This study shows that the exponential decrease of the energy spectra, accompanied by slight oscillations, with final-fragment energy in high-energy nuclear reaction, and independent of fragments, targets, projectiles, and projectile energies, can be explained under some conditions in the range of strongly overlapping compound resonances by a new phenomenon of time resonances (explosions). These time resonances (explosions) correspond to the formation of a few highlyexcited, non-exponentially decaying nuclear clots (partial compound nuclei consisting of certain small groups of target and projectile nucleons). The proposed approach is an alternative way of analyzing experimental data compared with the majority of known descriptions (for instance, fireball models). This is a new and more general version of the time-evolution approach compared with the Izumo-Araseki time compound-nucleus model.

The new applications of the three-dimensional tunnelling and time analysis to low-energy nuclear processes are presented. The three-dimensional tunnelling is strictly quantum-mechanical and considers the internal multiple reflections. The time analysis of the nucleon-nucleons scattering near a resonance, distorted by the non-resonant background, does show the solution in the L -system of the paradox of the delay-advance in the C -system.

A self-consistent space-time analysis (made in the laboratory system) of the interference between non-resonant (prompt) and resonant (delayed) processes in nuclear reactions with two-particle channels, leads to a generalization of the expressions obtained (in the center-mass system) in the framework of an almost stationary formalism. The role of a new phase parameter φ, which describes the space-time shifts between the sources of the final-particle emission caused by the motion in the laboratory system of the decaying compound-nucleus, is analyzed. We find that in many realistic cases (when φ ~ 1) the effect related to this motion produces noticeable changes in the cross-sections.

Abstract:Some new applications of the time resonances (explosions) to new experimental data on high-energy nuclear processes are presented. These new experimental data are fitted rather well by the approach of the time resonances for the compound nuclei and clots.

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In this paper, we report on a photoluminescence (PL) and EPR study of several semiinsulating (SI) 4H SiC samples showing the different compensation regimes due to the presence of V4+ and V3+of different concentration. The samples which contain only V3+ indicates the compensation regime NV≅ND-NA>0 with the Fermi level located in the upper half of the band gap. The presence of V4+ along with V3+ in the other two set of samples indicates the SI behavior of the samples with compensation regime NV>NA-ND>0. Considering that the samples revealed EPR spectrum of vanadium V3+, position of the Fermi level should be also in the upper half of the band gap and mixed conductivity could be expected. UD-3 PL spectrum was observed in vanadium doped SI 4H SiC presented in the samples in V3+/V4+ and V4+/V5+ charge states with compensation regime NV>NA-ND>0. The data obtained prove that the PL and EPR are suitable techniques in determination SI yield in SiC crystal.

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