Investigation of J=1 states and their γ -decay behavior in Cr52

Background: In the $A\ensuremath{\approx}50$ mass region $M1$ spin-flip transitions are prominent around 9 MeV. An accumulation of ${1}^{\ensuremath{-}}$ states between 5 and 8 MeV generating additional $E1$ strength, also denoted as pygmy dipole resonance, has been established in many nuclei with neutron excess within the last decade.Purpose: The $\ensuremath{\gamma}$-decay behavior of $J=1$ states has been investigated in an NRF experiment. $M1$ excitations have been compared to shell model calculations.Methods: $J=1$ states were excited by quasi-monoenergetic, linearly polarized $\ensuremath{\gamma}$-ray beams generated by laser-Compton backscattering at the $\mathrm{HI}\ensuremath{\gamma}\mathrm{S}$ facility, Durham, NC, USA. Depopulating $\ensuremath{\gamma}$ rays were detected with the multidetector array ${\ensuremath{\gamma}}^{3}$.Results: For eleven beam-energy settings the $\ensuremath{\gamma}$-decay behavior of dipole states was analyzed by a state-to-state analysis and average $\ensuremath{\gamma}$-decay branching ratios have been investigated. 34 parity quantum numbers were assigned to $J=1$ states.Conclusions: Six ${1}^{\ensuremath{-}}$ states and two ${1}^{+}$ states have been investigated in NRF experiments for the first time. The $M1$ strength distribution is in good agreement with shell-model calculations.