141 research outputs found
Understanding Supernova Neutrino Physics using Low-Energy Beta-Beams
We show that fitting linear combinations of low-energy beta-beam spectra to
supernova-neutrino energy-distributions reconstructs the response of a nuclear
target to a supernova flux in a very accurate way. This allows one to make
direct predictions about the supernova-neutrino signal in a terrestrial
neutrino detector.Comment: To appear in the proceedings of International School of Nuclear
Physics: 27th Course: "Neutrinos in Cosmology, in Astro, Particle and Nuclear
Physics". Erice, Sicily, Italy, 16-2
Reconstructing supernova-neutrino spectra using low-energy beta-beams
Only weakly interacting, neutrinos are the principal messengers reaching us
from the center of a supernova. Terrestrial neutrino telescopes, such as SNO
and SuperKamiokande, can provide precious information about the processes in
the core of a collapsing and exploding star. But the information about the
supernova that a neutrino detector can supply, is restricted by the fact that
little experimental data on the neutrino-nucleus cross sections exists and by
the uncertainties in theoretical calculations. In this letter, we propose a
novel procedure that determines the response of a target nucleus in a
supernova-neutrino detector directly, by using low-energy beta-beams. We show
that fitting 'synthetic' spectra, constructed by taking linear combinations of
beta-beam spectra, to the original supernova-neutrino spectra reproduces the
folded differential cross sections very accurately. Comparing the response in a
terrestrial detector to these synthetic responses provides a direct way to
determine the main parameters of the supernova-neutrino energy-distribution.Comment: 4 page
Thermodynamical properties of a mean-field plus pairing model and applications for the Fe nuclei
A mean-field plus pairing model for atomic nuclei in the Fe region was
studied using a finite-temperature quantum Monte-Carlo method. We present
results for thermodynamical quantities such as the internal energy and the
specific heat. These results give indications of a phase transition related to
the pairing amongst nucleons, around temperatures of 0.7 MeV. The influence of
the residual interaction and of the size of the model space on the nuclear
level densities is discussed too.Comment: 23 pages, including 17 eps figure
Pion production within the hybrid relativistic plane wave impulse approximation model at MiniBooNE and MINERvA kinematics
The hybrid model for electroweak single-pion production (SPP) off the
nucleon, presented in [Gonz\'alez-Jim\'enez et al., Phys. Rev. D 95, 113007
(2017)], is extended here to the case of incoherent pion-production on the
nucleus. Combining a low-energy model with a Regge approach, this model
provides valid predictions in the entire energy region of interest for current
and future accelerator-based neutrino-oscillation experiments. The Relativistic
Mean-Field model is used for the description of the bound nucleons while the
outgoing hadrons are considered as plane waves. This approach, known as
Relativistic Plane-Wave Impulse Approximation (RPWIA), is a first step towards
the development of more sophisticated models, it is also a test of our current
understanding of the elementary reaction. We focus on the charged-current
()-nucleus interaction at MiniBooNE and MINERvA kinematics. The
effect on the cross sections of the final-state interactions, which affect the
outgoing hadrons on their way out of the nucleus, is judged by comparing our
results with those from the NuWro Monte Carlo event generator. We find that the
hybrid-RPWIA predictions largely underestimate the MiniBooNE data. In the case
of MINERvA, our results fall below the -induced 1 production data,
while a better agreement is found for -induced 1 and
-induced 1 production.Comment: 13 pages, 10 figure
Untangling supernova-neutrino oscillations with beta-beam data
Recently, we suggested that low-energy beta-beam neutrinos can be very useful
for the study of supernova neutrino interactions. In this paper, we examine the
use of a such experiment for the analysis of a supernova neutrino signal. Since
supernova neutrinos are oscillating, it is very likely that the terrestrial
spectrum of supernova neutrinos of a given flavor will not be the same as the
energy distribution with which these neutrinos were first emitted. We
demonstrate the efficacy of the proposed method for untangling multiple
neutrino spectra. This is an essential feature of any model aiming at gaining
information about the supernova mechanism, probing proto-neutron star physics,
and understanding supernova nucleosynthesis, such as the neutrino process and
the r-process. We also consider the efficacy of different experimental
approaches including measurements at multiple beam energies and detector
configurations.Comment: 13 pages, 11 figures, accepted for publication in Phys. Rev.
