Observation of the ${}^7$H excited state

Abstract

The ${}^7$H system was populated in the ${}^2$H(${}^8$He,${}^3$He)${}^7$H reaction with a 26 AMeV ${}^8$He beam. The ${}^7$H missing mass energy spectrum, the ${}^3$H energy and angular distributions in the ${}^7$H decay frame were reconstructed. The ${}^7$H missing mass spectrum shows a peak which can be interpreted either as unresolved $5/2^{+}$ and $3/2^{+}$ doublet or one of these states at 6.5(5) MeV. The data also provide indications on the $1/2^{+}$ ground state of ${}^7$H located at 2.0(5) MeV with quite a low population cross section of $\sim 10$ $\hat{I}¼$b/sr within angular range $\hat{I}{¸}_{\text{cm}}\simeq 6^{\circ }-30^{\circ }$.