International Journal of Modern Physics E

The high-energy approximation is adapted for heavy ion scattering at energies of several dozen MeV/nucleon. It is shown that the closed form of the eikonal phase suggested for the realistic Woods–Saxon type potential is a hopeful one for further applications. The Glauber–Sitenko small angle approach is analyzed, and a role of the Coulomb deviation of the straight trajectory of motion is investigated. Methodical calculations and comparison with experimental data are made.

The reaction ²⁸Si+¹⁸¹Ta has been studied at E_Lab=125 and 135 MeV. Coincidences between high energy particles from abnormally long-lived states and various X- and γ-rays were observed, e.g. 7.8–8.6 MeV α-particles with γ-rays of a superdeformed band, 5.1–5.5 MeV α-particles with X- and γ-rays of W, Re and Pt, and 3.88 MeV particles (interpreted as protons) with 185.8 keV γ-rays. The data are interpreted in terms of the production of long-lived (t_1/2 of several months) high spin isomeric states in the second well of the potential in the parent nuclei, which decay to the normal states in the daughters, and in the third well of the potential, which decay to the second well.

Unidentified low energy and very enhanced α-particle groups have been observed in various actinide fractions produced via secondary reactions in a CERN W target which had been irradiated with 24-GeV protons. In particular, 5.14, 5.27 and 5.53 MeV α-particle groups with corresponding half-lives of 3.8±1.0 y, 625±84 d and 26±7d, have been seen in Bk, Es and Lr-No sources, respectively. The measured energies are a few MeV lower than the known ground state to ground state α-decays in the corresponding neutron-deficient actinide nuclei. The half-lives are 10⁴ to 10⁷ shorter than expected from energy versus lifetime relationship for such low-energy α-particles in this region of nuclei. The deduced evaporation residue cross sections are in the mb region, about 10⁴ times higher than expected. Not only is it impossible to identify these α-decays with any known activity in the whole nuclear chart, but they also could not be due to hypothetically unknown isomeric states in various conceivable neutron deficient nuclei, nor due to unknown isomeric states in the rare-earth region. Based on the fact that in other experiments we have found isomeric states in the second and third minima of the potential for other heavy ion reaction products, one can now understand in a quantitative way, both the unusual low energies, the unusual enhanced lifetimes and the unusual large production cross sections, in terms of production of similar isomeric states in appropriate actinide isotopes. Some consequences regarding the production of the long-lived superheavy elements are also discussed.

The internal Bremsstrahlung spectrum from ²⁰⁴Tl has been measured, using magnetic deflector method, in the X-ray region. The corrected spectral intensity is compared with the Coulomb-corrected KUB theory in the energy region of 10 to 30 keV. The good agreement between experiment and theory in this energy region, suggests that "detour effects" are negligible in the low energy region.

The role of effective hadron masses and effective couplings in nuclear matter is studied using a generalized effective Lagrangian for σ-ω model. A simple relation among the effective masses, the effective couplings and the incompressibility K is derived. Using the relation, it is found that the effective repulsive and the effective attractive forces almost cancel each other out at the normal density. Inversely, if this cancellation is almost complete, K is 250~350 MeV.