No abstract
Reactions of the halo systems lIBe and 11Li (at 460 and 280 MeV/nucleon) with a carbon target demonstrate that (n + 9Li) has an (unbound) l = O ground state very close to the threshold. The neutron halo of 11Li has appreciable (1S 1 / 2 )2 and (OP1/2)2 components. PACS numbers: 25.60.+v, 21.10.Pc, 25.70.Mn, 27.20.+n There is currently a surge of interest in the IOLi problem caused by the work of Kryger et al. [1], who reported a narrow central peak in the relative velocity spectrum of the fragments (n + 9Li) produced in fragmentation of an 18 0 beam at 80 MeV/nucleon. The peak was interpreted as evidence either for the ground state of IOLi, in this case probably the missing s state, or for an l = 0,1 resonance near 2.5 MeV. Weak evidence for a structure close to threshold [2] favors the first interpretation. A low-Iying P state is also present near 0.5 MeV according to very similar data presented by Young et al. [2] and by Bohlen el al. [3]. These two papers give a detailed summary of previous work on lOLi.The properties of IOLi are essential for the understanding of the neutron halo associated with the 11 Li ground state [4]. Thompson and Zhukov [5] found that a neutron s state at low energy would lead to an 11 Li halo with about egual admixtures of (lS 1 / 2 )2 and (OP1/2)2. This gave much better agreement with the narrow momentum distributions observed in fragmentation experiments and was in line with the suggestion by Barranco, Vigezzi, and Broglia [6], who attributed the forward-peaked angular distributions of neutrons from 11 Li incident on light targets to the decay in ftight of lOLi. (The 5He intermediate state also dominates the breakup of 6He [7]. ) We have produced the intermediate state lOLi in singlenucleon stripping reactions of the halo states 11 Be and 11 Li. The word "stripping" is employed here in the sense introduced in 1947 by Serber to describe reactions of 190 MeV deuterons; see his recent remarks on the subject [8]. At high bombarding energies, the sudden approximation is valid, and the halo neutron will, after the collision, to a good approximation be in a state characteristic of the projectile and not in an eigenstate of (9Li .+ n). We shall in the following develop a line of arguments that first infer the properties of IOLi from the known structure of 11 Be and then use the results to draw conclusions about the 11 Li halo.The radioactive beams were generated in a 8 g/cm 2 Be target by fragmentation of a 18 0 beam from the heavy-ion synchrotron SIS at GSI aod separated io the fragment separator [9] FRS by magnetic analysis. The secondary beams of 280 MeV / nucleon for 11 Li and 460 MeV / nucleon for 11 Be were transported via the storage ring ESR to a carbon target (thickness 1.29 g/cm 2 ) placed directIy in front of the large-gap magnetic spectrometer [10,11] ALADIN. Neutrons coincident with the nuclear fragment were detected in the calorimeter LAND [12] placed 11 m behind the carbon target and having an active detector area of 2 X 2 m 2 and a total thickness of 1 m. The neutron ...
An El A -65 MeV 78 Kr beam has been used to produce six new isotopes near the proton-drip line. The newly commissioned A1200 beam-analysis device was used to observe the astrophysically interesting isotope 65 As, as well as 6, Ga, 62 Ge, 63 Ge, 69 Br, and 75 Sr. Implications of the observation of these nuclei are discussed in terms of the astrophysical rp process. PACS numbers: 21.l0.Dr, 25.70.Np, 27.50.+e, 95.30.Cq The ability to study proton-drip-line nuclei in the mass range 50
On-line gas chromatography / Group 5 elements / Hahnium (element 105) / Chlorides / Relativistic effects SummaryThe retention behavior of volatile chlorides and oxychlorides of short-lived isotopes of group 5 elements Nb and 105 (Ha = hahnium) in quartz columns was studied using on-line isothermal gas chromatography. The 15-s " 8 Nb was produced from a 215 U-fission target at a reactor neutron beam line and 34-s 262 Ha in fusion reactions of ' 8 0 + 249 Bk. The reaction products were continuously and rapidly transported to the chromatography apparatus with a carbon aerosol gas-jet system using He as carrier gas. Volatile chloride molecules were formed in a 900°C reaction oven by adding HCl as reactive gas. Depending on trace amounts of 0 2 in the system, either the pentachlorides or the oxytrichlorides, or a mixture thereof, were formed. The isotopes "»Nb and 262 Ha were unambiguously identified after gas chromatographic separation by measuring the characteristic y-lines of " g Nb and by registering 262 Ha-25 *Lr mother-daughter a-a correlations as well as spontaneous fission decays, respectively. The adsorption enthalpies of the investigated species on quartz surfaces were determined by analyzing the measured retention curves with a Monte Carlo model. Using an empirical correlation, the adsorption enthalpies were converted to sublimation enthalpies. The sublimation enthalpies of 95 ± 16 kJ-mol" 1 and 124± 16 kJ · mol"' determined for NbCl s and NbOCl 3 , respectively, were in good agreement with literature data. In experiments with Ha-chlorides a yield curve with two components was observed. Sublimation enthalpies of ^ 120 kJ · mol -1 and 152 ±18 kJ-mol"' were estimated for HaCl 5 and HaOCl 3 , respectively. The estimated sublimation enthalpies were compared with theoretical predictions from relativistic calculations and with empirical extrapolations of chemical properties. In agreement with empirical extrapolations, a lower volatility was found for HaOCl 3 than for NbOCl·,.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.