Calculation Of Neutrino Fluxes Research Articles

Data-driven hadronic interaction model for atmospheric lepton flux calculations

The leading contribution to the uncertainties of atmospheric neutrino flux calculations arise from the cosmic-ray nucleon flux and the production cross sections of secondary particles in hadron-air interactions. The data-driven model developed in this work parametrizes particle yields from fixed-target accelerator data. The propagation of errors from the accelerator data to the inclusive muon and neutrino flux predictions results in smaller uncertainties than in previous estimates, and the description of atmospheric flux data is good. The model is implemented as part of the MCEq package, and hence can be flexibly employed for theoretical flux error estimation at neutrino telescopes.

Update of the atmospheric neutrino flux simulation ATMNC for next-generation neutrino experiment

Atmospheric neutrino flux calculation ATMNC has greatly contributed to the physics of neutrino experiments including Super-Kamiokande. Since next-generation large-scale experiments, such as Hyper-Kamiokande, are expected a large improvement of statistical errors, it is desirable to reduce systematic errors associated with uncertainty of the flux calculation. The dominant uncertainty of the ATMNC calculation arises from insufficient understanding of the hadron interactions inside air showers caused by cosmic rays. In order to improve the accuracy of the hadron interaction model, many precision measurements for hadron production using accelerator beams have been performed or planned. In this report, we discuss a strategy to update ATMNC calculation to reduce its uncertainty by incorporating such measurements.

Reduction of the uncertainty in the atmospheric neutrino flux prediction below 1 GeV using accurately measured atmospheric muon flux

We examine the uncertainty of the calculation of the atmospheric neutrino flux and present a way to reduce it using accurately measured atmospheric muon flux. Considering the difference of the hadronic interaction model and the real one as a variation of hadronic interaction, we find a quantitative estimation method for the error of the atmospheric neutrino flux calculation from the residual of the reconstruction of the atmospheric muon flux observed in a precision experiment, by the study of atmospheric neutrino and muon fluxes response to the variation of hadronic interaction. However, the efficiencty of this method is largely dependent on the observation site of the atmospheric muon flux, as the relation of the error of the atmospheric neutrino flux calculation and the residual of the reconstruction of the atmospheric muon flux is also largely dependent on the muon observation site, especially for the low energy neutrinos. We calculate several observation sites, near Kamioka at sea level, same but 2770m a.s.l.., Hanle India (4500m a.s.l.), and at Balloon altitude ($\sim$ 32km). Then we estimate how stringently can the atmospheric muon reduce the error in the calculation of the atmospheric neutrino flux. We also discuss on the source of error which is difficult to reduce by only the observation of atmospheric muon.

Production of Charmed Particles in the Quark-Gluon String Model and Estimate of Their Contributions to Atmospheric Neutrino Fluxes

An estimate of the flux of prompt atmospheric neutrinos produced in decays of charmed particles is obtained. Cross sections of the production of charmed particles (D, Λ c ) in pA and πA collisions are calculated in the quark-gluon string model (QGSM) for the energy range 1 TeV – 100 PeV. New data on the cross sections of charmed meson production at high energies, obtained in experiments at the Large Hadron Collider, make it possible to refine the values of the free parameters of the QGSM and obtain a preliminary estimate of the prompt atmospheric neutrino flux. A comparison is made with the results of other neutrino flux calculations carried out for other charm production models – the dipole model and SIBYLL 2.3rc1.

Revisiting the diffuse neutrino flux from the inner Galaxy using new constraints from very high energy [formula omitted]-ray observations

Following the MILAGRO collaborations recent publication of the detection of diffuse multi-TeV emission from a region close to the inner Galaxy, we revisit the diffuse neutrino flux calculation from this region. Conventional models following cosmic ray (CR) propagation through the Galaxy, tuned to reproduce the locally observed CR spectrum, give rise to diffuse fluxes that are significantly below the detected diffuse flux. Assuming that this excess is hadronic in origin and is representative of the whole inner Galactic region, we estimate the expected diffuse neutrino flux from a region of the Galactic disk with coordinates − 40 ∘ < l < 40 ∘ . The diffuse flux of neutrinos, for this hadronic only scenario, is found to be detectable by a km 3 -scale detector located in the northern hemisphere.

