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[en] Results: of the analysis of a time series of values of the half-life (τ) of the 214Po nucleus with a different time step obtained from the TAU-1 (354 days) and TAU-2 (973 days) installations are presented. The annual variation with an amplitude of (9.8 ± 0.6) × 10−4 and daily variations in the solar, lunar, and sidereal times with amplitudes of (5.3 ± 0.3) × 10−4, (6.9 ± 2.0) × 10−4, and (7.2 ± 1.2) × 10−4, respectively, are found in the series of τ values. It is shown that variations in microclimatic parameters cannot be a cause of τ variations.
[en] The brief description of installation TAU-2 intended for long-term monitoring of the half-life value τ(T1/2) of the 214Po is presented. The methods of measurement and processing of collected data are reported. The results of analysis of time series values of τ with different time step are presented. Total measurement time was equal to 590 days. Averaged value of the 214Po half-life was obtained τ = 163.46 ± 0.04 μs. The annual variation with an amplitude A = (8.9 ± 2.3) × 10−4, solar-daily variation with an amplitude ASo = (7.5 ± 1.2) × 10−4, lunar-daily variation with an amplitude AL = (6.9 ± 2.0) × 10−4 sidereal-daily variation with an amplitude AS = (7.2 ± 1.2) × 10−4 were found in a series of τ values. The maximal values of amplitude are observed at the moments when the projections of the installation Earth location velocity vectors toward the source of possible variation achieve its maximal magnitudes.
[en] Measurement of the 214Po half-life with the DEVIS track setup at the Institute of Theoretical and Experimental Physics (ITEP, Moscow) by means of a procedure based on determining lifetimes of individual nuclei is described. The value obtained for the 214Po half-life is 163.8 ± 3.0 µs. The possibility of reaching the accuracy of the measurements that is required for testing the statement that the decay of some nuclei has a nonexponential character and the source intensity necessary for this are discussed.
[en] Using a diffusion model we investigate deformation effects on the sensitivity of different light particles to nuclear dissipation for a rather neutron-deficient 178Pb system. Calculations show that deformation significantly increases the sensitivity of neutron emission to dissipation strength, and that this effect becomes stronger with increasing deformation.
[en] We propose a new method to extract the collective masses and momenta associated with a given set of collective coordinates, along a dynamical microscopic mean-field evolution. We apply our method to the symmetric fission of 258Fm nucleus, and analyze the dynamical evolution of the system in the collective space. We compare, between the dynamical and the adiabatic paths, the force acting on the quadrupole degree of freedom, which is closely related to the relative distance between fragments. It is shown that dynamical effects beyond the adiabatic limit are important for formation and scission of the neck between emitted fragments. (authors)
[en] The design changes of the Baksan low-background TAU-1 and TAU-2 set-ups allowed to improve a sensitivity of 214Po half-life (τ) measurements up to the 2.5 × 10−4 are described. Different possible sources of systematic errors influencing on the τ-value are studied. An annual variation of 214Po half-life time measurements with an amplitude of A = (6.9 ± 3) × 10−4 and a phase of φ = 93 ± 10 days was found in a sequence of the week-collected τ-values obtained from the TAU-2 data sample with total duration of 480 days. 24 hours’ variation of the t-value measurements with an amplitude of A = (10.0 ± 2.6) × 10−4 and phase of φ = 1 ± 0.5 hours was found in a solar day 1 hour step t-value sequence formed from the same data sample. It was found that the 214Po half-life averaged at 480 days is equal to 163.45 ± 0.04 μs.
[en] Multi-particle production and multifragment emission are crucial phenomena in high energy heavy ion interactions. Availability of beams of heavy ions with relativistic energies has made it possible to use nuclear collisions to study properties of nuclear matter of finite temperature and high densities. The detail studies on dependence of the emission angle of projectile fragments at various experimental and colliding system parameters helps us in understanding the reaction mechanism and provide in formations about the fragmentation properties. The participant-spectator model is the base line model for the study of the high energy nucleus-nucleus collisions. In the present paper we report on the emission angle dependence of projectile fragments on the charge of the fragments as well as on the different target groups of the detector
[en] The possibility of controlling the decay rate of low-lying nuclear states in a femtosecond laser plasma is demonstrated. In particular, for a ∼100-500-fs laser pulse with an intensity of ∼2x1016 W cm-2, a complete suppression of the conversion decay channel can be observed in a fraction of a 201Hg plasma expanding in vacuum. (letters)
[en] A projectile (84Kr36) having kinetic energy around 1A GeV has been used to expose NIKFI BR-2 emulsion target at GSI, Darmstadt, Germany. A total of 700 inelastic events has been identified and used in the present studies on projectile fragments. The multiplicity and normalized multiplicity of projectile's fragment are correlated with the compound particles, shower particles, black particles, grey particles. It is found that projectile's fragment is strongly correlated with compound particles and shower particles rather than other particles. The average multiplicity of projectile's fragment increases with increasing compound, shower and heavily ionizing charge particles. The multiplicity distribution of the projectile's fragment emitted in the 84Kr36 - emulsion interaction at around 1GeV per nucleon with different target has been well explained by KNO scaling. In this report, we will present the results of our investigations on the projectile's fragment multiplicity and probability distributions with 84Kr36 emulsion collision at around 1 GeV per nucleon. (author)
[en] This evaluation was completed in 2007. Literature available by December 2007 was included. Decay Scheme: 217Rn disintegrates 100% by α emission to the levels in 213Po. α decay of 217Rn occurs directly to the ground state of 213Po. 217Rn ground state has Jπ = 9/2+ (2007Ba19)