Extracting the Weinberg angle at intermediate energies
A recent experiment by the NuTeV collaboration resulted in a surprisingly
high value for the weak mixing angle . The Paschos-Wolfenstein
relation, relating neutrino cross sections to the Weinberg angle, is of pivotal
importance in the NuTeV analysis. In this work, we investigate the sensitivity
of the Paschos-Wolfenstein relation to nuclear structure aspects at neutrino
energies in the few GeV range. Neutrino-nucleus cross sections are calculated
for O and Fe target nuclei within a relativistic quasi-elastic
nucleon-knockout model.Comment: To appear in the proceedings of International School of Nuclear
Physics: 27th Course: "Neutrinos in Cosmology, in Astro, Particle and Nuclear
Physics", Erice, Sicily, Italy, 16-24 Sep 200
Identifying neutrinos and antineutrinos in neutral-current scattering reactions
We study neutrino-induced nucleon knockout from nuclei. Expressions for the
induced polarization are derived within the framework of the
independent-nucleon model and the non-relativistic plane-wave approximation.
Large dissimilarities in the nucleon polarization asymmetries are observed
between neutrino- and antineutrino-induced processes. These asymmetries
represent a potential way to distinguish between neutrinos and antineutrinos in
neutral-current neutrino-scattering on nuclei. We discuss astrophysical
applications of these polarization asymmetries. Our findings are illustrated
for neutrino scattering on O and Pb.Comment: 5 pages, 5 figures, accepted for publication in Phys. Rev. Let
Electroweak interactions in a relativistic Fermi gas
We present a relativistic model for computing the neutrino mean free path in
neutron matter. Thereby, neutron matter is described as a non-interacting Fermi
gas in beta-equilibrium. We present results for the neutrino mean free path for
temperatures from 0 up to 50 MeV and a broad range of neutrino energies. We
show that relativistic effects cause a considerable enhancement of
neutrino-scattering cross-sections in neutron matter. The influence of the
-dependence in the electroweak form factors and the inclusion of a weak
magnetic term in the hadron current is discussed. The weak-magnetic term in the
hadron current is at the origin of some selective spin dependence for the
nucleons which are subject to neutrino interactions.Comment: 11 pages, 7 figures, accepted to Phys. Rev. C, minor changes and
updates of the figures are mad
Seagull and pion-in-flight currents in neutrino-induced and knockout
[Background] The neutrino-nucleus () cross section is a major source
of systematic uncertainty in neutrino-oscillation studies. A precise
scattering model, in which multinucleon effects are incorporated, is pivotal
for an accurate interpretation of the data. [Purpose] In interactions,
meson-exchange currents (MECs) can induce two-nucleon () knockout from the
target nucleus, resulting in a two-particle two-hole (2p2h) final state. They
also affect single nucleon () knockout reactions, yielding a one-particle
one-hole (1p1h) final state. Both channels affect the inclusive strength. We
present a study of axial and vector, seagull and pion-in-flight currents in
muon-neutrino induced and knockout reactions on C. [Method]
Bound and emitted nucleons are described as Hartree-Fock wave functions. For
the vector MECs, the standard expressions are used. For the axial current,
three parameterizations are considered. The framework developed here allows for
a treatment of MECs and short-range correlations (SRCs). [Results] Results are
compared with electron-scattering data and with literature. The strengths of
the seagull, pion-in-flight and axial currents are studied separately and
double differential cross sections including MECs are compared with results
including SRCs. A comparison with MiniBooNE and T2K data is presented.
[Conclusions] In the 1p1h channel, the effects of the MECs tend to cancel each
other, resulting in a small effect on the double differential cross section.
knockout processes provide a small contribution to the inclusive double
differential cross section, ranging from the knockout threshold into the
dip region. A fair agreement with the MiniBooNE and T2K data is reached.Comment: 16 pages, 10 figure
Relativistic effects in neutrino-Fermi gas interactions
We study neutrino interactions in a hadron gas within a relativistic
framework. The hadron matter is described by a non-interacting Fermi gas in
beta equilibrium. We show that the introduction of relativistic effects causes
a sizable enhancement of the neutrino-scattering cross sections.Comment: To appear in the proceedings of International School of Nuclear
Physics: 27th Course: "Neutrinos in Cosmology, in Astro, Particle and Nuclear
Physics". Erice, Sicily, Italy, 16-2
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