16 research outputs found
Observation of Coherent Elastic Neutrino-Nucleus Scattering
The coherent elastic scattering of neutrinos off nuclei has eluded detection
for four decades, even though its predicted cross-section is the largest by far
of all low-energy neutrino couplings. This mode of interaction provides new
opportunities to study neutrino properties, and leads to a miniaturization of
detector size, with potential technological applications. We observe this
process at a 6.7-sigma confidence level, using a low-background, 14.6-kg
CsI[Na] scintillator exposed to the neutrino emissions from the Spallation
Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic
signatures in energy and time, predicted by the Standard Model for this
process, are observed in high signal-to-background conditions. Improved
constraints on non-standard neutrino interactions with quarks are derived from
this initial dataset
Measurement of scintillation response of CsI[Na] to low-energy nuclear recoils by COHERENT
We present results of several measurements of CsI[Na] scintillation response
to 3-60 keV energy nuclear recoils performed by the COHERENT collaboration
using tagged neutron elastic scattering experiments and an endpoint technique.
Earlier results, used to estimate the coherent elastic neutrino-nucleus
scattering (CEvNS) event rate for the first observation of this process
achieved by COHERENT at the Spallation Neutron Source (SNS), have been
reassessed. We discuss corrections for the identified systematic effects and
update the respective uncertainty values. The impact of updated results on
future precision tests of CEvNS is estimated. We scrutinize potential
systematic effects that could affect each measurement. In particular we confirm
the response of the H11934-200 Hamamatsu photomultiplier tube (PMT) used for
the measurements presented in this study to be linear in the relevant signal
scale region.Comment: The version accepted by JINST. The changes made as a result of the
peer review process: 1. Section 8 "Global CsI[Na] QF data fit" is expanded.
The main fit result and its uncertainty is NOT CHANGED. An alternative fit is
now shown in Figure 14, Figure 15 is added to further validate the
assumptions in the main fit. 2. The Appendix B is restructured for clarit
Neutrino-nucleus cross sections for oscillation experiments
Neutrino oscillations physics is entered in the precision era. In this
context accelerator-based neutrino experiments need a reduction of systematic
errors to the level of a few percent. Today one of the most important sources
of systematic errors are neutrino-nucleus cross sections which in the
hundreds-MeV to few-GeV energy region are known with a precision not exceeding
20%. In this article we review the present experimental and theoretical
knowledge of the neutrino-nucleus interaction physics. After introducing
neutrino oscillation physics and accelerator-based neutrino experiments, we
overview general aspects of the neutrino-nucleus cross sections, both
theoretical and experimental views. Then we focus on these quantities in
different reaction channels. We start with the quasielastic and
quasielastic-like cross section, putting a special emphasis on multinucleon
emission channel which attracted a lot of attention in the last few years. We
review the main aspects of the different microscopic models for this channel by
discussing analogies and differences among them.The discussion is always driven
by a comparison with the experimental data. We then consider the one pion
production channel where data-theory agreement remains very unsatisfactory. We
describe how to interpret pion data, then we analyze in particular the puzzle
related to the impossibility of theoretical models and Monte Carlo to
simultaneously describe MiniBooNE and MINERvA experimental results. Inclusive
cross sections are also discussed, as well as the comparison between the
and cross sections, relevant for the CP violation
experiments. The impact of the nuclear effects on the reconstruction of
neutrino energy and on the determination of the neutrino oscillation parameters
is reviewed. A window to the future is finally opened by discussing projects
and efforts in future detectors, beams, and analysis
Monitoring the SNS basement neutron background with the MARS detector
We present the analysis and results of the first dataset collected with the
MARS neutron detector deployed at the Oak Ridge National Laboratory Spallation
Neutron Source (SNS) for the purpose of monitoring and characterizing the
beam-related neutron (BRN) background for the COHERENT collaboration. MARS was
positioned next to the COH-CsI coherent elastic neutrino-nucleus scattering
detector in the SNS basement corridor. This is the basement location of closest
proximity to the SNS target and thus, of highest neutrino flux, but it is also
well shielded from the BRN flux by infill concrete and gravel. These data show
the detector registered roughly one BRN per day. Using MARS' measured detection
efficiency, the incoming BRN flux is estimated to be
for neutron energies
above ~MeV and up to a few tens of MeV. We compare our results with
previous BRN measurements in the SNS basement corridor reported by other
neutron detectors.Comment: Submitted to JINS
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.