[en] The NEMO collaboration team has undertaken a Phase-2 project, which aims at the realization and installation of a new infrastructure at the Capo Passero (Italy) deep-sea site at a depth of 3500 m. With this objective in mind, a fully equipped tower with 8-storey hosting two optical modules at each end is under construction. Following a well established procedure, 32 optical modules have been assembled. The optical module consists of a large area photomultiplier tube enclosed in a pressure resistant glass sphere with a diameter of 13 in. The photomultiplier is a R7081 type, produced by Hamamatsu, with a photocathode area with a diameter of 10 in. and 10 dynodes. Mechanical and optical contacts between the front of the photomultiplier tube and the glass surface are ensured by an optical bi-component silicone gel. A mu-metal cage is used to shield the photomultiplier against the influence of the Earth's magnetic field

No abstract available

[en] This volume contains the Proceedings of the 8. GIFCO Symposium, which was held in Como (Italy) from April 8. to 10. 1997. The Proceedings are introduced by two general lectures. The first of these highlights the x-ray astronomy satellite Beppo-SAX (named after Beppo Occhialini, President of GIFCO for many years), the success of which is due also to GIFCO researches. The second one presents the research activity in Cosmic Ray Physics in Milan between 1940 and 1960, well before the birth of GIFCO. The remaining invited lectures and contributions, grouped in four sections, namely a) High Energy Astrophysics (with special attention to Beppo-SAX results, b) Sun/Earth Relationship and the Interplanetary Medium (with special attention to observations from Antarctica, c) Cosmic Dust and Interstellar Matter, d) Cosmic Ray Physics, show the extent of GIFCO's present research activities. The Symposium was a national one; therefore, the oral presentations were mainly in Italian. The Proceedings, however, are written in English, to make the results available to the larger international astrophysical community, with which GIFCO people are used to work

[en] The temperature of graphite grains in the interstellar medium has been computed with different assumptions on the extrapolation of its optical constants into infrared. It is found that values computed up to now are generally underestimated by 10-20% in normal interstellar conditions. For extreme conditions (very dark clouds) errors by a factor of two are possible and more attention has to be paid in dealing with problems related to molecule formation. (Auth.)

[en] Short communication

No abstract available

[en] Energy correlation measurements were performed for the photofission of ²³⁸U with 100, 140, 180, 200, 230 and 260 MeV bremsstrahlung photons using silicon surface barrier detectors. Overall fragment mass and energy distributions were deduced. The behaviour of the total fragment yield and kinetic energy and average total kinetic energy as a function of the fragment mass and of the bremsstrahlung maximum energy were studied. The symmetric fission contribution was extracted from the contour plot of the two-dimensional E₁-E₂ array giving an identification without any constraint on the variance of the distribution itself. The symmetric-to-asymmetric fission yield ratio Y_S/Y_a was studied as a function of the end-point bremsstrahlung energy. The results were compared with all the relevant data on the ²³⁸U photofission and interpreted in terms of the two-component picture of the fission process of Fairhall et al

[en] Due to screening by dust particles, the UV radiation field of interstellar origin is practically inexistent within very dense interstellar clouds. However, it appears possible that the cosmic-ray excitation of the Lyman and Werner systems of the hydrogen molecule could originate a chemically-significant flux of UV photons even within such dense clouds. Computations of photon fluxes were carried out for two different models of radial density distribution inside the cloud (gas and dust densities were assumed to have the same density distribution). The result strongly support the suggestion that the low energy cosmic rays may generate inside dense interstellar clouds UV radiation fields that may significantly contribute to the gas and dust evolution

[en] Researchers considered the effect of extensive forces on dust grains subjected to the light and matter distribution of a spiral galaxy Greenberg et al. (1987), Ferrini et al. (1987), Barsella et al (1988). Researchers showed that the combined force on a small particle located above the plane of a galactic disk may be either attractive or repulsive depending on a variety of parameters. They found, for example, that graphite grains from 20 nm to 250 nm radius are expelled from a typical galaxy, while silicates and other forms of dielectrics, after initial expulsion, may settle in potential minimum within the halo. They discuss only the statistical behavior of the forces for 17 galaxies whose luminosity and matter distribution in the disk, bulge and halo components are reasonably well known. The preliminary results of the study of the motion of a dust grain for NGC 3198 are given

[en] The light response of large CsI(Tl) crystals supplied by various companies and coupled to photodiodes has been investigated. Energy resolution measurements and Z=1 isotopic identification using the two gates method have been performed with in-beam experiments. (orig.)