31 research outputs found
Final Measurement of the U235 Antineutrino Energy Spectrum with the PROSPECT-I Detector at HFIR
This Letter reports one of the most precise measurements to date of the
antineutrino spectrum from a purely U235-fueled reactor, made with the final
dataset from the PROSPECT-I detector at the High Flux Isotope Reactor. By
extracting information from previously unused detector segments, this analysis
effectively doubles the statistics of the previous PROSPECT measurement. The
reconstructed energy spectrum is unfolded into antineutrino energy and compared
with both the Huber-Mueller model and a spectrum from a commercial reactor
burning multiple fuel isotopes. A local excess over the model is observed in
the 5MeV to 7MeV energy region. Comparison of the PROSPECT results with those
from commercial reactors provides new constraints on the origin of this excess,
disfavoring at 2.2 and 3.2 standard deviations the hypotheses that
antineutrinos from U235 are solely responsible and non-contributors to the
excess observed at commercial reactors respectively.Comment: The paper has been updated with an improved parametrization of the
observed antineutrino spectrum excess and extended discussion on its
potential isotopic origi
PROSPECT-II Physics Opportunities
The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, has made
world-leading measurements of reactor antineutrinos at short baselines. In its
first phase, conducted at the High Flux Isotope Reactor (HFIR) at Oak Ridge
National Laboratory, PROSPECT produced some of the strongest limits on eV-scale
sterile neutrinos, made a precision measurement of the reactor antineutrino
spectrum from U, and demonstrated the observation of reactor
antineutrinos in an aboveground detector with good energy resolution and
well-controlled backgrounds. The PROSPECT collaboration is now preparing an
upgraded detector, PROSPECT-II, to probe yet unexplored parameter space for
sterile neutrinos and contribute to a full resolution of the Reactor
Antineutrino Anomaly, a longstanding puzzle in neutrino physics. By pressing
forward on the world's most precise measurement of the U antineutrino
spectrum and measuring the absolute flux of antineutrinos from U,
PROSPECT-II will sharpen a tool with potential value for basic neutrino
science, nuclear data validation, and nuclear security applications. Following
a two-year deployment at HFIR, an additional PROSPECT-II deployment at a low
enriched uranium reactor could make complementary measurements of the neutrino
yield from other fission isotopes. PROSPECT-II provides a unique opportunity to
continue the study of reactor antineutrinos at short baselines, taking
advantage of demonstrated elements of the original PROSPECT design and close
access to a highly enriched uranium reactor core
Accessing new physics with an undoped, cryogenic CsI CEvNS detector for COHERENT at the SNS
We consider the potential for a 10-kg undoped cryogenic CsI detector
operating at the Spallation Neutron Source to measure coherent elastic
neutrino-nucleus scattering and its sensitivity to discover new physics beyond
the standard model. Through a combination of increased event rate, lower
threshold, and good timing resolution, such a detector would significantly
improve on past measurements. We considered tests of several
beyond-the-standard-model scenarios such as neutrino non-standard interactions
and accelerator-produced dark matter. This detector's performance was also
studied for relevant questions in nuclear physics and neutrino astronomy,
namely the weak charge distribution of CsI nuclei and detection of neutrinos
from a core-collapse supernova
Measurement of Pb(,X) production with a stopped-pion neutrino source
Using neutrinos produced at the Spallation Neutron Source (SNS) at Oak Ridge
National Laboratory (ORNL), the COHERENT collaboration has studied the
Pb(,X) process with a lead neutrino-induced-neutron (NIN) detector.
Data from this detector are fit jointly with previously collected COHERENT data
on this process. A combined analysis of the two datasets yields a cross section
that is times that predicted by the MARLEY event
generator using experimentally-measured Gamow-Teller strength distributions,
consistent with no NIN events at 1.8. This is the first inelastic
neutrino-nucleus process COHERENT has studied, among several planned exploiting
the high flux of low-energy neutrinos produced at the SNS.Comment: 11 pages, 9 figures, version accepted by Phys. Rev.