Intermediate Neutrino Energies Research Articles

Simulated Neutrino Signals of Low and Intermediate Energy Neutrinos on Cd Detectors

Neutrino-nucleus reactions cross sections, obtained for neutrino energies in the range $\varepsilon_{\nu}\leq 100-120$ MeV (low- and intermediate-energy range), which refer to promising neutrino detection targets of current terrestrial neutrino experiments, are presented and discussed. At first, we evaluated original cross sections for elastic scattering of neutrinos produced from various astrophysical and laboratory neutrino sources with the most abundant Cd isotopes $^{112}$Cd, $^{114}$Cd and $^{116}$Cd. These isotopes constitute the main material of the COBRA detector aiming to search for neutrinoless double beta decay events and neutrino-nucleus scattering events at the Gran Sasso laboratory (LNGS). The coherent $\nu$-nucleus reaction channel addressed with emphasis here, dominates the neutral current $\nu$-nucleus scattering, events of which have only recently been observed for a first time in the COHERENT experiment at Oak Ridge. Subsequently, simulated $\nu$-signals expected to be recorded at Cd detectors are derived through the application of modern simulation techniques and employment of reliable neutrino distributions of astrophysical $\nu$-sources (as the solar, supernova and Earth neutrinos), as well as laboratory neutrinos (like the reactor neutrinos, the neutrinos produced from pion-muon decay at rest and the $\beta$-beam neutrinos produced from the acceleration of radioactive isotopes at storage rings as e.g. at CERN).

Measurement of theνμcharged-current quasielastic cross section on carbon with the ND280 detector at T2K

The Charged-Current Quasi-Elastic (CCQE) interaction, $\nu_{l} + n \rightarrow l^{-} + p$, is the dominant CC process at $E_\nu \sim 1$ GeV and contributes to the signal in accelerator-based long-baseline neutrino oscillation experiments operating at intermediate neutrino energies. This paper reports a measurement by the T2K experiment of the $\nu_{\mu}$ CCQE cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum ($p_\mu$) and angle with respect to the incident neutrino beam ($\theta_\mu$). The flux-integrated CCQE cross section was measured to be $(0.83 \pm 0.12) \times 10^{-38}\textrm{ cm}^{2}$ in good agreement with NEUT MC value of ${0.88 \times 10^{-38}} \textrm{ cm}^{2}$. The energy dependence of the CCQE cross section is also reported. The axial mass, $M_A^{QE}$, of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shape-only) $p_{\mu}cos\theta_\mu$ distribution, the effective $M_A^{QE}$ parameter was measured to be ${1.26^{+0.21}_{-0.18} \textrm{ GeV}/c^{2}}$ (${1.43^{+0.28}_{-0.22} \textrm{ GeV}/c^{2}}$).

Convolutedν-Signals on114Cd Isotope from Astrophysical and Laboratory Neutrino Sources

At first, we evaluate scattering cross sections of low, and intermediate-energy neutrinos scattered off the114Cd isotope, the most abundant Cd isotope present also in the COBRA detector (CdTe and CdZnTe materials) which aims to search for double beta decay events and neutrino observations at Gran Sasso laboratory (LNGS). The coherentν-nucleus channel addressed here is the dominant reaction channel of the neutral currentν-nucleus scattering. Ourν-nucleus cross sections (calculated with a refinement of the quasiparticle random-phase approximation, QRPA) refer to thegs→gstransitions forν-energiesεν≤100 MeV. Subsequently, simulatedν-signals on114Cd isotope are derived. Towards this purpose, the required folded cross section comes out of simulation techniques by employing several low, and intermediate-energy neutrino distributions of the astrophysicalν-sources, like the solar, supernova, and Earth neutrinos, as well as the laboratory neutrinos, the reactor neutrinos, the pion-muon stopped neutrinos, and theβ-beam neutrinos.

