Backward-angle high-resolution inelastic electron scattering on 40, 42, 44, 48Ca and observation of a very strong magnetic dipole ground-state transition in 48Ca

Magnetic excitations in nuclei with neutron excess

“…The main features pointed out in the discussion regarding the oxygen isotopes have been found also in this case. The B(M1)↑ values of the 40 Ca and 60 Ca isotopes are orders of magnitude smaller than those obtained in 48 Ca and 52 Ca. In this case, the cause of the effect is the occupancy of the 1f spin-orbit partner s.p.…”

“…levels. They are both empty in 40 Ca, and occupied in 60 Ca, while for the other two nuclei the (1f 7/2 ) −1 level is occupied, while the (1f 5/2 ) level is empty. The 1 + transition between these two levels is allowed and this produces the increase of the strength of various order of magnitude in 48 Ca and 52 Ca.…”

“…For this reason, we have chosen to study four oxygen isotopes, 16 O, 22 O, 24 O and 28 O, and four calcium isotopes, 40 Ca, 48 Ca, 52 Ca and 60 Ca, where the s.p. levels below the Fermi surface are fully occupied.…”

High-resolution study of Gamow-Teller excitations in theCa42(He3,t)Fujita1, Fujita2, Adachi3 et al. 2015Phys. Rev. C4391090View full textAdd to dashboardCite

“…A state excited in an M 1 transition with a strength of B(M 1) = 0.59(5)µ 2 N is reported at 11.235 MeV in an electron inelastic scattering experiment on a 42 Ca target [65]. This B(M 1) value corresponds to the excitation with a B(GT) ≈ 0.19 [4] in the 42 Ca( 3 He, t) 42 Sc reaction if we assume that the 11.235 MeV state has T = T 0 = 1 and that the state is mainly excited by the στ term of the electro-magnetic M 1 operator.…”

States in 40Ca near 12 MeV Excitation from the 39K(p, g)40Ca Reaction

“…For example, in (p, p') studies at a bombarding energy of 201 MeV and at very forward angles which select only a few states, Crawley et al (1982) and Anantaraman et al (1981 and personal communication) noted a state at 12'063±0'015 MeV which has a AI = 0 angular distribution and a strength similar to the known 1 + state at 10· 32 MeV. However, in measurements of electron inelastic scattering at backward angles, carried out with good resolution, Steffen et al (1980) and Gross et al (1979) claimed no state with any measurable strength at an excitation energy near 12 MeV. At least three explanations are possible.…”