The Large Volume Detector (LVD), hosted in the INFN Laboratori Nazionali del Gran Sasso, is triggered by atmospheric muons at a rate of $sim 0.1$~Hz. The data collected over almost a quarter of century are used to study the muon intensity underground. The 50-million muon series, the longest ever exploited by an underground instrument, allows for the accurate long-term monitoring of the muon intensity underground. This is relevant as a study of the background in the Gran Sasso Laboratory, which hosts a variety of long-duration, low-background detectors. We describe the procedure to select muon-like events as well as the method used to compute the exposure. We report the value of the average muon flux measured from 1994 to 2017: $mathrmI_mu^0 = 3.35 pm 0.0005^statpm 0.03^sys cdot 10^-4 ~m^-2 s^-1$. We show that the intensity is modulated around this average value due to temperature variations in the stratosphere. We quantify such a correlation by using temperature data from the European Center for Medium-range Weather Forecasts: we find an effective temperature coefficient $mathrmalpha_T = 0.94pm0.01^stat pm0.01^sys$, in agreement with other measurements at the same depth. We scrutinise the spectral content of the time series of the muon intensity by means of the Lomb-Scargle analysis. This yields the evidence of a 1-year periodicity, as well as the indication of others, both shorter and longer, suggesting that the series is not a pure sinusoidal wave. Consequently, and for the first time, we characterise the observed modulation in terms of amplitude and position of maximum and minimum on a year-by-year basis.

Characterization of the varying flux of atmospheric muons measured with the Large Volume Detector for 24 years

S. Rubinetti;C. Taricco;C. F. Vigorito;
2019

Abstract

The Large Volume Detector (LVD), hosted in the INFN Laboratori Nazionali del Gran Sasso, is triggered by atmospheric muons at a rate of $sim 0.1$~Hz. The data collected over almost a quarter of century are used to study the muon intensity underground. The 50-million muon series, the longest ever exploited by an underground instrument, allows for the accurate long-term monitoring of the muon intensity underground. This is relevant as a study of the background in the Gran Sasso Laboratory, which hosts a variety of long-duration, low-background detectors. We describe the procedure to select muon-like events as well as the method used to compute the exposure. We report the value of the average muon flux measured from 1994 to 2017: $mathrmI_mu^0 = 3.35 pm 0.0005^statpm 0.03^sys cdot 10^-4 ~m^-2 s^-1$. We show that the intensity is modulated around this average value due to temperature variations in the stratosphere. We quantify such a correlation by using temperature data from the European Center for Medium-range Weather Forecasts: we find an effective temperature coefficient $mathrmalpha_T = 0.94pm0.01^stat pm0.01^sys$, in agreement with other measurements at the same depth. We scrutinise the spectral content of the time series of the muon intensity by means of the Lomb-Scargle analysis. This yields the evidence of a 1-year periodicity, as well as the indication of others, both shorter and longer, suggesting that the series is not a pure sinusoidal wave. Consequently, and for the first time, we characterise the observed modulation in terms of amplitude and position of maximum and minimum on a year-by-year basis.
100
062002
1
13
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.100.062002
https://arxiv.org/abs/1909.04579
High Energy Physics - Experiment; Physics - Instrumentation and Detectors
N. Yu. Agafonova; M. Aglietta; P. Antonioli; V. V. Ashikhmin; G. Bari; G. Bruno; E. A. Dobrynina; R. I. Enikeev; W. Fulgione; P. Galeotti; M. Garbini; P. L. Ghia; P. Giusti; E. Kemp; A. S. Malgin; A. Molinario; R. Persiani; I. A. Pless; S. Rubinetti; O. G. Ryazhskaya; G. Sartorelli; I. R. Shakiryanova; M. Selvi; C. Taricco; G. C. Trinchero; C. F. Vigorito; V. F. Yakushev; A. Zichichi
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/1712107
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