Background radiation measurements at high power research reactors

Ashenfelter, J.; Balantekin, Baha; Baldenegro, Cristian; Band, H. R.; Barclay, Glen St. J.; Bass, C.D.; Berish, D.; Bowden, N. S.; Bryan, C. D.; Cherwinka, J. J.; Chu, Ran; Classen, T.; Davee, D.; Dean, D. J.; Deichert, G.; Dolinski, M. J.; Dolph, J.; Dwyer, D. A.; Fan, Shiyu; Gaison, Jeremy; Galindo-Uribarri, A.; Gilje, K.; Glenn, A.; Green, M. P.; Han, K.; Hans, S.; Heeger, K. M.; Heffron, B.; Jaffe, D. E.; Kettell, S. H.; Langford, T.; Littlejohn, B. R.; Martinez, D.; McKeown, R. D.; Morrell, Sean R.; Mueller, P. E.; Mumm, H. P.; Napolitano, J.; Norcini, D.; Pushin, D. A.; Romero, Enrique Pérez; Rosero, R.; Saldaña, L.; Seilhan, B.; Sharma, R.; Stemen, N. T; Surukuchi, P. T.; Thompson, Scott J.; Varner, R. L.; Wang, W.; Watson, Scott M.; White, B. R.; White, C.; Wilhelmi, J.; Williams, C. W.; Wise, T.; Yao, Haifeng; Yeh, M.; Yen, Y.-R.; Zhang, C.; Zhang, X.

doi:10.1016/j.nima.2015.10.023

Cited by 29 publications

(18 citation statements)

References 27 publications

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“…The increase in the γ-ray background in the reactor ON condition is attributed to the γ-ray coming from the thermal neutron capture on the surrounding material in the reactor and experimental hall. A detailed study of the γ-ray energy spectrum from neutron capture on different materials in the reactor hall can be found in reference [36]. Some of these γ-ray lines can be seen in our measurements from the BGO detector in reactor ON condition.…”

Section: Reactor Background Measurementsmentioning

confidence: 76%

A plastic scintillator array for reactor based anti-neutrino studies

Mulmule

Behera

Netrakanti

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN), a plastic scintillator array (10×10), is being constructed for the purpose of electron anti-neutrino (ν e ) detection for reactor monitoring applications. A prototype detector called mini-ISMRAN, which consists of 16% of ISMRAN, has been setup for studying the detector response, background rates and event characterization in the reactor and non-reactor environment. The data acquisition system based on waveform digitizers is being used for pulse processing and event triggering. Monte-Carlo based simulations using GEANT4 are performed to optimize lead (Pb) and borated polyethylene (BP) shielding for background reduction and to study the positron, neutron and γ-ray response in the ISMRAN detector. Characterization of plastic scintillator detectors with known radioactive sources is performed for energy, timing and position measurements.Using the energy summation and bar multiplicity selection, coincident events from 60 Co decay are reconstructed in non-reactor environment. Results from background measurements using various detectors are quantified in reactor ON and OFF condition. The shielding of 10 cm Pb and 10 cm BP along with the requirement of hits in multiple bars, reduces the uncorrelated background in reactor ON condition. been shown to be sensitive to the reactor ON and OFF cycles. Also, since the ν e rate and energy spectrum changes as the uranium in the core is consumed and plutonium is produced, it is possible to calculate the burn up and estimate the isotopic content of the core [3]. Several groups across different countries are already pursuing this activity [4,5,6].This technique of monitoring reactors remotely may be useful for the International Atomic Energy Agency's (IAEA) 'Reactor Safeguards Regime' aimed towards ensuring implementation of safeguards for reactor facilities [7].Apart from relatively small volume of the detector, factors such as mobility of the setup, safety and convenience of use, especially, from the point of view of long-term operation are crucial for the goal of reactor monitoring. Due to their chemical composition, LS are toxic, flammable and face issues of compatibility with the container material, as they are good solvents. Plastic scintillators (PS) on the other hand are 98% Polyvinyl chloride (PVC), Polyvinyl Toluene (PVT) or polystyrene i.e. similar to normal plastic with no toxic or radioactive component and non-flammable. Therefore, for long-term near reactor operation use of PS is preferable. However, PS suffers from issues such as reduced light output due to attenuation and radiation damage. These aspects have been extensively studied and addressed to a reasonable extent in modern commercially available PS detectors [8]. Also, majority of PS can not use pulse shape discrimination (PSD) technique for discrimination between neutron and γ-ray signals.However, a segmented geometry of many plastic scintillator bars, employing a thermal neutron capture agent, can make use of the hit patterns and energy deposition ...

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Section: Reactor Background Measurementsmentioning

confidence: 76%

A plastic scintillator array for reactor based anti-neutrino studies

Mulmule

Behera

Netrakanti

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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“…IBD candidates with the delayed cluster in a ð0; þ100Þ μs window around cosmic muon clusters (E rec > 15 MeV) or a ð−200; þ200Þ μs window around other high-PSD pulses with E rec > 0.25 MeV are also rejected. These veto criteria result in a well-determined inefficiency between 5.5% and 6.9% during this data taking period that varies due to contamination from time-varying γ-ray backgrounds [41]. Finally, IBD candidates with S rec in the outermost layer of segments or Z rec within 14 cm of a cell end are rejected.…”

mentioning

confidence: 99%

First Search for Short-Baseline Neutrino Oscillations at HFIR with PROSPECT

Ashenfelter¹,

Balantekin²,

Baldenegro³

et al. 2018

Phys. Rev. Lett.

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131

157

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This Letter reports the first scientific results from the observation of antineutrinos emitted by fission products of 235 U at the High Flux Isotope Reactor. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, consists of a segmented 4 ton 6 Li-doped liquid scintillator detector covering a baseline range of 7-9 m from the reactor and operating under less than 1 m water equivalent overburden. Data collected during 33 live days of reactor operation at a nominal power of 85 MW yield a detection of 25 461 AE 283 ðstatÞ inverse beta decays. Observation of reactor antineutrinos can be achieved in PROSPECT at 5σ statistical significance within 2 h of on-surface reactor-on data taking. A reactor model independent analysis of the inverse beta decay prompt energy spectrum as a function of baseline constrains significant portions of the previously allowed sterile neutrino oscillation parameter space at 95% confidence level and disfavors the best fit of the reactor antineutrino anomaly at 2.2σ confidence level.

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“…The PROSPECT collaboration has conducted a careful assessment of natural and reactor generated background radiation that is reported in [54]. These measurements included high and moderate resolution γray spectroscopy, fast and thermal neutron flux, muon flux, and fast neutron spectroscopy.…”

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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Background radiation measurements at high power research reactors

Cited by 29 publications

References 27 publications

A plastic scintillator array for reactor based anti-neutrino studies

A plastic scintillator array for reactor based anti-neutrino studies

First Search for Short-Baseline Neutrino Oscillations at HFIR with PROSPECT

The PROSPECT physics program

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