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951.
Mathew D. Penrose 《Journal of statistical physics》1994,77(1-2):3-15
LetG
R
be the graph obtained by joining all sites ofZ
d which are separated by a distance of at mostR. Let (G
R
) denote the connective constant for counting the self-avoiding walks in this graph. Let (G
R
) denote the coprresponding constant for counting the trees embedded inG
R
. Then asR, (G
R
) is asymptotic to the coordination numberk
R ofG
R
, while (G
R
) is asymptotic toek
R. However, ifd is 1 or 2, then (G
R
)-k
R
diverges to –.Dedicated to Oliver Penrose on this occasion of his 65th birthday. 相似文献
952.
Yu. I. Orekhov L. P. Khokhrin A. V. Gavrin L. D. Rasnetsov L. I. Matusis 《Radiophysics and Quantum Electronics》1994,37(1):89-90
The devices and systems for EHF therapy and diagnosis of the BAYuR series are examined and compared with known analogs.Scientific-Research Measuring-Systems Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 1, pp. 155–157, January, 1994. 相似文献
953.
954.
There is an intriguing discrepancy between
values measured directly at the CERNZ
0-factory and low-energy (at few GeV) measurements transformed toQ=M
z0 by a massless QCD
evolution relation. There exists and attempt to reconcile this discrepancy by introducing a light gluinog in the MSSM. We study in detail the influence of heavy thresholds on
evolution. First, we construct the exact explicit solution to the mass-dependent two-loop RG equation for the running
. This solution describes heavy thresholds smoothly. Second, we use this solution to recalculate a new
values corresponding to low-energy input data. Our analysis demonstrates that usingmass-dependent RG procedure generally produces corrections of two types: Asymptotic correction due to effective shift of threshold position; Local threshold correction only for the case when input experiment lies in the close vicinity of heavy particle threshold:Q
expt
-M
h
. Both effects result in the effective shift of the
values of the order of 10–3. However, the second one could be enhanced when the gluino mass is close to a heavy quark mass. For such a case the sum effect could be important for the discussion of the light gluino existence as it further changes theg mass.Work supported in part by INTAS-93-1180 相似文献
955.
J. B?chler J. Bartke H. Bia?kowska R. Bock D. Brinkmann R. Brockmann P. Buncic S. I. Chase I. Derado V. Eckardt et al. 《Zeitschrift fur Physik C Particles and Fields》1994,61(4):551-561
The intermittency phenomenon is investigated in proton-gold, oxygen-gold, sulphur-gold and sulphur-sulphur collisions at 200 GeV per nucleon. The data were taken with the NA 35 streamer chamber detector at the CERN SPS. The data samples are carefully corrected for double counting of tracks and for contamination from photon conversions, particle decays and secondary interactions. The analysis is carried out in terms of factorial moments, using a new definition, and of correlation integrals. Both methods show the presence of nonstatistical fluctuations (intermittency). The main conclusions are: The observation of the effect for pairs of hadrons with negative charges and its near absence for pairs of opposite charges is consistent with the assumption that Bose-Einstein correlations yield the dominant contribution. The intermittency effect is not proportional to (dn/dy)–1 which would be expected in superposition models. The measured relation between the second and third factorial moment for negative hadrons indicates that genuine 3-particle correlations are small. The predictions of a Monte Carlo simulation which is based on the Lund Fritiof model with the inclusion of Bose-Einstein correlations agree with the experimental results.Deceased 相似文献
956.
G. K. Vlasov E. I. Chizhikova D. N. Vylegzhanin 《International Journal of Infrared and Millimeter Waves》1994,15(1):121-135
The theory of new type detectors based on the quenching of secondary emission in direct-gap semiconductors (lines of Raman light scattering due to interaction between free and bound excitons in the crystal, and also bands of edge radiation) caused by IR or submillimeter radiation is proposed. The results obtained are confirmed by the experiment performed for CdS crystal excited by ultraviolet radiation of mercury lamp, at liquid helium temperature. 相似文献
957.
