Search results for "Mass number"
showing 10 items of 51 documents
Identification of yrast states in187Pb
1998
gamma-ray spectroscopy of the high-spin states of the neutron-deficient nucleus Pb-187 has been conducted with the Gd-155(Ar-36,4n) reaction. A cascade of three transitions was deduced from gamma-gamma coincidence data gated by detection of recoiling evaporation residues in a gas-filled recoil separator. In an earlier, separate experiment, two of these gamma rays were positively identified with Pb-187 by recoil-gamma coincidence measurements with a high-resolution, recoil mass spectrometer. From comparison with similar sequences in heavier odd-A lead isotopes, the cascade in Pb-187 is associated with the sequence of three E2 transitions from the yrast 25/2(+) level to a low-lying 13/2(+) is…
Hyperfine and Isotope Shift Measurements Far off Stability by Optical Pumping
1977
In this talk I will review optical pumping (OP) experiments performed by our group to ISOLDE, CERN, in a series of Hg isotopes spanning from mass number 181 to 205 (first results in refs. [1] and [2], final in refs. [3] and [4]. I will then discuss what impact these measurements had on nuclear structure research far off stability and how the results of the latter are retroacting again on the optical work. In particular they ask for isotope shifts (IS) of light even Hg isotopes which we are prepared to measure by laser spectroscopy. Further I would like to communicate briefly first results of optical pumping experiments on “exotic” Rb and Cs isotopes. Finally I will discuss plans for laser s…
Gamow-Teller strengths in proton-rich exotic nuclei deduced in the combined analysis of mirror transitions
2005
Isospin symmetry is expected for the T-z=+/- 1 -> 0 isobaric analogous transitions in isobars with mass number A, where T-z is the z component of isospin T. Assuming this symmetry, strengths of analogous Gamow-Teller (GT) transitions within A=50 isobars were determined from a high energy-resolution T-z=+1 -> 0, Cr-50(He-3,t)Mn-50 study at 0 degrees in combination with the decay Q value and lifetime from the T-z=-1 -> 0, Fe-50 ->Mn-50 beta decay. This method can be applied to other pf-shell nuclei and can be used to study GT strengths of astrophysical interest.
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.
Production and Characterization of the $^{7}$H Resonance
2006
Détecteur MAYA; International audience; The 7H resonance was produced via one-proton transfer reaction between a 8He beam at 15.4A MeV and a 12C gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The characterization of the identified 7H events resulted in a resonance energy of 600 keV above the 3H+4n threshold and a resonance width of 100 keV. This study represents the first unambiguous proof of the existence of the 7H state.
Total photoabsorption cross section for4He from 200 to 800 MeV
1997
The total photoabsorption cross section for ${}^{4}$He has been measured for the first time over a wide photon energy range (200 MeV$l~{E}_{\ensuremath{\gamma}}l~$800 MeV). By using the large acceptance detector DAPHNE at the tagged photon facility of the MAMI microtron in Mainz high precision results with small systematic errors were obtained. This measurement shows that ${}^{4}$He has a behavior similar to heavy nuclei and, in particular, a reduction of the cross section with respect to the lighter nuclei is found for ${E}_{\ensuremath{\gamma}}g$600 MeV.
Discovery of the proton emitting nucleus $^{159}$Re
2007
Fund. para Cienc. Tecnol., FCT, Minist. Cienc. Tecnol.;Fundacao Calouste Gulbenkian;Fundacao Luso-Americana
Lifetime measurement of neutron-rich even-even molybdenum isotopes
2017
D. Ralet et al. -- 11 pags., 10 figs., 3 tabs.
Theoretical study of neutrino scattering off the stable even Mo isotopes at low and intermediate energies
2011
A systematic study of the cross sections of neutral-current neutrino scattering off the stable even Mo isotopes (mass number A = 92, 94, 96, 98, 100), at low and intermediate neutrino energies (E(nu) <= 130 MeV), is presented and discussed. The required wave functions for the initial (ground state) and all accessible final nuclear states are constructed in the context of the quasi-particle random-phase approximation (QRPA) and tested against data on the low-lying energy spectra of the isotopes in question. The individual contributions coming from the polar-vector and axial-vector components of the hadronic current for the coherent and incoherent channels of each isotope are investigated. Th…
Trap-assisted studies of odd, neutron-rich isotopes from Tc to Pd
2012
We review the present and future of trap-assisted structure studies of odd, neutron-rich Tc, Ru, Rh and Pd isotopes at the limits of present experimental techniques. These nuclei of refractory elements are produced in light-particle induced fission and filtered by their mass number with the IGISOL mass separator. Further mass separation with the JYFLTRAP Penning trap system provides a clean, monoisotopic beam perfectly suited for precise nuclear spectroscopy. Connecting the IGISOL and the JYFLTRAP facilities to the recently installed MCC30/15 cyclotron opens new prospects for post-trap spectroscopy of very exotic, neutron-rich nuclei. peerReviewed