Search results for "Helium"
showing 10 items of 1689 documents
Cluster Structure of9Be from3He+9Be Reaction
2016
The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a 9Be target with a 3He beam at an incident energy of 30 MeV. Angular distributions for 9Be(3He,3He)9Be, 9Be(3He,4He)8Be, 9Be(3He,7Be)5He, 9Be(3He,6Li)6Li and 9Be(3He,7Li)5Li reaction channels were measured. Cross sections for channels leading to unbound 5He g.s ., 5Li g.s . and 8Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile is constrained by two-body kinematics. Information on the cluster structure of 9Be was obtained from the transfer channels. It was concluded that cluster transfer is an …
A study of a helium-jet ion guide for an on-line isotope separator
1981
Abstract A new method based on helium-jet techniques permits primary recoil ions, produced in radioactive decay or in nuclear reactions to be run directly through a mass separator. Results obtained with a 227 Ac source promise qualities complementary with those obtained with conventional ion sources and indicate an overall efficiency of the order of 10%. Preliminary results with 20 Na recoils from the 20 Ne(p,n)-reaction indicate that most of the ionic species transported out from the target chamber are negatively charged.
Submillisecond On-Line Mass Separation of Nonvolatile Radioactive Elements: An Application of Charge Exchange and Thermalization Processes of Primary…
1985
Transportation of thermalized primary recoil ions from nuclear reactions by helium flow has been investigated as a means of injecting short-lived radioactive nuclides into an on-line isotope separator. Several short-lived radioactive isotopes of highly nonvolatile elements such as B, Sc, Nb, and W have been separated. The efficiency for heavy nuclides with half-lives above 1 ms is between 1 and 10%. The shortest-lived activity identified in an on-line separation is the 182-\ensuremath{\mu}s isomeric state in $^{207}\mathrm{Bi}$.
Helium-jet ion guide for an on-line isotope separator
1981
Abstract A new method based on helium-jet techniques permits primary recoil ions produced in radioactive decay or in nuclear reactions to be run directly through a mass separator. Test results with a 227 Ac source give promise of qualities complementary to those obtained with conventional ion sources. This, 69 ± 5 per cent of the recoil particles transported with pure, commercial helium are positive ions, and 66 ± 5 per cent of them are mass separated. Nearly equal efficiencies are expected for most chemical elements and compounds. The mass spectra are remarkably free from groups caused by impurities. The shortest achievable separation time is estimated to be of the order of one millisecond.
TheNd150(He3,t) andSm150(t,He3) reactions with applications toββdecay ofNd150
2011
The {sup 150}Nd({sup 3}He,t) reaction at 140 MeV/u and {sup 150}Sm(t,{sup 3}He) reaction at 115 MeV/u were measured, populating excited states in {sup 150}Pm. The transitions studied populate intermediate states of importance for the (neutrinoless) {beta}{beta} decay of {sup 150}Nd to {sup 150}Sm. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of the quasiparticle random-phase approximation, which is one of the main methods employed for estimating the half-life of the neutrinoless {beta}{beta} decay (0{nu}{b…
The astrophysical implications of low-energy resonances in 22Ne + α
1993
Abstract The 22 Ne( 6 Li, d) α-transfer reaction has been used to search for α-unbound levels in 26 Mg of importance for resonant α-capture on 22 Ne in stellar helium burning. To determine the resonance strengths of the observed states the 22 Ne(α, n) 25 Mg reaction was investigated in the energy range between 600 and 900 keV. One resonance was identified and its strength determined. The astrophysical implications of the present results are discussed.
Activation cross-sections for some 14·8 MeV neutron-induced nuclear reactions on caesium: Isomer ratios of 134Cs, 133Xe and 130I
1970
Abstract Absolute cross-sections for 14·8 MeV neutron-induced reactions on 133Cs were determined using the activation technique. The results, with maximum errors of 15 per cent, are: ρ(n,γ)=7·1 mb (ρ(n,γ) 134m Cs =1·82 mb , ρ(n,γ) 134g Cs =5·3 mb ; ρ(n,2n) 132 Cs =1620 mb ; ρ(n,p)=10·5 mb (ρ(n,p) 133m Xe =4·8 mb , ρ(n,p) 133g Xe =5·7 mb ; ρ(n,α)=1·14 mb (ρ(n,α) 130m I =0·54 mb , ρ(n,α) 130g I =0·6 mb ; ρ(n, 3 He ) 131 I =3·2 μ barn ; ρ(n,2p) 132 I ⩽12 μ barn . At this particle energy direct interaction processes also contribute. The isomer cross-section ratios σ m σ g for 134Cs, 133Xe and 130I are 0·34±0·08, 0·85±0·15 and 0·91±0·2 respectively. A reinvestigation of the alleged 127I (n, 3n)1…
Efficient numerical method for simulating static and dynamic properties of superfluid helium
2004
Density functional theory (DFT) offers computationally affordable way of describing static and dynamic properties of superfluid 4He. In general, the DFT models yield single particle-like Schrodinger equations with a nonlinear potential term that accounts for all the many-body interactions. The resulting equations can be solved for small amplitude plane wave excitations in the bulk whereas fully numerical solution must be sought in more complicated cases. In this paper we propose a numerical method that can be used in solving the time-dependent nonlinear Schrodinger equation in both real and imaginary times. The method is based on operator splitting technique where each component operator is…
Phytosterols: to be or not to be toxic; that is the question
2008
Plant sterols (phytosterols) are membrane constituents of all plants with a structure analogous to that of cholesterol. Thus, phytosterols have either an additional methyl or ethyl group on the carbon-24 position or an additional double bond in the side chain (1) . Noteworthy, in patients with the rare inherited disease of phytosterolaemia characterized by a hyperabsorption and diminished biliary secretion of cholesterol and phytosterols as well as by tendon and tuberous xanthoma, elevated plasma concentrations of phytosterols (campesterol, sitosterol) have been shown to constitute a risk factor for premature atherosclerosis (2) . However, whether plasma concentrations of campesterol and si…
Activity and expression of drug metabolizing enzymes in olfactory mucosa of rats treated by hepatic inducers
2008
International audience; Several drug-metabolizing enzymes (DME), such as cytochrome P450- dependent monooxygenases (CYP) and transferases have been characterized in the olfactory epithelium. Some of them are preferentially expressed in this tissue, while others are similar to those present in the liver. The role of these enzymes remains unclear. Since the olfactory mucosa is in direct contact with the external environment, these enzymes can contribute to the detoxification of chemical compounds. In addition, these enzymes could be involved in the olfaction process, especially in the biotransformation of odorants. Indeed, the rapid inactivation and clearance of odorants is a prerequisite for…