First on-line results for As and F beams from HRIBF target/ion sources

The first on-line tests of the ion sources to provide radioactive ion beams of 69/7OAs and 17>18F for the Holifield Radioactive Ion Beam Facility have been performed using the UNISOR facility at HRIBF. For 70As the measured efficiency is 0.8+ 0.3% with a hold-up time of 3.6 ± 0.3 hours as measured with ^As at a target temperature of 1270°C. For 17F the efficiency for A117F is 0.0024 + 0.0008% with a hold-up time of 16.4 + 0.8 m as measured with A118F at a target temperature of 1470°C

UNISOR on-line nuclear orientation facility (UNISOR/NOF)

The UNISOR on-line nuclear orientation facility (UNISOR/NOF) consists of a3He-4He dilution refrigerator on line to the isotope separator. Nuclei are implanted directly into a target foil which is soldered to the bottom accessed cold finger of the refrigerator. A 1.5 T superconducting magnet polarizes the ferromagnetic target foils and determines the axis of symmetry. Up to eight gamma detectors can be positioned around the refrigerator, each 9 cm from the target. A unique feature of this system is that the k=4 term in the directional distribution function can be directly and unambigously deduced so that a single solution for the mixing ratio can be found. The first on-line experiment at this facility reported here was a study of the decay of the191Hg and193Hg isotopes. © 1998 J.C. Baltzer A.G., Scientific Publishing Company

5He ternary fission yields of 252Cf and 235U(n,f)

The relative 4He and 5He ternary fission yields were determined from a careful analysis of the energy distribution of α spectra from a new measurement with a 252Cf source and from published data on 252Cf and 235U(n,f). The kinetic energies of the 5He and 4He ternary particles were found to be approximately 11 and 16 MeV, respectively. 5He particles contribute 10-20% to the total alpha yield with the remainder originating from 4He accompanied fission

Observation of rotational bands in the neutron-rich 107Ru nucleus

Levels in the neutron-rich, odd-mass 107Ru nucleus have been reinvestigated with Gammasphere by measuring high-fold, prompt coincidence events following spontaneous fission of 252Cf. The ground state band has been extended up to 27/2ℏ. The structure associated with the h11/2 excitation has been confirmed and extended to higher spin. The h11/2 band head has been established to lie at 301.8 keV. These results clear up differences between our earlier work and results from another experiment published recently. A new collective band based on a 9/2- level has been identified for the first time. Some distinct features of the level scheme are discussed

Identification of 181Hg and shape coexistence in odd-A Hg isotopes

In-beam γ-ray transitions in 181Hg, the lightest odd-A Hg isotope known thus far, have been identified from fragment mass-γ and γ-γ coincidence measurements. Five prolate deformed rotational bands were placed in the level scheme. A decoupled band built on the strongly prolate deformed 1/2-[521] ground state was observed up to 29/2-. A 5/2-[512] configuration is suggested for a pair of strongly coupled bands displaying no signature splitting. The other two bands are also signature partner bands. They are populated with the largest intensity and exhibit splitting. They have been associated with the mixed neutron i13/2 orbitals and are proposed to decay to an i13/2 isomeric state associated with an oblate state

First on-line results for As and F beams from HRIBF target/ion sources

The first on-line tests of the ion sources to provide radioactive ion beams of {sup 69,70}As and {sup 17,18}F for the Holifield Radioactive Ion Beam Facility (HRIBF) have been performed using the UNISOR facility at HRIBF. The target/ion source is an electron beam plasma (EBP) source similar to the ISOLDE design. The measured efficiencies for {sup 69}As and {sup 70}AS were 0.5 {+-} 0.2% and 0.8 {+-} 0.3%, respectively. The arsenic hold-up time in the tested target ion source was 3.6 {+-} 0.3 hours as measured with {sup 72}As at a target temperature of 1300 {degrees}C. The measured efficiencies for {sup 17}F and {sup 18}F were 0.0052 {+-} 0.0008% and 0.06 {+-} 0.02%, respectively. The source hold-up time for fluorine was measured with Al{sup 18}F since 88% of the observed radioactive fluorine was found in this molecule. The Al{sup 18}F hold-up time was 16.4 {+-} 0.8 minutes at a target temperature of 1470 {degrees}C

Element/Target-Dependent Release Times and Release Efficiencies for the Proposed OREB Facility

Experiments have been initiated which are designed to measure the time release characteristics of stable ion implanted species from selected refractory target materials which are potential candidates for forming radioactive beans at the proposed Oak Ridge Exotic Beam Facility. In this report, we provide thermal time release data and estimates of the efficiencies for releasing Cl from Zr{sub 5}Si{sub 3} and {sup 75}As, {sup 79}Br, and {sup 78}Se from Zr{sub 5}Ge{sub 3}. 14 refs., 1 fig., 1 tab