BREMSSTRAHLUNG OF ELECTRONS AND YIELD OF NEUTRONS FROM THICK CONVERTERS, PASSING OF GAMMA RADIATION AND NEUTRONS THROUGH BIOLOGICAL SHIELDING

In GEANT4 spectral-angular distributions of the bremsstrahlung of medium-energy electrons from amorphous targets of different thickness and atomic charge were calculated. The total yield of gamma quanta in the forward hemisphere and at large scattering angles were determined depending on the converter thickness. The difference in the characteristics of gamma radiation for thin and thick targets was shown. The neutron yield is calculated due to photonuclear reactions for various converters. Numerical estimates of the radiation spectra after passing through the biological shielding for neutron and bremsstrahlung were carried out.

Measurement and analysis of 10B +12C elastic scattering at energy of 41.3MeV

Angular distribution of the [Formula: see text] elastic scattering was measured at [Formula: see text][Formula: see text]MeV. Experimental data showed a significant increase in differential cross-sections at backward angles. The optical model with phenomenological potentials reproduces well the experimental cross-sections in the region of the angles of the forward hemisphere, but is not able to explain the increase in cross-sections at large angles. The distorted wave Born approximation method was used to reproduce the experimental data at large angles [Formula: see text] by taking into consideration a deuteron transfer. Spectroscopic amplitude has been extracted for the configuration [Formula: see text]C[Formula: see text]B + [Formula: see text] from the analysis.

Numerical Investigation of the First Booster Stage Tone Noise of a High Bypass Ratio Turbofan

The results of the first booster stage tone noise numerical investigation for a model of low pressure compressor are presented. The investigation was performed using the frequency domain numerical method of multistage turbomachines tone noise simulation, developed in CIAM (Central Institute of Aviation Motors) and implemented in the 3DAS (3 Dimensional Acoustics Solver) in-house solver. The model under consideration included high bypass ratio fan, stator, booster and bypass duct. Calculation was performed at the approach operating conditions. Far field directivities for two tones in the forward hemisphere were obtained. One tone corresponded to the blade passing frequency of the first stage rotor, the other - to the sum of this frequency with the blade passing frequency of the fan. The results of the computation were compared with the experimental data obtained in the CIAM C-3A acoustic test facility. In general satisfactory correspondence between calculation and experiment was obtained.

Emission characteristics of fast target protons in ultrarelativistic16O–nucleus collisions

The target fragmentation in 60A and 200A GeV16O interactions with emulsion nuclei is analyzed. The validity of the nuclear limiting fragmentation hypothesis is confirmed at ultrarelativistic energies. The emission mechanism of the fast target proton (grey particle) is investigated in terms of the multiplicity characteristics. The anisotropy ratio and asymmetry parameter, while found to be independent of the projectile size or incident energy, are dependent on the target size and system centrality. This dependence is insignificant for heavy targets and in more central regions, where constancy exists. In this species, the system of the grey particle emission cannot exhibit the optimum symmetry or asymmetry between the forward and backward hemispheres. It is seen that these target protons originate from two emission sources in the earlier stage of the target fragmentation. One them emits nucleons isotropically in the 4π space. The other is the main emission source, which emits nucleons, in the forward hemisphere only, as a result of the binary nucleon–nucleon collisions and (or) intranuclear cascade.

Study of hadrons emission in 4.5A GeV/c32Sinteractions with emulsion

An experimental study of the forward and backward emission of relativistic and fast hadrons in the interactions of 4.5 A,GeV/c 32S with emulsion was carried out. The study supports the conclusion that a collective mechanism is responsible for the production of particles in the backward hemisphere (which is restricted beyond the kinematics limit). The backward emission of both shower and grey particles can be described by an exponential decay law independent of the projectile size. The experimental results suggest that the backward particles result from the decay of the system in a latter stage of the interaction. While the average multiplicities of the shower particles emitted in the forward hemisphere are strongly dependent on the projectile size and incident momentum, the average values of those emitted into the backward hemisphere are found to be only a function of the target size (i.e., impact parameter). Thus, the backward particle production can be considered as a yield of a highly excited target system, in its rest frame.PACS Nos.: 25.75.–q, 25.75.Dw, 25.75.Gz, 25.75.Ld, 25.70.Mn, 25.70.Pq,41.75.Ak, 41.75.Cn, 29.40.Rg, 07.68.+m

TERNARY REACTIONS IN 197AU + 197AU COLLISIONS REVISITED

Ternary events originating from the 197 Au + 197 Au reaction at 15 MeV/nucleon, studied by using the multidetector array CHIMERA at LNS Catania, have been collected in almost complete 2π range of the forward hemisphere of CHIMERA thus extending the angular range of our previously reported preliminary data. Energy- and time calibrations for heavy fragments at large angles were supplemented with an analysis of coincidence events of binary strongly damped reactions. Contrary to the previous preliminary results, the new complete data clearly show presence of sequential fission processes in which one of Au -like nuclei undergoes fission after re-separation of the primary binary system. Mechanism of these two types of reactions observed in our data, sequential fission reactions and prompt ternary processes, are presently studied using comparisons with predictions of the stochastic BNV model of Baran, Colonna and Di Toro and the QMD model of Łukasik.

Transition state dynamics of F + Br2 reactive scattering

Reactive scattering of F atoms with Br2 molecules has been studied at an initial translational energy E ∼ 16 kJ mol−1 using a supersonic beam of F atoms seeded in Ne buffer gas. Laboratory angular and velocity distributions of BrF product have been measured. They show sharp peaking in the forward direction with almost isotropic wide angle scattering of relative intensity ∼ 0.2. Approximately half the total available energy is disposed into product translation for scattering in the forward and backward directions with slightly lower translational energy for the sideways scattering. The combination of sharp forward scattering and high product translational energy is attributed to early migratory trajectories in large impact parameter collisions whereby the F atom reacts with the more distant Br atom of the Br2 molecule lying in the forward hemisphere. The isotropic wide angle scattering arises from direct trajectories in which the F atom reacts with the nearer Br atom of the Br2 molecule. Migratory dynamics are promoted by charge transfer interaction of the form Br2+F− which stabilises the potential energy surface in elongated isosceles triangular FBr2 configurations as well as in slightly bent FBrBr configurations. Comparison is made with the dynamics of the F + Cl2, I2, and CCl3Br reactions.