ASSOCIATED HYPERON–KAON PRODUCTION VIA NEUTRINO–NUCLEUS SCATTERING

We present the investigation of the neutrino-induced strangeness associated production on nuclei in the relativistic plane wave impulse approximation (RPWIA) framework at the intermediate neutrino energies. In this study, the elementary hadronic weak amplitudes are embedded inside the nuclear medium for the description of the exclusive channels of neutrino–nucleus interactions. These amplitudes are extracted using a model-dependent evaluation of the hadronic vertex using the Born term approximation in which the application of the Cabibbo V–A theory and SU(3) symmetry are assumed to be valid. The nuclear effects are included via the bound state wave functions of the nucleon obtained from the relativistic mean field (RMF) models. Two kinematics settings are used to examine various distributions of the differential cross-section in the rest frame of the target nuclei. The numerical results are obtained for the neutrino-induced charged-current (CC) K +Λ-production on bound neutrons in 1s1/2 and 1p3/2 orbitals of 12 C . The angular distributions are forward peaked under both kinematic settings, whereas under the quasifree setting, the cross-sections tend to mimic the missing momentum distribution of the bound nucleon inside the nucleus.

Theoretical study of neutrino scattering off the stable even Mo isotopes at low and intermediate energies

Abstract A systematic study of the cross sections of neutral-current neutrino scattering off the stable even Mo isotopes (mass number A = 92 , 94 , 96 , 98 , 100 ), at low and intermediate neutrino energies ( E ν ⩽ 130 MeV ), is presented and discussed. The required wave functions for the initial (ground state) and all accessible final nuclear states are constructed in the context of the quasi-particle random-phase approximation (QRPA) and tested against data on the low-lying energy spectra of the isotopes in question. The individual contributions coming from the polar-vector and axial-vector components of the hadronic current for the coherent and incoherent channels of each isotope are investigated. The studied Mo isotopes are contents of the detector of the MOON experiment operating at Japan with a hybrid aim to search for neutrinoless double beta decay events and to detect low- and intermediate-energy astrophysical neutrinos (solar, supernova, geo-neutrinos), and also of the NEMO neutrinoless double beta decay detector in Modane at France. For such purposes our cross section calculations are of significant importance.

Low-energy neutral-current neutrino scattering onTe128,130isotopes

Differential, total, and cumulative cross section calculations for neutral current neutrino scattering on $^{128,130}\mathrm{Te}$ isotopes are performed in the context of the quasiparticle random phase approximation by utilizing realistic two-nucleon forces. These isotopes are the main contents of detectors of ongoing experiments with multiple neutrino physics goals (COBRA and CUORE at Gran Sasso), including potential low-energy astrophysical neutrino (solar, supernova, geoneutrinos) detection. The incoming neutrino energy range adopted in our calculations (${\ensuremath{\varepsilon}}_{\ensuremath{\nu}}\ensuremath{\leqslant}100$ MeV) covers the low-energy $\ensuremath{\beta}$-beam neutrinos and the pion-muon stopped neutrino beams existing or planned to be conducted at future neutron spallation sources. The aim of these facilities is to measure neutrino-nucleus cross sections at low and intermediate neutrino energies with the hope of shedding light on open problems in neutrino-induced reactions on nuclei and neutrino astrophysics. Such probes motivate theoretical studies on weak responses of various nuclear systems; thus the evaluated cross sections may be useful in this direction.

Neutral current neutrino–98Mo reaction cross sections at low and intermediate energies

Inelastic neutrino–nucleus reaction cross sections at low and intermediate neutrino energies are studied. The required many-body nuclear wavefunctions are calculated in the context of a quasi-particle random phase approximation that uses realistic two-body forces. The results presented here refer to the differential, integrated and total cross sections of the neutral-current-induced reaction of νe with the 98Mo nucleus. Exploiting the obtained results, we investigate the response of this isotope as a supernova neutrino detector, assuming a two-parameter Fermi–Dirac distribution for the supernova neutrino energy spectra.

Paschos-Wolfenstein relation in a hadronic picture

The Paschos-Wolfenstein (PW) relation joins neutral- and charged-current neutrino- and antineutrino-induced cross sections into an expression that depends on the weak mixing angle $\mathrm{sin}{}^{2}{\ensuremath{\theta}}_{W}$. Contrary to the traditional approach with partonic degrees of freedom, we adopt a model built on hadronic degrees of freedom to perform a study of the PW relation at intermediate neutrino energies (100 MeV to 2 GeV). Running and upcoming high-statistics scattering experiments such as MiniBooNE, MINER\ensuremath{\nu}A, FINeSSE and beta-beam experiments make a scrutiny of the PW relation timely. Employing a relativistic Glauber nucleon knockout model for the description of quasielastic neutrino-nucleus reactions, the influence of nuclear effects on the PW relation is investigated. We discuss nuclear model dependences and show that the PW relation is a robust ratio, mitigating the effect of final-state interactions, for example, to the $1%$ level. The role played by a possible strangeness content of the nucleon is investigated. It appears that the uncertainties arising from the poorly known strangeness parameters and the difficulties in nuclear modeling seriously limit the applicability of the PW relation as an intermediate-energy electroweak precision tool. On the other hand, we show that nuclear effects may be sufficiently well under control to allow the extraction of new information on the axial strangeness parameter. Results are presented for $^{16}\mathrm{O}$ and $^{56}\mathrm{Fe}$.

