Fp-shell Nuclei Research Articles

Excitation of the N = 28 Core in 53Mn

The structure of 53Mn is examined using a shell model basis of f7/2−2 and all f7/2−4j states, with an effective interaction derived from previous studies of fp shell nuclei. With few exceptions, the lowest one particle, four hole states are found to be predominantly neutron excitations, which make up over 99% of the lowest J = 13/2 level. The calculation successfully accounts for the observed high spin states, but comparison with experiment strongly suggests that two particle excitations from the f7/2 shell are the dominant configuration of several states lying below 3.5 MeV.

Possible nuclear structure effects seen in ( 6Li, d) f-p shell reactions

A finite range DWBA analysis has been made of ground state angular distributions from ( 6Li, d) experiments on twelve fp shell nuclei at 28 or 32 MeV. Good fits were obtained. A systematic variation in bound-state radius was required. The interpretation of this effect using microscopic wavefunctions suggests that four-nucleon structure information may be obtained from the shapes of the angular distributions.

Are there low-lying, intrashell-excited, highly deformed states in the 1f-2p shell nuclei?

It is shown that the improved effective interactions in the fp shell imply the existence of an excited band of states which is much more deformed than the ground state band for some fp shell nuclei. Such states are to a certain extent analogous to the fission isomers occurring in heavy nuclei. Their experimental identification would be interesting and might also help to further improve the effective interaction.

Das Niveauschema von 47V aus dem γ-zerfall von Analogresonanzen

A high-accuracy investigation of the level scheme of 47V has been performed using the 46Ti(p, γ) 47V reaction. The γ-decay schemes of the strong (p, γ) resonances at E p = 1546, 1549, 1565 and 1572 keV lead to 17 new energy levels in 47V with excitation energies between 2.7 and 5.1 MeV. From the (p,γ) angular distributions mixing ratios of the primary γ-transitions and J π values of the resonances and of many states populated in the γ-decay have been determined. The total width of the E p = 1549, 1565 and 1572 keV resonances for γ-decay are found to be Γ γ = 0.12, 0.15 and 0.03 eV, respectively. The Q-value of the 46Ti(p,γ) 47V reaction is found to be 5168.6 keV. The two resonances at E p = 1549 and 1565 keV, which have J π = 3 2 − , are interpreted as fine structure components of the analogue state of the E ∗ = 2.545 MeV J π = 3 2 − level in 47Ti while the ( 7 2 ) resonance at E p = 1546 keV might correspond to the E ∗ = 2.615 MeV 7 2 − parent state in 47Ti. The analogue-antianalogue M1 transition strength of the split 3 2 − analogue state is 0.01 single-particle units and fits well into our systematics of IAS → AIAS transitions in fp-shell nuclei.

Quartet states in the sd and fp shells

Two-proton-two-neutron correlations are studied in psd and fp shell nuclei in the frame of the aligned scheme approximation. Four-particle rotational states are obtained in terms of linear combinations of projected aligned Slater determinants and the resulting excitation energies and wave functions are compared with those of elaborate shell-model calculations. The close agreement obtained both for single j-shell and complete shell configuration spaces shows that rotational or quasi-rotational states are almost entirely generated by aligned configurations. The lowest four-particle states obtained in one j-shell can be explained as the rotational spectrum of an oblate intrinsic state. The lowest four-particle states of 16O, 20Ne, 44Ti and 60Zn, calculated in a major shell, correspond to the rotational spectrum of a prolate intrinsic state and fit the existing data. Higher states are the result of a mixed deformation.