The ${}^8$He and ${}^{10}$He spectra studied in the $(t$,$p)$ reaction

Abstract

The low-lying spectra of ${}^8$He and ${}^{10}$He nuclei were studied in the ${}^3$H(${}^6$He,$p$)${}^8$He and ${}^3$H(${}^8$He,$p$)${}^{10}$He transfer reactions. The $0^{+}$ ground state (g.s.) of ${}^8$He and excited states, $2^{+}$ at $3.6-3.9$ MeV and $(1^{+})$ at $5.3-5.5$ MeV, were populated with cross sections of 200, 100-250, and 90-125 $\mu$b/sr, respectively. Some evidence for ${}^8$He state at about 7.5 MeV is obtained. We discuss a possible nature of the near-threshold anomaly above 2.14 MeV in ${}^8$He and relate it to the population of a $1^{-}$ continuum (soft dipole excitation) with peak value at about 3 MeV. The lowest energy group of events in the ${}^{10}$He spectrum was observed at $\sim 3$ MeV with a cross section of $\sim 140$ $\mu$b/sr. We argue that this result is possibly consistent with the previously reported observation of ${}^{10}$He, in that case providing a new g.s. position for ${}^{10}$He at about 3 MeV.

arXiv comment18 pages, 8 figures, submitted to Phys. Lett. B

References in corpus (4)

• Quantum Monte Carlo calculations of excited states in A = 6--8 nuclei
• Discrete and continuum spectra in the unified shell model approach
• New insight into the low-energy ${}^9$He spectrum
• Problems with interpretation of ${}^{10}$He ground state

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