Vadim A. Naumov

Atmospheric muon flux at sea level, underground, and underwater

The vertical sea-level muon spectrum at energies above 1 GeV and the muon intensities at depths up to 18 km w.e. in different rocks and in water are calculated. The results are particularly collated with a great body of the ground-level, underground, and underwater muon data. In the hadron-cascade calculations, we take into account the logarithmic growth with energy of inelastic cross sections and pion, kaon, and nucleon generation in pion-nucleus collisions. For evaluating the prompt-muon contribution to the muon flux, we apply the two phenomenological approaches to the charm production problem: the recombination quark-parton model and the quark-gluon string model. To solve the muon transport equation at large depths of a homogeneous medium, we used a semianalytical method, which allows the inclusion of an arbitrary ~decreasing! muon spectrum at the medium boundary and real energy dependence of both continuous and discrete muon energy losses. The method is checked for accuracy by direct Monte Carlo calculation. Whenever possible, we give simple fitting formulas describing our numerical results. @S0556-2821~98!00313-0# PACS number~s!: 13.85.Tp, 96.40.Tv

On the interpretation of the KAMIOKANDE neutrino experiment

Abstract The comparison between the KAMIOKANDE data and theoretical estimations of the low-energy ( E ν of ν e ↔ ν μ - type predominantly ), or by misidentifying the particle species of single-ring events.

Atmospheric neutrino flux supported by recent muon experiments

We present a new one-dimensional calculation of low and intermediate energy atmospheric muon and neutrino fluxes, using up-to-date data on primary cosmic rays and hadronic interactions. We study several sources of uncertainties relevant to our calculations. A comparison with the muon fluxes and charge ratios measured in several modern balloon-borne experiments suggests that the atmospheric neutrino flux is essentially lower than one used for the standard analyses of the sub-GeV and multi-GeV neutrino induced events in underground detectors.

Neutrino propagation through dense matter

Abstract We propose a simple approach to solving the transport equation for high-energy neutrinos in dense and thick media. Illustrative results obtained from some specific models for the initial spectra of muon neutrinos and antineutrinos propagating through a normal cold medium are presented.

Berry phases for three-neutrino oscillations in matter

Abstract We show that nontrivial Berry phase factors can arise in the evolution operator of the standard, three-flavor-neutrino system when a neutrino beam propagates through a medium whose parameters - number densities of scatterers - vary cyclically with distance. The conditions are established whereby the Berry phases take their extreme (resonance) values independently of the density distribution in the background. This universal “geometric” resonance is capable to change drastically the survival and transition probabilities for neutrinos in matter.

High-energy neutrino oscillations in absorbing matter

The impact of neutrino mixing, refraction and absorption on high-energy neutrino propagation through a thick medium is studied using the MSW evolution equation with complex indices of refraction. It is found that, owing to the mixing with sterile neutrinos, the penetrability of active neutrinos may be many orders of magnitude larger than it would be in the absence of mixing. The effect is highly sensitive to changes in density and composition of the matter background as well as to neutrino energy and mixing parameters. This may lead to observational consequences in neutrino astrophysics.

Simple method for solving transport equations describing the propagation of cosmic ray nucleons in the atmosphere

A simple and efficient method is proposed for solving transport equations that describe the propagation of cosmic-ray protons and neutrons in the atmosphere at high energies. It is shown that, upon taking into account a non-power-law character of the primary spectrum, a growth of total cross sections for inelastic nucleon-nucleus interactions, and violation of scaling in such interactions, the effective absorption ranges of nucleons come to be dependent not only on energy but also on the depth in the atmosphere. The results of the calculations are compared with available experimental data.

Potential of deep-underwater neutrino telescopes for recording muons from charm decay

Within several models of charm production in hadron-nucleus interactions, it is shown that prompt-muon fluxes at the depths of operating and designed neutrino telescopes (1–4 km) can in principle be measured in experiments with a high detection threshold.

Flux limits for relativistic cosmic photinos from the KAMIOKANDE neutrino experiment

Abstract The cross-sections of massive photino scattering on electron and nucleon are calculated. The flux limits of the cosmic-origin relativistic photinos for different values of photino and scalar fermion masses are obtained on the basis of underground KAMIOKANDE experiment and computation of neutrino event numbers in the detector.