Search results for "Nucleon"
showing 10 items of 1041 documents
High-resolution study of Gamow-Teller transitions in the47Ti(3He,t)47V reaction
2013
In this work we have studied ${T}_{z}=+2\ensuremath{\rightarrow}+1$, Gamow-Teller (GT) transitions in the $^{48}\mathrm{Ti}(^{3}\mathrm{He},t)^{48}\mathrm{V}$ charge-exchange reaction at 140 MeV/nucleon and ${0}^{\ensuremath{\circ}}$ at the Research Center for Nuclear Physics, Osaka. From the high-resolution facility, consisting of a high-dispersion beamline and the Grand Raiden spectrometer, the spectrum had an energy resolution of 21 keV, among the best achieved. Individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy of 12 MeV. The total sum of the $B$(GT) strength observed in discrete states was 4.0, which is 33% of the sum…
New lifetime measurements inPd109and the onset of deformation atN=60
2015
Several new subnanosecond lifetimes were measured in Pd-109 using the fast-timing beta gamma gamma (t) method. Fission fragments of the A = 109 mass chain were produced by bombarding natural uranium with 30 MeV protons at the Jyvaskyla Ion Guide Isotope Separator On-Line (IGISOL) facility. Lifetimes were obtained for excited states in Pd-109 populated following beta decay of Rh-109. The new lifetimes provide some insight into the evolution of nuclear structure in this mass region. In particular, the distinct structure of the two low-lying 7/2(+) states occurring systematically across the Pd isotopic chain is supported by the new lifetime measurements. The available nuclear data indicate a s…
β-Decay Studies Close to the N=82 r-process Path
2005
New half-lives for neutron-rich ruthenium, rhodium and palladium isotopes close to the r-process path along the N=82 closed shell have been measured at the National Superconducting Cyclotron Laboratory at Michigan State University. The studied isotopes are close to the critical A=118-126 mass region in the astrophysical r-process, where incorrect nuclear structure development towards the shell closure may have the most pronounced effect on the abundances of elements produced. Neutron-rich nuclei were produced by fragmentation of a 120-MeV per nucleon 136 Xe beam on Be and were separated by the A1900 fragment separator. The nuclei of interest were implanted into a double-sided Si strip detec…
Fully self-consistent calculations of nuclear Schiff moments
2010
We calculate the Schiff moments of the nuclei 199Hg and 211Ra in completely self-consistent odd-nucleus mean-field theory by modifying the Hartree-Fock-Bogoliubov code HFODD. We allow for arbitrary shape deformation, and include the effects of nucleon dipole moments alongside those of a CP-violating pion-exchange nucleon-nucleon interaction. The results for 199Hg differ significantly from those of previous calculations when the CP-violating interaction is of isovector character.
Mass Measurement on the rp-Process Waiting Point 72Kr
2004
The mass of one of the three major waiting points in the astrophysical rp process $^{72}$Kr was measured for the first time with the Penning trap mass spectrometer ISOLTRAP. The measurement yielded a relative mass uncertainty of $\deltam/m = 1.2\times 10–7 (\deltam$ = 8 keV). $^{73,74}$Kr, also needed for astrophysical calculations, were measured with more than 1 order of magnitude improved accuracy. We use the ISOLTRAP masses of $^{72–74}$Kr to reanalyze the role of $^{72}$Kr (T$_{1/2}$ = 17.2 s) in the rp process during x-ray bursts and conclude that $^{72}$Kr is a strong waiting point delaying the burst duration with at least 80\% of its $\beta$-decay half-life.
ϒ production and nuclear modification at forward rapidity in Pb–Pb collisions at sNN=5.02TeV
2021
Abstract The production of ϒ mesons in Pb–Pb collisions at a centre-of-mass energy per nucleon pair s NN = 5.02 TeV is measured with the muon spectrometer of the ALICE detector at the LHC. The yields as well as the nuclear modification factors are determined in the forward rapidity region 2.5 y 4.0 , as a function of rapidity, transverse momentum and collision centrality. The results show that the production of the ϒ ( 1S ) meson is suppressed by a factor of about three with respect to the production in proton–proton collisions. For the first time, a significant signal for the ϒ ( 2S ) meson is observed at forward rapidity, indicating a suppression stronger by about a factor 2–3 with respec…
Non-zero chemical potential and the shape of the pT-distribution of hadrons in heavy-ion collisions
1990
Abstract The pT-spectra of negative particles from 200 GeV/nucleon O + Au and S + S collisions, measured at CERN by the NA35 collaboration, are fitted by a thermal distribution of massive pions which are strongly out of chemcial equilibrium. Both sets of data are consistent with the same values of temperature and chemical potential, T ≈ 165 MeV and μ ≈ 120 MeV. The low pT behaviour of the measured spectra seems to indicate that the transverse flow in these collisions is not strong.
Nuclear ground-state spins and magnetic moments ofMg27,Mg29, andMg31
2008
The ground-state spins and magnetic moments of neutron-rich {sup 27}Mg, {sup 29}Mg, and {sup 31}Mg were measured for the first time with laser and {beta}-NMR spectroscopy at ISOLDE/CERN. The hyperfine structure of {sup 27}Mg--observed in fluorescence--confirms previous assignments of the spin I=1/2 and reveals the magnetic moment {mu}{sub I}({sup 27}Mg)=-0.4107(15){mu}{sub N}. The hyperfine structure and nuclear magnetic resonance of optically polarized {sup 29}Mg--observed in the asymmetry of its {beta} decay after implantation in a cubic crystal--give I=3/2 and {mu}{sub I}({sup 29}Mg)=+0.9780(6){mu}{sub N}. For {sup 31}Mg they yield together I=1/2 and {mu}{sub I}({sup 31}Mg)=-0.88355(15){…
Model-independent separation of structure functions over an extended kinematical region
1994
A method for the separation of structure functions in (e, e′ p) experiments is proposed, which is an extension of the traditional Rosenbluth-type techniques of [1,2]. In our approach, we use a very flexible Ansatz to describe the structure functions within an extended kinematical regionG and determine its free parameters with a x2 minimization. The procedure is tested by pseudo data (12C(e, e′p)11Bg.s.) in the quasi-free region.
Experimental study of theγp→ηpreaction with the Crystal Ball detector at the Mainz Microtron (MAMI-C)
2010
The gamma p - = W >= 1.87 GeV). Bremsstrahlung photons produced by the 1.5-GeV electron beam of the Mainz Microtron MAMI-C and momentum analyzed by the Glasgow tagging spectrometer were used for the eta-meson production. Our accumulation of 3.8 x 10(6) gamma p -< eta p -< 3 pi(0) p -< 6 gamma p events allows a detailed study of the reaction dynamics. The gamma p -< eta p differential cross sections were determined for 120 energy bins and the full range of the production angles. Our data show a dip near W = 1680 MeV in the total cross section caused by a substantial dip in eta production at forward angles. The data are compared to predictions of previous SAID and MAID partial-wave analyses a…