Unbound isobaric analog states inMn53: The reactionsCr52(He3,d)Mn53andCr52(He3,dp)Cr52

Abstract

The $^{52}\mathrm{Cr}(^{3}\mathrm{He},d)^{53}\mathrm{Mn}$ reaction investigated at 25 MeV incident energy with a split pole spectrometer was used to populate highly excited analog states in $^{53}\mathrm{Mn}$. Fifty-two levels between 6.9 and 12.0 MeV excitation energy were observed in $^{53}\mathrm{Mn}$. The main components of the ${T}_{>}2{p}_{\frac{3}{2}}$, $2{p}_{\frac{1}{2}}$, $1{f}_{\frac{5}{2}}$, and $1{g}_{\frac{9}{2}}$ single-particle strengths were identified. Angular distributions of transitions to 38 unbound-levels in $^{53}\mathrm{Mn}$ have been extracted and analyzed with distorted-wave Born approximation and Gamov functions (as form factors for the transferred proton) to yield the absolute spectroscopic strength. An appreciable amount of the missing $2{p}_{\frac{3}{2}}$, $2{p}_{\frac{1}{2}}$, and $1{f}_{\frac{5}{2}}$ proton ${T}_{<}$ strengths is observed in $^{53}\mathrm{Mn}$ between 7.0 and 8.5 MeV whereas a small fraction of the $1{g}_{\frac{9}{2}}$ and $2{d}_{\frac{5}{2}}$ single-particle orbitals appears between 7.0 and 12 MeV excitation energy. The $^{52}\mathrm{Cr}(^{3}\mathrm{He},dp)^{52}\mathrm{Cr}$ reaction was performed at 24 MeV incident energy using a triplet of magnetic quadrupole lenses. The angular correlations of the emitted protons were measured in coincidence using method II of Litherland and Ferguson with zero degree detection of deuteron groups. Spins, population parameters, and branching ratios of proton partial widths to the ground and excited states of the target were determined for 14 unbound levels in $^{53}\mathrm{Mn}$ from the analysis of the angular correlation data. These two experiments provide a rather complete description of the spectroscopic properties of the analog of the levels of $^{53}\mathrm{Cr}$ up to 5.0 MeV excitation energy. A comparison is made with the previous ($^{3}\mathrm{He},d$), ($p,\ensuremath{\gamma}$), ($p,p$), and ($d,p$) results on the same target. Components of the $^{53}\mathrm{Cr}$ parent states which consist of a neutron coupled to an excited state of the $^{52}\mathrm{Cr}$ nucleus are also determined.NUCLEAR REACTIONS $^{52}\mathrm{Cr}(^{3}\mathrm{He},d)$, $E=25$ MeV; measured $\ensuremath{\sigma}({E}_{d},\ensuremath{\theta})$, $^{52}\mathrm{Cr}(^{3}\mathrm{He},dp)$, $E=24$ MeV; measured $\ensuremath{\sigma}({E}_{d},{E}_{p},{\ensuremath{\theta}}_{p})$. $^{53}\mathrm{Mn}$ deduced IAS, $L$, $J$, $\ensuremath{\pi}$, $S$, ${\ensuremath{\Gamma}}_{p}$, proton branching. $^{53}\mathrm{Cr}$, $^{53}\mathrm{Mn}$ analog pairs deduced Coulomb displacement energies. DWBA analysis using Gamov functions as form factors. Natural targets.