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991.
A. Mischke 《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):159-162
In this contribution a first STAR measurement on two heavy-flavor particle correlations in p+p collisions at RHIC is presented.
Heavy-flavor (charm and bottom) events are identified and separated on a statistical basis by the azimuthal correlation of
their decay electrons and open charm mesons, which provide decisive information about the underlying production process. The
azimuthal correlation distribution exhibits a two-peak structure which can be attributed to B decays on the near side and predominantly charm pair production on the away side. These assumptions are supported by dedicated
simulations using PYTHIA and MC@NLO event generators. This new correlation method has the potential for comprehensive energy
loss measurements of heavy quarks in heavy-ion collisions.
Original article based on material presented at HADRON 2007. 相似文献
992.
S. Agnello A. Alessi F. M. Gelardi R. Boscaino A. Parlato S. Grandi A. Magistris 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(1):25-31
We report experimental investigation by electron paramagnetic resonance (EPR) measurements of room temperature γ-ray irradiation
effects in sol-gel Ge doped amorphous SiO2. We used materials with Ge content from 10 up to 104 part per million (ppm) mol obtained with different preparations. These latter gave rise to samples characterized by different
extents of oxygen deficiency, estimated from the absorption band at ~5.15 eV of the Ge oxygen deficient centers (GeODC(II)).
The irradiation at doses up to ~400 kGy induces the E'-Ge, Ge(1) and Ge(2) paramagnetic centers around g ~ 2 with concentrations
depending on Ge and on GeODC(II) content. We found correlation between Ge(2) and GeODC(II) contents, supporting the suggestion
that the latter defect is the precursor of Ge(2). Even if the concentration of E'-Ge and Ge(1) defects cannot be strictly
related to GeODC(II) one, the concentration growth of these paramagnetic defects with irradiation evidences that the radiation
sensitivity is enhanced by the oxygen deficiency for Ge doping above 1000 ppm mol and it is reduced below 100 ppm mol. Moreover,
the investigation of samples with different GeODC(II) concentration but fixed Ge content has shown that the oxygen deficiency
enhances the overall radiation sensitivity for [GeODC(II)]/[Ge] in the range 10-3
10-2. 相似文献
993.
Thermodynamic models with an increasing number of moments are here compared, in the frame-work of relativistic extended thermodynamics. They constitute a family of models depending on a parameter n. In these models, some constitutive functions occur; a part of them are determined by imposing that they satisfy exactly the entropy and the relativity principles. It is pleasant to see how many elegant symmetries, which are present in the pioneering work by Liu, Müller and Ruggeri about the 14 fields model, nicely extend also to the general case.The other constitutive functions are production terms and they must satisfy a residual inequality which is consequence of the entropy principle; other restrictions on their generality are imposed by considering a well-known iterative procedure, and one of its possible generalizations, and by imposing that the results dont depend on n. It is proved that all these conditions are consistent. 相似文献
994.
J.E. Amaro M.B. Barbaro J.A. Caballero T.W. Donnelly A. Molinari 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):421-427
The impact of Hartree-Fock correlations on the nuclear momentum distribution is studied in a fully relativistic one-boson-exchange
model. Hartree-Fock equations are exactly solved to first order in the coupling constants. The renormalization of the Dirac
spinors in the medium is shown to affect the momentum distribution, as opposed to what happens in the non-relativistic case.
The unitarity of the model is shown to be preserved by the present renormalization procedure.
Received: 7 June 2002 / Accepted: 24 September 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: juan@nucle.us.es
Communicated by G. Orlandini 相似文献
995.
We analyze the 2×2 nonhomogeneous relativistic Euler equations for perfect fluids in special relativity. We impose appropriate conditions on the lower order source terms and establish the existence of global entropy solutions of the Cauchy problem under these conditions. 相似文献
996.
Dong-Won Kim 《Solid State Communications》2006,140(5):215-218
Optoelectronic characteristics of CdTe/HgTe/CdTe quantum-dot quantum-well (QDQW) nanoparticles synthesized by the colloidal method are investigated in this study. Strong exciton bands were observed in absorption and photoluminescence (PL) spectra taken for the CdTe/HgTe/CdTe QDQW nanoparticles. The energy difference between the exciton absorption and PL bands is larger than those obtained with CdTe and HgTe nanoparticles. Photocurrent-voltage curves and time-dependent photocurrent curves were obtained for the CdTe/HgTe/CdTe QDQW nanoparticles. With regard to the photocurrent mechanism of these QDQW nanoparticles, those charge carriers participating in the formation of excitons may not contribute to the photocurrent, because of the large binding energy of the excitons. Moreover, it is suggested in this paper that free holes in the HgTe quantum-well in the valance band, rather than free electrons, are the main contributors to the photocurrent. 相似文献
997.
998.
Global existence proof for relativistic Boltzmann equation 总被引:2,自引:0,他引:2
The existence and causality of solutions to the relativistic Boltzmann equation inL
1 and inL
loc
1
are proved. The solutions are shown to satisfy physically naturala priori bounds, time-independent inL
1. The results rely upon new techniques developed for the nonrelativistic Boltzmann equation by DiPerna and Lions. 相似文献
999.
W. Eichhammer M. Hage-Ali R. Stuck P. Siffert 《Applied Physics A: Materials Science & Processing》1990,50(4):405-410
This work presents direct evidence for a correlation between rapid thermal process-induced recombination centers and co-implanted metallic impurities in ion implanted silicon. Experimental evidence includes the dose dependence of the minority carrier diffusion length measured by the SPV technique, SIMS and RBS analysis of high-dose implantations which show the presence of heavy metals, the dependence of the final diffusion lengths on the mass of the implanted ions, as well as the successful modification of an implantation equipment. 相似文献
1000.
T.?Van CauterenEmail author J.?Ryckebusch B.?Metsch H.?-R.?Petry 《The European Physical Journal A - Hadrons and Nuclei》2005,26(3):339-359
We present results for the helicity amplitudes of the lowest-lying hyperon resonances Y*, computed within the framework of the Bonn Constituent-Quark model, which is based on the Bethe-Salpeter approach. The seven
parameters entering the model were fitted to the best-known baryon masses. Accordingly, the results for the helicity amplitudes
are genuine predictions. Some hyperon resonances are seen to couple more strongly to a virtual photon with finite Q2 than to a real photon. Other Y*'s, such as the S01(1670) Λ-resonance or the S11(1620) Σ-resonance, couple very strongly to real photons. We present a qualitative argument for predicting the behaviour of
the helicity asymmetries of baryon resonances at high Q2.-1 相似文献