Role of cross-shell excitations in the reaction 54Fe(d_pol,p)55Fe

TL;DR

This study investigates the role of cross-shell excitations in the 54Fe(d_pol,p)55Fe reaction, revealing that including up to 6 particle excitations across the N=28 gap improves agreement with experimental data, especially below 2.5 MeV.

Contribution

It demonstrates the importance of cross-shell excitations in shell model calculations for accurately describing 55Fe states.

Findings

Reasonable agreement for energies and spectroscopic factors below 2.5 MeV when including up to 6 particle excitations.

Experimental strength distribution above 2.5 MeV is more fragmented than shell model predictions.

Cross-shell excitations are crucial for understanding nuclear structure in this region.

Abstract

The reaction 54Fe(d_pol,p)55Fe was studied at the Munich Q3D spectrograph with a 14 MeV polarized deuteron beam. Excitation energies, angular distributions and analyzing powers were measured for 39 states up to 4.5 MeV excitation energy. Spin and parity assignments were made and spectroscopic factors deduced by comparison to DWBA calculations. The results were compared to predictions by large scale shell model calculations in the full pf-shell and it was found that reasonable agreement for energies and spectroscopic factors below 2.5 MeV could only be obtained if up to 6 particles were allowed to be excited from the f_7/2 orbital into p_3/2, f_5/2, and p_1/2 orbitals across the N=28 gap. For levels above 2.5 MeV the experimental strength distribution was found to be significantly more fragmented than predicted by the shell model calculations.