On the Interpretation of Neutron Measurements in Cosmic Radiation

Bethe, Hans A.; Korff, S. A.; Placzek, G.

doi:10.1103/physrev.57.573

Cited by 136 publications

(38 citation statements)

References 26 publications

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“…Theoretical work more than half a century ago showed that the intensity of low-energy cosmic-ray neutrons depends on the chemical composition of the material, and particularly on its hydrogen content (Fermi, 1938;Bethe et al, 1940). Measurements (Hendrick and Edge, 1966) showed that the intensity of "fast" neutrons above the ground depends on water content of the ground (Fig.…”

Section: Cosmic-ray Soil Moisture Methodsmentioning

confidence: 99%

COSMOS: the COsmic-ray Soil Moisture Observing System

Zréda

Shuttleworth

Zeng

et al. 2012

Hydrol. Earth Syst. Sci.

487

538

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Abstract. The newly-developed cosmic-ray method for measuring area-average soil moisture at the hectometer horizontal scale is being implemented in the COsmic-ray Soil Moisture Observing System (or the COSMOS). The stationary cosmic-ray soil moisture probe measures the neutrons that are generated by cosmic rays within air and soil and other materials, moderated by mainly hydrogen atoms located primarily in soil water, and emitted to the atmosphere where they mix instantaneously at a scale of hundreds of meters and whose density is inversely correlated with soil moisture. The COSMOS has already deployed more than 50 of the eventual 500 cosmic-ray probes, distributed mainly in the USA, each generating a time series of average soil moisture over its horizontal footprint, with similar networks coming into existence around the world. This paper is written to serve a community need to better understand this novel method and the COSMOS project. We describe the cosmic-ray soil moisture measurement method, the instrument and its calibration, the design, data processing and dissemination used in the COS-MOS project, and give example time series of soil moisture obtained from COSMOS probes.

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Section: Cosmic-ray Soil Moisture Methodsmentioning

confidence: 99%

COSMOS: the COsmic-ray Soil Moisture Observing System

Zréda

Shuttleworth

Zeng

et al. 2012

Hydrol. Earth Syst. Sci.

487

538

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“…Although early studies have attempted to identify the effect of water vapor on thermal (Bethe et al 1940;Lockwood and Yingst 1956) and high-energy neutrons (Bercovitch and Robertson 1965;Chasson et al 1966), no study has yet attempted to determine the fast neutron sensitivity to water vapor. In this paper we identify and evaluate the sensitivity of cosmic-ray probes to the hydrogen present as water vapor in the near-surface atmosphere.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Atmospheric Water Vapor on Neutron Count in the Cosmic-Ray Soil Moisture Observing System

Rosolem

Shuttleworth

Zréda

et al. 2013

Journal of Hydrometeorology

168

159

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The cosmic-ray method for measuring soil moisture, used in the Cosmic-Ray Soil Moisture Observing System (COSMOS), relies on the exceptional ability of hydrogen to moderate fast neutrons. Sources of hydrogen near the ground, other than soil moisture, affect the neutron measurement and therefore must be quantified. This study investigates the effect of atmospheric water vapor on the cosmic-ray probe signal and evaluates the fast neutron response in realistic atmospheric conditions using the neutron transport code Monte Carlo N-Particle eXtended (MCNPX). The vertical height of influence of the sensor in the atmosphere varies between 412 and 265 m in dry and wet atmospheres, respectively. Model results show that atmospheric water vapor near the surface affects the neutron intensity signal by up to 12%, corresponding to soil moisture differences on the order of 0.10 m 3 m 23 . A simple correction is defined to identify the true signal associated with integrated soil moisture that rescales the measured neutron intensity to that which would have been observed in the atmospheric conditions prevailing on the day of sensor calibration. Use of this approach is investigated with in situ observations at two sites characterized by strong seasonality in water vapor where standard meteorological measurements are readily available.

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“…This idea led to the development of the EN-detector, made of a mixture of the well-known inorganic scintillator ZnS(Ag) with 6 LiF, capable of recording both thermal neutrons and charged particles [27] [28]. The study of neutrons in EAS was started in the 1930s [29] and experiments in the late Forties succeeded in demonstrating the production of neutrons in the nuclear interaction of cosmic rays [30][31] [32]. With the appearance of neutron monitors, invented by John A. Simpson in 1948, developed primarily to measure the intensity of solar cosmic rays, some air shower experiments operated them to study the hadrons in EAS [24][33] [34][35] [36].…”

Section: Introductionmentioning

confidence: 99%

Detection of thermal neutrons with the PRISMA-YBJ array in extensive air showers selected by the ARGO-YBJ experiment

Bartoli

Bernardini

et al. 2016

Astroparticle Physics

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We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and 6 LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector.2

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On the Interpretation of Neutron Measurements in Cosmic Radiation

Cited by 136 publications

References 26 publications

COSMOS: the COsmic-ray Soil Moisture Observing System

COSMOS: the COsmic-ray Soil Moisture Observing System

The Effect of Atmospheric Water Vapor on Neutron Count in the Cosmic-Ray Soil Moisture Observing System

Detection of thermal neutrons with the PRISMA-YBJ array in extensive air showers selected by the ARGO-YBJ experiment

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