Photon scattering off 52Cr: Two-phonon E1 strength at the N = 28 shell closure?

• Published in: Nuclear physics. A 1998-06, Vol.636 (2), p.139-155
• Main Authors: Enders, J., von Brentano, P., Eberth, J., Herzberg, R.-D., Huxel, N., Lenske, H., von Neumann-Cosel, P., Nicolay, N., Pietralla, N., Prade, H., Reif, J., Richter, A., Schlegel, C., Schwengner, R., Skoda, S., Thomas, H.G., Wiedenhöver, I., Winter, G., Zilges, A.
• Format: Article
• Language: English
• Subjects: Nuclear reactions
• ISSN: 0375-9474
• DOI: 10.1016/S0375-9474(98)00213-9

Results of a natCr(γ,γ′) experiment at the S-DALINAC are reported for energies up to 7 MeV utilizing a Euroball Cluster detector. The excitation of a J = 1 state at 5544 keV is observed which is believed to belong to 52Cr because of the strength of the signal and the large natural abundance. By a variety of empirical arguments a quadrupole-octupole-coupled two-phonon 1 − character is suggested for this transition. Quasiparticle random-phase approximation (QRPA) calculations are able to reproduce the energy and B(E1) transition strength remarkably well. The underlying microscopic structure is suggested to be more complex than a pure two-phonon picture. Furthermore, the calculations indicate a pure neutron ( 2p 3 2 −12p 1 2 ) magnetic dipole structure for an excitation experimentally seen at 5098 keV which would provide a direct measure of ground-state correlations in 52Cr.