Neutron spectrum at the underground laboratory for the ultra low background experiment

Park, Hyeonseo; Kim, Jungho; Hwang, Yeong‐Maw; Choi, Kil-Oung

doi:10.1016/j.apradiso.2013.03.068

Cited by 18 publications

(27 citation statements)

References 6 publications

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“…Using two sets of altogether nine moderated 3 He counters and one unmoderated 3 He counter, the neutron flux and [18,19]). For comparison, the plot includes previous spectra from the Earth's surface (purple line [65]), YangYang/South Korea (black line [66] and Gran Sasso (green dotted line [16]). [16,18,19,65,66] and from the present work.…”

Section: Discussionmentioning

confidence: 99%

“…The first example, the YangYang laboratory in South Korea, is located below 700 m of rock (2000 m.w.e.). There, the neutron flux was studied using a Bonner sphere spectrometer modeled on the PTB NEMUS system [69], including several modified spheres with neutron multipliers [66]. The YangYang spectrum is much flatter than the present one, and the downscattered neutron peak at 0.3 MeV is not evident at YangYang.…”

Section: Neutron Flux At Various Underground Sitesmentioning

confidence: 91%

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Neutron flux and spectrum in the Dresden Felsenkeller underground facility studied by moderated He3 counters

et al. 2020

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Ambient neutrons may cause significant background for underground experiments. Therefore, it is necessary to investigate their flux and energy spectrum in order to devise a proper shielding. Here, two sets of altogether ten moderated 3 He neutron counters are used for a detailed study of the ambient neutron background in tunnel IV of the Felsenkeller facility, underground below 45 m of rock in Dresden/Germany. One of the moderators is lined with lead and thus sensitive to neutrons of energies higher than 10 MeV. For each 3 He counter moderator assembly, the energy-dependent neutron sensitivity was calculated with the FLUKA code. The count rates of the ten detectors were then fitted with the MAXED and GRAVEL packages. As a result, both the neutron energy spectrum from 10 −9 to 300 MeV and the flux integrated over the same energy range were determined experimentally. The data show that at a given depth, both the flux and the spectrum vary significantly depending on local conditions. Energy-integrated fluxes of (0.61 AE 0.05), (1.96 AE 0.15), and ð4.6 AE 0.4Þ × 10 −4 cm −2 s −1 , respectively, are measured for three sites within Felsenkeller tunnel IV which have similar muon flux but different shielding wall configurations. The integrated neutron flux data and the obtained spectra for the three sites are matched reasonably well by FLUKA Monte Carlo calculations that are based on the known muon flux and composition of the measurement room walls.

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Section: Discussionmentioning

confidence: 99%

Section: Neutron Flux At Various Underground Sitesmentioning

confidence: 91%

Neutron flux and spectrum in the Dresden Felsenkeller underground facility studied by moderated He3 counters

et al. 2020

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“…• neutron captures in the window and body of R1250 photomultiplier made of borosilicate glass containing Boron oxide (the 10 • the thermal neutron flux reduction by a 40 cm-thick wall assembled of Boron loaded polyethylene bricks stockpiled in the same room.…”

Section: Tests Of the Detector Performancementioning

confidence: 99%

“…In addition, the thermal neutron flux was measured recently at the Baksan Neutrino Observatory [7] by using a scintillator detector based on 6 LiF:ZnS(Ag) components. The 3 He proportional counters were used at Canfranc Underground Laboratory (Spain) [8], Kamioka neutrino observatory (Japan) [9], and YangYang underground laboratory (South Korea) [10].…”

Section: Introductionmentioning

confidence: 99%

A large area detector for thermal neutron flux measurements at the KamLAND site

Kozlov

Chernyak

2018

Nuclear Instruments and Methods in Physics Research Section A:

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A large area (0.5 m × 0.5 m) thermal neutron detector was developed based on 0.32 mm-thick 6 LiF:ZnS(Ag) scintillator sheets. The detector was constructed for measurements of seasonal variations in low intensity thermal neutron flux at deep underground sites. The detector response to neutrons was studied using a low intensity 241 Am/ 9 Be(α,n) neutron source. The digital pulse shape discrimination technique was applied to separate neutron capture events from the background caused by traces of α-emitters from Uranium and Thorium decay chains in scintillator components. The thermal neutron detection efficiency was 0.368±0.018 (0.155±0.009) before (after) event selection based on the digital pulse shape discrimination method. The measured α-particle background event rate in the 6 LiF:ZnS(Ag) scintillator was (4.88±0.06(stat))×10 −6 α cm −2 sec −1 . As a test of detector performance we measured the thermal neutron flux at the KamLAND area of the Kamioka neutrino observatory and compared it with result of the neutron flux measurement carried out at the Super-Kamiokande site. The thermal neutron flux at KamLAND was (6.43±0.50)×10 −6 n cm −2 sec −1 that included ∼10 % contribution from neutrons with energies above 1 eV. During the detector construction we identified a source of high amplitude noise pulses generated by 5-inch R1250 photomultipliers manufactured by Hamamatsu Photonics K. K..

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“…It is clear to the community of researchers in underground physics that reliable measurements of both the fluxes and energy spectra are essential to understanding their backgrounds [19]. A num-ber of collaborations address this concern by measuring fast neutron parameters directly at their experimental facility [20,21,22,23,24,25,26,27] and by benchmarking the codes that they use for simulations [17,18].…”

Section: Introductionmentioning

confidence: 99%

Fast neutron detection with a segmented spectrometer

Langford

Bass

Beise

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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A fast neutron spectrometer consisting of segmented plastic scintillator and 3 He proportional counters was constructed for the measurement of neutrons in the energy range 1 MeV to 200 MeV. We discuss its design, principles of operation, and the method of analysis. The detector is capable of observing very low neutron fluxes in the presence of ambient gamma background and does not require scintillator pulse-shape discrimination. The spectrometer was characterized for its energy response in fast neutron fields of 2.5 MeV, 14 MeV, and the results are compared with Monte Carlo simulations. Measurements of the fast neutron flux and energy response at 120 m above sea-level (39.130 • N, 77.218• W) and at a depth of 560 m in a limestone mine are presented. Finally, the design of a spectrometer with improved sensitivity and energy resolution is discussed.

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Neutron spectrum at the underground laboratory for the ultra low background experiment

Cited by 18 publications

References 6 publications

Neutron flux and spectrum in the Dresden Felsenkeller underground facility studied by moderated He3 counters

Neutron flux and spectrum in the Dresden Felsenkeller underground facility studied by moderated He3 counters

A large area detector for thermal neutron flux measurements at the KamLAND site

Fast neutron detection with a segmented spectrometer

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