A plastic scintillator array for reactor based anti-neutrino studies

Abstract

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 ...

Colloquium : Neutrino detectors as tools for nuclear security

“…Operation of the PANDA-360 prototype at a reactor in Japan without overburden provided a low significance hint of reactor state determination with S:B of less than 1:15 (Oguri et al, 2014). Similar approaches have been pursued by groups in India (Mulmule et al, 2018) and the United Kingdom (Carroll et al, 2018).…”

Sensitivity to sterile neutrino mixing using reactor antineutrinos

“…The ISMRAN experimental set-up is being developed for detecting reactor ν e , searching for possible existence of sterile neutrino and monitoring of reactor power at the DHRUVA reactor facility in Bhabha Atomic Research Centre (BARC), India. The ISMRAN detector set-up will consist of an array of 100 plastic scintillator (PS) bars with weight of about 1 ton [24]. The dimension of each PS bar is 100 cm×10 cm×10 cm wrapped with Gadolinium coated aluminized mylar foils.…”

“…With this experimental set-up, it can be possible to confirm or reject the existence of a light sterile neutrino by measuring the ν e flux and energy spectra. At present a proto-type ISM-RAN set-up of 1/5-th of the final detector volume which is under operation at DHRUVA reactor facility [24].…”

“…Here it is to be mentioned that the precision on the ∆m 2 41 is controlled by the precise measurement of energy (and also L) for individual events which depends on the resolution of the detector. Further studies are carried out considering the detector resolution of σ/E = 20% (which is the energy resolution of the PS obtained from the measurements) [24]. We have also studied the active-sterile neutrino mixing angle, sin 2 2θ 14 sensitivity by varying the detector efficiencies from 20% to 50% as shown in Fig 5. It is observed that the sensitivity on sin 2 2θ 14 improves with increase of detector efficiency for ∆m 2 41 ≤ 4.0 eV 2 and has less impact beyond this value.…”

Comparison of plastic antineutrino detector designs in the context of near field reactor monitoring

“…In this section, we describe a few existing detector designs such as Panda [12,13], Panda2 [14] 2 , Ismran [15] 3 , and Cormorad [16] along with our proposed design. The Panda/Ismran design consists of 100 identical modules and each module has a plastic scintillator bar of dimension 10cm×10cm×100cm, two acrylic cubic light guides of 10cm×10cm×10cm and two photomultipliers (PMTs).…”