ABSTRACT The Large Volume Detector (LVD) has been continuously taking data since 1992 at the INFN Gran Sasso National Laboratory. The LVD is sensitive to neutrino bursts from gravitational stellar ...collapses with full detection probability over the Galaxy. We have searched for neutrino bursts in LVD data taken over 7,335 days of operation. No evidence of neutrino signals has been found between 1992 June and 2013 December. The 90% C.L. upper limit on the rate of core collapse and failed supernova explosions out to distances of 25 kpc is found to be 0.114 yr−1.
We correct an overestimation of the production rate of
137
Xe in the DARWIN detector operated at LNGS. This formerly dominant intrinsic background source is now at a level similar to the irreducible ...background from solar
8
B neutrinos, thus unproblematic at the LNGS depth. The projected half-life sensitivity for the neutrinoless double beta decay (
0
ν
β
β
) of
136
Xe improves by
22
%
compared to the previously reported number and is now
T
1
/
2
0
ν
=
3.0
×
10
27
yr
(90% C.L.) after 10 years of DARWIN operation.
The Large Volume Detector (LVD) at INFN Laboratori Nazionali del Gran Sasso, Italy is a 1 kt liquid scintillator neutrino observatory mainly designed to study low energy neutrinos from Gravitational ...Stellar Collapses (GSC) with 100% efficiency over the entire Galaxy. Here we summarize the results of the search for supernova neutrino bursts over the full data set lasting from June 1992 to May 2016 for a total live time of 8211 days. In the lack of a positive observation, either in standalone mode or in coincidence with other experiments, we establish the upper limit to the rate of GSC event in the Milky Way: 0.1 year−1 at 90% c.l..
Experimental data obtained using three scintillation detectors are analyzed. The characteristics of cosmogenic neutrons in underground experiments their analytic dependences are considered. The ...behavior of background counting rate for the LVD detector for two measuring thresholds (0.5 and 5 MeV) are discussed.
Cosmic radiation is a potential additional tool for atmospheric monitoring. High-energy cosmic rays, interacting in the atmosphere, produce secondary particles, the production and propagation of ...which are ruled by the state of the atmosphere. Atmospheric muons carry information on the stratosphere, as its temperature modulates their intensity. Here, we present a comprehensive investigation of the 24-year series of the muon flux recorded underground with the Large Volume Detector in the Gran Sasso Laboratory in Italy. Using advanced spectral-analysis methods, we reveal, in addition to the well-known annual cycle, two significant variations with periods of about four and ten years. These two multiannual components, however, are not present in the series of the so-called effective temperature—an average parameter commonly used to describe the entire atmospheric profile in relationship to the detected muon flux—but we find them in the series of the raw temperatures in the lower-stratospheric levels. We show that the weaker multiannual cycles emerge in the temperature series thanks to the dampening of the dominant annual radiative cycle at these levels, which are affected by higher-frequency variability related to transport and wave processes. We also show that the multiannual variations are not typical only of the Gran Sasso area but are present at large scales throughout the Northern Hemisphere. The analysis of the series of the muon flux also reveals evidence of daily to monthly scale variations, especially during the highly variable winter period. Although such short-term modulations are also found in the series of the effective temperature, we show that the variations of the two series are brought to better agreement when considering only specific layers of the atmosphere depending on the event. The amplitudes of the multiannual variations are significantly larger than those expected based on the temperature modulations. Such differences may be due to acknowledged difficulties of the adopted temperature reanalysis dataset to thoroughly represent long-term variability scales, so that long-term modulations in the raw temperature series and, consequently, in the effective temperature record would result as artificially attenuated. The muon flux therefore may be envisaged as a high time-resolution integrated proxy of lower-stratospheric temperatures.
The main goal of the Large Volume Detector (LVD), in the INFN Gran Sasso National Laboratory (Italy), is the study of neutrino bursts from gravitational stellar collapses in the Milky Way. Both the ...detector and the data analysis procedure have been actually optimized for this purpose. Moreover the modularity of the apparatus allows to obtain a duty cycle that is very close to 100%, so that the experiment is continuously monitoring the Galaxy. The search for Supernova neutrino signal is performed online, within fixed duration time windows (20 s), and offline with variable duration time windows from few ms up to 200 s. In both cases, LVD is able to disentangle a cluster of neutrino signals from the background fluctuations, and its sensitivity extends to the whole Galaxy. No candidates have been detected during almost 18 years of observation (6013 days of lifetime): the resulting 90% c.l. upper limit to the rate of gravitational stellar collapses in the Galaxy is 0.14 events/year. Detector performances, search method and data results are here reported.
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