H. D. Helb

Search for quasimolecules in heavy-ion reactions in the region of the coulomb barrier

Abstract We have been looking for resonant structures of the well-known 12C-12C type in the excitation functions of some selected heavy-ion reactions. The reactions investigated are 12C(13C, α)21Ne, 12C(13C, p)24Na; 12C(14N, α)22Na, 12C(14N, p) 25Mg; 10B(14N, α) 20Ne and 10B(14N,12C)12C. The excitation functions have been measured using thin targets of 10–15 μg cm 2 in small energy intervals of 50–100 keV in the region of the Coulomb barrier. The excitation functions show no evidence for correlated structure as measured in the 12C-12C system.

Resonances in the excitation functions of the alpha-particle and proton exit channels of the16O +12C system near the coulomb barrier

Correlated resonances have been found in the excitation functions of the α-particle and proton exit channels of the16O+12C system at energies in the region of the Coulomb barrier. These resonances cannot be explained as statistical fluctuations. There are experimental indications that these resonances may be due to α-particle doorway states.

Phase-shift analysis of 16O + 16O elastic scattering

Abstract A phase-shift analysis of precisely measured elastic 16 O + 16 O data has been carried out in order to establish the existence of molecular resonances between E c.m = 15.5 and 18 MeV and to investigate the possible structure of these resonances.

Transferreaktionen beim beschuss von 10B MIT 16O und 14N

Abstract Differential cross sections for the deuteron and alpha transfer of the reaction 10 B( 16 O, 14 N) 12 C and the deuteron transfer of the reaction 10 B( 14 N, 12 C) 12 C were measured at the Erlangen tandem Van de Graaff accelerator in the energy range from 22.5 to 32.5 MeV (lab). The production of negative ions, the preparation of self-supporting boron targets and the methods of detection and analysis with an on-line computer are described. The angular distributions partially show regular oscillations, which can be interpreted within the framework of the diffraction model of Dar.

Elastische Streuung von16O an9Be,10B und12C

The differential cross sections of the elastic scattering of16O on9Be,10B and12C were measured on-line in the energy range from 26.0 to 32.5 MeV. The reaction products were identified by adE/dx-E-counter telescope. The experimental results were analysed with the aid of the McIntyre model and the optical model. The mutual dependence of the parameters and their influence on the reflection coefficients were investigated within the frame of the optical model. Merely the boundary form of the potentials proved as an essential parameter of the fit. The calculations demanded a description with a very deep absorption potential, which gives the optical model the characteristic features of a diffraction model. The angular distributions at larger angles for16O+10B and16O+12C could be interpreted as contributions of transfer reactions.

Elastic scattering of 13C from 13C

Abstract Angular distributions and excitation functions for 13 C+ 13 C elastic scattering have been measured in the energy range E (lab) = 14.0–27.5 MeV. The angular distributions at E (lab) = 15, 16, 18 and 20 MeV can be described fairly well with the method of molecular wave functions.

Elastische Streuung von 16 O an 9 Be, 10 B und 12 C

The differential cross sections of the elastic scattering of16O on9Be,10B and12C were measured on-line in the energy range from 26.0 to 32.5 MeV. The reaction products were identified by adE/dx-E-counter telescope. The experimental results were analysed with the aid of the McIntyre model and the optical model. The mutual dependence of the parameters and their influence on the reflection coefficients were investigated within the frame of the optical model. Merely the boundary form of the potentials proved as an essential parameter of the fit. The calculations demanded a description with a very deep absorption potential, which gives the optical model the characteristic features of a diffraction model. The angular distributions at larger angles for16O+10B and16O+12C could be interpreted as contributions of transfer reactions.

Elastische Streuung von16O an9Be,10B und12C@@@Elastic scattering of16 O on9 Be,10 B and12 C

The differential cross sections of the elastic scattering of16O on9Be,10B and12C were measured on-line in the energy range from 26.0 to 32.5 MeV. The reaction products were identified by adE/dx-E-counter telescope. The experimental results were analysed with the aid of the McIntyre model and the optical model. The mutual dependence of the parameters and their influence on the reflection coefficients were investigated within the frame of the optical model. Merely the boundary form of the potentials proved as an essential parameter of the fit. The calculations demanded a description with a very deep absorption potential, which gives the optical model the characteristic features of a diffraction model. The angular distributions at larger angles for16O+10B and16O+12C could be interpreted as contributions of transfer reactions.