A novel segmented-scintillator antineutrino detector ; Journal of Instrumentation

Abstract

The next generation of very-short-baseline reactor experiments will require compact detectors operating at surface level and close to a nuclear reactor. This paper presents a new detector concept based on a composite solid scintillator technology. The detector target uses cubes of polyvinyltoluene interleaved with (LiF)-Li-6:ZnS(Ag) phosphor screens to detect the products of the inverse beta decay reaction. A multi-tonne detector system built from these individual cells can provide precise localisation of scintillation signals, making efficient use of the detector volume. Monte Carlo simulations indicate that a neutron capture efficiency of over 70% is achievable with a sufficient number of 6LiF: ZnS( Ag) screens per cube and that an appropriate segmentation enables a measurement of the positron energy which is not limited by gamma-ray leakage. First measurements of a single cell indicate that a very good neutron-gamma discrimination and high neutron detection efficiency can be obtained with adequate triggering techniques. The light yield from positron signals has been measured, showing that an energy resolution of 14%/root E(MeV) is achievable with high uniformity. A preliminary neutrino signal analysis has been developed, using selection criteria for pulse shape, energy, time structure and energy spatial distribution and showing that an antineutrino efficiency of 40% can be achieved. It also shows that the fine segmentation of the detector can be used to significantly decrease both correlated and accidental backgrounds. ; Agence Nationale de la Recherche grant [ANR-16-CE31-0018-03]; Institut Carnot Mines, France; CNRS/IN2P3 et Region Pays de Loire, France; FWO-Vlaanderen, Belgium; Vlaamse Herculesstichting, Belgium; Science AMP; Technology Facilities Council (STFC), United Kingdom; FWO-Vlaanderen; Belgian Federal Science Policy Office (BelSpo) under the IUAP network programme; STFC Rutherford Fellowship program; European Research Council under the European Union's Horizon Programme (H-CoG) / ERC Grant [682474]; Merton College Oxford ; This work was supported by the following funding agencies: Agence Nationale de la Recherche grant ANR-16-CE31-0018-03, Institut Carnot Mines, CNRS/IN2P3 et Region Pays de Loire, France; FWO-Vlaanderen and the Vlaamse Herculesstichting, Belgium; The U.K. groups acknowledge the support of the Science & Technology Facilities Council (STFC), United Kingdom; We are grateful for the early support given by the sub-department of Particle Physics at Oxford and High Energy Physics at Imperial College London. We thank also our colleagues, the administrative and technical staffs of the SCK.CEN for their invaluable support for this project. Individuals have received support from the FWO-Vlaanderen and the Belgian Federal Science Policy Office (BelSpo) under the IUAP network programme; The STFC Rutherford Fellowship program and the European Research Council under the European Union's Horizon 2020 Programme (H2020-CoG) / ERC Grant Agreement n. 682474 (corresponding author); Merton College Oxford.