Volume 28, Issue 1, January 1997
28(1997); http://dx.doi.org/10.1134/1.953030View Description Hide Description
The current experimental data on the solar-neutrino problem are reviewed. The possibilities offered by the radiochemical lithium detector for solving this problem, in particular, for determining the contribution of medium-energy and boronneutrinos in chlorine and gallium detectors, are discussed. A brief description is given of the prototype of the lithium detector containing a target of 300 kg of metallic lithium, which is presently under construction at the Nuclear Research Institute of the Russian Academy of Sciences.
28(1997); http://dx.doi.org/10.1134/1.953032View Description Hide Description
The experimental results from a systematic study of cumulative and production in the inclusive process are presented. The beam was protons, deuterons, helium nuclei, or carbon nuclei with momentum per nucleon equal to 4.5 GeV/ The dependence of the cross sections was measured for these beams for fixed secondary-particle momentum equal to 0.5 GeV/ and emission angle The fragmenting nuclei are D, He, Li, Li, C, Al, Si, Cu,Ni,Ni,Zn,Sn, Sn, and Pb. The energy dependence of the -meson, proton, and deuteron cross sections in the momentum range 0.3–0.7 GeV/ was measured for Ni,Ni,Zn,Sn, Sn, and Pb nuclei using an 8.9 GeV/proton beam. Details of the behavior of the cross sections were found in various nuclear fragmentation regions. The behavior of the exponent of the dependence of the proton, deuteron, and pion cross sections as a function of the mass number of the nuclei in the primary beam was studied. The results are compared with the data available in the literature. Various models of cumulative particle production in interactions of hadrons and nuclei with nuclei at various beam energies are discussed. Tables of invariant differential cross sections are presented, along with the results of fitting the energy dependence of the cross sections in various representations.
28(1997); http://dx.doi.org/10.1134/1.953031View Description Hide Description
The state of the art in studying thermodynamic properties of hot and dense nuclear matter is reviewed with special emphasis on the confinement–deconfinement transition between hadron matter and quark–gluon plasma. The most popular models used for describing deconfinement are analyzed, including statistical bootstrap models, pure phase models, the model of clustered quarks, and the string-flip potential model. Predictions of these models are compared with lattice numerical simulations. It is concluded that precursor fluctuation effects must be taken into account in order to get a realistic description of the deconfinement transition. The existence of precursor fluctuations is in line with the dynamical confinement scenario and suggests that deconfinement cannot be considered as a transition between pure hadron and quark–gluon phases. All this supports the concept of cluster coexistence advocated by the authors of this review: Quark–gluon plasma and hadron clusters are different quantum states of the same system, so that any statistical model pretending to treatnuclear matter under extreme conditions must incorporate the probability of these different channels. The ways of constructing statistical models with plasma–cluster coexistence are discussed, and thermodynamic properties of such models are analyzed.
28(1997); http://dx.doi.org/10.1134/1.953033View Description Hide Description
A review is given of the results obtained by the authors concerning the uncertainties in the velocity and acceleration of a freely moving particle in the Dirac theory. It is shown that these uncertainties are an inherent consequence of the relativistic quantum mechanics of spin- 1/2 particles. The magnetic analogy of Zitterbewegung is discussed.
28(1997); http://dx.doi.org/10.1134/1.953029View Description Hide Description
The current status and future perspectives of the development of high-precision microvertex detectors are reviewed. A description is given of the characteristics, operating principles, and methods of signal readout from microvertex detectors designed on the basis of semiconductor technology and fiber-optics light-guide techniques. The parameters of the best known microvertex detectors used in fixed-target and collider experiments are given in tables. The specialized processors used for fast calculation of the impact parameter and selection of events containing decay vertices are discussed.