325 research outputs found
Neutrino Experiments: Status, Recent Progress, and Prospects
Neutrino physics has seen an explosion of activity and new results in the
last decade. In this report the current state of the field is summarized, with
a particular focus on progress in the last two years. Prospects for the near
term (roughly 5 years) are also described.Comment: 14 pages, 10 figures, proceedings of plenary talk at EPS HEP 2007
Conference, Manchester, UK. Updated with citation added to Figure 1
The Cross Section of 3He(3He,2p)4He measured at Solar Energies
We report on the results of the \hethet\ experiment at the underground
accelerator facility LUNA (Gran Sasso). For the first time the lowest
projectile energies utilized for the cross section measurement correspond to
energies below the center of the solar Gamow peak (=22 keV). The
data provide no evidence for the existence of a hypothetical resonance in the
energy range investigated. Although no extrapolation is needed anymore (except
for energies at the low-energy tail of the Gamow peak), the data must be
corrected for the effects of electron screening, clearly observed the first
time for the \hethet\ reaction. The effects are however larger than expected
and not understood, leading presently to the largest uncertainty on the quoted
value for bare nuclides (=5.40 MeV b).Comment: 18 pages, 10 postscript figures, Calculations concerning hypothetical
resonanz added, Submitted to Phys. Rev. C., available at this URL:
HTTP://www.lngs.infn.it/lngs/htexts/luna/luna.htm
Neutrino Magnetic Moment and Solar Neutrino Experiments
We have studied the effect of a non-vanishing neutrino magnetic moment \
() on the ({x=}) elastic scattering off
electrons for the Super-Kamiokande detector. The bounds on the we
have obtained are comparable to that extracted from laboratory experiments.
Furthemore, we outline the potential of the Borexino experiment which may be
sensitive to neutrino magnetic moments \lsim 10^{-10}\mu_B. In our analysis
we have considered both cases of Majorana and Dirac neutrinos.Comment: latex file, 4 pages, including 3 postscript figures. Talk given by A.
Mourao at the Neutrino 98 Conference (Japan). To appear in the Proceeding
Observation of beta decay of In-115 to the first excited level of Sn-115
In the context of the LENS R&D solar neutrino project, the gamma spectrum of
a sample of metallic indium was measured using a single experimental setup of 4
HP-Ge detectors located underground at the Gran Sasso National Laboratories
(LNGS), Italy. A gamma line at the energy (497.48 +/- 0.21) keV was found that
is not present in the background spectrum and that can be identified as a gamma
quantum following the beta decay of In-115 to the first excited state of Sn-115
(9/2+ --> 3/2+). This decay channel of In-115, which is reported here for the
first time, has an extremely low Q-value, Q = (2 +/- 4) keV, and has a much
lower probability than the well-known ground state-ground state transition,
being the branching ratio b = (1.18 +/- 0.31) 10^-6. This could be the beta
decay with the lowest known Q-value. The limit on charge non-conserving beta
decay of In-115 is set at 90% C.L. as tau > 4.1 10^20 y.Comment: 19 pages, 5 figures, 2 table
Constraining Non-Standard Interactions of the Neutrino with Borexino
We use the Borexino 153.6 ton.year data to place constraints on non-standard
neutrino-electron interactions, taking into account the uncertainty in the 7Be
solar neutrino flux, and backgrounds due to 85Kr and 210Bi beta-decay. We find
that the bounds are comparable to existing bounds from all other experiments.
Further improvement can be expected in Phase II of Borexino due to the
reduction in the 85Kr background.Comment: 21 pages, 16 pdf figures, 2 tables. Analysis updated including the
uncertainty in sin^2\theta_{23}. Accepted in JHE
Measurement of Ultra-Low Potassium Contaminations with Accelerator Mass Spectrometry
Levels of trace radiopurity in active detector materials is a subject of
major concern in low-background experiments. Among the radio-isotopes, \k40
is one of the most abundant and yet whose signatures are difficult to reject.
Procedures were devised to measure trace potassium concentrations in the
inorganic salt CsI as well as in organic liquid scintillator (LS) with
Accelerator Mass Spectrometry (AMS), giving, respectively, the
\k40-contamination levels of and g/g.
Measurement flexibilities and sensitivities are improved over conventional
methods. The projected limiting sensitivities if no excess of potassium signals
had been observed over background are g/g and g/g for the CsI and LS, respectively. Studies of the LS samples
indicate that the radioactive contaminations come mainly in the dye solutes,
while the base solvents are orders of magnitude cleaner. The work demonstrate
the possibilities of measuring naturally-occurring isotopes with the AMS
techniques.Comment: 18 pages, 4 figures, 3 table
Last Hope for an astrophysical solution to the solar neutrino problem
We discuss what appears the last hope for an astrophysical solution to the
solar neutrino problem: a correlated variation of the astrophysical factors for
the helium burning cross sections ( and ) and either
or the central temperature . In this context, we recognize the important
role played by the CNO neutrinos. In fact, we can obtain a fair fit to the
experimental data only if three conditions are met simultaneously: the
astrophysical factor is about 200 times what is presently estimated,
the astrophysical factor is about 3 times larger and the N and
O neutrino fluxes are negligible compared to the ones predicted by
standard solar models. These conditions are not supported by the present data
and their correlated combination is improbable.Comment: 11 pages, ReVTeX, plus 3 figures added as uuencoded compressed
postscript files. The postscript file with the text and 3 figures is
available at ftp://risc0.ca.infn.it/pub/private/lissia/infnca-th9511.p
Geoneutrinos in Borexino
This paper describes the Borexino detector and the high-radiopurity studies
and tests that are integral part of the Borexino technology and development.
The application of Borexino to the detection and studies of geoneutrinos is
discussed.Comment: Conference: Neutrino Geophysics Honolulu, Hawaii December 14-16, 200
GEMMA experiment: three years of the search for the neutrino magnetic moment
The result of the 3-year neutrino magnetic moment measurement at the Kalinin
Nuclear Power Plant with the GEMMA spectrometer is presented.
Antineutrino-electron scattering is investigated. A high-purity germanium
detector of 1.5 kg placed at a distance of 13.9 m from the 3 GW(th) reactor
core is used in the spectrometer. The antineutrino flux is 2.7E13 1/scm/s. The
differential method is used to extract (nu-e) electromagnetic scattering
events. The scattered electron spectra taken in 5184+6798 and 1853+1021 hours
for the reactor ON and OFF periods are compared. The upper limit for the
neutrino magnetic moment < 3.2E-11 Bohr magneton at 90% CL is derived from the
data processing.Comment: 4 pages, 4 figure
Mimicking diffuse supernova antineutrinos with the Sun as a source
Measuring the electron antineutrino component of the cosmic diffuse supernova
neutrino background (DSNB) is the next ambitious goal for low-energy neutrino
astronomy. The largest flux is expected in the lowest accessible energy bin.
However, for E < 15 MeV a possible signal can be mimicked by a solar electron
antineutrino flux that originates from the usual 8B neutrinos by spin-flavor
oscillations. We show that such an interpretation is possible within the
allowed range of neutrino electromagnetic transition moments and solar
turbulent field strengths and distributions. Therefore, an unambiguous
detection of the DSNB requires a significant number of events at E > 15 MeV.Comment: 4 pages, 1 figur
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