Pair breaking and even-odd structure in fission-fragment yields

The probabilities of single-particle excitations which preserve completely paired configurations of the nuclear proton and neutron subsystems are formulated as a function of excitation energy in the framework of the superfluid nuclear model. These calculations are used to analyse measured data on even-odd structure in fission-fragment yields. Excitation energies acquired at scission are deduced. The strongly differing even-odd structures in proton and neutron numbers are explained within the assumption of thermal equilibrium of intrinsic excitations at scission. (orig.)37 refs.Available from TIB Hannover: RO 801(99-05) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Production of neutron-rich isotopes by cold fragmentation in the reaction "1"9"7Au + Be at 950 A MeV

The production cross sections and longitudinal-momentum distributions of very neutron-rich isotopes have been investigated in the fragmentation of a 950 A MeV "1"7"9Au beam in a beryllium target. Seven new isotopes ("1"9"3Re, "1"9"4Re, "1"9"1W, "1"9"2W, "1"8"9Ta, "1"8"7Hf and "1"8"8Hf) and the five-proton-removal channel were observed for the first time. The reaction mechanism leading to the formation of these very neutron-rich isotopes is explained in terms of the cold-fragmentation process. An analytical model describing this reaction mechanism is presented. (orig.)Available from TIB Hannover: RO 801(99-35) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Possibilities for the production of non-stable isotopes

The production of neutron-rich isotopes is discussed in terms of the two main reaction mechanisms leading to the formation of these nuclei, projectile fragmentation and fission. Production cross sections are calculated for cold-fragmentation and fission. The expected yields are estimated taking into account different technical approaches actually discussed for the production of radioactive beams. (orig.)Contribution to th 37. Int. Winter Meeting on Nuclear Physics, Bormio (IT), Feb. 1999, 25 refs.Available from TIB Hannover: RO 801(99-14) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

#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

Systematic experimental survey on projectile fragmentation and fission induced in collisions of "2"3"8U at 1 A GeV with lead

Projectile fragmentation and fission, induced in collisions of "2"3"8U at 1 A GeV with lead, have systematically been studied. A complete survey on the isotopic production cross sections of all elements between vanadium (Z = 23) and rhenium (Z = 75) down to a cross section of 0.1 mb is given. About 600 isotopes produced in fragmentation and about 600 isotopes produced in fission were identified in the GSI fragment separator FRS from magnetic rigidities, time-of-flight values, and the energy loss in an ionisation chamber. In addition, the velocity distributions of all these reaction products have been mapped, and the products are unambiguously attributed to the different reaction mechanisms due to their kinematical properties. The results are compared with empirical systematics and previous data. The velocity of the fragments obtained in the fission process by the Coulomb repulsion allows to reconstruct the TKE-value of the break-up and to identify the atomic number of the fissioning nucleus in hot fission. The mean velocities of light projectile fragments were found to be higher than the beam velocity. (orig.)41 refs.SIGLEAvailable from TIB Hannover: RO 801(99-11) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman