Cosmic-Ray Neutron Sensing (CRNS) is the technology indicated by FAO as the most promising new approach to face food availability and management of water resources. A flux of muons and fast neutrons originated by the interactions of primary cosmic rays with the upper atmosphere hit continuously the ground. Fast neutrons, in particular, undergo many scatterings inside the soil before being slowed down to thermal energy and get captured or decay. During this slowing phase, part of them can escape from the soil and fly for tens of meters in the atmosphere just above the ground. The flux of these slow "reflected" neutrons that one can measure a couple of meters above the ground has been demonstrated to be strongly correlated with the amount of hydrogen present in the soil, and therefore can be used as measurement of the water content in the soil (the so called CRNS" technology). Of course, the slow neutrons measured above the ground will be also proportional to the flux of incoming fast neutrons (the "incoming"). To get a correct water content assessment, it is therefore mandatory to normalize the measured flux of slow neutrons with the reference flux of incoming fast neutrons. Currently, the incoming is usually taken from the Neutron Monitor Data Base (NMDB) network, a number of laboratories around the world equipped with big cosmic-ray neutron detectors that provide free online and/or offline data. The most used in our region is the Jungfraujoch IGY NMDB at the Sphinx Observatory, Switzerland, 3570 m asl and more than 300 km far from Padova. A research group at Finapp srl is been developing a new simplest way to measure locally the incoming, based on the measurements of muons at ground. The muon flux is directly related to the incoming neutron flux and can be used, after proper environmental corrections, as reference measurement of the local incoming neutron flux variations. This method has several advantages: it provides the reference flux independently on the availability of the NMDB data and the internet connection, moreover it is a local measurement, in the same site where neutrons are measured. The proposed thesis work deals with the analysis of the cosmic muons at ground measured with Finapp CRNS probes, with the aim to better clarify the correlation between the incoming neutron flux and the measured muon flux. A dedicated muon detection system has been assembled and tested in lab, then placed in field in different sites to get real muon data series to be compared with NMDB data.
Analysis of cosmic muons at ground to be used as normalization for CRNS probes
SARETTO, ALBERTO
2023/2024
Abstract
Cosmic-Ray Neutron Sensing (CRNS) is the technology indicated by FAO as the most promising new approach to face food availability and management of water resources. A flux of muons and fast neutrons originated by the interactions of primary cosmic rays with the upper atmosphere hit continuously the ground. Fast neutrons, in particular, undergo many scatterings inside the soil before being slowed down to thermal energy and get captured or decay. During this slowing phase, part of them can escape from the soil and fly for tens of meters in the atmosphere just above the ground. The flux of these slow "reflected" neutrons that one can measure a couple of meters above the ground has been demonstrated to be strongly correlated with the amount of hydrogen present in the soil, and therefore can be used as measurement of the water content in the soil (the so called CRNS" technology). Of course, the slow neutrons measured above the ground will be also proportional to the flux of incoming fast neutrons (the "incoming"). To get a correct water content assessment, it is therefore mandatory to normalize the measured flux of slow neutrons with the reference flux of incoming fast neutrons. Currently, the incoming is usually taken from the Neutron Monitor Data Base (NMDB) network, a number of laboratories around the world equipped with big cosmic-ray neutron detectors that provide free online and/or offline data. The most used in our region is the Jungfraujoch IGY NMDB at the Sphinx Observatory, Switzerland, 3570 m asl and more than 300 km far from Padova. A research group at Finapp srl is been developing a new simplest way to measure locally the incoming, based on the measurements of muons at ground. The muon flux is directly related to the incoming neutron flux and can be used, after proper environmental corrections, as reference measurement of the local incoming neutron flux variations. This method has several advantages: it provides the reference flux independently on the availability of the NMDB data and the internet connection, moreover it is a local measurement, in the same site where neutrons are measured. The proposed thesis work deals with the analysis of the cosmic muons at ground measured with Finapp CRNS probes, with the aim to better clarify the correlation between the incoming neutron flux and the measured muon flux. A dedicated muon detection system has been assembled and tested in lab, then placed in field in different sites to get real muon data series to be compared with NMDB data.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/68314