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

Investigation of the new isotope "1"7"2Ho and of "1"7"4Er

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

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

The beta-decay of "2"0Mg and its implications for the astrophysical rp-process

We have studied the #beta#-delayed proton and #gamma#-decay of "2"0Mg, produced by means of 95 MeV/u "2"4Mg+Ni reactions and implanted into a detector array after electromagnetic separation at GANIL. The experimental data obtained for excitation energies, #beta#-decay branching ratios, log-ft values and J"#pi#-assignments are given. No feeding has been observed to the 2646 keV state in "2"0Na, which plays an important role in the "1"9Ne(p, #gamma#)"2"0Na breakout reaction from the hot CNO cycle. A large difference of log ft values for mirror states in "2"0Na and "2"0F was found. The experimentally determined level properties, including B(GT) values, are discussed with reference to model calculations performed within the complete sd-shell space. (orig.)Available from TIB Hannover: RO 801(93-47) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beta-decay of "2"0Mg

The #beta#-decay of "2"0Mg was investigated. A secondary beam of "2"0Mg ions, produced in reactions between a 95 A x MeV "2"4Mg-beam and a "n"a"t".Ni-target, was isotopically separated by means of the LISE3 spectrometer at GANIL. This secondary beam was implanted into a silicon detector array surrounded by germanium #gamma#-detectors. The #beta#-delayed proton and #gamma#-ray data, measured for this short-lived nucleus (T_1_/_2=95#+-#3 ms), were incorporated into an improved "2"0Mg#->#"2"0Na decay scheme. The 2645 keV level in "2"0Na is of importance for the breakout from the astrophysical hot CNO-cycle and the onset of the rapid proton capture process via the reaction "1"9Ne(p,#gamma#)"2"0Na. An upper limit of 0.1% for the #beta#-decay feeding of the 2645 keV level and a lower limit for the corresponding log ft value of 6.24 were determined. The implications of this result for the spin and parity assignment of the 2645 keV state are discussed. Concerning the isobaric multiplet mass equation no significant deviation from its quadratic form was found. By comparing the "2"0Mg #beta#-decay into the proton-unbound 3001 keV state in "2"0Na and the isospin-mirrored decay into the particle-bound 3488 keV level in "2"0F, an asymmetry ft"+/ft"--1=1.69_-_0_._6_5"+"0"."8"6 was observed. (orig.)SIGLEAvailable from TIB Hannover: RO 801(94-52) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman