#beta#-decay of "4"0Ti

The #beta#-decay of "4"0Ti was studied. The Fermi and Gamow-Teller strength function was deduced from the observed #beta#-delayed emission of protons and #gamma#-rays and from the measured half-life of 55(2) ms. The results are compared to shell-model predictions and are used to estimate the neutrino-capture rate of the solar-neutrino detector ICARUS. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beta-decay of "4"0Ti and "4"1Ti and implication for solar-neutrino detection

The #beta#-decay of "4"0Ti and "4"1Ti was studied by measuring the #beta#-delayed proton- and #gamma#-emission. The half-lives for "4"0Ti and "4"1Ti were determined to be 54(2) and 82(3) ms, respectively. The experimental #beta#-decay strengths are compared with shell-model calculations and results from other measurements. The integrated Gamow-Teller strengths for "4"0Ti and "4"1Ti were found to be quenched, compared to the calculations, by factors of 0.79(3) and 0.93(3), respectively. Based on the experimental "4"0Ti #beta#-decay strength, the neutrino absorption cross-section and induced neutrino event rates for "4"0Ar were determined to be 14.3(3) x 10"-"4"3 cm"2 and 9.4#+-#0.2(stat.)_-_1_._6"+"1"."3(syst.) SNU, respectively. (orig.)Available from TIB Hannover: RO 801(98-19) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beta decay of medium and high spin isomers in "9"4Ag

The very neutron-deficient isotope "9"4Ag was produced at the GSI on-line mass separator by using the reaction "5"8Ni("4"0Ca,p3n). The #beta#-decay properties of "9"4Ag were studied by detecting for the first time #beta#-delayed #gamma# rays and #beta#-#gamma#-#gamma# coincidences. Both the population of excited levels in the daughter nucleus "9"4Pd and the #beta#-decay half-life of "9"4Ag were investigated. The major part of the feeding was assigned to the decay of an I"#pi#=(7"+) isomer with a half-life of (0.36#+-#0.03) s. A weak #beta#-decay branch was found to populate high-spin levels in the "9"4Pd daughter with I#>=#18. It is tentatively assigned to the decay of a high-spin parent state in "9"4Ag with I#>=#17 and a half-life (0.3#+-#0.2) s. The measured #beta#-decay properties as well as the level structure of "9"4Ag and "9"4Pd are discussed in comparison with shell-model predictions. (orig.)SIGLEAvailable from TIB Hannover: RO 801(2002-19) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Nuclear structure from N #approx =# Z to N >> Z - "1"0"0Sn, "7"8Ni, "2"0"8Pb

The single particle (hole) energies in "1"0"0Sn, as extrapolated by a shell model analysis of the neighbouring nuclei, show a remarkable similarity to those in "5"6Ni, one major shell lower. This is borne out in nearly identical I"#pi#=2"+ excitation energies, implying E(2"+)#approx =#3 MeV in "1"0"0Sn, and a large neutron effective E2 charge e#>=#1.6e. In contrast a small proton polarisation charge #delta#e#<=#0.3e is found, pointing to a large isovector charge. In "1"0"4Sn for the first time in this region strong E3 transitions with B(E3)#>=#17 Wu were identified, indicating E(3"-)#approx =#3 MeV in "1"0"0Sn. Isomer spectroscopy beyond "6"8Ni following fragmentation of a 60.3 A MeV "8"6Kr beam has provided first evidence on the neutron polarisation charge and the occupation of the #nu#g_9_/_2 orbital beyond N=40, which is at variance with shell model calculations using realistic interactions. The N=40 subshell effect seen in E(2"+) is not borne out in 2n separation energies. On the other hand the #nu#g_9_/_2-f_5_/_2 splitting of single quasiparticle energies in Ni, Fe and Cr isotopes, as deduced from M2 isomers, give no hint for deformation at Z<28, N#approx =#40. In neutron-rich nuclei around "2"0"8Pb a number of new isomers were observed in the fragmentation of a 1000 A MeV "2"3"8U beam, while 3"-excitations on high spin configurations in and adjacent to "2"0"8Pb were identified in inelastic collisions of "2"0"8Pb+"2"0"8Pb. E2 and E3 strengths from stretched configurations are compared to model expectations. (orig.)SIGLEAvailable from TIB Hannover: RO 801(98-41) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Exclusive measurement of breakup reactions with the one-neutron halo nucleus "1"1Be

