283 research outputs found
DANSSino: a pilot version of the DANSS neutrino detector
DANSSino is a reduced pilot version of a solid-state detector of reactor
antineutrinos (to be created within the DANSS project and installed under the
industrial 3 GW(th) reactor of the Kalinin Nuclear Power Plant -- KNPP).
Numerous tests performed at a distance of 11 m from the reactor core
demonstrate operability of the chosen design and reveal the main sources of the
background. In spite of its small size (20x20x100 ccm), the pilot detector
turned out to be quite sensitive to reactor antineutrinos, detecting about 70
IBD events per day with the signal-to-background ratio about unity.Comment: 16 pages, 11 figures, 3 tables. arXiv admin note: substantial text
overlap with arXiv:1304.369
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
Search for sterile neutrinos at the DANSS experiment
DANSS is a highly segmented 1~m plastic scintillator detector. Its 2500
one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS
detector is placed under an industrial 3.1~ reactor of the
Kalinin Nuclear Power Plant 350~km NW from Moscow. The distance to the core is
varied on-line from 10.7~m to 12.7~m. The reactor building provides about 50~m
water-equivalent shielding against the cosmic background. DANSS detects almost
5000 per day at the closest position with the cosmic
background less than 3. The inverse beta decay process is used to detect
. Sterile neutrinos are searched for assuming the model
(3 active and 1 sterile ). The exclusion area in the plane is obtained using a ratio of positron energy
spectra collected at different distances. Therefore results do not depend on
the shape and normalization of the reactor spectrum, as well
as on the detector efficiency. Results are based on 966 thousand antineutrino
events collected at 3 distances from the reactor core. The excluded area covers
a wide range of the sterile neutrino parameters up to
in the most sensitive region.Comment: 10 pages, 13 figures, version accepted for publicatio
The first result of the neutrino magnetic moment measurement in the GEMMA experiment
The first result of the neutrino magnetic moment measurement at the
Kalininskaya Nuclear Power Plant (KNPP) with the GEMMA spectrometer is
presented. An antineutrino-electron scattering is investigated. A high-purity
germanium detector of 1.5 kg placed 13.9 m away from the 3 GW reactor core is
used in the spectrometer. The antineutrino flux is . The differential method is used to extract the -e
electromagnetic scattering events. The scattered electron spectra taken in 6200
and 2064 hours for the reactor ON and OFF periods are compared. The upper limit
for the neutrino magnetic moment Bohr magnetons
at 90{%} CL is derived from the data processing.Comment: 9 pages, 10 figures, 2 table
Flux Modulations seen by the Muon Veto of the GERDA Experiment
The GERDA experiment at LNGS of INFN is equipped with an active muon veto.
The main part of the system is a water Cherenkov veto with 66~PMTs in the water
tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows
a seasonal modulation. Two effects have been identified which are caused by
secondary muons from the CNGS neutrino beam (2.2 %) and a temperature
modulation of the atmosphere (1.4 %). A mean cosmic muon rate of /(sm) was found in good agreement with other experiments at
LNGS at a depth of 3500~meter water equivalent.Comment: 7 pages, 6 figure
Background free search for neutrinoless double beta decay with GERDA Phase II
The Standard Model of particle physics cannot explain the dominance of matter
over anti-matter in our Universe. In many model extensions this is a very
natural consequence of neutrinos being their own anti-particles (Majorana
particles) which implies that a lepton number violating radioactive decay named
neutrinoless double beta () decay should exist. The detection
of this extremely rare hypothetical process requires utmost suppression of any
kind of backgrounds.
The GERDA collaboration searches for decay of Ge
(^{76}\rm{Ge} \rightarrow\,^{76}\rm{Se} + 2e^-) by operating bare detectors
made from germanium with enriched Ge fraction in liquid argon. Here, we
report on first data of GERDA Phase II. A background level of
cts/(keVkgyr) has been achieved which is the world-best if
weighted by the narrow energy-signal region of germanium detectors. Combining
Phase I and II data we find no signal and deduce a new lower limit for the
half-life of yr at 90 % C.L. Our sensitivity of
yr is competitive with the one of experiments with
significantly larger isotope mass.
GERDA is the first experiment that will be background-free
up to its design exposure. This progress relies on a novel active veto system,
the superior germanium detector energy resolution and the improved background
recognition of our new detectors. The unique discovery potential of an
essentially background-free search for decay motivates a
larger germanium experiment with higher sensitivity.Comment: 14 pages, 9 figures, 1 table; ; data, figures and images available at
http://www.mpi-hd.mpg/gerda/publi
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