16327532
Radiation-hard photodetectors based on fine-mesh phototubes for calorimetry in very forward rapidity
Abstract This paper presents results of a study of a very radiation-hard photodetector—a high-gain fine-mesh PMT with a highly radiation-hard faceplate made of UV-transparent glass. Radiation resistance of these PMTs to gamma rays and neutrons was investigated at the PNPI gamma facility and nuclear reactor with neutron fluences of up to 10 16 n / cm 2 at 0.95 MeV and gamma ray doses of 20–50 kGy with excellent results. Measurements of insensitivity to magnetic fields and immunity of the PMT against helium at levels expected in the LHC environment are also presented.
119211412
Electron Capture in a Fully Ionized Plasma
Properties of fully ionized water plasmas are discussed including plasma charge density oscillations and the screening of the Coulomb law especially in the dilute classical Debye regime. A kinetic model with two charged particle scattering events determines the transition rate per unit time for electron capture by a nucleus with the resulting nuclear transmutations. Two corrections to the recent Maiani et al. calculations are made: (i) The Debye screening length is only employed within its proper domain of validity. (ii) The WKB approximation employed by Maiani in the long De Broglie wave length limit is evidently invalid. We replace this incorrect approximation with mathematically rigorous Calogero inequalities in order to discuss the scattering wave functions. Having made these corrections, we find a verification for our previous results based on condensed matter electro-weak quantum field theory for nuclear transmutations in chemical batteries.
119376204
Extragalactic sources for ultrahigh energy cosmic ray nuclei
In this article we examine the hypothesis that the highest energy cosmic rays are complex nuclei from extragalactic sources. Under reasonable physical assumptions, we show that the nearby metally rich starburst galaxies (M82 and NGC 253) can produce all the events observed above the ankle. This requires diffusion of particles below ${10}^{20} \mathrm{eV}$ in extragalactic magnetic fields $B\ensuremath{\approx}15 \mathrm{nG}.$ Above ${10}^{19} \mathrm{eV},$ the model predicts the presence of significant fluxes of medium mass and heavy nuclei with small rate of change of composition. Notwithstanding, the most salient feature of the starburst-hypothesis is a slight anisotropy induced by iron debris just before the spectrum cutoff.
122685808
Opacity of the microwave background radiation to ultrahigh energy cosmic rays
In this work we re-examine the influence of the microwave background radiation on the propagation of extremely high energy cosmic rays. We present a recalculation of the rate of fractional energy loss in the continuous energy loss approximation including the effects of resonances other than the Δ. We also discuss the distortion of the cosmic ray spectrum due to interactions with the relic photons.
14956820
A pot of gold at the end of the cosmic “raynbow”?
Abstract We critically review the common belief that ultrahigh energy cosmic rays are protons or atomic nuclei with masses not exceeding that of iron. We find that heavier nuclei are indeed possible, and discuss possible sources and acceleration mechanisms for such primaries. We also show detailed simulations of extensive air showers produced by “superheavy” nuclei, and discuss prospects for their detection in future experiments.
122969664
Radiation damage studies of multipixel geiger-mode avalanche photodiodes
Abstract Results on the radiation hardness of multipixel Geiger-mode avalanche photodiodes (G-APDs) are presented. Recently developed G-APDs from three manufacturers (Hamamatsu (Japan), CPTA(Russia) and Mikron/Dubna(Russia)) were exposed to 28 MeV positrons with fluences up to 8 × 10 10 positrons / cm 2 at the Paul Scherrer Institute. The effects of this radiation on many G-APD parameters such as gain, photon detection efficiency, dark current and count rate for these devices are shown and discussed.
122452337
THE PLUNGING MAGNET SYSTEM FOR THE NIMROD EXTRACTED PROTON BEAM
117183644
FEASIBILITY STUDY OF A 15- TO 70-Mev SEPARATED-ORBIT CYCLOTRON AS A BOOSTER INJECTOR