E. Yu. Nikolskii

Observation of 10He

Abstract The reactions 11 Li + CD 2 → 10 He + X and 11 Li + C → 10 He + X at a beam energy of 61A MeV have been studied by measuring the triple coincidence of 8He and two neutrons. Experimental data show a peak that can be explained as a resonance 10He, which is unbound by 1.2±0.3 MeV and its width is less than 1.2 MeV. Theinvariant mass spectra of 8He+n show a peak that is consistent with the decay 10 He → 8 He + n + n .

Scattering of radioactive nuclei 6He and 3H by protons: Effects of neutron skin and halo in 6He, 8He, and 11Li

In an experimental study of 6He+p and 3H+p collisions at ∼70 A MeV, the elastic scattering angular distributions were measured and the known excited state 6He1.8∗ was observed. Comparative analysis of existing experimental data on proton elastic scattering by 4He, 6He, 6Li, 8He, 9Li, and 11Li was performed. Effects of valence neutrons were investigated using the eikonal approach. A difference between 11Li and 6,8He was found.

Spectroscopy of 12Be and 13Be using a 12Be radioactive beam

Abstract We have studied 12 Be + p elastic and inelastic scattering and observed new levels of 12 Be at E 12 Be ∗ = 8.6, 10 and ∼ 14 MeV in the vicinity of He-emission thresholds, which can be candidates for states having an exotic cluster structure with He-like subsystems. Some new states were tentatively assigned to 13 Be in studies of the d( 12 Be, p) reaction.

Experimental study of 8He + p elastic and inelastic scattering

Abstract An experimental study of 8He + p elastic scattering and a search for 8He∗ as observed in two independent experimental methods. The obtained parameters of the excited state are E 8 He ∗ = 3.57±0.12 MeV , Γ =0.5±0.35 MeV, Γ 4 He+4n /Γ 6 He+n+n ⩽ 5% . Angular distributions for elastic and inelastic scattering are measured. The inelastic angular distribution is consistent with Jπ = 2+ for 8He3.55∗.

The 8He and 10He spectra studied in the (t, p) reaction

The low-lying spectra of 8He and 10He nuclei were studied in the 3H(6He, p)8He and 3H(8He, p)10He transfer reactions. The 0+ ground state (g.s.) of 8He 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 μb/sr, respectively. Some evidence for a 8He state at about 7.5 MeV was obtained. We discuss a possible nature of the nearthreshold anomaly above 2.14 MeV in 8He and relate it to the population of a 1− continuum (soft dipole excitation) with a peak value at about 3 MeV. The lowest energy group of events in the 10He spectrum was observed at ∼ 3 MeV with a cross section of ∼ 140 μb/sr. We argue that this result is consistent with the previously reported observation of 10He providing the new 10He g.s. position at about 3 MeV

Evidences for resonance states in 5H

Resonance states of H-5 were investigated through the two-neutron transfer reaction t(t, P)(5) H. A triton beam at 57.5 MeV and a cryogenic liquid tritium target were used. The H-5 missing mass spectrum in triple coincidence, proton + triton + neutron, shows a resonance at 1.8 +/- 0.1 MeV above the t + 2n decay threshold. This energy is in good agreement with the result reported in Phys. Rev. Lett. 87 (2001) 092501. The resonance width, Gamma(intr) less than or equal to 0.5 MeV, is surprisingly small and difficult to reconcile with theory predictions

Elastic and inelastic scattering of exotic nuclei

Abstract Experimental studies of 11 Li+p, 8 He+p, 6 He+p, 3 H+p, and 14 Be+p at E ∼ 65–75 A MeV are reported. The elastic scattering cross sections are measured. Effects of extended neutron distributions in 11 Li, 8 He, 6 He are investigated. Spectroscopy of 11 Li, 6 He, 14 Be is performed.

Spectroscopy of 13Be

Abstract Six quasi-stationary states of 13 Be populated in the 14 C( 11 B, 12 N) 13 Be reaction at E lab = 190 MeV are reported. A Q -value = −39.60(9) MeV and a mass excess, M.E.= 33.95(9) MeV, have been found for the lowest observed spectral line. The ground state is unstable with respect to one-neutron emission by 0.80(9) MeV. Excitation energies of 1.22(10), 2.10(16), 4.14(12), 5.09(14) and 7.0(2) MeV have been obtained for the observed spectral lines.

24.5 A MeV 6He+p elastic and inelastic scattering

The structure of 6 He is explored with proton elastic and inelastic scattering to the first 2 + excited state (Q =− 1. 8M eV) of 6 He in the inverse kinematics using a 24.5 A MeV 6 He beam. The distorted wave approximation (DWA) with an optical potential obtained by folding an effective nucleon–nucleon (NN) g-matrix with the 6 He density matrix elements as given by a large basis shell model is used to analyse the data. The comparison of predictions with the data confirms the view that 6 He has

New insight into the low-energy

The spectrum of