[en] A great deal of interest has been shown in mapping out the proton drip-line and in measuring the properties of nuclei in the 60< A<100 region. In part, this is due to their role in determining the path of the rapid proton capture (rp-) process. By measuring the half-lives and binding energies of these nuclei, the path and extent of this process can be determined. In a series of experiments, the authors have used the A1200 projectile fragment separator at NSCL to produce secondary beams of very proton-rich nuclei at, or close to, the proton drip-line, including ⁶⁵As, ⁶⁹Br, and ⁹⁵Ag. The reaction products are unambiguously identified by a combination of their time-of-flight through the separator and their partial and total energy loss in a solid-state detector telescope. The decay properties of the implanted nuclei can then be studied. The methods used at NSCL to measure beta-decay half-lives of exotic nuclei and the results of some recent experiments are presented

[en] Three γ-decaying isomers in the N=Z+1 nucleus ⁹⁵Ag have been identified for the first time. The ⁹⁵Ag nuclei were produced via the ⁵⁸Ni(⁴⁰Ca,p2n) reaction and separated by using the GSI on-line mass separator. The emitted γ rays were measured with a multi-Ge detector setup in anticoincidence with positrons. Three individual γ-decay cascades have been identified and assigned to ⁹⁵Ag, representing the depopulation of isomers at 344-, 2531-, and 4859-keV excitation energy with tentative spin-parity assignments of (1/2^-), (23/2⁺), and (37/2⁺), respectively. The spin and parity assignments are based on a comparison with shell-model predictions employing empirical interactions

[en] Full text: The results of a program of investigation of the nuclei with N=Z and N=Z + 1 from the mass region A ≅ 80-100 with the gamma-ray array GASP (Italian Gamma-ray SPHERE) are presented. Eight such nuclei, between Zr-81 and Ag-95, have been spectroscopically investigated for the first time. The special techniques that allowed the study of such nuclei, which are populated with very small cross sections in the reactions available today, are briefly illustrated. This nuclear region stands out through unique phenomena, such as rapid structure changes (particle alignments, shape changes and shape coexistence) with both mass number and angular momentum, as well as the possibility to search for the experimental signal of enhanced neutron-proton (np) correlations, especially in the pairing channel (both T=1 and T=0 modes). Experimental evidence for such phenomena are presented. This nuclear region remains interesting for future studies with new, more efficient gamma-spectroscopy arrays, and radioactive beams. Such detailed studies will address not only the problem of the np pairing, but other interesting topics as well, such as nuclei at critical points, and unusual (tetrahedral) nuclear shapes. (author)

[en] By using a ⁴⁰Ca beam of the UNILAC accelerator, the new isotopes ⁹⁴Ag and ⁹⁵Ag were produced through ⁵⁸Ni(⁴⁰Ca,p3n) and ⁵⁸Ni(⁴⁰Ca,p2n) reactions, respectively, and identified by detecting β-delayed protons from mass-separated sources. ⁹⁴Ag represents the heaviest N=Z nucleus with known decay properties. The β-decay half-lives of ⁹⁴Ag and ⁹⁵Ag were determined to be 0.42±0.05 s and 2.0±0.1 s, respectively. The measured β-decay properties are compared with model predictions. (orig.)

[en] The results of a program of investigation of the nuclei with N = Z and N = Z + 1 from the mass region A ∼ 80 - 100 with the gamma-ray array GASP (Italian Gamma-ray SPHERE) are presented. Eight such nuclei, between Zr-81 and Ag-95, have been spectroscopically investigated for the first time. The special techniques that allowed the study of such nuclei, which are populated with very small cross sections in the reactions available today, are briefly illustrated. This nuclear region stands out through unique phenomena, such as rapid structure changes (particle alignments, shape changes and shape coexistence) with both mass number and angular momentum, as well as the possibility to search for the experimental signal of enhanced neutron-proton (np) correlations, especially in the pairing channel (both T=1 and T=0 modes). Experimental evidence for such phenomena are presented. This nuclear region remains interesting for future studies with new, more efficient gamma-spectroscopy arrays, and radioactive beams. Such detailed studies will address not only the problem of the np pairing, but other interesting topics as well, such as nuclei at critical points, and unusual (tetrahedral) nuclear shapes. (authors)

[en] The neutron-deficient 1g/sub 9/2/-shell nuclei are studied in the framework of the shell model with the (1g/sub 9/2/,2p/sub 1/2/)/sup -n/ configuration. Several ''spin-gap'' isomers with a half-life of an order of a second are predicted in ⁹⁵Pd, ⁹⁵Ag, ⁹⁶Cd, and ⁹⁷Cd. Among them, the J = (21/2)⁺ state in ⁹⁵Pd is predicted to be an isomer which corresponds to ⁹⁵Pd/sup m/ recently observed by Nolte and Hick. It is also shown that the high-spin isomers above the proton threshold are rather stable against the proton emission

[en] We studied the β-decay properties of the N=Z+1 nucleus ⁹⁵Ag by measuring β-delayed γ rays and β-γ-γ coincidences with a plastic scintillator as β detector and a Ge-detector array. The ⁹⁵Ag nuclei were produced by means of the ⁵⁸Ni(⁴⁰Ca,p2n) reaction and separated with the GSI online mass separator. The previously reported level scheme of the ⁹⁵Pd daughter nucleus was extended considerably. The deduced level scheme is compared with different shell-model calculations with or without breaking the ¹⁰⁰Sn core

[en] The decays of the neutron deficient nuclei 94,95Ag, 100,102In and 102Sn were investigated at the GSI on-line mass separator. The Gamow-Teller decay of 100,102In and 102Sn was studied by using an array of germanium detectors and a total absorption spectrometer. In 94Ag and 95Ag, spin-gap isomers were identified and their decays were investigated. Results obtained in these studies are discussed and compared to predictions of shell model calculations

[en] Nine new very neutron-deficient isotopes of Ag, Pd, Rh, and Ru have been identified among the reaction products of an E/A=60 MeV ¹⁰⁶Cd beam using the A1200 projectile fragment separator at the National Superconducting Cyclotron Laboratory. One of these isotopes, ⁹⁴Ag, is among the heaviest N=Z nuclei observed so far. The resulting mass spectra are presented and the astrophysical implications of the stability towards proton emission of one of the new isotopes, ⁹⁵Ag, are discussed

[en] Recently, we studied isomeric decays of ⁹⁵Ag at the RIKEN Nishina Center using a fragmentation reaction of ¹²⁴Xe on a ⁹Be target. The separated and identified reaction products were implanted in the modified SIMBA Silicon calorimeter, which was surrounded by the EURICA Germanium array, to measure the isomer and particle decays. The half-lives of all three isomeric states previously identified by Doering were measured from the analysis of the gamma-ray and conversion-electron (CE) data. Analysis of coincident gamma-rays and CE-gamma-ray data was used to verify the published level scheme. We have performed new shell-model calculations in a larger model space pn(f_5/2, p_3/2, p_1/2, g_9/2) using a modified interaction. These calculations provide an improved description of the isomers and the reduced transition rates extracted from the experimental half-lives. While for the isomeric states (1/2^-) and (23/2⁺) the choice of E3 for the depopulating transitions is appropriate, the comparison of the shell-model to the experimental results is used as a basis to suggest a change of the spin and parity assignment of the high-spin isomer in with the former assignment of (37/2⁺).