Results 1 - 10 of 496348
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[en] Generic shielding criteria have been employed at Fermilab to determine the shielding adequacy and to screen for areas which require more detailed analysis of beam loss events and are based on the calculations reported in technical report TM-1140. The calculations in that report were done 30 years ago using CASIM, a Monte Carlo program. CASIM uses the Hagedorn-Ranft to model inclusively hadronic interactions. It is valid in the energy range of 10 GeV to 20 TeV and has a lower momentum threshold of 300 MeV/c (47 MeV kinetic energy for nucleons). The goal of this study is to update the original soil shielding calculation with those estimated from the MARS code, which has a more robust and detailed physics model. Hadron-nuclear interactions are simulated with a combination of the modern theoretical models (CEM and LAQGSM) and up-to-date phenomenological models. All other processes of particle interactions with matter are described in MARS on the basis of the modern models and algorithms. MARS is valid for hadrons, leptons, photons and heavy ions with kinetic energy less than 100 TeV and greater than 1 keV (greater than 0.0215 eV for neutrons).
[en] A novel toggled flip-flop (TFF) divide-by-two circuit (DTC) and its optimization method based on a large-signal analysis approach are proposed. By reducing the output RC constant in tracking mode and making it large in latching mode, compressing the internal signal swing as well as compensating the current leaked in the latching mode, the operating frequency range is greatly expanded. Implemented in a SMIC 0.13 μm RF CMOS process with a 1.2 V power supply, it can work under an ultra-wide frequency band ranging from 320 MHz to 29.6 GHz. Experimental results show that two phase-locked loops (PLLs) with the proposed DTC can achieve in-band phase noise of -94 dBc/Hz - 10 kHz under 4224 MHz operating frequency and -84 dBc/Hz - 10 kHz under 10 GHz operating frequency, respectively. The power consumption of the proposed DTC is reduced by almost 50% compared with the conventional counterparts.
[en] By virtue of the normalisation of the curves giving the electron transmission coefficient for amorphous or polycrystalline targets, the electron range is obtained as a function of cross-section. The relation proposed depends only on the incident electron energy and the atomic number of the element used; we have verified the correctness of this relation for incident electron energies ranging from 30 keV to 3 MeV
[fr]En se basant sur la normalisation des courbes donnant les coefficients de transmission des electrons par des echantillons amorphes ou polycristallins, nous obtenons le parcours entier des electrons dans la matiere a partir de l'expression de la section efficace d'interaction. La relation ainsi proposee ne depend que de l'energie des electrons incidents et du numero atomique de l'element considere; nous avons pu la verifier pour des energies des electrons incidents allant de 30 keV a 3 MeV
[en] A brief introduction to High Energy Cosmic Ray Astronomy is presented. This field covers a 17 decade energy range (2.104-1020) eV. Recent discoveries done with gamma-ray detectors on-board satellites and ground-based Cherenkov devices are pushing for a fast development of new and innovative techniques, specially in the low energy region which includes the overlapping of satellite and ground-based measurements in the yet unexplored energy range 20 keV-250 GeV. Detection of unexpected extremely high energy events have triggered the interest of the international scientific community. (orig.)
[en] This report describes a computer program (developed for analysis of Bevalac data) that calculates stopping power, range, or energy, and which includes the necessary corrections for accuracy in the high Z1, β regime, as discussed in the theoretical and review papers of S.P. Ahlen. The program is also available on PSS at LBL's Computer Center
[en] SS433 is a Galactic microquasar with powerful jets, where very-high-energy particles are produced. We study particle acceleration in the jets of SS433 through the use of recent multiwavelength data from radio to TeV gamma-ray. We first present a general framework for the particle acceleration, cooling, and transport in relativistic jets. We then apply this to two X-ray knots in the jets of SS433, focusing on leptonic emission. Our detailed treatment of particle transport and evolution produces substantially different predictions from previous papers. For both regions, our model can account for the multiwavelength data except for the GeV data. This suggests that GeV emission is mostly from different regions and/or mechanisms. We find that the acceleration process should be efficient, which could be realized by diffusive shock acceleration close to the Bohm limit. Provided that protons are accelerated at the same efficiency as electrons, our results imply that SS433 is a PeVatron, i.e., can accelerate protons beyond a PeV. Future hard X-ray and MeV gamma-ray observations can critically test our models by detecting the spectral turnover or cutoff.
[en] Data representation from the PROM library in the ENDL format described. New types of data in comparison with the official ENDL format characterizing the multiplying properties of elements and the total kinetic energy release are introduced. A new description of energy distribution of secondary particles as two-dimensional tables with equiprobable representation of intermediate tables is introduced. 5 refs.; 1 tab
[en] The electrophysical properties of slightly altered sample of lignin are studied via dielectric spectroscopy in the frequency range of 10–2 to 106 Hz and temperature range from −120 to 160°C. The results are processed using the Havriliak–Negami frequency dispersion model. The presence of several dielectric constant relaxation mechanisms is confirmed. The energy of activation for temperature-dependent relaxation is determined.