LMA and sterile neutrinos: a case for resonance spin flavour precession

Open questions remain after the confirmation of LMA as the dominant solution to the solar neutrino deficit. These are the apparent time modulation of the solar neutrino event rates in the Homestake, Gallium and SuperKamiokande experiments, possibly related to solar magnetic activity, the discrepancy between the event rate in the Homestake experiment and its theoretical prediction and the absence of the electron spectrum upturn in SuperKamiokande at energies below 6-8 MeV. We search for a possible understanding of these questions in the context of resonant spin flavour precession to sterile neutrinos, assuming a class of magnetic field profiles anchored in the upper radiation/lower convection zone. We consider the simplest such model beyond the standard 2$\nu$ flavour LMA one, with one single magnetic moment transition between active and sterile state and vanishing vacuum mixing. The preferred mass square difference is $\Delta m^2_{10}=O(10^{-8}eV^2)$. The Ga rate appears to be the most sensitive of all to solar activity. It is also found that a field profile extending within a longer region in the radial direction is favoured over another with a shorter span, and leads to a stronger suppression than in the LMA case of the intermediate energy neutrinos and some of the $^8 B$ ones.

Neutrino–nucleus cross-section measurements at intense, pulsed spallation sources

There are several proposals to build facilities similar to the neutron spallation source (SNS) under construction at the Oak Ridge National Laboratory (ORNL). These are also prolific sources of intermediate energy neutrinos. We have used the parameters of the SNS to compute the spectra, flux and time structure of neutrinos from stopped-pions and muons from protons impinging on a high-Z target. We demonstrate the feasibility of a broad programme of measurements of neutrino–nucleus cross-sections, important in weak interaction nuclear physics and nuclear astrophysics that could be carried out at such facilities.

Approximate treatment of lepton distortion in charged-current neutrino scattering from nuclei

The partial-wave expansion used to treat the distortion of scattered electrons by the nuclear Coulomb field is simpler and considerably less time-consuming when applied to the production of muons and electrons by low- and intermediate-energy neutrinos. For angle-integrated cross sections, however, a modification of the {open_quotes}effective-momentum{close_quotes} approximation seems to work so well that for muons the full distorted-wave treatment is usually unnecessary, even at kinetic energies as low as 1 MeV and in nuclei as heavy as lead. The method does not work as well for electron production at low energies, but there a Fermi function often proves perfectly adequate. Scattering of electron neutrinos from muon decay on iodine and of atmospheric neutrinos on iron is discussed in light of these results. {copyright} {ital 1998} {ital The American Physical Society}

Neutrino magnetic moment upper bound from solar neutrino observations

Using the data from SuperKamiokande, Kamiokande and Homestake solar neutrino experiments we derive an upper bound on the magnetic moment of the neutrino and find $\mu_{\nu_e}\leq(2.2-2.3)\times 10^{-10}\mu_{B}$, within four different standard solar models. We assume equal magnetic moments for all neutrino flavours. This limit is obtained when neutrinos do not undergo any "disappearence" mechanism other than the magnetic moment conversion due to the solar magnetic field and for a total or nearly total suppression of the intermediate energy neutrinos. In our work we consider an energy dependent suppression of solar neutrinos. We also point out that the limit may be further reduced if the detector threshold energy in $\nu_{e,x}e^{-}$ scattering with solar neutrinos is decreased.

Coherent pion production in neutrino nucleus collision in the 1 GeV region

We calculate cross sections for coherent pion production in nuclei induced by neutrinos and antineutrinos of the electron and muon types. The analogies and differences between this process and the related ones of coherent pion production induced by photons or the $(p,n)$ and ${(}^{3}\mathrm{He},t)$ reactions are discussed. The process is one of the several ones occurring for intermediate energy neutrinos, to be considered when detecting atmospheric neutrinos. For this purpose the results shown here can be easily extrapolated to other energies and other nuclei.

