[en] Short communication

No abstract available

[en] It is known that the efficiency of a detector epsilon(x) is connected to the escape function P(x) by the relation epsilon(x) = xP(x). In this paper, a specific detector is considered (3'' x 3'' NaI), and the results obtained are compared with previously results. (orig.)

[en] Stopping muons were investigated at a depth of 850 gg/cm^-₂ by means of the Baksan underground scintillation telescope. Mean lifetime of a nuon obtained from the decays recorded constitutes 2.14+-0.14 μs. For muons of atmospheric origin determined was the ratio of the muon quantity stopping in 100 gxcm^-₂ thick layer of a standard ground and the number of muons passing through this layer Rsub(atm)=(2.5+-0.1)x1a^-₃. For locally produced muons Rsub(l.p.)=(0.8+-0.1)x10^-₃. The results obtained agree well enough with theoretical predictions

[en] Edge penetration through a collimator system by radiation emitted from either a point or an extended source is studied, using the small angle approximation. Extremely accurate formulas are drived for calculating the penetration fluence. We find that the ratio of the penetrated fluence to the unimpeded fluence has a remarkably simple form; its leading term is independent of both the length and the radius of the collimator. Furthermore, the same results are applicable to a point source as well as an extended source, for a wide class of aperture shapes the collimator may take. We have also derived the formulas to computed the edge penetration at the near end of the collimator, which occurs when the distance from the source to the collimator axis exceeds the collimator radius. The accuracy of our results has been checked by Monte Carlo calculations for both neutron and gamma-ray radiations. We found excellent agreement between the analytical and numerical results. (orig.)

[en] The absolute intensity of vertical cosmic ray muons at sea level with momentum above 0.32 - 1.78 GeV/c at a geomagnetic latitude 25.5⁰N have been carefully measured by means of a narrow angle proportional counter telescope, which can distinguish a passage of penetrating muon. The present spectrum after being corrected scattering, proton contribution and geomagnetic latitude effect, has been compared with the some other spectrum. Our results are in good agreement with Allkofer et al's result. The differential and integral intensity have been found to be (7.30+-0.17)x10^-3/cm² s sr and (3.02+-0.17)x10^-3/cm² s sr (GeV/c), at momentum 1 GeV/c, respectively

[en] The MACRO detector, located in the underground Gran Sasso Laboratory, had its initial data run from February 27 to May 30, 1989, using the first supermodule (SΩ ≅ 800 m² sr). Approximately 245000 muon events were recorded. Here are reported the results of the analysis of penetrating muons which determine the measured vertical muon flux at depths greater than 3000 m.w.e. In addition the data have been used to search for large scale anisotropies. (orig.)

No abstract available

[en] New measurements of the radiative flux deficits of two large sunspots are presented, based on detailed isophotometric maps. Results are given separately for umbrae and penumbrae. The umbral and penumbral deficits are 4-5 x 10¹⁰ and 1-1.5 x 10¹⁰ erg cm^-2s^-1 respectively, the larger figures referring to the larger spot. Over limited areas centered on the umbral cores the deficits for the two spots amount to 76 and 86% of the photospheric flux. (orig.)

[en] A generalized nodal finite element formalism is presented, which englobes virtually all known finite difference approximations to the discrete-ordinates equations in slab geometry. Corresponding numerical results are available, in the unaccelerated as well as in the accelerated case, where a mixed-hybrid implementation of the diffusion synthetic acceleration method is proposed