W.E. Ang, “Coherent Elastic Neutrino Nucleus Scatter Response of Semiconductor Detectors to Nuclear Reactor Antineutrinos and Safeguards Applications”, Ph.D. Dissertation, Nuclear Engineering, Texas A&M University, College Station, TX (2022).
In this work, semiconductor CEνNS detector response to reactor antineutrinos is studied. In particular, pulse height distributions and reaction rates are used for nonproliferation and power-monitoring analysis of a research and commercial reactor. The antineutrino spectrum of 235U, 238U, 239Pu, and 241Pu are modeled using summation method with corrections for the finite-size-nucleus, weak magnetism, and radiative losses. The modeled antineutrino spectrum is also compared to previous studies using the summation and conversion methods from the literature to validate the results. Following the antineutrino spectrum modeling, the CEνNS and IBD cross-sections are calculated. The cross-sections are later used to calculate the detector response in terms of CEνNS-IBD detector reaction rates. Detector measurables such as distribution of recoil energies for a given incident antineutrino energy or CEvNS pulse height distribution for a threshold, detector size, and distance are also calculated to investigate the importance of background levels and resolution on antineutrino spectroscopy for nuclear security applications and nuclear physics studies.rnThe findings suggest that a CEνNS detector made of natural Ge with a mass of 100-kg and 20-eVNR thresholds is over 27 times more efficient compared to the IBD detector, and over 2 times more efficient compared to the Si detector. The results show that a threshold of 20-eVNR renders 33% of antineutrinos from a 1-MW TRIGA reactor undetected in natural Ge and 20% of antineutrinos undetectable in natural Si. In both natural Ge and natural Si, increasing the threshold to 100-eVNR renders 67% and 46% ofrnantineutrinos undetected, respectively. The current IBD threshold leaves 66% of the antineutrino population undetected. A CEνNS Ge detector can be used to detect antineutrinos outside the AP1000-type reactor containment with 1,977 events/day, given a 100-eVNR threshold and background levels of 100-DRU can be achieved. The diversion detection is difficult with detection probability less than 7% when the operator intervenes and recovers the reactor power, or when the diverted fuel assemblies are substituted with fresh fuel assemblies. For the case of diversion without operator intervention by reducing reactor power, removing three or more fuel assemblies can be detected with detection probabilities of more than 30%.