He3+He4→Be7astrophysicalSfactor

We present precision measurements of the $^{3}\mathrm{He}+^{4}\mathrm{He}$ $\ensuremath{\rightarrow}$ $^{7}\mathrm{Be}$ reaction in the range ${E}_{\mathrm{c}.\mathrm{m}.}=0.33$ to 1.23 MeV using a small gas cell and detection of both prompt \ensuremath{\gamma} rays and $^{7}\mathrm{Be}$ activity. Our prompt and activity measurements are in good agreement within the experimental uncertainty of several percent. We find $S(0)=0.595\ifmmode\pm\else\textpm\fi{}0.018$ keV b from fits of the Kajino theory to our data. We compare our results with published measurements, and we discuss the consequences for Big Bang Nucleosynthesis and for solar neutrino flux calculations.

Study of cosmic ray interaction model based on atmospheric muons for the neutrino flux calculation

We have studied the hadronic interaction for the calculation of the atmospheric neutrino flux by summarizing the accurately measured atmospheric muon flux data and comparing with simulations. We find the atmospheric muon and neutrino fluxes respond to errors in the $\ensuremath{\pi}$-production of the hadronic interaction similarly, and compare the atmospheric muon flux calculated using the HKKM04 [M. Honda, T. Kajita, K. Kasahara, and S. Midorikawa, Phys. Rev. D 70, 043008 (2004).] code with experimental measurements. The ${\ensuremath{\mu}}^{+}+{\ensuremath{\mu}}^{\ensuremath{-}}$ data show good agreement in the $1\ensuremath{\sim}30\text{ }\text{ }\mathrm{GeV}/c$ range, but a large disagreement above $30\text{ }\text{ }\mathrm{GeV}/c$. The ${\ensuremath{\mu}}^{+}/{\ensuremath{\mu}}^{\ensuremath{-}}$ ratio shows sizable differences at lower and higher momenta for opposite directions. As the disagreements are considered to be due to assumptions in the hadronic interaction model, we try to improve it phenomenologically based on the quark parton model. The improved interaction model reproduces the observed muon flux data well. The calculation of the atmospheric neutrino flux will be reported in the following paper [M. Honda et al., Phys. Rev. D 75, 043006 (2007).].

Simulation of neutrino and charged particle production and propagation in the atmosphere

A precise evaluation of the secondary particle production and propagation in the atmosphere is very important for the atmospheric neutrino oscillation studies. The issue is addressed with the extension of a previously developed full 3-dimensional Monte-Carlo simulation of particle generation and transport in the atmosphere, to compute the flux of secondary protons, muons, and neutrinos. Recent balloon borne experiments have performed a set of accurate flux measurements for different particle species at different altitudes in the atmosphere, which can be used to test the calculations for the atmospheric neutrino production, and constrain the underlying hadronic models. The simulation results are reported and compared with the latest flux measurements. It is shown that the level of precision reached by these experiments could be used to constrain the nuclear models used in the simulation. The implication of these results for the atmospheric neutrino flux calculation are discussed.

A simple model of reactor cores for reactor neutrino flux calculations for the KamLAND experiment

KamLAND is a reactor neutrino oscillation experiment with a very long baseline. This experiment successfully measured oscillation phenomena of reactor antineutrinos coming mainly from 53 reactors in Japan. In order to extract the results, it is necessary to accurately calculate time-dependent antineutrino spectra from all the reactors. A simple model of reactor cores and code implementing it were developed for this purpose. This paper describes the model of the reactor cores used in the KamLAND reactor analysis.

Status of global fits to neutrino oscillations

We review the present status of global analyses of neutrino oscillations, taking into account the most recent neutrino data including the latest KamLAND and K2K updates presented at Neutrino 2004, as well as state-of-the- art solar and atmospheric neutrino flux calculations. We give the two-neutrino solar + KamLAND results, and the two-neutrino atmospheric + K2K oscillation regions, discussing in each case the robustness of the oscillation interpretation against departures from the Standard Solar Model and the possible existence of non-standard neutrino physics. Furthermore, we give the best-fit values and allowed ranges of the three-flavour oscillation parameters from the current worlds' global neutrino data sample and discuss in detail the status of the small parameters α ≡ �m 2 /�m 2M as well as sin 2 θ13, which characterize the strength of CP violating effects in neutrino oscillations. We also update the degree of rejection of four-neutrino interpretations of the LSND evidence in view of the most recent developments.

