| 1. |
- Syndikus, I., et al.
(författare)
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Probing the Z = 6 spin-orbit shell gap with (p,2p) quasi-free scattering reactions
- 2020
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 809
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of the traditional nuclear magic numbers away from the valley of stability is an active field of research. Experimental efforts focus on providing key spectroscopic information that will shed light into the structure of exotic nuclei and understanding the driving mechanism behind the shell evolution. In this work, we investigate the Z=6 spin-orbit shell gap towards the neutron dripline. To do so, we employed NA(p,2p)CA−1 quasi-free scattering reactions to measure the proton component of the 21+ state of 16,18,20C. The experimental findings support the notion of a moderate reduction of the proton 1p1/2−1p3/2 spin-orbit splitting, at variance to recent claims for a prevalent Z=6 magic number towards the neutron dripline.
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| 2. |
- Simpson, J., et al.
(författare)
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Evolution of structure and shapes in Er 158 to ultrahigh spin
- 2023
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Ingår i: Physical Review C. - 2469-9985. ; 107:5
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Tidskriftsartikel (refereegranskat)abstract
- The level structure of Er158 has been studied using the Gammasphere spectrometer via the Cd114(Ca48,4n) reaction at 215 MeV with both thin (self-supporting) and thick (backed) targets. The level scheme has been considerably extended with more than 200 new transitions and six new rotational structures, including two strongly coupled high-K bands. Configuration assignments for the new structures are based on their observed alignments, B(M1)/B(E2) ratios of reduced transition probabilities, excitation energies, and comparisons with neighboring nuclei and theoretical calculations. With increasing angular momentum, this nucleus exhibits Coriolis-induced alignments of both neutrons and protons before it then undergoes a rotation-induced transition from near-prolate collective rotation to a noncollective oblate configuration. This transition occurs via the mechanism of band termination around spin 45ħ in three rotational structures. Two distinct lifetime branches, consistent with the crossing of a collective "fast"rotational structure by an energetically favored "slow"terminating sequence, are confirmed for the positive-parity states, and similar behavior is established in the negative-parity states. Weak-intensity, high-energy transitions are observed to feed into the terminating states. At the highest spins, three collective bands with high dynamic moments of inertia and large quadrupole moments were identified. These bands are interpreted as triaxial strongly deformed structures and mark a return to collectivity at ultrahigh spin.
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| 3. |
- Pore, J. L., et al.
(författare)
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Identification of the New Isotope 244Md
- 2020
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Ingår i: Physical Review Letters. - 1079-7114. ; 124:25
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Tidskriftsartikel (refereegranskat)abstract
- In an experiment performed at Lawrence Berkeley National Laboratory’s 88-inch cyclotron, the isotope 244Md was produced in the 209Bi(40Ar,5n) reaction. Decay properties of 244Md were measured at the focal plane of the Berkeley Gas-filled Separator, and the mass number assignment of A = 244 was confirmed with the apparatus for the identification of nuclide A. The isotope 244Md is reported to have one, possibly two, α-decaying states with α energies of 8.66(2) and 8.31(2) MeV and half-lives of 0.4+0.4-0.1 and ∼6 s, respectively. Additionally, first evidence of the α decay of 236Bk was observed and is reported.
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| 4. |
- Clark, R. M., et al.
(författare)
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Enhancement of α-particle formation near 100Sn
- 2020
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Ingår i: Physical Review C. - 2469-9985. ; 101:3
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Tidskriftsartikel (refereegranskat)abstract
- The superfluid tunneling model is applied to the calculation of ground-state–to–ground-state α decay in the even-even neutron-deficient Te-Ba nuclei. We show that there is a larger α-particle formation probability in nuclei of this region above 100Sn when compared to analogous nuclei above 208Pb. This is consistent with the expected systematic variation of the pair gap Δ as a function of mass number. The recent experimental data on the α decay of the N = Z nuclei 104Te and 108Xe are shown to leave open the possibility of enhanced α-particle formation involving nucleon correlations beyond the standard treatment of like-nucleon pairing, which is the mechanism suggested as underlying “superallowed” α decay.
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| 5. |
- Macchiavelli, A. O., et al.
(författare)
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"Piston" mechanism in a time-dependent two-level model
- 2021
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Ingår i: Physical Review C. - : American Physical Society (APS). - 2469-9985 .- 2469-9993. ; 104:6
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Tidskriftsartikel (refereegranskat)abstract
- We analyze a recent study of the one-proton knockout reaction on N-19 in the framework of a time-dependent two-level model. Focusing on the specific case of C-18, we quantify the validity of the so-called "piston" mechanism in terms of the timescales involved in the process, namely, the reaction time, the period of oscillation between the mixed states, and the lifetime of the excited unbound state.
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