known time bounds for the problem. The result is
achieved using a novel implementation of the Landau-Vishkin algorithm based on
tabulation and word-level parallelism.Comment: To appear in Theory of Computing System
Search for an annual modulation of dark-matter signals with a germanium spectrometer at the Sierra Grande Laboratory
Data collected during three years with a germanium spectrometer at the Sierra
Grande underground laboratory have been analyzed for distinctive features of
annual modulation of the signal induced by WIMP dark matter candidates. The
main motivation for this analysis was the recent suggestion by the DAMA/NaI
Collaboration that a yearly modulation signal could not be rejected at the 90%
confidence level when analyzing data obtained with a high-mass low-background
scintillator detector. We performed two different analyses of the data: First,
the statistical distribution of modulation-significance variables (expected
from an experiment running under the conditions of Sierra Grande) was compared
with the same variables obtained from the data. Second, the data were analyzed
in energy bins as an independent check of the first result and to allow for the
possibility of a crossover in the expected signal. In both cases no
statistically significant deviation from the null result was found, which could
support the hypothesis that the data contain a modulated component. A plot is
also presented to enable the comparison of these results to those of the DAMA
collaboration.Comment: New version accepted by Astroparticle Physics. Changes suggested by
the referee about the theoretical prediction of rates are included.
Conclusions remain unaffected. 14 pages, LaTeX, 7 figures. Uses epsfig macr
Experimental Search for Solar Axions
A new technique has been used to search for solar axions using a single crystal germanium detector. It exploits the coherent conversion of axions into photons when their angle of incidence satisfies a Bragg condition with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1-kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of g_{a,\gamma\gamma}<2.7\times 10^{-9} GeV^{-1} independent of axion mass up to \sim 1 keV
The Majorana Project
Building a \BBz experiment with the ability to probe neutrino mass in the
inverted hierarchy region requires the combination of a large detector mass
sensitive to \BBz, on the order of 1-tonne, and unprecedented background
levels, on the order of or less than 1 count per year in the \BBz signal
region. The MAJORANA Collaboration proposes a design based on using high-purity
enriched Ge-76 crystals deployed in ultra-low background electroformed Cu
cryostats and using modern analysis techniques that should be capable of
reaching the required sensitivity while also being scalable to a 1-tonne size.
To demonstrate feasibility, the collaboration plans to construct a prototype
system, the MAJORANA DEMONSTRATOR, consisting of 30 kg of 86% enriched \Ge-76
detectors and 30 kg of natural or isotope-76-depleted Ge detectors. We plan to
deploy and evaluate two different Ge detector technologies, one based on a
p-type configuration and the other on n-type.Comment: paper submitted for the 2008 Carolina International Symposium on
Neutrino Physic
Double-beta decay of Te to the first 0 excited state of Xe with CUORICINO
The CUORICINO experiment was an array of 62 TeO single-crystal
bolometers with a total Te mass of kg. The experiment finished
in 2008 after more than 3 years of active operating time. Searches for both
and double-beta decay to the first excited state in
Xe were performed by studying different coincidence scenarios. The
analysis was based on data representing a total exposure of
N(Te)t=y. No evidence for a signal was
found. The resulting lower limits on the half lives are y (90% C.L.), and
y (90%
C.L.).Comment: 6 pages, 4 figure
CUORE and beyond: bolometric techniques to explore inverted neutrino mass hierarchy
The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will
search for neutrinoless double beta decay of Te. With 741 kg of TeO
crystals and an excellent energy resolution of 5 keV (0.2%) at the region of
interest, CUORE will be one of the most competitive neutrinoless double beta
decay experiments on the horizon. With five years of live time, CUORE projected
neutrinoless double beta decay half-life sensitivity is y
at ( y at the 90% confidence level), which
corresponds to an upper limit on the effective Majorana mass in the range
40--100 meV (50--130 meV). Further background rejection with auxiliary light
detector can significantly improve the search sensitivity and competitiveness
of bolometric detectors to fully explore the inverted neutrino mass hierarchy
with Te and possibly other double beta decay candidate nuclei.Comment: Submitted to the Proceedings of TAUP 2013 Conferenc
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