Status of global fits to neutrino oscillations

We review the present status of global analyses of neutrino oscillations, taking into account the most recent neutrino data including the latest KamLAND and K2K updates presented at Neutrino 2004, as well as state-of-the-art solar and atmospheric neutrino flux calculations. We give the two-neutrino solar + KamLAND results, and the two-neutrino atmospheric + K2K oscillation regions, discussing in each case the robustness of the oscillation interpretation against departures from the Standard Solar Model and the possible existence of non-standard neutrino physics. Furthermore, we give the best-fit values and allowed ranges of the three-flavour oscillation parameters from the current worlds' global neutrino data sample and discuss in detail the status of the small parameters α ≡ ΔmSOL2/ΔmATM2 as well as sin2 θ13, which characterize the strength of CP violating effects in neutrino oscillations. We also update the degree of rejection of four-neutrino interpretations of the LSND evidence in view of the most recent developments.

The East-West effect of the muon charge ratio at energies relevant to the atmospheric neutrino anomaly

The charge ratio of atmospheric muons is rather sensitive to effects of the geomagnetic field and to the hadronic interaction. Experimental information about this quantity is very useful for tuning the ingredients of models used for calculations of atmospheric neutrino fluxes. For experimental observations, and in particular regarding the asymmetry in the charge ratio of muons from the east and West directions (East-West effect) a rotatable device has been installed in NIPNE-HH (National Institute of Physics and Nuclear Engineering — Horia Hulubei) Bucharest (44° 26'N, 26° 04' E, 85 m above sea-level at a vertical cut-off rigidity of 5.6 GV). The detector is mounted in a rotatable frame, consisting of a stack of 16 modules, 90 × 90 cm 2, formed by plastic scintillator layers (3 cm thick) and aluminum support (1.2 cm thick), surrounded by 4 lateral veto counters. The measurements are based on observation of the life time of muons stopped in the absorber layers of the detector. At a mean zenith angle of 35° the East West asymmetry in the ratio has been found to decrease from 0.25 to 0.20, in the momentum range 0.35 – 0.50 GeV/c.

The FLUKA atmospheric neutrino flux calculation

The 3-dimensional (3-D) calculation of the atmospheric neutrino flux by means of the FLUKA Monte Carlo model is here described in all details, starting from the latest data on primary cosmic ray spectra. The importance of a 3-D calculation and of its consequences have been already debated in a previous paper. Here instead the focus is on the absolute flux. We stress the relevant aspects of the hadronic interaction model of FLUKA in the atmospheric neutrino flux calculation. This model is constructed and maintained so to provide a high degree of accuracy in the description of particle production. The accuracy achieved in the comparison with data from accelerators and cross-checked with data on particle production in atmosphere certifies the reliability of shower calculation in atmosphere. The results presented here can be already used for analysis by current experiments on atmospheric neutrinos. However, they represent an intermediate step towards a final release, since this calculation does not yet include the bending of charged particles in atmosphere. On the other hand this last aspect, while requiring a considerable effort in a fully 3-D description of the Earth, if a high level of accuracy has to be maintained, does not affect in a significant way the analysis of atmospheric neutrino events.

Determination of neutrino oscillation parameters with atmospheric neutrinos

Fully contained events(F.C.), partially contained events(P.C.) and upward going μ events generated by the interactions for atmospheric neutrinos are measured and analyzed in Super-Kamiokande. The zenith angle distributions of all atmospheric neutrino events strongly suggest the neutrino oscillation. The SK-1 data are consistent with ν μ — ν τ oscillation with Δm 2=1.6–3.9×10 −3eV 2 and sin 22θ ≥ 0.92 at 90% C.L. The Super-Kamiokande oscillation analysis is robust to the uncertainty of the atmospheric neutrino flux calculations and the neutrino interaction cross sections. The zenith angle distributions which are used for ν μ — ν τ oscillation analysis are also consistent with ν μ — ν s oscillation. However, high-energy P.C., upward through going μ events and NC-enrich multi-ring events disfavor ν μ — ν s oscillation hypothesis at 99% C.L. The ν μ — ν s oscillation analysis will be improved by K2K π 0 study.