A. D. Al-Rawwas C. E. Johnson M. F. Thomas S. E. Dann M. T. Weiler 《Hyperfine Interactions》1994,93(1):1521-1529
Mössbauer spectra have been recorded at 4.2 and 300 K on the series La1–x
Sr
x
FeO3, wherex varies from 0 to 1.0 in steps of 0.1. Neutron diffraction experiments have shown that the crystal structure is orthorhombic for 0x<0.3, rhombohedral for 0.4x0.7, and cubic for 0.8<x1.0. Mössbauer spectra at 4.2 K are composed of magnetic sextet components arising from different charge states of iron ions. In the orthorhombic and rhombohedral phases, the charge states Fe3+ and Fe5+ coexist. In the cubic phase, iron is present as Fe3+ and Fe4+ states. At 300 K, the samples are magnetically ordered in the range 0 x0.3 and the coexistence of Fe3+ and Fe5+ remains. For samples 0.4x1.0, the samples are paramagnetic. Fits to these spectra require two components, one corresponding to an Fe4+ state, the other being best described as an Fe3+ ion forx0.7 but forx>0.7 having a mean charge state which increases to 3.5 forx=1.0. 相似文献
958.
J. -M. R. Génin A. A. Olowe B. Resiak M. Confente N. Rollet-Benbouzid S. L'Haridon D. Prieur 《Hyperfine Interactions》1994,93(1):1807-1812
An unusual low-water corrosion of steel sheet piles has been systematically investigated in a channel harbour (Boulogne sur Mer, France). An analysis of the environment reveals that all sampling of dark rust taken at different heights above marine sediments and kept in anaerobic conditions present unusual concentrations of sulfate-reducing bacteria. The rust products have been characterized by Mössbauer spectroscopy and X-ray diffraction, comprising the ferrous—ferric sulfated compounds of formula 4Fe(OH)2 · 2FeOOH · FeSO4 ·nH2O, called green rust 2, mixed sometimes with magnetite and a small amount of ferrous sulfide. 相似文献
959.
Zero field SR has been used to probe spin dynamics in the concentrated spin glass Y(Mn0.9Al0.1)2. The spectra follow a stretched exponential form, Gz(t)=exp(–(t)), with reaching 1/3 as the freezing temperature, Tg=60K, is approached. The evolution of Gz(t) with temperature is suggestive of the behaviour of the spin correlation function found by Ogielski in Monte Carlo simulations of the dynamics of the Ising spin glass model. The SR results are correlated with results previously obtained by inelastic neutron scattering. 相似文献
960.
Richard Ley D. Hagena D. Weil G. Werth W. Arnold H. Schneider 《Hyperfine Interactions》1994,89(1):327-341
Electric dipole transitions in the microwave range have been induced between the fine-structure levels of positronium in the excited staten=2. As an indication of the transitions, we used the increase in Lyman- radiation when the metastable 23S1-level is depopulated. The results for the transitions 23S123P0,1,2 are
0=18499.65±1.20±4.00 MHz,
1=13012.42 ±0.65±1.54 MHz and
2=8624.38±0.54±1.40 MHz. The first error is statistical and the second systematic. The precision of the present measurement has improved by a factor of 3, compared to previous data. Recent bound state QED-calculations have been extended to the orderR
t8
4ln
–1. The not yet completely calculated orderR
t8
4 is estimated to contribute less than 1 MHz. Our experimental results are in good agreement with theory. By applying a weak magnetic field, we were able to observe the transition 23S121P1 which is strictly forbidden byC-invariance in zero field. Our result, corrected for Zeeman- and motional Starkeffect, is
3=11180.0±5.0±4.0 MHz. An upper limit for theC-violating matrix element of
MHz could be deduced. Our experiment used moderated slow positrons from the bremsstrahlung and pair production of a pulsed electron linear accelerator (TEPOS facility at the university of Giessen). 相似文献