First measurement of #beta#-decay properties of the drip-line nucleus "6"0Ga

By using the fusion-evaporation reaction "2"8Si("3"6Ar,p3n) and spectroscopy of #beta#-delayed #gamma# rays and charged particles on mass-separated sources, #beta#-decay properties of the neutron-deficient isotope "6"0Ga were studied for the first time. The half-life of "6"0Ga was determined to be 70(15) ms, and, based on #beta#_#gamma#_#gamma# coincidences, the isobaric-analogue state in "6"0Zn was identified at 4851.9(7) keV. A semiempirical proton separation energy value of 70(70) keV was deduced for "6"0Ga. The experimental results on half-life, mass excess, proton separation energy, and structure of the "6"0Zn daughter states are discussed in comparison with various model predictions, including large scale shell model calculations. (orig.)Available from TIB Hannover: RO 801(2001-27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Recent experiments on N#approx =#Z nuclei, performed at the GSI on-line mass separator Contributions to the international workshop

The high-spin investigation of "5"2Fe (N=Z=26) presents a particular difficulty due to the presence of a 12"+ isomer, with T_1_/_2=45.9(6) s which acts as a ''trap'' for the de-exciting #gamma#-ray flux. In this contribution we present results from our investigations on the #gamma# and #beta# decays of the 12"+ isomer performed at the GSI on-line mass separator. The excitation energy and precise #gamma#-de-excitation branching ratios per parent decay have been established and are compared with the large-scale shell-model calculations performed with the KB3G and FPD6 interactions. (orig.)Available from TIB Hannover: RO 801(2000-23) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Study of the #beta#-decays of "3"7Ca and "3"6Ca

The #beta#-delayed proton and #gamma#-ray emission of "3"7Ca and "3"6Ca was studied at the projectile fragment separator at GSI Darmstadt. In the "3"7Ga study, the #beta#-delayed #gamma#-decay was observed for the first time, and the half-life was redetermined, under essentially background-free conditions, as 181.1#+-#1.0 ms. The surprisingly high #GAMMA#_#gamma#/#GAMMA#_p values found for proton-unbound states in "3"7K drastically reduce former discrepancies between the Gamow-Teller strength value B(GT) measured in the "3"7Ca #beta#-decay and those deduced from the "3"7Cl(p, n)"3"7Ar mirror reaction. Our data provide evidence, on a level of 1.6 standard deviations, for isospin-mixing of the lowest T=3/2 level in "3"7K. In the "3"6Ca study, a complete #beta#-decay scheme, including the #beta#-delayed proton emission into the ground and first excited states of "3"5Ar as well as the #beta#-delayed #gamma#-decay, was measured for the first time. The "3"6Ca half-life was remeasured with improved accuracy to be 102#+-#2 ms. Our data exclude a 1"+ assignment for two near-threshold states in "3"6K that could be important resonances in "3"5Ar(p, #gamma#) reactions of astrophysical interest. The B(GT) distributions in "3"7","3"6Ca decays are compared to results obtained from large-scale sd shell-model calculations. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beta-decay of "5"6Cu

By measuring positrons and #beta#-delayed #gamma#-rays emitted from mass-separated sources, the decay of "5"6Cu(4"+,T_z=-1,T=1) to states in the doubly-magic nucleus "5"6Ni was studied for the first time. The half-life of "5"6Cu was measured to be 78(15) ms, and four #beta#-delayed #gamma#-rays were assigned to its decay. The resulting experimental data on Fermi and Gamow-Teller strength are compared with shell-model predictions. (orig.)Available from TIB Hannover: RO 801(98-12) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Production and identification of heavy Ni isotopes: Evidence for the doubly magic nucleus "7"8_2_8Ni Short note

We report the first observation of the doubly magic nucleus "7"8Ni_5_0 and the heavy isotopes "7"7Ni, "7"3","7"4","7"5Co, "8"0Cu. The isotopes were produced by nuclear fission in collisions of 750 A.MeV projectiles of "2"3"8U on Be target nuclei. The fully-stripped fission products were separated in-flight by the fragment separator FRS and identified event-by-event by measuring the magnetic rigidity, the trajectory, the energy deposit, and the time of flight. Production cross-sections and fission yields for the new Ni-isotopes are given. (orig.)Available from TIB Hannover: RO 801(95-35) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beta-delayed proton decay of a high-spin isomer of "9"4Ag

We have observed the high-spin states in "9"3Rh populated by delayed-proton emission following the #beta# decay of "9"4Ag. The existence of a second isomer in "9"4Ag with I#>=#17, T1/2=0.42(5) s, whose #beta#-decay energy is at least 15.5 MeV, has been established. This state features most likely the highest spin ever observed for #beta#-decaying nuclei. (orig.)SIGLEAvailable from TIB Hannover: RO 801(03-08) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Beta decay of the new isotope "1"0"1Sn

The very neutron-deficient isotope "1"0"1Sn has been produced in a "5"0Cr("5"8Ni, 2p5n) reaction and its decay has been studied for the first time. Energy and time spectra of beta-delayed protons emitted from samples that were prepared by using chemically selective ion sources of an on-line mass separator have been measured. The half-life of "1"0"1Sn was determined to be 3#+-#1 s. The results obtained are compared to theoretical predictions. (orig.)SIGLEAvailable from TIB Hannover: RO 801(94-47) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Gamow-Teller strength in the beta-decay of "3"7Ca and its implications for the detection of the solar neutrino flux

We have studied the #beta#-decay of "3"7Ca at the projectile fragment separator FRS and GSI Darmstadt. The resulting Gamow-Teller strength function B(GT) which is important for determining the detection efficiency of the Homestake mine "3"7Cl detector is significantly changed by the inclusion of previously unobserved #beta#-delayed #gamma#-rays. With the new results former discrepancies between the B(GT) values measured in the "3"7Ga #beta#-decay and those extracted from "3"7Cl(p, n)"3"7Ar reactions are drastically reduced. Additionally, our data yield evidence for an isospin-forbidden Fermi transition in the #beta#-decay of "3"7Ca. (orig.)SIGLEAvailable from TIB Hannover: RO 801(94-67) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Gamow-Teller strength in the #beta#-decay of "3"6Ca

The #beta#-decay of "3"6Ca has been studied at the projectile fragment separator at GSI Darmstadt. The Gamow-Teller strength function B(GT), deduced from the observed #beta#-delayed proton- and #gamma#-emission and from the measured half-life of 102(2) ms, is compared to results obtained from large-scale sd-shell model calculations. (orig.)SIGLEAvailable from TIB Hannover: RO 801(94-84) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Decay studies of the neutron-deficient isotopes "1"1"4"-"1"1"8Ba

Radioactivity "1"1"4","1"1"5","1"1"6Ba [from "5"8","6"0Ni("5"8Ni, xn), E=3.5-4.3 MeV/u]; "1"1"6","1"1"7","1"1"8Ba [from "6"3Cu("5"8Ni, pxn), E=4.3-4.9 MeV/u]; Measured E_p, I_p, E_#gamma#, I_#gamma#, #gamma##gamma#-coin, T_1_/_2; deduced cross-sections. Ge, Si, scintillator detectors, on-line mass separation. (orig.)Available from TIB Hannover: RA 801(97-36) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman