The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest of all low-energy neutrino couplings. This ...mode of interaction offers new opportunities to study neutrino properties and leads to a miniaturization of detector size, with potential technological applications. We observed this process at a 6.7σ̃ confidence level, using a low-background, 14.6-kilogram CsINa scintillator exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the standard model for this process, were observed in high signal-to-background conditions. Improved constraints on nonstandard neutrino interactions with quarks are derived from this initial data set.
Precision measurement of the neutral pion lifetime Larin, I; Zhang, Y; Gasparian, A ...
Science (American Association for the Advancement of Science),
05/2020, Letnik:
368, Številka:
6490
Journal Article
Recenzirano
Odprti dostop
The explicit breaking of the axial symmetry by quantum fluctuations gives rise to the so-called axial anomaly. This phenomenon is solely responsible for the decay of the neutral pion π
into two ...photons (γγ), leading to its unusually short lifetime. We precisely measured the decay width Γ of the Formula: see text process. The differential cross sections for π
photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding Formula: see text, where stat. denotes the statistical uncertainty and syst. the systematic uncertainty. We combined the results of this and an earlier experiment to generate a weighted average of Formula: see text Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics.
Two different nuclear-medium effects are isolated using a low three-momentum transfer subsample of neutrino-carbon scattering data from the MINERvA neutrino experiment. The observed hadronic energy ...in charged-current ν_{μ} interactions is combined with muon kinematics to permit separation of the quasielastic and Δ(1232) resonance processes. First, we observe a small cross section at very low energy transfer that matches the expected screening effect of long-range nucleon correlations. Second, additions to the event rate in the kinematic region between the quasielastic and Δ resonance processes are needed to describe the data. The data in this kinematic region also have an enhanced population of multiproton final states. Contributions predicted for scattering from a nucleon pair have both properties; the model tested in this analysis is a significant improvement but does not fully describe the data. We present the results as a double-differential cross section to enable further investigation of nuclear models. Improved description of the effects of the nuclear environment are required by current and future neutrino oscillation experiments.
We report on multinucleon effects in low momentum transfer (<0.8 GeV/c) antineutrino interactions on plastic (CH) scintillator. These data are from the 2010-2011 antineutrino phase of the MINERvA ...experiment at Fermilab. The hadronic energy spectrum of this inclusive sample is well described when a screening effect at a low energy transfer and a two-nucleon knockout process are added to a relativistic Fermi gas model of quasielastic, Δ resonance, and higher resonance processes. In this analysis, model elements introduced to describe previously published neutrino results have quantitatively similar benefits for this antineutrino sample. We present the results as a double-differential cross section to accelerate the investigation of alternate models for antineutrino scattering off nuclei.
Charged-current antineutrino interactions on a hydrocarbon scintillator in the MINERvA detector are used to study activity from their final-state neutrons. To ensure that most of the neutrons are ...from the primary interaction, rather than hadronic reinteractions in the detector, the sample is limited to momentum transfers below 0.8 GeV/c. From 16 129 interactions, 15 246 neutral particle candidates are observed. The reference simulation predicts 64% of these candidates are due to neutrons from the antineutrino interaction directly but also overpredicts the number of candidates by 15% overall. This discrepancy is beyond the standard uncertainty estimates for models of neutrino interactions and neutron propagation in the detector. We explore these two aspects of the models using the measured distributions for energy deposition, time of flight, position, and speed. We also use multiplicity distributions to evaluate the presence of a two-nucleon knockout process. These results provide critical new information toward a complete description of the hadronic final state of neutrino interactions, which is vital to neutrino oscillation experiments.
Purpose
Suicide is a leading cause of death among Nepali women of reproductive age. Suicidal ideation has known associations with stressful life events, which Nepali widows disproportionately ...experience. We aimed to identify risk and protective factors that could lead to effective interventions for this population.
Methods
To study suicidal ideation in Nepali widows, we collected data from 204 women in urban, semi-urban, and rural areas whose husbands died at least one year prior. The questionnaire included sociodemographic information, the Hopkins Symptom Checklist-25, PTSD Checklist—Civilian Version, Somatic Symptom Scale–8, and the Multidimensional Scale of Perceived Social Support. Overall severity of prolonged grief was assessed by a counselor after completing a structured clinical interview. Using multivariate regression models, we assessed associations of sociodemographic and psychosocial indicators with past-year suicidal ideation. Latent profile analysis was also performed to estimate profiles of comorbidities.
Results
Past-year suicidality was high, with 16.2% (
N
= 33). Each year increase since husband's death was protective and reduced odds of ideation 8% (95% CI 0.85–0.98) and being educated and of older age also reduced the odds of ideation by 0.21 (95% CI 0.06–0.70), and 0.09 (95% CI 0.01–0.64), respectively. Depression (OR = 6.37, 95% CI 2.78–14.59), PTSD (OR = 3.84, 95% CI 2.15–6.86), prolonged grief (OR = 6.04, 95% CI 3.04–12.00) and anxiety (OR = 6.52, 95% CI 2.96–14.38) were highly associated with suicidality, and mapped onto the three profiles of increasing mental distress severity.
Conclusion
Suicide remains a major issue among Nepali widows, showing high comorbidity with other mental disorders. Screening for depression, anxiety, and prolonged grief, may aid in identifying widows at increased risk of suicidal ideation.
We present measurements of the neutrino and antineutrino total charged-current cross sections on carbon and their ratio using the MINERvA scintillator-tracker. The measurements span the energy range ...2–22 GeV and were performed using forward and reversed horn focusing modes of the Fermilab low-energy NuMI beam to obtain large neutrino and antineutrino samples. The flux is obtained using a subsample of charged-current events at low hadronic energy transfer along with precise higher energy external neutrino cross section data overlapping with our energy range between 12–22 GeV. We also report on the antineutrino-neutrino cross section ratio, RCC, which does not rely on external normalization information. Our ratio measurement, obtained within the same experiment using the same technique, benefits from the cancellation of common sample systematic uncertainties and reaches a precision of ∼5% at low energy. Our results for the antineutrino-nucleus scattering cross section and for RCC are the most precise to date in the energy range Eν<6 GeV.
Charged-current ν_{μ} interactions on carbon, iron, and lead with a final state hadronic system of one or more protons with zero mesons are used to investigate the influence of the nuclear ...environment on quasielasticlike interactions. The transferred four-momentum squared to the target nucleus, Q^{2}, is reconstructed based on the kinematics of the leading proton, and differential cross sections versus Q^{2} and the cross-section ratios of iron, lead, and carbon to scintillator are measured for the first time in a single experiment. The measurements show a dependence on the atomic number. While the quasielasticlike scattering on carbon is compatible with predictions, the trends exhibited by scattering on iron and lead favor a prediction with intranuclear rescattering of hadrons accounted for by a conventional particle cascade treatment. These measurements help discriminate between different models of both initial state nucleons and final state interactions used in the neutrino oscillation experiments.
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