[en] Off-line experiments indicated that fluorides of As, Se, Br, Kr, Zr, Nb, Mo, Tc, Ru, Sb, Te, I and Xe could be volatilized, but except for Br, Kr, I and Xe, none of these elements were observed after mass separation in the on-line experiments. The results of the on-line experiments indicated a very low level of hydride contamination at ambient temperature and consequently, uranium tetrafluoride replaced uranyl stearate as the primary gaseous fission product target. Possible reasons for the failure of the heated target system to yield non-rare gas activities are discussed and suggestions for designing a new heated target system are presented

[en] The nuclear physics program at the fission product mass separator, TRISTAN, has greatly expanded, both in the types of experiments possible and in the range of nuclei available. Surface ionization, FEBIAD, high-temperature thermal, high-temperature plasma, and negative surface ionization ion sources are routinely available. Experimental facilities developed to further expand the capabilities of TRISTAN include a superconducting magnet for g-factor and Q/sub β/ measurements, a windowless Si(Li) detector for conversion electron measurements, and a colinear fast-beam dye laser system for hyperfine interaction studies. This combination of ion sources, experimental apparatus, and the long running time available at a reactor makes TRISTAN a powerful tool for nuclear structure studies of neutron-rich nuclei. The effect of these developments on the nuclear physics program at TRISTAN will be discussed and recent results from some of these facilities will be presented. 6 refs., 3 figs

[en] The ISOL facility, TRISTAN, is a user facility located at Brookhaven National Laboratory's High Flux Beam Reactor. Short-lived, neutron-rich nuclei, far from stability, are produced by thermal neutron fission of ²³⁵U. An extensive array of experimental end stations are available for nuclear structure studies. These studies are augmented by a variety of long-lived ion sources suitable for use at a reactor facility. Some recent results at TRISTAN are presented as examples of using an ISOL facility to study series of nuclei, whereby an effective means of conducting nuclear structure investigations is available

[en] A technique to measure the lifetimes of nuclear states with half lives <10 ps has been developed in conjunction with the TRISTAN mass separator at the High Flux Beam Reactor at BNL. The method uses fast plastic and BaF₂ scintillators and Ge detectors in a triple coincidence (β-γ-γ) fast-slow counting system. The timing information is derived from the fast plastic-BaF₂ coincidence, while the higher resolution of the Ge detector (in slow coincidence) serves to insure that the β-γ event lies in the cascade of interest. The calibrations and corrections necessary to achieve precise results and the methods of data reduction and results from recent measurements on the A = 97 mass chain are presented. 11 refs., 7 figs

No abstract available

[en] It is empirically observed that the non-leptonic decay of strange hadrons is enhanced when the change in isospin is 1/2. This is generalized in the ''ΔI = 1/2 rule'' that states that all such decays proceed predominantly through ΔI = 1/2 amplitudes. However, there is no definitive explanation for this apparently universal rule. Non-mesonic decay of Λ-hypernuclei can occur through a weak decay process ΛN -> ηN. When stimulated by a neutron, two neutrons are emitted from the nucleus, and when stimulated by a proton, a proton and neutron are emitted. By measuring the relative decay widths (Γ_n/Γ_p) in the full set of s-shell hypernuclei, a sensitive test of the ΔI = 1/2 rule, and the determination of its applicability to non-mesonic decays can be made. In addition, information about the spin-isospin dependence of the weak decay process can be extracted. A measurement of Γ_n/Γ_p, to an accuracy of even 50% will be sufficient to address important issues relating to the ΔI = 1/2 rule and to the weak decay process. The experiment will measure the ratio Γ_n/Γ_p, following the decay of ⁴H which is produced by a stopped K^- beam in a liquid Helium target. The Neutral Meson Spectrometer will be used to identify stopped kaon events by detection of the gamma rays that follow the decay of the emitted π⁰. Arrays of charged particle and neutron detectors will measure the relative neutron and proton emission probabilities. An engineering run was performed in 1998, without the Helium target, which demonstrated that the technique is feasible. The full experiment is scheduled at the Alternating Gradient Synchrotron for the spring 2001 running period

[en] The development of a heated uranium tetrafluoride target system for the TRISTAN isotope separator to release non-rare gas fission products is presented. Off-line experiments indicated that fluorides of As, Se, Br, Kr, Zr, Nb, Mo, Tc, Ru, Sb, Te, I and Xe could be volatilized, but except for Br, Kr, I and Xe, none of these elements was observed after mass separation in the on-line experiments. The results of the on-line experiments indicated a very low level of hydride contamination at ambient temperature and consequently, uranium tetrafluoride replaced uranyl stearate as the primary gaseous fission product target. Possible reasons for the failure of the heated target system to yield non-rare gas activities are discussed and suggestions for designing a new heated target system are presented

[en] TRISTAN is an on-line isotope separator (ISOL) facility located at Brookhaven National Laboratory's High Flux Beam Reactor. Short-lived neutron-rich nuclei, far from stability, are produced by thermal neutron fission of ²³⁵U. These nuclei can be studied using facilities at the five available beam lines. These facilities include: a 4-detector angular correlation system, a delayed neutron spectroscopy facility, a conversion electron detector, a colinear fast beam dye laser system and a superconducting magnet for g-factor measurements. Ion sources of the surface ionization, negative surface ionization, thermal, FEBIAD, and plasma types are used to provide high yields over a wide range of elments for experiments at the available detector stations

[en] A vigorous program of ion source development at TRISTAN has led to several types of ion sources that are especially suited to extended operation at a reactor-based ISOL facility. The latest of these is a high temperature plasma ion source in which a 5 gm ²³⁵U target is located in the cathode and can be heated to 2500⁰C. The ion source has a lifetime of >1000 hours and produces a wide array of elements, including Pd. Off-line investigations indicate that the source functions primarily in an electron impact mode of ionization and exhibits typical ionzation efficiencies of >30% for Xe

[en] The nuclear physics program at the fission product mass separator, TRISTAN, has greatly expanded, both in the types of experiments possible and in the range of nuclei available. Surface ionization, FEBIAD, high-temperature thermal, high-temperature plasma, and negative surface ionization ion sources are routinely available. Experimental facilities developed to further expand the capabilities of TRISTAN include a superconducting magnet for g-factor and Q/sub β/ measurements, a windowless Si(Li) detector for conversion electron measurements, and a colinear fast-beam dye laser system for hyperfine interaction studies. This combination of ion sources, experimental apparatus, and the long running time available at a reactor makes TRISTAN a powerful tool for nuclear structure studies of neutron-rich nuclei. The effect of these developments on the nuclear physics program at TRISTAN is discussed and recent results from some of these facilities are presented