Atmospheric gamma-ray observation with the BETS detector for calibrating atmospheric neutrino flux calculations

We observed atmospheric gamma-rays around 10 GeV at balloon altitudes (15~25 km) and at a mountain (2770 m a.s.l). The observed results were compared with Monte Carlo calculations to find that an interaction model (Lund Fritiof1.6) used in an old neutrino flux calculation was not good enough for describing the observed values. In stead, we found that two other nuclear interaction models, Lund Fritiof7.02 and dpmjet3.03, gave much better agreement with the observations. Our data will serve for examining nuclear interaction models and for deriving a reliable absolute atmospheric neutrino flux in the GeV region.

Comparison of the FLUKA calculations with CAPRICE94 data on muons in atmosphere

In order to benchmark the three-dimensional calculation of the atmospheric neutrino flux based on the FLUKA Monte Carlo code, muon fluxes in the atmosphere have been computed and compared with data taken by the CAPRICE94 experiment at ground level and at different altitudes in the atmosphere. For this purpose only two additions have been introduced with respect to the neutrino flux calculation: the specific solar modulation corresponding to the period of data taking and the bending of charged particles in the atmosphere. Results are in good agreement with experimental data, although improvements in the model are possible. At this level, however, it is not possible to disentangle the interplay between the primary flux and the interaction model.

Calculation of atmospheric neutrino flux

A calculation of the fluxes of primary particles arriving to the Earth's vicinity as well as those produced in the interactions of the primaries with the atmosphere is presented. The result of calculations is compared with the experimental data obtained with the Alpha Magnetic Spectrometer (AMS). A good agreement of calculated and measured fluxes of charged particles supports the viability of the atmospheric neutrino flux calculation.

Electromagnetic dissociation of8Band the rate of the7Be(p,γ)8Breaction in the Sun

In an effort to better determine the Be-7(p, gamma)B-8 reaction rate, we have performed inclusive and exclusive measurements of the Coulomb dissociation of B-8. The former was a study of longitudinal momentum distributions of Be-7 fragments emitted in the Coulomb breakup of intermediate energy B-8 beams on Pb and Ag targets. Analysis of these data yielded the E2 contribution to the breakup cross section. In the exclusive measurement. we determined the cross section for the Coulomb breakup of B-8 on Pb at low relative energies in order to infer the astrophysical S factor for the Be-7(p, gamma)B-8 reaction. Interpreting the measurements with first-order perturbation theory, we obtained S-E2/S-E1 = 4.7(-1.3)(+2.0) x 10(-4) at E-rel = 0.6 MeV, and S-17(0) =17.8(-1.2)(+1.4) eV b. Semiclassical first-order perturbation theory and fully quantum mechanical continuum-discretized coupled channels analyses yield nearly identical results for the El strength relevant to solar neutrino flux calculations, suggesting that theoretical reaction mechanism uncertainties need not limit the precision of Coulomb breakup determinations of the Be-7(p, gamma)B-8 S factor. A recommended value of S-17(0) based on a weighted average of this and other measurements is presented.

On particle production for high energy neutrino beams

Analytical formulae for the calculation of secondary particle yields in p-A interactions are given. These formulae can be of great practical importance for fast calculations of neutrino fluxes and for designing new neutrino beam-lines. The formulae are based on a parameterization of the inclusive invariant cross sections for secondary particle production measured in p-Be interactions. Data collected in different energy ranges and kinematic regions are used. The accuracy of the fit to the data with the empirical formulae adopted is within the experimental uncertainties. Prescriptions to extrapolate this parameterization to finite targets and to targets of different materials are given. The results obtained are then used as an input for the simulation of neutrino beams. We show that our approach describes well the main characteristics of measured neutrino spectra at CERN. Thus it may be used in fast simulations aiming at the optimisation of the proposed long-baseline neutrino beams at CERN and FNAL. In particular we will show our predictions for the CNGS beam from CERN to Gran Sasso.

Measurements of the charge ratio of atmospheric muons in the range 0.2 – 1.0 GeV/c by observing the decay electrons from muonic atoms

The method of measuring precisely the different life times of negative and positive muons when stopped in matter, realised with the compact scintillator detector setup WILLI in the NIPNE-HH Bucharest, has been used to study the charge ratio of atmospheric muons. The results in the examined low energy range are relevant for recent investigations of atmospheric neutrinos and can be applied to verify calculations of atmospheric neutrino fluxes and the hadronic interaction models, used as generators in Monte Carlo simulations.