Deo, A. Y., Podolyak, Z., Walker, P. M., Algora, A., Rubio, B., Agramunt, J., et al. (2010). Structures of Po-201 and Rn-205 from EC/beta(+)-decay studies. Phys. Rev. C, 81(2), 024322–8pp.
Abstract: Several low-lying excited states in Rn-205(86)119 and Po-201(84)117 were identified for the first time following EC/beta(+) decay of Fr-205 and At-201, respectively, using gamma-ray and conversion electron spectroscopy at the CERN isotope separator on-line (ISOLDE) facility. The EC/beta(+) branch from Fr-205 was measured to be 1.5(2)%. The excited states of the daughter nuclei are understood in terms of the odd nucleon coupling to the neighboring even-even core. The neutron single-particle energies of the p(3/2) orbital relative to the f(5/2) ground state in Rn-205, and the f(5/2) orbital relative to the p(3/2) ground state in Po-201, were determined to be 31.4(2) and 5.7(3) keV, respectively. We tentatively identify a 13/2(+) isomeric level at 657.1(5) keV in Rn-205. The systematic behavior of the 13/2(+) and 3/2(-) levels is also discussed.
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Valiente-Dobon, J. J., Poves, A., Gadea, A., & Fernandez-Dominguez, B. (2018). Broken mirror symmetry in S-36 and Ca-36. Phys. Rev. C, 98(1), 011302–5pp.
Abstract: Shape coexistence is a ubiquitous phenomenon in the neutron-rich nuclei belonging to (or sitting at the shores of) the N = 20 island of inversion (IoI). Exact isospin symmetry predicts the same behavior for their mirrors and the existence of a proton-rich IoI around Z = 20, centered in the (surely unbound) nucleus Ca-32. In this article we show that in Ca-36 and S-36, Coulomb effects break dramatically the mirror symmetry in the excitation energies due to the different structures of the intruder and normal states. The mirror energy difference (MED) of their 2(+) states is known to be very large at – 246 keV. We reproduce this value and predict the first excited state in Ca-36 to be a 0(+) at 2.7 MeV, 250 keV below the first 2(+). In its mirror S-36 the 0(+) lies at 55keV above the 2(+) measured at 3.291 MeV. Our calculations predict a huge MED of -720 keV, that we dub the “colossal” mirror energy difference. A possible reaction mechanism to access the O-2(+) in Ca-36 will be discussed. In addition, we theoretically address the MEDs of the A = 34, T = 3 and A = 32, T = 4 mirrors.
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Spataru, A., Kripkó-Koncz, G., Dickel, T., Hornung, C., Plass, W. R., Constantin, P., et al. (2025). Broadband mass measurements with the FRS Ion Catcher facility at GSI and theory developments investigating the shape-phase transition near N=90. Phys. Rev. C, 111(5), 054307–13pp.
Abstract: Simultaneous, broadband, high-precision direct mass measurements of thermalized exotic nuclides are reported. The FRS Ion Catcher and, in particular, its high-resolution multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) was used to measure neutron-rich nuclides in the element range from barium to europium, produced by the spontaneous fission of 252Cf. Results include the measurement of 64 masses, including 13 masses with no previous direct determination; for four nuclides, a measurement with improved uncertainty is reported. Relative mass uncertainties below 1 x 10-7are routinely achieved. This work shows the first use of a multiple-reflection time-of-flight mass spectrometer to map a larger region of the nuclear chart covering 51 masses measured simultaneously in a single setting. The broadband capability is a design feature of the MR-TOF-MS of the FRS Ion Catcher which enables the large-scale mapping of the mass surface. The obtained data are compared to existing literature values and predictions of mass models and are used to study the shape-phase transition at N = 90. A theoretical study, employing a Hartree-Fock-BCS approach with adjustable pairing strengths, is implemented to examine the evolution of the two-neutron separation energies along this region of the chart of nuclei.
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Davesne, D., Navarro, J., Meyer, J., Bennaceur, K., & Pastore, A. (2018). Two-body contributions to the effective mass in nuclear effective interactions. Phys. Rev. C, 97(4), 044304–7pp.
Abstract: Starting from general expressions of well-chosen symmetric nuclear matter quantities derived for both zero-and finite-range effective theories, we derive some universal relations between them. We first showthat, independently of the range, the two-body contribution is enough to describe correctly the saturation mechanism but gives an effective mass value around m(*)/m similar or equal to 0.4 when the other properties of the saturation point are set near their generally accepted values. Then, we show that a more elaborated interaction (for instance, an effective two-body density-dependent term on top of the pure two-body term) is needed to reach the accepted value m(*)/m similar or equal to 0.7-0.8.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cantero, J., et al. (2023). Measurements of the suppression and correlations of dijets in Pb plus Pb collisions at root s(NN)=5.02 TeV. Phys. Rev. C, 107(5), 054908–31pp.
Abstract: Studies of the correlations of the two highest transverse momentum (leading) jets in individual Pb+Pb colli-sion events can provide information about the mechanism of jet quenching by the hot and dense matter created in such collisions. In Pb+Pb and pp collisions at root NN = 5.02 TeV, measurements of the leading dijet transverse momentum (pT) correlations are presented. Additionally, measurements in Pb+Pb collisions of the dijet pair nuclear modification factors projected along leading and subleading jet pT are made. The measurements are per-formed using the ATLAS detector at the LHC with 260 pb(-1) of pp data collected in 2017 and 2.2 nb(-1) of Pb+Pb data collected in 2015 and 2018. An unfolding procedure is applied to the two-dimensional leading and sublead-ing jet pT distributions to account for experimental effects in the measurement of both jets. Results are provided for dijets with leading jet pT greater than 100 GeV. Measurements of the dijet-yield-normalized xJ distributions in Pb+Pb collisions show an increased fraction of imbalanced jets compared to pp collisions; these measurements are in agreement with previous measurements of the same quantity at 2.76 TeV in the overlapping kinematic range. Measurements of the absolutely normalized dijet rate in Pb+Pb and pp collisions are also presented, and show that balanced dijets are significantly more suppressed than imbalanced dijets in Pb+Pb collisions. It is observed in the measurements of the pair nuclear modification factors that the subleading jets are significantly suppressed relative to leading jets with pT between 100 and 316 GeV for all centralities in Pb+Pb collisions.
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