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Levels in 223Th populated by the a decay of 227U were investigated using α-γ decay spectroscopy. The 227U isotope was produced in the fusion-evaporation reaction Ne22+Pb208 at the velocity filter separator for heavy-ion reaction products at Gesellschaft für Schwerionenforschung in Darmstadt (Germany). Several new excited levels and γ transitions were identified in 223Th. An improved α-decay scheme of 227U was suggested. The experimental α-decay energy spectrum of 227U was compared with the Monte Carlo simulation performed using the toolkit geant4. [ABSTRACT FROM AUTHOR]

Background: Mass-asymmetric fission has been observed in low energy fission of 180Hg. Calculations predicted the persistence of asymmetric fission in this region even at excitation energies of 30-40 MeV. Purpose: To investigate fission mass distributions by populating different isotopes of Hg using heavy ion fusion reactions. Methods: Fission fragment mass-angle distributions have been measured for two reactions, 40Ca + 142Nd and 13C + 182W, populating 182Hg and 195Hg, respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Measurements were made at beam energies around the capture barrier for the two reactions and mass ratio distributions were obtained using the kinematic reconstruction method. Results: Asymmetric fission has been observed following the population of 182Hg at an excitation energy of 22.8 MeV above the saddle point. A symmetric peaked mass ratio distribution was observed for 195Hg nuclei at a similar excitation energy above the saddle point. Conclusions: Mass-asymmetric fission has been observed in neutron deficient Hg nuclei populated via heavy ion fusion for the first time. The results are consistent with observations from beta-delayed fission measurements and provide a proof-of-principle for expanding experimental studies of the influence of shell effects on the fission processes. [ABSTRACT FROM AUTHOR]

The isotope 176Au has been studied in the complete fusion reaction 40Ca + 141Pr → 176Au + 5n at the velocity filter SHIP (GSI, Darmstadt). The complex fine-structure α decay of two isomeric states in 176Au feeding several previously unknown excited states in the daughter nucleus 172Ir is presented. An α-decay branching ratio of bα = 9.5(11)% was deduced for the high-spin isomer in 172Ir. [ABSTRACT FROM AUTHOR]

Decay properties of the neutron-deficient nuclides 201-203Ra and 200-202Fr were investigated using α- and γ-decay spectroscopy. The nuclei were produced in fusion-evaporation reactions of 56Fe projectiles with enriched 147Sm and 149Sm targets at the velocity filter SHIP at GSI in Darmstadt (Germany). The α decay from the (3/2-) state in 201Ra was identified with an energy Eα = 7842(12) keV and half-life T1/2 = 8-4+40 ms. Ambiguous decay properties for 202Ra from previous measurements were clarified by remeasuring with significantly improved precision, resulting in values of Eα = 7722(7) keV and T1/2 = 3.8-0.8+1.3 ms. New short-lived isomeric states were identified in 200Fr and 201Fr with half-lives of 0.6-0.2+0.5 μs and 0.7-0.2+0.5 μs, respectively. A tentative spin and parity of 13/2+ were assigned to the latter. One event attributed to β-delayed fission of 200Fr was observed. [ABSTRACT FROM AUTHOR]

Detailed α-decay studies of 179TIg and its daughter products 175Aug and 17lIrg were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the α-decay properties of 175Aug was performed as follows: Ea = 6433(4) keV, T1/2 = 207(7) ms, and α-decay branching ratio 90(7)%. First determination of the α-decay branching ratios for 179TIg and 171Irg was also made:ba(179TIg) = 60(2)% and ba(171Irg) = 15(2)%. The spins of the ground states in 175Au and 171Ir are established as l/2+. [ABSTRACT FROM AUTHOR]

Decay properties of the very neutron-deficient isotopes 197-199Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the 2n-4n evaporation channels of the fusion-evaporation reaction 60Ni + 141Pr &#rarr; 201Fr*. Improved α-decay properties of 199Fr were determined and the possible existence of two α-decaying states in this nucleus is discussed. For the isotope 198Fr a broad α-decay energy distribution was detected in the range of (7470-7930) keV and two α-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope l97Fr was identified based on the observation of one α-decay chain yielding Eα = 7728(15) keV and 71/2 = 0.6-0.3+0.3 ms. The systematics of reduced α-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes. [ABSTRACT FROM AUTHOR]

By using the technique of correlating implanted evaporation residues and their subsequent fission decay, β-delayed fission βDF) of 186Bi has been identified for the first time and βDF of 188Bi has been unambiguously confirmed. The experiments were performed at the velocity filter SHIP (GSI, Darmstadt). The βDF probabilities for both nuclides were qualitatively estimated, and, in particular indications for a large value in the case of 186Bi are regarded. [ABSTRACT FROM AUTHOR]

By using the recoil-fission correlation technique, the exotic process of beta-delayed fission (βDF) was unambiguously identified in the very neutron-deficient nuclei 192,194At in experiments at the velocity filter SHIP at Gesellschaft für Schwerionenforschung (GSI). The upper limits for the total kinetic energy release in fission of 192,194Po, being the daughter products of 192-194At after β+/EC decay, were estimated. The possibility of an unusually high βDF probability for 192 At is discussed. [ABSTRACT FROM AUTHOR]

The one-neutron removal cross sections of neutron-rich Al isotopes and longitudinal momentum distributions of the residues have been measured for A = 33 to 36 at relativistic energies (≈900 MeV/u). The inclusive data have been interpreted within the eikonal approximation. The evolution of the single-particle occupancy in the ground state of 33,34,35A1 has been studied and compared with shell model predictions. The inferred 2s1/2 neutron occupancy in the 33A1 ground-state wave function is 20% to 40% lower than the predicted one. The inclusive data do not exclude the presence of intruder states. Some intruder / = 1 occupancy is found in 34A1, similarly to 33Mg. The single-particle 1 f7/2 occupancy shows a gradual increase at N = 22. Correspondingly, a decrease of the lrf3/2 strength has been observed. [ABSTRACT FROM AUTHOR]

New measurements of the interaction cross sections of 22,230 at 900A MeV performed at the GSI, Darmstadt are reported that address the unsolved puzzle of the large cross section previously observed for 230. The matter radii for these oxygen isotopes extracted through a Glauber model analysis are in good agreement with the new predictions of the ab initio coupled-cluster theory reported here. They are consistent with a 220 + neutron description of 230 as well. [ABSTRACT FROM AUTHOR]

The production of residual nuclei in the reactions 25Mg + 206Pb, 36S + natPt, 48Ca + natW was investigated at low bombarding energies at the velocity filter SHIP (GSI, Darmstadt). The data are discussed within the dinuclear System model. In particular, the emission of complex fragments with Z > 2 from heavy compound nuclei is treated within the model and supported by the experimental data. The production Channels and cross sections, Charge, isotopic distributions of the residual heavy nuclei are presented. [ABSTRACT FROM AUTHOR]

The interaction cross sections of 32-35Mg at 900A MeV have been measurmed using the fragment separator at GSI. The deviation from the r0A1/3 trend is slightly larger for 35Mg, signaling the possible formation of a longer tail in the neutron distribution for 35Mg. The radii extracted from a Glauber model analysis with Fermi densities are consistent with models predicting the development of neutron skins. [ABSTRACT FROM AUTHOR]