Evaluation of the Altitude Variation of the Cosmic-ray Induced Environmental Neutrons in the Mt. Fuji Area

Kowatari, Munehiko; Nagaoka, Kazunori; Satoh, Shoji; Ohta, Yuji; Abukawa, Johji; Tachimori, Shoichi; Nakamura, Takashi

doi:10.3327/jnst.42.495

Cited by 8 publications

(15 citation statements)

References 10 publications

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“…Recently, Goldhagen et al [14], Sheu and Jiang [16] and Kowatari et al [15] have measured differential neutron spectra at different altitudes, solar conditions and geomagnetic fields using Bonner Spheres, which are multiple neutron monitors with unique energy response functions [14]. These measurements provide data on the cosmic ray neutron energy spectrum that we can use for detailed comparisons with our calculations.…”

Section: Introductionmentioning

confidence: 90%

“…[9][10][11][12]). Excitation functions are unique to each nuclide production reaction, and there is evidence the energy distribution of cosmic ray neutrons and protons in the atmosphere changes with altitude and geomagnetic latitude [13][14][15] -hence it is likely that production rate scaling might differ from nuclide to nuclide. Our results presented below suggest that the assumption that nuclide production ratios are constant is incorrect, and that variations in production ratios may range up to 8% at sampling altitudes (between sea level and 6 km).…”

Section: Introductionmentioning

confidence: 98%

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Modeling the earth’s cosmic radiation

Argento

Reedy

Stone

2013

Nuclear Instruments and Methods in Physics Research Section B:

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 98%

Modeling the earth’s cosmic radiation

Argento

Reedy

Stone

2013

Nuclear Instruments and Methods in Physics Research Section B:

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“…The flux and spectrum of cosmogenic fast neutrons observed within the minimal overburden provided by the HFIR building is essentially unaltered compared to standard reference measurements (e.g. [70,71]), which can therefore be used as source terms in simulation studies. The results of these studies have been integral to the design of the Phase I PROSPECT AD-I and have been validated using a series of prototype detectors as described in Section IV D 3.…”

Section: Reactor Facility Background Measurementsmentioning

confidence: 99%

The PROSPECT physics program

Ashenfelter¹,

Balantekin²,

Band³

et al. 2016

J. Phys. G: Nucl. Part. Phys.

105

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The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and probe eV-scale sterile neutrinos by searching for neutrino oscillations over meter-long distances. PROSPECT is conceived as a 2-phase experiment utilizing segmented 6 Li-doped liquid scintillator detectors for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT Phase I consists of a movable 3-ton antineutrino detector at distances of 7-12 m from the reactor core. It will probe the best-fit point of the ν e disappearance experiments at 4σ in 1 year and the favored region of the sterile neutrino parameter space at >3σ in 3 years. With a second antineutrino detector at 15-19 m from the reactor, Phase II of PROSPECT can probe the entire allowed parameter space below 10 eV 2 at 5σ in 3 additional years. The measurement of the reactor antineutrino spectrum and the search for short-baseline oscillations with PROSPECT will test the origin of the spectral deviations observed in recent θ 13 experiments, search for sterile neutrinos, and conclusively address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly.

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“…8) In recent years, several experiments have been performed at low geomagnetic latitudes. [9][10][11][12][13] United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR) 2000 reported the neutron fluence rate of 0.013 n cm À2 s À1 at sea level in high geomagnetic latitude area. 14) The average neutron dose equivalent rate of 8.5 nSv h À1 has been derived from the measurement at the Physikalisch-Technische Bundesanstalt (PTB) site.…”

Section: Introductionmentioning

confidence: 99%

“…6) These values are overestimated in low geomagnetic latitude areas, since smaller neutron fluence and dose rate were obtained in our former study in Japan than those obtained in high geomagnetic latitude. 13) Detailed information is required on total fluence rate and energy spectrum of the cosmic-ray induced neutrons with respect to the geomagnetic latitude, in order to assess the natural neutron dose rates at sea level in Japan. The cosmic-ray induced neutrons have been measured since 2002 by Japan Chemical Analysis Center.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Geomagnetic Latitude Dependence of the Cosmic-ray Induced Environmental Neutrons in Japan

Kowatari

Ohta

Satoh

et al. 2007

J. Nucl. Sci. Technol.

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A series of precise measurements of the cosmic-ray induced neutron energy spectra have been performed to assess the natural background neutron dose rate in whole Japan. The energy spectra were measured in two regions with different altitudes and geomagnetic latitudes, Hokkaido (northernmost main island) and Kagoshima (southernmost main island), by means of a multi-sphere neutron spectrometer, so called the Bonner Sphere (BS). The total neutron fluence rate, the ambient dose equivalent rate H Ã (10) and the effective dose rate in isotropic geometry were obtained from the measured neutron energy spectra, and the dependence of these dose rates on geomagnetic latitude was also evaluated.

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Evaluation of the Altitude Variation of the Cosmic-ray Induced Environmental Neutrons in the Mt. Fuji Area

Cited by 8 publications

References 10 publications

Modeling the earth’s cosmic radiation

Modeling the earth’s cosmic radiation

The PROSPECT physics program

Evaluation of Geomagnetic Latitude Dependence of the Cosmic-ray Induced Environmental Neutrons in Japan

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