Investigation of the Excited States of⁴⁰Ca by the (p, p') Reaction at 185 MeV

Abstract

In an experiment on inelastic scattering of 185 MeV protons from 40Ca differential cross sections have been determined for scattering from individual excited states of the target nucleus. The measurements have been extended over the angular range 4° to 40° (lab. system), and the results are presented in the form of angular distributions of the most prominent peaks in the energy spectra. The identification with known states of 40Ca is made by the determination of the excitation energy, and, in the cases where the energy resolution (approximately 250 keV, FWHM) is not sufficient, by the shape of the angular distributions. The results are compared with previously published measurements on other nuclei at the same incoming proton energy as well as with inelastic scattering data at lower energies. In particular, it is shown that the results on the two closed-shell nuclei 16O and 40Ca are very similar and that these nuclei behave differently from other 1p- and 2s-1d shell nuclei studied.

Scattering of 185 MeV Protons from90Zr

“…The corresponding state is the one most strongly excited at this proton energy, and it has been described as a highly collective vibration [81. Again this resembles W a [15] and l6O [14] where the excitation of a 3level dominates (Table V). As pointed out by Kallne et al [15], Physica Scripta 3 this is not the case for [14], 24Mg [29] and 28Si 1301 where a 2+ level dominates in the spectra.…”

“…Again this resembles W a [15] and l6O [14] where the excitation of a 3level dominates (Table V). As pointed out by Kallne et al [15], Physica Scripta 3 this is not the case for [14], 24Mg [29] and 28Si 1301 where a 2+ level dominates in the spectra.…”

“…In earlier experiments at this Institute the first excited 0-states in l*C [14], **Mg [29] and *SS [30] have been observed. However, in l60 [I41 and 40Ca [15] the O+ states are hardly excited at all. In this respect 90Zr is seen to behave in the same way as l0Ca and leO.…”

Polarization in the Excitation of the 3-Level at 3.74 MeV in40Ca by 185 MeV Protons

“…For small scattering angles the relative intensity could be obtained quite accurately from the cross sections determined in ref. 5 and considering the actual overlap of the 3-and 2+ levels in the recorded spectra for the spectrometer setting used. As can be seen from Table I the background from the 2+ level could be kept very low and never exceeded 15 Yo in the angular region bslow 25'.…”

“…Guided by these spectra, and the spectra and cross sections obtained in ref. 5 we could choose a spectrometer setting which favoured the peak to be measured with regard to adjacent structure in the spectra. The separation problem is further discussed in section 4.…”