126031532
EMISSION OF COMPOUND LIGHT FRAGMENTS IN COLLISIONS BETWEEN RELATIVISTIC NUCLEI. (IN RUSSIAN)
117029742
Two-particle correlations of pions and light nuclear fragments in nucleus-nucleus interactions at an energy of 3.6 GeV/nucleon
ACorrelations between a charged particle emitted in the angular interval 10-32{degrees} (in the lab system) and a pion emitted in the angular interval 45-135{degrees} are measured for the interactions of {sup 12}C and {sup 4}He nuclei of energy 3.6 GeV/nucleon with various nuclear targets. In all cases, the correlated emission of such particles is discovered. As in the case of baryonic nuclear fragments, correlations are negative for light targets (a fragment and the first particle are emitted preferentially in opposite directions). However, in contrast to the case of baryonic fragments, the amplitudes of the correlations decrease with increasing mass of the target nucleus, and correlations even become positive in the case of a Pb target. The magnitudes of the correlations depend systematically on the characteristics of the entrance and exit channels. As in the case of baryonic nuclear fragments, these observations are consistent with the notion of collective motion in nuclear matter. In addition, the effect of pion rescattering with reflection in nuclear matter is observed. 6 refs., 3 figs.
115322655
Single photon and neutral meson production in nuclear collisions at 200-A/GeV
118798878
Two particle correlations for light nuclear fragments in nucleus-nucleus collisions at 3.6-GeV/nucleon
109550892
A new VME-based high voltage power supply for large photomultiplier systems
Abstract We describe a new high voltage power supply, developed for the leadglass calorimeter of the WA98 experiment at CERN. The high voltage is produced for each of the 10 080 photomultiplier tubes of the detector individually, by the same number of active bases with on-board Greinacher voltage multipliers. The full VME-based HV controller system, which addresses each base via bus cables once per second, is miniaturized and fits into a single VME crate. The main advantages of this approach are the low heat dissipation, the considerably reduced amount of cabling and cost, as well as the high stability and low noise of the system.
125898346
Photons and neutral mesons from hot hadronic matter
Results from the experimental program with light ion beams and heavy target nuclei at the CERN SPS could demonstrate the occurrence of an unprecedented state of high density in hadronic matter. The thermal nature of the hadronic system has been investigated by analyzing spectra and production ratios of hadrons which reveal a large degree of rescattering of primary and secondary hadrons.Thermal photons from elementary quark-gluon interactions are considered a promising signal for the occurrence of a phase transition to the quark-gluon plasma. The predictions for thermal photons from elementary parton interactions are discussed and compared to the thermal emission rate of photons from a hot hadronic gas. Recent results from the photon spectrometers in heavy ion experiments are presented. Production cross sections of pi0 and eta mesons are determined and the projectile and target mass dependence is discussed. An upper limit for the single photon yield was determined for central O+Au reactions. Recent S+Au reactions exhibit an excess of photons over the yield expected from hadronic decays. The spectral shape of the expected single photon signal is discussed which might reveal the temperature of hot matter and indicate a phase transition.
116200939
Self-Stimulated Undulator Radiation and its Possible Applications
We investigated the phenomena of self-stimulation of incoherent emission from an undulator installed in the linear accelerator or quasi-isochronous storage ring. We discuss possible applications of these phenomena for the beam physics also.
13357439
Cherenkov glue in opaque nuclear medium
Abstract The spectrum of Cherenkov gluons is calculated within the framework of in-medium QCD. It is compared with experimental data on the double-humped structure around the away-side jet obtained in the experiments STAR and PHENIX at RHIC. The values of the real and imaginary parts of the permittivity of the medium created in ultrarelativistic nuclear collisions are obtained from these fits. It is shown that accounting for an additional smearing of transverse momenta of Cherenkov gluons in the medium allows to provide a very good description of the experimental data.
173184854
Proposal of a compact repetitive dichromatic x-ray generator with millisecond duty cycle for medical applications
Main practical applications of X-rays lie in the important for the society fields of medical imaging, custom, transport inspection and security. Scientific applications besides of fundamental research include material sciences, biomicroscopy, and protein crystallography. Two types of X-ray sources dominate now: conventional tubes and electron accelerators equipped with insertion devices. The first are relatively cheap, robust, and compact but have low brightness and poorly controlled photon spectrum. The second generate low divergent beams with orders of magnitude higher brightness and well-controlled and tunable spectrum, but are very expensive and large in scale. So accelerator based X-ray sources are mainly still used for scientific applications and X-ray tubes--in commercial equipment. The latter motivated by the importance for the society made an impressive progress during last decades mostly due to the fast developments of radiation detectors, computers and software used for image acquisition and processing. At the same time many important problems cannot be solved without radical improvement of the parameters of the X-ray beam that in commercial devices is still provided by conventional X-ray tubes. Therefore there is a quest now for a compact and relatively cheap source to generate X-ray beam with parameters and controllability approaching synchrotron radiation. Rapid developments of lasers and particle accelerators resulted in implementation of laser plasma X-ray sources and free electron lasers for various experiments requiring high intensity, shrt duration and monochromatic X-ray radiation. Further progress towards practical application is expected from the combination of laser and particle accelerator in a single unit for efficient X-ray generation.
7992539
Vacuum Einstein metrics with bidimensional Killing leaves ∗ I-Local aspects.
Abstract The solutions of vacuum Einstein's field equations, for the class of Riemannian metrics admitting a non-Abelian bidimensional Lie algebra of Killing fields, are explicitly described. They are parametrized either by solutions of a transcendental equation (the tortoise equation ), or by solutions of a linear second order differential equation in two independent variables. Metrics, corresponding to solutions of the tortoise equation, are characterized as those that admit a 3-dimensional Lie algebra of Killing fields with bidimensional leaves.