Resonance states of superheavy hydrogen nuclei obtained in transfer reactions with exotic beams

A resonance state situated at 1.8 ± 0.1 and, most likely, another state positioned at 2.7 ± 0.1 MeV above the t+n+n decay threshold were observed in the missing mass energy spectrum of the 5H nucleus produced in the reaction 3H(t,p) 5H. The peak located close to E 5 ≈ H = 1.8 MeV also was seen in the 5H spectrum obtained from the energy distributions of 3H nuclei emitted in the reaction 2H( 6He, 5H) 3He. The width ( ≤ obs ≤ 0.5 MeV) obtained for the two 5H resonance states is surprisingly small. A state of 4H with E res = 3.3 MeV and γ 2 = 2.3 MeV was obtained in the reaction 2H(t,p) 4H from the proton spectrum.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

Resonance States of Hydrogen Nuclei 4H and 5H Obtained in Transfer Reactions with Exotic Beams

To investigate 5H resonance states with a better instrumental resolution, we utilized the two-neutron transfer reaction 3H(t, p)5H 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 θlab = 18°-32° in ptn coincidence events was attributed to the states of the 5H nucleus. Two resonance states situated at 1.8 plusmn; 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 5H nucleus. The peak located close to E5H = 1.8 MeV was clearly seen in the H spectrum obtained from the energy distributions of 3H nuclei emitted in the reaction 2H(6He, 5H)3He at θ lab = 17°-32°. The width (Γobs ≤ 0.5 MeV) obtained for the two 5H resonance states is surprisingly small. A state of 4H with Eres = 3.3 MeV and γ2 = 2.3 MeV was obtained in the reaction 2H(t, p)4H from the spectra of protons leaving the target at θlab = 18°-32° and detected in coincidence with neutrons emitted in the decay of 4H nuclei. © 2003 MAIK "Nauka/Interperiodica".SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Study of complete and incomplete fusion for loosely bound projectiles 6He and 6Li on 165Ho and 166Er targets

Complete fusion (CF) and incomplete fusion (ICF) reactions were studied for the cases of the loosely bound 6He and 6Li projectiles bombarding 166Er and 165Ho targets at energy of about 10 MeV/nucleon. Experiments were carried out to test an approach exploiting the measured intensities of γ rays emitted at the transitions between the yrast-band levels of reaction products formed after the termination of neutron evaporation. Partial waves feeding the CF reactions 165Ho ( 6Li, 5n) 166Yb and 166Er( 6He, 6n) 166Yb as well as ICF 165Ho ( 6Li, α3n) 164Er and 166Er( 6He, α4n) 164Er reaction channels were revealed from the obtained γ-ray data. The method of exit channel identification via the triple coincidence (γ1-γ2-light charged particle) was employed for these reactions study. © 2012 Pleiades Publishing, Ltd.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Low-energy spectra of 8He and 10He studied in (t,p) type reactions in inverse kinematics

Missing mass spectra for 8He and 10He obtained in the reactions 3H( 6He, p) 8He and 3H( 8He, p) 10He, respectively, are presented.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Properties of very n-rich He isotopes

Low-energy spectra of the 8,10He nuclei were investigated in the (t, p) -type reactions at small centre-of-mass angles using ̃ 25 AMeV beams of 6He and 8He nuclei. The 0+ ground state (g. s.) of 8He and excited states, 2+ at 3. 6-3. 9MeV and (1+) at 5. 3-5. 5MeV, were populated with cross-sections of 200, 100-250, and 90-125μb/sr, respectively. To account for a near-threshold anomaly observed in the 8He spectrum the population of a 1- continuum (soft dipole excitation) was considered. The lowest-energy group of events in the 10He spectrum was observed at ̃ 3 MeV with a cross-section of ̃ 140 μb/sr. This result is consistent with the previously reported observation of 10He providing a new g. s. position for 10He at about 3MeV. © Societá Italiana di Fisica / Springer-Verlag 2009.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Complete and Incomplete Fusion of6He and6Li Projectiles with Medium Mass Targets at Energy ∼10 AMeV

Complete fusion (CF) and incomplete fusion (ICF) reactions were studied with the beams of loosely bound 6He and 6Li bombarding 166Er and 165Ho targets. Experiments were carried out to test an approach exploiting the measured intensities of y rays emitted at the transitions between the yrast-band levels of reaction products formed after the termination of neutron evaporation. Partial waves feeding the CF [ 165Ho(6Li,5n)166Yb, 166Er( 6He,6n)166Yb] and ICF [165Ho( 6Li,α3n)164Er, and 166Er( 6He,α4n)164Er] reaction channels were revealed from the obtained γ-ray data. © 2009 American Institute of Physics.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Soft dipole mode in 8He

The low-lying spectrum of 8He was studied in the 3H(6He, p)8He transfer reaction for small center of mass angles. 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. Some evidence for the excited state at about 7.5 MeV can be found in the data. The possible nature of the near-threshold anomaly above 2.14 MeV in 8He is related to the population of a 1- continuum (soft dipole excitation) with a peak energy value at about 3 MeV. This assumption can probably resolve the problem of a large uncertainty existing in the experimental data on the 8He 2+ state energy. © Pleiades Publishing, Ltd. 2009.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

New insights into the resonance states of 5H and 5He

The 5H system was produced in the 3H(t, p) 5H reaction studied at small CM angles with a 58MeV tritium ion beam. High statistics data were used to reconstruct the energy and angular correlations between the 5H decay fragments. A broad structure in the 5H missing-mass spectrum showing up above 2.5MeV was identified as a mixture of the 3/2+ and 5/2+ states. The data also present an evidence that the 1/2+ ground state of 5H is located at about 2MeV. Then, the 5H and 5He systems were explored by means of transfer reactions occurring in the interactions of 132MeV 6He beam nuclei with deuterium. In the 2H( 6He, 3H) reaction a T = 3/2 isobaric analog state of 5H in 5He was observed at an excitation energy of 22.0±0.3MeV with a width of 2.5±0.3MeV. © Società Italiana di Fisica / Springer-Verlag 2005.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

Correlation studies of the H5 spectrum

The nuclear system H5 was studied using the H3(t,p)H5 transfer reaction at a laboratory energy of 57.7 MeV and small center of mass angles. The energy and angular correlations among the H5 decay fragments were obtained by complete kinematical reconstruction. A broad structure in the H5 missing mass spectrum above 2.5 MeV with a typical width of several MeV was identified as a mixture of 3/2+ and 5/2+ states. Analysis of interference patterns observed in the measured angular correlations disclosed the 1/2+ ground state of H5 concealed in the smooth missing mass spectrum. The deduced values for the resonance energy and width are Eg.s. 1.8 MeV and Γg.s. 1.3 MeV. The estimated cross sections for population of the ground state and the doublet of excited states at θc.m.=5°-10° are 150±50 μb/sr and 4.6±2 mb/sr, respectively. © 2005 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Identification of levels in162,164Gd and decrease in moment of inertia between N = 98-100

From prompt γ-γ-γ coincidence studies with a 252Cf source, the yrast levels were identified from 2+ to 16+ and 14+ in neutron-rich 162,164Gd, respectively. Transition energies between the same spin states are higher and moments of inertia lower at every level in N = 100 164Gd than in N = 98 162Gd. These observations are in contrast to the continuous decrease in the 2+ energy to a minimum at neutron midshell (N = 104) in Er, Yb and Hf nuclei. Mean-field calculations of the deformations do not follow the data, but give a smooth increase in β2 deformation to N = 102 for Gd nuclei.SCOPUS: ar.jinfo:eu-repo/semantics/publishe