N. Anantaraman

An effective interaction for inelastic scattering derived from the Paris potential

An effective interaction for inelastic scattering of nucleons from nuclei is derived by fitting oscillator G-matrix elements of the Paris nucleon-nucleon potential to the matrix elements of a sum of Yukawa terms. Except for the singlet-odd channel, these G-matrix elements do not differ in any significant respect from those obtained from the Reid soft-core potential, and give similar results for inelastic proton scattering.

Systematics of the excitation of M1 resonances in medium heavy nuclei by 200 MeV proton inelastic scattering

Abstract In a series of seventeen nuclei ranging from 51 V to 14 Ce, broad resonance structures are observed at energies between 8 and 10 MeV, nearly mass independent. These resonances have very forward peaked angular distributions which imply that they are populated by an angular momentum transfer of zero. This together with the observed excitation energies suggests an M1 character for these resonances. In 51 V, 58 Ni, 60 Ni, 62 Ni, a sharp peak located at an excitation energy above the threshold for neutron emission is interpreted as a part of the T 0 + 1 component of the M1 resonance. Cross sections are given for all the M1 resonances. For 58 Ni, 90 Zr, 92 Mo, 120 Sn and 140 Ce, an “attenuation” factor for the cross sections is extracted in a DWIA calculation assuming simple shell-model structures for these resonances.

Excitation of ΔL = 0 spin-flip transitions in the N = 28 isotones by 201 MeV proton inelastic scattering

Abstract The excitation of 1 + states by inelastic scattering of 201 Me V protons, studied previously on the N = 28 nuclei 48 Ca and 51 V, has been pursued on 50 Ti, 52 Cr and 54 Fe; for the three latter nuclei, many sharp states are observed which have a very forward-peaked angular distribution characteristic of a ΔL = 0 transition. The results agree reasonably well with (e, e) measurements. A comparison with ( γ−1 , γ) results demonstrated the 1 + nature of these states. The data are compared with DWIA calculations performed using the shell-model wave functions of Metsch and Knupfer. This comparison indicates that he isoscalar excitations are probably weaker than predicted. The ratio of experimental to predicted cross sections ranges from 0.25 for 50 Ti to 0.44 for 54 Fe.

Proton excitation of the M1 resonances in the Ni isotopes

Abstract The giant M1 excitation has been studied by inelastic scattering of 200 MeV protons from the four isotopes 58, 60, 62, 64Ni isotopes, structures assigned to the To and the To + 1 components of the M1 resonance are excited ; their relative strengths are compared with those obtained in (ee) and (γγ ) experiments when available. The strength of the isovector part of the M1 resonance in 58Ni is compared to theoretical predictions

Excitation of M1 strength in N=28 isotones by inelastic proton scattering at 200 MeV

High-energy inelastic proton scattering at very forward angles has been found to selectively excite M1 states. This reaction has been used to study the M1 strength distribution in the N-28 isotones /sup 48/Ca, /sup 50/Ti, /sup 51/V and /sup 54/Fe. The measurements were performed with a beam of 201 MeV protons from the Orsay synchrocyclotron. 2 references.

Observation of M1 Strength in Medium-Heavy Nuclei via the (p,p′) Reaction

A broad resonance has been observed by inelastic scattering of 200 MeV protons from 51V, 58,60,62Ni, 68Zn, 90,92,94,96Zr, 92,94,96,98,100Mo, 120,124Sn and 140Ce. The resonance occurs between 8 and 9 MeV in most of the nuclei and has a width of around 2 MeV. In all cases, the angular distribution is very sharply forward peaked and is consistent with an orbital angular momentum transfer of zero. The excitation energy, angular distribution and strength of the resonance suggest that it is the giant M1 resonance. In the nickel isotopes, and in 51V, both the To and To+1 components of the resonance are observed.