[en] Ultra-high energy cosmic neutrinos are versatile probes of astrophysics, astronomy, and particle physics. They represent the messengers of hadronic processes in cosmic accelerators and survive the propagation through the interstellar medium practically unscathed. We investigate the neutrino fluxes associated with optically thin proton sources which provide a diagnostic of the transition between galactic and extragalactic cosmic rays. The center of mass energies in collisions of these cosmic neutrinos with atomic nuclei in the atmosphere or the Earth's interior easily exceed those so far reached in man-made accelerators. We discuss the prospects of observing supersymmetric neutrino interactions with Cherenkov telescopes and speculate about a neutrino component in extremely high energy cosmic rays from exotic interactions in the atmosphere. (orig.)

[en] In R-parity conserving supersymmetric (SUSY) models the lightest SUSY particle (LSP) is stable and a candidate for dark matter. Depending on the coupling and mass of this particle the life time of the next-to-lightest SUSY particle (NLSP) may be large compared to experimental time scales. In particular, if the NLSP is a charged particle and its decay length is of the order of the Earth's diameter Cherenkov telescopes might observe parallel muon-like tracks of NLSP pairs produced in neutrino-nucleon interactions in the Earth's interior. We have investigated two SUSY scenarios with a long-lived τ NLSP and a gravitino LSP in view of the observability at the IceCube detector. (orig.)

[en] The stability of the martensite is controlled by the electron concentration and by the electronegativity, which is described in terms of pair interchange energies. Although the contribution of the conduction electrons determines the difference in stability between the disordered equilibrium face centred cubic and body centred cubic phases at elevated temperatures, they are only partly responsible for the enthalpy difference between the β phase matrix and the martensite. For a quantitative evaluation of the martensitic transformation it is therefore necessary to have also information on the differences in electronegativity, which control a large fraction of the enthalpy of mixing of the disordered phases, and contribute to the changes from long-range ordering. Long-range ordering takes place generally at lower temperatures in the β phase matrix, and is inherited in the martensite after the diffusionless transformation. The aim of this paper is to derive pair interchange energies that permit to describe quantitatively the martensitic transformation in noble metal alloys. As their prototypes the binary Cu-Zn, Cu-Al and ternary Cu-Zn-Al alloys are analysed in detail, because most information is available for them. It will be shown that for the quantitative description of the enthalpy of formation of the martensite and of the equilibrium phases, pair interchange energies are required which include important contributions also from more distant than first and second nearest neighbour pairs. However, the difference in enthalpy of formation between the martensite and the high temperature β phase can be well described by composition independent nearest and next nearest neighbour pair interchange energies alone

[en] The spectrum of extra-galactic cosmic rays (CRs) is expected to follow the Greisen-Zatsepin-Kuzmin (GZK) cutoff at about 5 x 10¹⁰ GeV which results from energy losses of charged nuclei in the cosmic microwave background. So far the confrontation of this feature with CR data is inconclusive. In the absence of close-by sources a power-law continuation of the spectrum might signal the contribution of new physics. We have investigated the statistical significance of a model where exotic interactions of cosmogenic neutrinos are the origin of super-GZK events. A strong neutrino-nucleon interaction is favored by CR data, even if we account for a systematic shift in energy calibration. (orig.)

[en] The changes in Gibbs energy were evaluated for the atomic configurations resulting after different diffusional processes, in order to detect the mechanisms that are responsible for stabilisation and rubber-like behaviour. The energies and the proposed atom interchanges were compared with the experimental evidence. The influence of the changes in short- and long-range order was evaluated in the binary and ternary Cu-based alloys

[en] The relevant aspects of martensite stabilization and ferroelasticity in Cu-Zn and Cu-Zn-Al alloys have been described. The need of a thermodynamic driving force, as also of appropriate vacancy diffusion paths to produce both phenomena has been emphasized

[en] The stabilisation of the 18R stress induced martensite in Cu-Zn-Al single crystals has been measured as a function of the ageing time and the previous thermal treatment in the high temperature β phase. It is found that the initial and final stages of the stabilisation present a different behavior, and only the latter is related to the quenched-in vacancy concentration. It is confirmed that the martensite does not reach its thermodynamical equilibrium state, although the vacancies remain mobile. It is suggested that the evolution of the martensite can be rationalised by the combined action of mobile vacancies and precursors of the γ equilibrium phase

[en] The origin and chemical composition of ultra high energy cosmic rays is still an open question in astroparticle physics. The observed large-scale isotropy and also direct composition measurements can be interpreted as an extragalactic proton dominance above the ankle at about 10¹⁰ GeV. Photopion production of extragalactic protons in the cosmic microwave background predicts a cutoff at about 5 x 10¹⁰ GeV in conflict with excesses reported by some experiments. In this report we outline a recent statistical analysis of cosmic ray data using strongly interacting neutrinos as primaries for these excesses. (orig.)

[en] We point out that chameleon field theories might reveal themselves as an ''afterglow'' effect in axion-like particle search experiments due to chameleon-photon conversion in a magnetic field. We estimate the parameter space which is accessible by currently available technology and find that afterglow experiments could constrain this parameter space in a way complementary to gravitational and Casimir force experiments.In addition, one could reach photon-chameleon couplings which are beyond the sensitivity of common laser polarization experiments. We also sketch the idea of a Fabry-Perot cavity with chameleons which could increase the experimental sensitivity significantly. (orig.)

[en] The Cu-Zn-Al alloys present an equilibrium phase diagram whose copper rich zone is basically governed by the e/a electronic concentration and by the temperature. In a range of compositions with an e/a of around 1.48 and at elevated temperatures the β phase (cubic centered in the body) is stable and can be retained in a metastable form if it is rapidly cooled. In the specific case of the alloy studied in this work (with e/a=1.53), tempering in water at room temperature from 800^oC is necessary to avoid decomposition in the equilibrium phases. Based on the phase β thus obtained martensitic transformations can be induced in other metastable phases, as for example the hexagonal 2H martensite. This work studied the transformation of the monocrystalline 2H martensite into other phases by means of calorimetry, beginning with 2H martensite at different degrees of stability, obtained by aging with different applied loads. The martensite did not decompose in equilibrium phases but first retransformed to phase β. If the 2H martensite is not very stabilized two transformations are observed, one at phase β around 100^oC and another at the decomposition of phase β, which begins at 260^oC (at a heating speed of 1^oC/min). If very stabilized both transformations are displaced at temperatures above 320^oC. The study includes the influence of the heating speed on the temperature of decomposition (CW)