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81.
D. Allasia C. Angelini A. Baldini L. Bertanza F. Bianchi A. Bigi F. Bobisut A. Borg P. Capiluppi R. Cirio J. Derkaoui M. L. Faccini-Turluer A. G. Frodesen D. Gamba G. Giacomelli B. Jongejans G. Mandrioli A. Margiotta-Neri A. Marzari-Chiesa R. Pazzi L. Patrizii C. Petri F. Predieri A. Romero A. M. Rossi A. Sconza P. Serra-Lugaresi M. Spurio A. G. Tenner G. W. van Apeldoorn P. H. A. van Dam N. A. M. van Eijndoven D. Vignaud WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,37(4):527-533
Bose-Einstein correlations between pions of equal charge have been observed in Charged Current and Neutral Current (anti)neutrino-deuterium interactions in the BEBC bubble chamber exposed to the SPS wide band beam. The pion emission region is found to be essentially spherical with a mean radius of (0.48±0.07) fm; the chaoticity parameter is 0.36±0.04. 相似文献
82.
We consider an impacting mechanical system in which a particle at position u(t) impacts with a periodically moving obstacle at position z(t), the motion of which is non-smooth. In particular we look at corner events when u impacts with z very close to a point where z loses smoothness. We show that this leads, through a corner bifurcation, to complex dynamics in u which can include periodic orbits of arbitrary period and period-adding cascades. By analysing associated maps close to the corner event, we show that this dynamics can be understood in terms of the iterations of a two-dimensional, piecewise linear, discontinuous map. We also show some links between this analysis and the difficult problem of understanding the motion of three objects which may have simultaneous impacts. 相似文献
83.
S. Sudarti H. Petri M. Rossbach 《Journal of Radioanalytical and Nuclear Chemistry》1997,223(1-2):177-185
Sensitive environmental radioactivity measurement using direct γ-spectroscopy needs to be carried out under particular low-level conditions as the quantity to be determined generally is very close to the natural background. Passive shielding of the detectors in addition to electronic suppression of Compton background resulting from scattering of high energy γ-rays in the gemanium detector seems to be the most promising approach to obtain statistically well defined peaks within reasonable measurement time. Results obtained with a heavily shielded anti-coincidence spectrometer installed at the Research Center Jülich, ideally suited for the measurement of low-level environmental radioactivity in various materials are described. 相似文献
84.
We demonstrate how Mellin operator calculus can be used to study the mapping properties of the Dirichlet to Neumann map on graphs. These operators naturally arise in photonic crystal theory. The calculus adds rigour to some previously given heuristic arguments. 相似文献
85.
86.
We report detailed statistical mechanics calculations to analyse the field-temperature phase diagram of a fully connected Maier–Saupe–Zwanzig (MSZ) lattice model for the nematic transitions in liquid-crystalline systems. If the field is applied along the uniaxial direction, with positive anisotropy, there is a first-order boundary between distinct uniaxial paranematic phases, which ends at a simple critical point. For negative values of the anisotropy, the first-order boundary becomes continuous at a tricritical point, and the transition is between field-induced uniaxial and biaxial structures. This elementary MSZ lattice model provides a way to systematically regain all of the main features of earlier phenomenological and model calculations. Due to the simplicity of the calculations, critical and tricritical points, as well as critical lines, can be located analytically, which leads to a possibility of comparisons with values for real experimental systems. Also, we formulate a generalised six-state MSZ model, which takes into account intrinsic molecular biaxiality, and perform calculations to determine the location of the critical point in the field-temperature phase diagram. 相似文献
87.
88.
89.
Lionello Petri 《Colloid and polymer science》1926,39(1):63-67
Ohne Zusammenfassung 相似文献
90.
M. Ibáñez de Berganza E. E. Ferrero S. A. Cannas V. Loreto A. Petri 《The European physical journal. Special topics》2007,143(1):273-275
When the two dimensional q-color Potts model in the square lattice is quenched at zero temperature with Glauber dynamics,
the energy decreases in time following an Allen-Cahn power law, and the system converges to a phase with energy higher than
the ground state energy after an arbitrary large time when q>4. At low but finite temperature, it cesses to obey the power-law
regime and orders after a very long time, which increases with q, and before which it performs a domain growth process which
tends to be slower as q increases. We briefly present and comment numerical results on the ordering at nonzero temperature. 相似文献