3,511 research outputs found
Challenges in Double Beta Decay
After nearly 80 years since the first guess on its existence, neutrino still
escapes our insight: the mass and the true nature (Majorana or Dirac) of this
particle is still unknown. In the past ten years, neutrino oscillation
experiments have finally provided the incontrovertible evidence that neutrinos
mix and have finite masses. These results represent the strongest demonstration
that the Standard Model of electroweak interactions is incomplete and that new
Physics beyond it must exist. None of these experimental efforts could however
shade light on some of the basic features of neutrinos. Indeed, absolute scale
and ordering of the masses of the three generations as well as charge
conjugation and lepton number conservation properties are still unknown. In
this scenario, a unique role is played by the Neutrinoless Double Beta Decay
searches: these experiments can probe lepton number conservation, investigate
the Dirac/Majorana nature of the neutrinos and their absolute mass scale
(hierarchy problem) with unprecedented sensitivity. Today Neutrinoless Double
Beta Decay faces a new era where large scale experiments with a sensitivity
approaching the so-called degenerate-hierarchy region are nearly ready to start
and where the challenge for the next future is the construction of detectors
characterized by a tonne-scale size and an incredibly low background, to fully
probe the inverted-hierarchy region. A number of new proposed projects took up
this challenge. These are based either on large expansions of the present
experiments or on new ideas to improve the technical performance and/or reduce
the background contributions. n this paper, a review of the most relevant
ongoing experiments is given. The most relevant parameters contributing to the
experimental sensitivity are discussed and a critical comparison of the future
projects is proposed.Comment: 70 pages, 16 figures, 6 tables. arXiv admin note: text overlap with
arXiv:1109.5515, arXiv:hep-ex/0501010, arXiv:0910.2994 by other author
Expectations for a new calorimetric neutrino mass experiment
A large calorimetric neutrino mass experiment using thermal detectors is
expected to play a crucial role in the challenge for directly assessing the
neutrino mass. We discuss and compare here two approaches to the estimation of
the experimental sensitivity of such an experiment. The first method uses an
analytic formulation and allows to readily obtain a sensible estimate over a
wide range of experimental configurations. The second method is based on a
frequentist Montecarlo technique and is more precise and reliable. The
Montecarlo approach is then exploited to study the main sources of systematic
uncertainties peculiar to calorimetric experiments. Finally, the tools are
applied to investigate the optimal experimental configuration for a
calorimetric experiment with Rhenium based thermal detectors.Comment: 25 pagers, 16 figure
Generation of Noise Time Series with arbitrary Power Spectrum
Noise simulation is a very powerful tool in signal analysis helping to
foresee the system performance in real experimental situations. Time series
generation is however a hard challenge when a robust model of the noise sources
is missing. We present here a simple computational technique which allows the
generation of noise samples of fixed length, given a desired power spectrum. A
few applications of the method are also discussed.Comment: 4 pages, 7 figure
3d N = 2 mirror symmetry, pq-webs and monopole superpotentials
D3 branes stretching between webs of (p,q) 5branes provide an interesting
class of 3d N=2 theories. For generic pq-webs however the low energy field
theory is not known. We use 3d mirror symmetry and Type IIB S-duality to
construct Abelian gauge theories corresponding to D3 branes ending on both
sides of a pq-web made of many coincident NS5's intersecting one D5. These
theories contain chiral monopole operators in the superpotential and enjoy a
non trivial pattern of global symmetry enhancements. In the special case of the
pq-web with one D5 and one NS5, the 3d low energy SCFT admits three dual
formulations. This triality can be applied locally inside bigger quiver gauge
theories. We prove our statements using partial mirror symmetry `a la
Kapustin-Strassler, showing the equality of the S^3_b partition functions and
studying the quantum chiral rings
A staggered fully explicit lagrangian Finite Element Method for Fluid-Structure-Interaction problems
A bolometric measurement of the antineutrino mass
High statistics calorimetric measurements of the beta spectrum of 187Re are
being performed with arrays of silver perrhenate crystals operated at low
temperature. After a modification of the experimental set-up, which allowed to
substantially reduce the background of spurious counts and therefore to
increase the sensitivity on the electron antineutrino mass, a new measurement
with 10 silver perrhenate microbolometers is running since July 2002. The
crystals have masses between 250 and 350 micrograms and their average FWHM
energy resolution, constantly monitored by means of fluorescence X-rays, is of
28.3 eV at the beta end-point. The Kurie plot collected during 4485 hours x mg
effective running time has an end-point energy of 2466.1 +/- 0.8{stat} +/- 1.5
{syst} eV, while the half lifetime of the decay is found to be 43.2 +/-
0.2{stat} +/- 0.1{syst} Gy. These values are the most precise obtained so far
for 187Re. From the fit of the Kurie plot we can deduce a value for the squared
electron antineutrino mass m(nu)^2 of 147 +/- 237{stat} +/- 90{syst} eV^2. The
corresponding 90% C.L. upper limit for m(nu) is 21.7 eV.Comment: 3 pages, 3 figures. Submitted to Phys. Rev. Let
The 4 K outer cryostat for the CUORE experiment: construction and quality control
The external shell of the CUORE cryostat is a large cryogen-free system
designed to host the dilution refrigerator and the bolometers of the CUORE
experiment in a low radioactivity environment. The three vessels that form the
outer shell were produced and delivered to the Gran Sasso underground
Laboratories in July 2012. In this paper, we describe the production techniques
and the validation tests done at the production site in 2012.Comment: 11 pages, 13 figures; to appear in NIM
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