Electromagnetic and nuclear inelastic scattering of the halo nucleus "1"1Be have been investigated by a measurement of the one-neutron removal channel, utilizing a secondary "1"1Be beam with an energy of 520 MeV/nucleon impinging on lead and carbon targets. All decay products, i.e. "1"0Be fragments, neutrons, and gamma-rays have been detected in coincidence. Partial cross sections for the population of ground and excited states in "1"0Be were determined for nuclear diffractive breakup as well as for electromagnetically induced breakup. The partial cross sections for ground-state transitions have been differentiated further with respect to excitation energy, and the dipole-strength function associated solely with transitions of the halo 2s_1_/_2 neutron to the continuum has been derived. The extracted dipole strength integrated from the neutron threshold up to 6.1 MeV excitation energy amounts to 0.90(6) e"2fm"2. A spectroscopic factor for the #nu#2s_1_/_2 x "1"0Be(0"+) single-particle configuration of 0.61(5) and a root-mean-square radius of the 2s_1_/_2 neutron wave function of 5.7(4) fm have been deduced. (orig.)SIGLEAvailable from TIB Hannover: RO 801(03-21) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Invariant mass spectrum and #alpha# - n correlation function studied in the fragmentation of "6He on a carbon target

Momentum distributions and invariant mass spectra from the breakup of "6He ions with an energy of 250 MeV/u interacting with a carbon target have been studied. The data were used to extract information about the reaction mechanism which is influenced by the structure of "6He. It is found that the dominant reaction mechanism is a two-step process: knock out of one neutron followed by the decay of the "5He resonance. The shape of the (#alpha#+n) two-body invariant mass spectrum is interpreted as mainly reflecting the "5He ground state which is a J "#pi# =3/2"- resonance. However, no evidence for correlations between #alpha# particles and neutrons is observed in the momentum widths of the distributions. It is demonstrated that a combined analysis of the two-body invariant mass spectrum and an appropriate correlation function may be used to determine the properties of the intermediate resonance. (orig.)Available from TIB Hannover: RO 801(97-61) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Searching for the "5H resonance for the t+n+n system

The unbound hydrogen isotopes "4","5H have been studied in the one-proton knockout channel of "6He (240 MeV/u) impinging on a carbon target. The triton fragments originating from this channel were detected in coincidence with neutrons. Relative energy spectra as well as energy and angular correlations have been studied for the t+n and t+n+n systems. The analysis of the energy and angular correlations by the method of hyperspherical harmonic expansion allows to determine the relative weights of the most relevant partial waves in the three-body t+n+n final state. It is shown that the neutrons to a large extent occupy the p-shell and that the I"#pi# = 1/2"+ state is strongly populated as expected for the "5H ground state. No evidence for a narrow resonance in the t+n+n system is obtained, instead a broad structure peaked at 3 MeV above the threshold with about 6 MeV as a full width at half maximum is observed. The two-body t+n system reveals a resonance compatible with earlier results for "4H. (orig.)SIGLEAvailable from TIB Hannover: RO 801(03-10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Large spin alignment of the unbound "5He fragment after fragmentation of 240 MeV/u"6He

Peripheral fragmentation of a 240 MeV/u beam of the halo nucleus "6He incident on carbon target has been studied in a kinematically complete experiment. It is found that one-neutron stripping to the unbound nucleus "5He is the dominant fragmentation mechanism and that it leads to a spin alignment of "5He in a plane perpendicular to the "5He momentum vector. This is expected to be a common feature for all neutron halo nuclei. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman