Beta decay of "9"7Ag: evidence for the Gamow-Teller resonance near "1"0"0Sn

In two complementary measurements, a cube-like array of 6 Euroball-Cluster germanium detectors and a total-absorption #gamma#-spectrometer were used to investigate the #beta# decay of "9"7Ag, a three proton-hole nucleus with respect to the "1"0"0Sn core. The half-life and Q_E_C value of the decay of the 9/2"+ ground-state of "9"7Ag were determined to be 25.9(4)s and 6.98(11) MeV, respectively. A total of 603 #gamma# rays (578 new) was observed, and 151 levels (132 new) in "9"7Pd have been identified. An interesting #beta#-delayed #gamma# cascade was observed, which comprises 6 #gamma#-transitions with a de-excitation pattern involving an initial increase of the level spin. The Gamow-Teller (GT) #beta#-decay strength distributions from the two measurements reveal a large GT resonance around 1 MeV with a width of about 1.8 MeV. The hindrance factor for the total GT strength, summed from the ground-state up to 6 MeV excitation energy in "9"7Pd, amounts to 1.3(6) with reference to a shell-model prediction. This factor is discussed in comparison with a core-polarization and a Monte-Carlo shell-model calculation. (orig.)Available from TIB Hannover: RO 801(99-08) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Beta decay of "9"8Ag: evidence for the Gamow-Teller resonance near "1"0"0Sn

In two complementary measurements, a cube-like array of 6 Euroball-Cluster germanium detectors and a total-absorption #gamma#-spectrometer were used to investigate the #beta# decay of "9"8Ag, a three-proton-hole and one-neutron-particle nucleus with respect to the "1"0"0Sn core. The half-life and Q_E_C value of the decay were determined to be 47.7(0.3) s and 8200(70) MeV, respectively. A total of 438 #gamma# rays (414 new) was observed, and 173 levels (163 new) in "9"8Pd have been identified. The Gamow-Teller (GT) #beta#-decay strength distribution from the total-absorption #gamma#-spectroscopy reveals a large GT resonance around 6 MeV with a width of about 2 MeV. The hindrance factor for the total GT strength, summed from the ground state up to 7.8 MeV excitation energy in "9"8Pd, amounts to 4.6(6) with reference to a shell-model calculation which yields good agreement with the shape of the experimental GT resonance. (orig.)Available from TIB Hannover: RO 801(2000-34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Energy and efficiency calibration of an array of six Euroball Cluster detectors used for beta-decay studies

The use of an array of 6 euroball cluster detectors, i.e. 42 large-volume germanium detectors, for beta-decay studies is described. The solid angle with respect to a source placed in the center of the array amounts to 65% of 4#pi# sr. The total photo-peak efficiency for 1.33 MeV #gamma#-rays is 10.2(5)%, without ''adding back'' the Compton-scattered events. For this #gamma#-ray energy, the energy resolution of the entire setup is 2.8 keV. The performance of the array up to #gamma#-ray energies of 8 MeV is discussed, and alternative ways of determining the photo-peak efficiency are presented. (orig.)13 refs.Available from TIB Hannover: RO 801(98-37) / 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 near "1"0"0Sn and "1"4"6Gd: experiments performed by using a total absorption spectrometer or an array of six Euroball CLUSTER detectors

The GT beta decay of "1"5"0Ho has been studied with a Total Absorption Spectrometer (TAS), with an array of 6 Euroball CLUSTER Ge detectors (the CLUSTER CUBE), and with an alpha detector. The three techniques complement each other. The results provide the first observation of an extremely sharp resonance in GT beta decay. (orig.)Available from TIB Hannover: RO 801(98-44) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Nuclear structure near the doubly-magic "1"0"0Sn

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 "3"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 #epsilon##>=#1.6#epsilon#. In contrast a small proton polarisation charge #delta##epsilon##<=#0.3#epsilon# is found, pointing to a large isovector charge. Mean field predictions for single particle energies show substantial deviations from the experimental extrapolation. From the experimental two-proton hole spectrum in "9"8Cd an improved empirical interaction is extracted for the #pi#(p_1_/_2,g_9_/_2) model space yielding a good description of the N=50 isotones "9"5Rh to "9"8Cd. In "1"0"4Sn, for the first time in this region, strong E3 transitions with B(E3)#>=#17 W.u. were identified, indicating E(3"-)#approx =#3 MeV in "1"0"0Sn. New experimental devices, as the Ge-cluster cube and total absorption spectrometers, applied in a pioneering experiment to the #beta#"+/EC decay of "9"7Ag, have led to a consistent picture of the Gamow-Teller quenching around "1"0"0Sn. The experimental results are discussed in the framework of various shell model approaches by using both empirical and realistic interactions. (orig.)Available from TIB Hannover: RO 801(98-62) / 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 "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

Interfaces of nuclear structure studies-decay vs. in-beam experiments

The common interface of #beta#-decay and particle-decay experiments and in-beam studies following fusion, relativistic fission and projectile fragmentation is defined by the search for the best way to extract nuclear structure information. For a few examples selected from the exotic regions of nuclei around "1"0"0Sn and between "6"8Ni and "7"8Ni it is demonstrated, that complementary spectroscopic data extracted by various methods lead to an understanding of the shell structure at these keypoints of the nuclidic chart. (orig.)24 refs.SIGLEAvailable from TIB Hannover: RO 801(99-16) / 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