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Klawitter, R.

Publications and source records attributed to Klawitter, R..

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Mass measurements of neutron-rich gallium isotopes refine production of nuclei of the first r -process abundance peak in neutron-star merger calculations

We report mass measurements of neutron-rich Ga isotopes 80–85 Ga with TRIUMF's Ion Trap for Atomic and Nuclear science. The measurements determine the masses of 80–83 Ga in good agreement with previous measurements. Here, the masses of 84 Ga and 85 Ga were measured for the first time. Uncertainties between 25 and 48 keV were reached. The new mass values reduce the nuclear uncertainties associated with the production of A ≈ 84 isotopes by the r-process for astrophysical conditions that might be consistent with a binary neutron star (BNS) merger producing a blue kilonova. Our nucleosynthesis simulations confirm that BNS merger may contribute to the first abundance peak under moderate neutron-rich conditions with electron fractions Y e = 0.35–0.38.

59 ≤ A ≤ 89↗
DOE OSTI2018

Mass measurements of neutron-rich indium isotopes toward the N = 82 shell closure

Precise mass measurements of the neutron-rich 125–130 In isotopes have been performed with the TITAN Penning trap mass spectrometer. TITAN's electron beam ion trap was used to charge breed the ions to charge state q = 13+ thus providing the necessary resolving power to measure not only the ground states but also isomeric states at each mass number. Here, the properties of the ground states are investigated through a series of mass differentials, highlighting trends in the indium isotopic chain as compared to its proton-magic neighbor, tin (Z = 50). In addition, the energies of the indium isomers are presented. The (8 - ) level in 128 In is found to be 78 keV lower than previously thought and the (21/2 - ) isomer in 127 In is shown to be lower than the literature value by more than 150 keV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Precision mass measurements of magnesium isotopes and implications for the validity of the isobaric mass multiplet equation

If the mass excess of neutron-deficient nuclei and their neutron-rich mirror partners are both known, it can be shown that deviations of the isobaric mass multiplet equation (IMME) in the form of a cubic term can be probed. Such a cubic term was probed by using the atomic mass of neutron-rich magnesium isotopes measured using the TITAN Penning trap and the recently measured proton-separation energies of 29 Cl and 30 Ar. The atomic mass of 27 Mg was found to be within 1.6σ of the value stated in the Atomic Mass Evaluation. The atomic masses of 28,29 Mg were measured to be both within 1σ, while being 7 and 33 times more precise, respectively. Using the 29 Mg mass excess and previous measurements of 29 Cl, we uncovered a cubic coefficient of d = 28(7)keV, which is the largest known cubic coefficient of the IMME. This departure, however, could also be caused by experimental data with unknown systematic errors. Hence there is a need to confirm the mass excess of 28 S and the one-neutron separation energy of 29 Cl, which have both come from a single measurement. Lastly, our results were compared with ab initio calculations from the valence-space in-medium similarity renormalization group, resulting in a good agreement.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Mass determination near N = 20 for Al and Na isotopes

We report on the mass measurements of 31;32 Na and 29;34;35 Al, performed with the TITAN Penning trap mass spectrometer at TRIUMF. The mass excesses were found to be 12246(14) keV and 18638(37) keV for 31;32 Na and -18207:77(37) keV, -3000:5(29) keV, and -223:7(73) keV for 29;34;35 Al, respectively. Our measurements con rm the observation of a crossover in the two-neutron separation energies of 33 Mg and 34 Al. We did not observe the recently reported, long-lived, isomeric state of 34 Al, but, based on the previously measured half-lives, the mass value of the ground state was determined.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Forbidden optical transition in Ti-like Xe, Ba, and Ir

We present measurements of the (3d{sup 4}){sup 5}D{sub 2}−{sup 5}D{sub 3} transitions in the Ti-like ions Xe{sup 32+}, Ba{sup 34+}, and Ir{sup 55+} produced and trapped in the Heidelberg electron beam ion trap. The obtained wavelengths have a precision at the few ppm-level and are thereby the most precise measurements of these transitions up to date. For Z=60−75 semi-empirical calculations have shown excellent agreement, however our measurements combined with data from other works shows that outside this range predictions quickly deviate. The value obtained for Ir{sup 55+} 357.434(2) nm confirms the linear mismatch to ab initio calculations for Z > 70, as hypothesized in Utter et al., Phys. Rev. A 67, 012508 (2003)

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Progress at the TITAN-EBIT

Precision mass measurements of short-lived isotopes provide insight into a wide array of physics, including nuclear structure, nucleosynthesis, and tests of the Standard Model. The precision of Penning trap mass spectrometry (PTMS) measurements is limited by the lifetime of the isotopes of interest, but scales proportionally with their charge state q, making highly charged ions attractive for mass measurements of nuclides far from stability. TITAN, TRIUMF's Ion Trap(s) for Atomic and Nuclear science, is currently the only setup in the world coupling an EBIT to a rare isotope facility for the purpose of PTMS. Charge breeding ions for Penning trap mass spectrometry, however, entails specific set of challenges. To make use of its potential, efficiencies have to be high, breeding times have to be short and the ion energy spread has to be small. An overview of the TITAN facility and charge-breeding program is given, current and future developments are highlighted and some selected results are presented.

74 ATOMIC AND MOLECULAR PHYSICS↗