The laser calibration monitor of the KARMEN scintillation calorimeter

Abstract The KARMEN (KArlsruhe Rutherford intermediate Energy Neutrino) experiment identifies and analyses nuclear reactions induced by ISIS beam-dump neutrinos in a segmented liquid scintillation detector. A pulsed laser beam, distributed and transformed through a network of light guides and scintillation light splitters, is used to monitor calorimetric and timing properties of the 512 central detector segments. This report describes the setup and applications of the laser calibration monitor at KARMEN. Data obtained with the laser system concern energy- and position resolutions, the linearity and offset of energy measurements, the correction of timing signals for energy-dependent walk effects, and the determination of absolute event times.

The Karmen Neutrino Experiment

The Karmen (Karlsruhe–Rutherford intermediate energy neutrino) experiment, conducted at the Isis spallation neutron facility, is designed to investigate fundamental properties of neutrinos and their interactions with matter. Low energy neutrinos with energies up to 50 MeV emitted by the Isis pulsed neutrino source are detected by a 56 t high resolution liquid scintillation calorimeter. Clear neutrino signatures allow a reliable search for neutrino oscillations of the type v μ → v e and v μ → v e as well as a detailed investigation of neutrino–nucleus interactions in an energy range important for astrophysics. Results from the first 3 years of the Karmen experiment are presented.

The Karmen Neutrino Experiment

The Karmen (Karlsruhe–Rutherford intermediate energy neutrino) experiment, conducted at the Isis spallation neutron facility, is designed to investigate fundamental properties of neutrinos and their interactions with matter. Low energy neutrinos with energies up to 50 MeV emitted by the Isis pulsed neutrino source are detected by a 56 t high resolution liquid scintillation calorimeter. Clear neutrino signatures allow a reliable search for neutrino oscillations of the type v μ → v e and v μ → v e as well as a detailed investigation of neutrino–nucleus interactions in an energy range important for astrophysics. Results from the first 3 years of the Karmen experiment are presented.

The role of low energy neutrinos in the solar neutrino problem

>We study the time variation of a solar neutrino in the light of spin-flavour precession. There seem to exist parameter regions that can explain the different time variation features of the solar neutrino flux in the Homestake and Kamiokande-II experiments. It is emphasized that the intermediate-energy neutrinos in these parameter regions play an important role in the results of the Homestake experiment.

A detector system for the study of intermediate energy neutrino interactions

A 15 t fine-grained neutrino detector and high efficiency anticoincidence system are in operation at the LAMPF beam stop, an intense source of neutrinos with a maximum energy of 53 MeV. The primary use of this equipment is in an experiment which is directed towards the observation and cross section measurement of the ν ee − elastic scattering reaction. The design, operation, and performance of the apparatus is reported.

The interaction of intermediate energy neutrinos with nuclei

Abstract The interaction of the electron neutrino with the nuclei 12 C, 16 O, 37 CL, 56 Fe, 71 Ga, and 81 Br is considered for neutrino energies up to 300 MeV. The nuclei are described by a single-particle shell model with a Woods-Saxon (WS) potential. The parameters of the potential are specially chosen for each nucleus in order to describe correctly the upper occupied single-particle levels of the nuclei. The cross sections for inelastic and elastic interactions of neutrinos with nuclei are calculated within this model, taking into account charged and neutral currents of the weak interaction. The neutral currents are described by the Weinberg theory. The results of the cross-section calculations are presented and comparisons with the results of other authors are given.

Neutrino (antineutrino) disintegration of the deuteron and the structure of the neutral weak current

We study the neutrino (antineutrino) disintegration of the deuteron with the view of determining the isospin and Lorentz character of the neutral weak current. Neutrino-induced transition rates between the $^{3}S\ensuremath{\rightarrow}^{1}S$, $^{3}S\ensuremath{\rightarrow}^{1}P$, and $^{3}S\ensuremath{\rightarrow}^{3}P$ of the neutron-proton system are derived for the most general form of the neutral weak current, valid up to intermediate neutrino energies (0-500 MeV). Explicit results are presented for the Weinberg-Salam model, the B\'eg-Zee model, and the case of an isoscalar neutral weak current. It is argued that this process can be, in principle, used to distinguish between the various assignments of the Lorentz and isospin properties of the hadronic neutral weak current.