Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session JD: Mini-symposium on Investigations of the Reactor Neutrino Anomalies: IMini-Symposium
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Chair: Alan Poon, Lawrence Berkeley National Laboratory Room: Junior Ballroom C |
Saturday, October 15, 2016 10:30AM - 11:06AM |
JD.00001: Reactor Antineutrinos: From Confusion to Clarity Invited Speaker: Dan Dwyer Antineutrinos emitted by nuclear reactors have been a powerful tool for particle physics, demonstrating the existence of these weakly-interacting particles as well as their flavor oscillation. Despite these successes, our understanding of the total flux and energy spectra of reactor antineutrinos has been fraught with problems. I will give a brief overview of the unexpected developments in this field, and discuss upcoming measurements of antineutrinos, beta decays, and nuclear fission which are relevant to these questions. These measurements are expected to clarify many currently murky issues, including the hypothetical oscillation of reactor antineutrinos to sterile states. The results should also provide a unique perspective into the nuclear physics of fission reactors. [Preview Abstract] |
Saturday, October 15, 2016 11:06AM - 11:18AM |
JD.00002: Recent Improvements in the Summation Calculation of Antineutrino Spectra Alejandro Sonzogni, Timothy Johnson, Elizabeth McCutchan, Paraskevi Dimitriou The antineutrino spectrum following the fission of an actinide nucleus can be calculated using a comprehensive set of fission yields and decay data, an approach known as the summation method. We have recently updated our databases to incorporate newly published results as well as to perform some corrections and updates. These summation calculations are now in better agreement with those from the conversion method. The advantage of the summation method is that one can understand the rich correlations between the different radiation types - gammas, electrons, neutrons and antineutrinos -- as well as study the time dependence of the radiation intensity in a variety of situations. Additionally, we have performed a sensitivity study to identify different elements of the input nuclear data which have an important impact in the calculation of antineutrino spectra and which would benefit from a precise measurement. [Preview Abstract] |
Saturday, October 15, 2016 11:18AM - 11:30AM |
JD.00003: ABSTRACT WITHDRAWN |
(Author Not Attending)
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JD.00004: Total absorption spectroscopy study of the beta decay of fission products for reactor anti-neutrino energy spectra calculation Aleksandra Fijalkowska Thanks to its high efficiency for the detection of gamma-radiation, total absorption spectroscopy is an ideal technique to establish the true beta-decay feeding. The knowledge of the decay scheme is used to determine the distribution of anti-neutrino energy released in the decay. The anti-neutrino energy spectrum is used to calculate the total anti-neutrino flux emitted by reactor cores and the number of reactor anti-neutrino interactions with the detector matter. The number of measured anti-neutrino interactions with detector matter is about 6\% smaller than the expected number of events. The measurements of beta decay of fission products by means of total absorption technique allow to verify expected number of anti-neutrino interactions with matter. In this contribution we would like to present the results of total absorption measurement of the beta decay of 86Br, 89Rb, 89Kr, 90gsRb, 90mRb, 90Kr and 139Xe, nuclei abundantly produced in the reactor core. The results and their impact on the anti-neutrino spectra reconstruction will be presented and discussed. [Preview Abstract] |
Saturday, October 15, 2016 11:42AM - 11:54AM |
JD.00005: Beta-delayed neutron spectroscopy of spherical and deformed neutron emitters with VANDLE Thomas King, C. J. Gross, R. K. Grzywacz, S.V. Paulauskas, K.P. Rykaczewski, D.W, Stracener, S.Z. Taylor For many neutron-rich isotopes, the main decay mode is through beta-delayed neutron and gamma emission. Neutron and gamma coincidences provide information necessary to extract the beta-strength distribution. These distributions are inputs to test nuclear models needed for r-process modeling. The detailed data on beta decay feeding to neutron-unbound states are used to calculate reactor decay heat and understand the antineutrino spectrum. A series of measurements with selective ion sources was performed at the On-Line Test Facility (OLTF) at Oak Ridge National Laboratory with the Versatile Array of Neutron Detectors at Low Energy (VANDLE). These experiments revisited decays of spherical and deformed isotopes produced in proton induced fission of 238U, which included beta delayed precursors of bromine, rubidium, cesium, and iodine. Unique data sets with neutron and gamma ray coincidences were collected. Achieving high coincidence efficiency required the addition of high-efficiency gamma-ray detectors consisting of 16 LaBr3 crystals (HAGRiD) and a large volume set of NaI detectors to VANDLE. Preliminary results will be presented. [Preview Abstract] |
Saturday, October 15, 2016 11:54AM - 12:06PM |
JD.00006: Improving reactor models with a precision beta spectroscopy experiment of the $^{235}$U fission spectrum Melissa Boswell, Amanda Gehring, John Ullmann, Todd Haines, Matthew Devlin, Steven Elliott, Keith Rielage, John Goett, Brandon White The reactor neutrino anomaly could be an indication of non-standard neutrino physics models (e.g. sterile neutrinos), or the discrepancy could be the result of uncertainties in the modeled reactor neutrino spectrum. Understanding the aggregate $\beta$ spectrum is extremely important for improving the confidence in the underlying predicted reactor neutrino spectrum. The original $\beta$ spectrum measurement was preformed at the Institut Laue-Langevin (ILL) reactor in the early 1980’s and suffered from a number of limitations. A recent attempt at reproducing the ILL experiment concluded that their uncertainties were driven by a low signal to noise ratio, and that the best way to decrease the uncertainties was to conduct the experiment at a neutron beam line similar to the one at Los Alamos. In this talk I will discuss the advantages of reproducing this experiment at the Lujan center at LANL, our proposed experimental setup, and finally steps we are taking to evaluate the systematics associated with these measurements at an accelerator-based neutron beam. Furthermore we will also discuss additional measurement with $^{238}$U and $^{239}$Pu that are also important to the non-proliferation communities. [Preview Abstract] |
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