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991.
992.
U. Ritschel I. Stancu P. M. Stevenson 《Zeitschrift fur Physik C Particles and Fields》1992,54(4):627-634
In the conventional large-N limit the coupling constant is required to scale as 1/N. While the Gaussian effective potential (GEP) is known to contain the exact result in this limit, it shows a phase transition only when 1/N (in units of the renormalized mass in the symmetric vacuum). Here we determine the asymptotic behaviour, asN, of and other quantities at the phase transition of the GEP. We find crit to be finite in 0+1 dimensions; of order 1/lnN in 1+1 dimensions; 1/N
1/3 in 2+1 dimensions; and
in 3+1 dimensions. The GEP's first-order phase transition is shown to become asymptotically second-order in 1+1 dimensions and below. We also discuss non-integer dimensions and the approach to the non-trivial autonomous theory in 3+1 dimensions. 相似文献
993.
D. Choudhury P. J. O'Donnell U. Sarkar 《Zeitschrift fur Physik C Particles and Fields》1992,54(2):307-309
The EMC collaboration have reported a measurement of the proton structure function which has been interpreted to mean that the spin of the proton is not predominantly that of the quarks (=u+d+s=0.13±0.19). We show that the magnetic moments of the baryons are independent of this measurement and are given (within 10–20%) for a range of including the valence model value =1. The magnetic moments of the quarks can only be fixed if the quantity is determined very accurately. 相似文献
994.
C. T. Simmons S. L. Molodtsov S. I. Fedoseenko J. C. Allman C. Laubschat G. Kaindl S. V. Moshikin M. A. Kuzmina M. U. Vlasov O. F. Vyvenko 《Zeitschrift für Physik B Condensed Matter》1992,87(3):271-273
The results of a high-resolution photoemission study using synchrotron radiation of two single crystals of Bi2Sr2CaCu2O8+, with different critical temperaturesT
c
due to a variation in oxygen stoichiometry are reported. Within experimental accuracy, the energy gap 2 is found to scale withT
c
, amounting to a reduced gap parameter of 2/k
BTc7.4. Employing resonant photoemission at the O–2s and Cu–3p thresholds, two spectral peaks at binding energies of 180 meV and 320 meV were identified as predominantly O–2p-and Cu–3d 4s-derived states, respectively. 相似文献
995.
A. Jörg U. Meier R. Kienle K. Kohse-Höinghaus 《Applied physics. B, Lasers and optics》1992,55(4):305-310
State-to-state rotational energy transfer (RET) co-efficients were determined for inelastic collisions of OH (A
2+, v=0) with N2, CO2, and H2O at 300 K. The experimental procedure described previously allows the direct evaluation of state-specific RET coefficients from time-resolved laser-induced fluorescence (LIF) measurements without any assumptions on the RET. The results show strikingly different RET behaviour for the three collision partners. The data can serve as a basis for a comparison with dynamic collision models.A. Jörg is now with IBM Corporation, Frankfurt, Fed. Rep. Germany 相似文献
996.
F. Meissner H. Salewski W. -D. Schmidt-Ott U. Bosch-Wicke R. Michaelsen 《Zeitschrift für Physik A Hadrons and Nuclei》1992,343(3):283-292
The neutron-deficient rhenium isotopes166–170Re were investigated using reactions of32S with monoisotopic141Pr targets. Gamma-rays following the-decays of166–169Re were measured for the first time. Four new-rays with energies of 4.70,4.83, 4.87, and 5.02 MeV were detected in addition to the known 5.50, 5.26, and 5.06 MeV-rays. Alpha-decaying isomer pairs were discovered in167Re and169Re. The measured half-lives are 2.3(2)s for166Re, 3.4(4)s and 6.2(5)s for167Re, 4.4(1)s for168Re, 8.1(5)s and 16.3(8)s for169Re, and 9.2(2)s for170Re. The nuclear structure is discussed in terms of single-particle states.This work has been funded by the German Federal Minister for Research and Technology (BMFT) under contract number 06GÖ105 相似文献
997.
R. Menges U. Dinger N. Boos G. Huber S. Schröder S. Dutta R. Kirchner O. Klepper T. Kühl D. Marx G. D. Sprouse 《Zeitschrift für Physik A Hadrons and Nuclei》1992,341(4):475-479
The hyperfine structure, isotope and isomeric shifts in the atomic transition 6p
2
P
3/2–7s
2
S
1/2, =535 nm have been measured for theI=7 andI=2 states of190, 192, 194, 196Tl; theI=1/2 andI=9/2 states of191Tl and the I=7 isomer of188Tl. The thallium isotopes were prepared as fast atomic beams at the GSI on-line mass separator following fusion reactions and — in some cases — subsequent-decay. The nuclear dipole moments, electric quadrupole moments and the change in the nuclear mean square charge radius are evaluated. Theuu-isotopes show an isomeric shift which changes sign between192Tl and194Tl.Dedicated to P. Armbruster on the occasion of his 60th birthday 相似文献
998.
A. Lang B. Blättel W. Cassing V. Koch U. Mosel K. Weber 《Zeitschrift für Physik A Hadrons and Nuclei》1991,340(3):287-295
Within a covariant BUU-approach we simulate heavyion collisions at various bombarding energies from 400 MeV/u to 1 GeV/u. We evaluate locally the energymomentum tensorT
v
(x), and extract pressures, energydensities and temperatures. The connection of these thermodynamical quantities to experimental observables and their sensitivity to the equation of state is discussed. Furthermore, we investigate the question of local equilibration and evaluate the entropy produced in these reactions.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday. Work supported by BMFT and GSI Darmstadt 相似文献
999.
K. -H. Speidel J. Cub U. Reuter F. Passek H. -J. Wollersheim N. Martin P. Egelhof H. Emling W. Henning R. S. Simon R. Schmidt H. -J. Simonis N. Gollwitzer 《Zeitschrift für Physik A Hadrons and Nuclei》1991,339(2):265-268
It is shown that transient magnetic fields in Gd-host for20Ne ions at a mean velocity of 12.5v0(v0=c/137), considerably beyond the Bohr velocity of 1s electrons of Ne ions (v1s=10v0), are dominated by the Fermi contact field of these electrons. The first excited 2+-state of2Ne was used as probe. The derived value for the mean degree of polarization p1s=0.32(13), is surprisingly large, though still consistent with values obtained at lower velocities. Present calculations of spin exchange cross sections severely underestimate the observed polarization at this high velocity.The authors are grateful to the operating staff of the UNILAC for providing excellent beam conditions. They also thank Dr. P. Maier-Komor for preparing the delicate targets. Support by the BMFT is acknowledged. 相似文献
1000.
G. Krausch T. Detzel H. Bielefeldt R. Fink B. Luckscheiter R. Platzer U. Wöhrmann G. Schatz 《Applied Physics A: Materials Science & Processing》1991,53(4):324-329
Growth and melting behaviour of thin indium films on Ge(100) have been investigated by Auger-electron spectroscopy (AES), atomic force microscopy (AFM) and perturbed angular correlation (PAC) spectroscopy, respectively. At room temperature inidium is found to grow in three-dimensional islands even at submonolayer coverages. A very rough film surface is observed for thicknesses up to 230 ML. The melting behaviour of such films has been studied by PAC. A reduction of the melting temperature T
m as well as a strong supercooling of the films is observed. The electric field gradient for 111In(111Cd) in the indium islands is determined as a function of temperature and is used to monitor the local crystalline order of the films up to temperatures just below the melting point. 相似文献