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To investigate [sup 5]H resonance states with a better instrumental resolution, we utilized the two-neutron transfer reaction [sup 3]H(t,p)[sup 5]H accomplished with the use of a cryogenic liquid-tritium target and 57.5-MeV triton beam. As a result of this study, a valuable fraction of protons detected at θ[sub lab]=18[sup °]–32[sup °] in ptn coincidence events was attributed to the states of the [sup 5]H nucleus. Two resonance states situated at 1.8±0.1 and 2.7±0.1 MeV above the t+n+n decay threshold were obtained in the missing mass energy spectrum of the [sup 5]H nucleus. The peak located close to E[sub [sup 5]H]=1.8 MeV was clearly seen in the [sup 5]H spectrum obtained from the energy distributions of [sup 3]H nuclei emitted in the reaction [sup 2]H([sup 6]He, [sup 5]H)[sup 3]He at θ[sub lab]=17[sup °]–32[sup °]. The width (Γ[sub obs]≤0.5 MeV) obtained for the two [sup 5]H resonance states is surprisingly small. A state of [sup 4]H with E[sub res]=3.3 MeV and γ[sup 2]=2.3 MeV was obtained in the reaction [sup 2]H(t, p)[sup 4]H from the spectra of protons leaving the target at θ[sub lab]=18[sup °]–32[sup °] and detected in coincidence with neutrons emitted in the decay of [sup 4]H nuclei.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The angular distribution of 26 MeV/n 8He ions elastically scattered from a gaseous helium target was measured in a wide CM angular range. Results are discussed in terms of the potential scattering and neutron transfer. The angular distributions of elastic scattering as well as 1n and 2n transfer reactions of these ions on protons are presented. Finite-range DWBA calculations made for the 2n transfer reaction leading to the ground (0+) and excited (2+) states of 6He underestimate the cross section for 2n transfer to 6He(0+). Analysis of data for this reaction channel suggests the importance of a direct 5H-cluster exchange process. A resonance state of 5H with an energy of 2 MeV above the decay threshold n+n+ 3H was obtained for the first time by making use of the reaction p(6He,2He)5H. [ABSTRACT FROM AUTHOR]

The 0+ ground state of the 10He nucleus produced in the 3H(8He, p)10He reaction was found at about 2.1 ± 0.2 MeV (T ∼ 2 MeV) above the three-body 8He + n + n breakup threshold. Angular correlations observed for 10He decay products show prominent interference patterns allowing us to draw conclusions about the structure of low-energy excited states. We interpret the observed correlations as a coherent superposition of a broad 1 state having a maximum at energy 4-6 MeV and a 2+ state above 6 MeV, setting both on top of the 0+ state "tail." This anomalous level ordering indicates that the breakdown of the N = 8 shell known in 12Be thus extends also to the 10He system. [ABSTRACT FROM AUTHOR]