Calculation of atmospheric neutrino fluxes

Abstract

The atmospheric neutrino fluxes at the Kamioka site are calculated semianalytically. We investigate the dependence of various physical parameters on the resultant fluxes. Both the absolute value of the fluxes and the (v, +V, )/(v,+V,) ratio agree with those of the previous calculation. In particular, it is found that the (v, + V , )/(v,+V,) ratio is almost independent of the method or the details of calculation.

Effects for atmospheric neutrino experiments from electron neutrino oscillations

“…The results of these experiments are usually expressed in terms of the quantity R, where R ≡ (n µ /n e ) data (n µ /n e ) M C (1) and n µ and n e are the numbers of ν µ and ν e induced events respectively. The ratio (n µ /n e ) M C is obtained from Monte Carlo simulated events based on theoretical calculations of the fluxes [6]. The experimental results are summarized in Table 1 for the low energy (sub GeV) data.…”

“…Note that equal number densities for electrons and protons has been assumed in Eq. (6). For neutrino propagation through the Earth, N e = N p ≃ N n where N p is the number density of protons.…”

Selected Experimental Results from Neutrino Physics

“…4p+2e·~4He+2v.+27MeV (12) where 27 Me V is the difference of the masses between the particles involved in the initial state and those involved in the final state (the energy of the neutrinos and the kinetic energy of the nuclei can be neglected in this approximate relation). It is then easy to derive the total flux of neutrinos expected to reach the earth : Nv = 2 L = 6.5 10 10 cm-2 s· 1 (13) 27 MeV 41t d2…”

“…Starting from primary cosmic ray fluxes, their interactions on nitrogen and oxygen nuclei, and the propagation of the decay pions and muons in the atmosphere, many groups ( [5] to [12]) have calculated the fluxes of v 11 and v. reaching the earth, taking into account the geomagnetic effects and the rime dependent solar activity. The results may be summarised as follows: a) Mainly due to uncertainties on cosmic primary flux and composition, the total neutrino flux is known to about 20% at low energy ($10GeV) and to 30% at high energy (~ 10 GeV).…”

Energy spectra, altitude profiles, and charge ratios of atmospheric muons

“…Model predictions [2][3][4][5][6] of the absolute flux of neutrinos produced in air showers are uncertain due to a number of difficulties: one problem is the normalization of the primary cosmic-ray flux, for which measurements vary by ±15% or more. Because of this, different assumptions are made by different authors.…”