55 research outputs found
Search for neutrinoless double beta decay with enriched 76Ge in Gran Sasso 1990-2003
The results of the HEIDELBERG-MOSCOW experiment which searches with 11 kg of
enriched 76Ge for double beta decay in the GRAN Sasso underground laboratory
are presented for the full running period August 1990 - May 2003. The duty
cycle of the experiment was ~80%, the collected statistics is 71.7 kg y. The
background achieved in the energy region of the Q value for double beta decay
is 0.11 events/ kg y keV. The two-neutrino accompanied half-life is determined
on the basis of more than 100 000 events. The confidence level for the
neutrinoless signal has been improved to 4.2 sigma.Comment: 19 pages, latex, 9 figures, 2 table
Measurement of the 214Bi spectrum in the energy region around the Q-value of 76Ge neutrinoless double-beta decay
In this work we present the results obtained measuring the 214Bi spectrum
from a 226Ra source with a high purity germanium detector. Our attention was
mostly focused on the energy region around the Q-value of 76Ge neutrinoless
double-beta decay (2039.006 keV). The results of this measurement are strongly
related to the first indication for the neutrinoless double beta decay of 76Ge,
given by a recent analysis \cite{Evidence,KK02-PN,KK02-Found,KK-BigArt02} of
the data collected during ten years of measurements from the HEIDELBERG-MOSCOW
experiment.Comment: 10 pages, latex2e, 5 figures, see also Home Page of HEIDELBERG
Non-Accelerator Particle Physics Group: http://www.mpi-hd.mpg.de/non_acc
First 10 kg of Naked Germanium Detectors in Liquid Nitrogen installed in the GENIUS-Test-Facility
The first four naked high purity Germanium detectors were installed
successfully in liquid nitrogen in the GENIUS-Test-Facility (GENIUS-TF) in the
GRAN SASSO Underground Laboratory on May 5, 2003. This is the first time ever
that this novel technique aiming at extreme background reduction in search for
rare decays is going to be tested underground. First operational parameters are
presented.Comment: 10 pages, latex2e, 8 figures, Was presented (first presentation) at
4th International Conference on Particle Physics Beyond the Standard Model
BEYOND'2003, Castle Ringberg, Germany, 9-14 June, 2003, Springer, Heidelberg,
Germany, 2003, edited by H.V. Klapdor-Kleingrothau
Improved search for invisible modes of nucleon decay in water with the SNO+ detector
This paper reports results from a search for single and multi-nucleon
disappearance from the O nucleus in water within the \snoplus{} detector
using all of the available data. These so-called "invisible" decays do not
directly deposit energy within the detector but are instead detected through
their subsequent nuclear de-excitation and gamma-ray emission. New limits are
given for the partial lifetimes:
years, years, years,
years, and years at 90\% Bayesian
credibility level (with a prior uniform in rate). All but the () results improve on existing limits by a factor of about 3.info:eu-repo/semantics/publishedVersio
Measurement of the 8B solar neutrino flux in SNO+ with very low backgrounds
A measurement of the 8B solar neutrino flux has been made using a 69.2 kt-day dataset acquired with the SNO+ detector during its water commissioning phase. At energies above 6 MeV the dataset is an extremely pure sample of solar neutrino elastic scattering events, owing primarily to the detector’s deep location, allowing an accurate measurement with relatively little exposure. In that energy region the best fit background rate is 0.25+0.09−0.07  events/kt−day, significantly lower than the measured solar neutrino event rate in that energy range, which is 1.03+0.13−0.12  events/kt−day. Also using data below this threshold, down to 5 MeV, fits of the solar neutrino event direction yielded an observed flux of 2.53+0.31−0.28(stat)+0.13−0.10(syst)×106  cm−2 s−1, assuming no neutrino oscillations. This rate is consistent with matter enhanced neutrino oscillations and measurements from other experiments
Search for invisible modes of nucleon decay in water with the SNO+ detector
This paper reports results from a search for nucleon decay through invisible modes, where no visible energy is directly deposited during the decay itself, during the initial water phase of SNO+. However, such decays within the oxygen nucleus would produce an excited daughter that would subsequently deexcite, often emitting detectable gamma rays. A search for such gamma rays yields limits of 2.5×1029  y at 90% Bayesian credibility level (with a prior uniform in rate) for the partial lifetime of the neutron, and 3.6×1029  y for the partial lifetime of the proton, the latter a 70% improvement on the previous limit from SNO. We also present partial lifetime limits for invisible dinucleon modes of 1.3×1028  y for nn, 2.6×1028  y for pn and 4.7×1028  y for pp, an improvement over existing limits by close to 3 orders of magnitude for the latter two
Measurement of neutron-proton capture in the SNO+ water phase
The SNO+ experiment collected data as a low-threshold water Cherenkov
detector from September 2017 to July 2019. Measurements of the 2.2-MeV
produced by neutron capture on hydrogen have been made using an Am-Be
calibration source, for which a large fraction of emitted neutrons are produced
simultaneously with a 4.4-MeV . Analysis of the delayed coincidence
between the 4.4-MeV and the 2.2-MeV capture revealed a
neutron detection efficiency that is centered around 50% and varies at the
level of 1% across the inner region of the detector, which to our knowledge is
the highest efficiency achieved among pure water Cherenkov detectors. In
addition, the neutron capture time constant was measured and converted to a
thermal neutron-proton capture cross section of mb
Current Status and Future Prospects of the SNO+ Experiment
SNO+ is a large liquid scintillator-based experiment located 2 km underground at SNOLAB, Sudbury, Canada. It reuses the Sudbury Neutrino Observatory detector, consisting of a 12 m diameter acrylic vessel which will be filled with about 780 tonnes of ultra-pure liquid scintillator. Designed as a multipurpose neutrino experiment, the primary goal of SNO+ is a search for the neutrinoless double-beta decay (0] ) of 130 Te. In Phase I, the detector will be loaded with 0.3% natural tellurium, corresponding to nearly 800 kg of 130 Te, with an expected effective Majorana neutrino mass sensitivity in the region of 55-133 meV, just above the inverted mass hierarchy. Recently, the possibility of deploying up to ten times more natural tellurium has been investigated, which would enable SNO+ to achieve sensitivity deep into the parameter space for the inverted neutrino mass hierarchy in the future. Additionally, SNO+ aims to measure reactor antineutrino oscillations, low energy solar neutrinos, and geoneutrinos, to be sensitive to supernova neutrinos, and to search for exotic physics. A first phase with the detector filled with water will begin soon, with the scintillator phase expected to start after a few months of water data taking. The 0] Phase I is foreseen for 2017
Development, characterisation, and deployment of the SNO+ liquid scintillator
A liquid scintillator consisting of linear alkylbenzene as the solvent and 2,5-diphenyloxazole as the fluor was developed for the SNO+ experiment. This mixture was chosen as it is compatible with acrylic and has a competitive light yield to pre-existing liquid scintillators while conferring other advantages including longer attenuation lengths, superior safety characteristics, chemical simplicity, ease of handling, and logistical availability. Its properties have been extensively characterized and are presented here. This liquid scintillator is now used in several neutrino physics experiments in addition to SNO+
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