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Lopez-Martens, A.*; Henning, G.*; Khoo, T. L.*; Seweryniak, D.*; Alcorta, M.*; Asai, Masato; Back, B. B.*; Bertone, P. F.*; Boilley, D.*; Carpenter, M. P.*; et al.
EPJ Web of Conferences, 131, p.03001_1 - 03001_6, 2016/12
Times Cited Count:1 Percentile:42.67(Chemistry, Inorganic & Nuclear)Fission barrier height and its angular-momentum dependence have been measured for the first time in the nucleus with the atomic number greater than 100. The entry distribution method, which can determine the excitation energy at which fission starts to dominate the decay process, was applied to No. The fission barrier of
No was found to be 6.6 MeV at zero spin, indicating that the
No is strongly stabilized by the nuclear shell effects.
Hota, S.*; Tandel, S.*; Chowdhury, P.*; Ahmad, I.*; Carpenter, M. P.*; Chiara, C. J.*; Greene, J. P.*; Hoffman, C. R.*; Jackson, E. G.*; Janssens, R. V. F.*; et al.
Physical Review C, 94(2), p.021303_1 - 021303_5, 2016/08
Times Cited Count:7 Percentile:47.19(Physics, Nuclear)The decay of a = 8
isomer in
Pu and the collective band structure populating the isomer are studied using deep inelastic excitations with
Ti and
Pb beams, respectively. Precise measurements of
branching ratios in the band confirm a clean 9/2
[734]
7/2
[624]
for the isomer, validating the systematics of K
= 8
two-quasineutron isomers observed in even-
,
= 150 isotones. These isomers around the deformed shell gap at
= 152 provide critical benchmarks for theoretical predictions of single-particle energies in this gateway region to superheavy nuclei.
Henning, G.*; Khoo, T. L.*; Lopez-Martens, A.*; Seweryniak, D.*; Alcorta, M.*; Asai, Masato; Back, B. B.*; Bertone, P. F.*; Boilley, D.*; Carpenter, M. P.*; et al.
Physical Review Letters, 113(26), p.262505_1 - 262505_6, 2014/12
Times Cited Count:34 Percentile:82.19(Physics, Multidisciplinary)Fission barrier heights of a shell-stabilized superheavy nucleus No have been determined as a function of spin up to 19
through the measured distribution of entry points of
deexcitations in the excitation energy vs. spin plane. The fission barrier height of
No was determined to be 6.0 MeV at spin 15
, and 6.6 MeV at spin 0
by extrapolation. This demonstrates that the shell effect actually enlarges the fission barrier in such heavy nuclei and keeps the barrier high even at high spin.
Henning, G.*; Lopez-Martens, A.*; Khoo, T. L.*; Seweryniak, D.*; Alcorta, M.*; Asai, Masato; Back, B. B.*; Bertone, P. F.*; Boilley, D.*; Carpenter, M. P.*; et al.
EPJ Web of Conferences, 66, p.02046_1 - 02046_8, 2014/03
Times Cited Count:3 Percentile:68.41(Physics, Nuclear)Fission barrier heights of No have been determined through the entry distribution method. The entry distribution is the initial distribution of excitation energy and spin from which the
deexcitation starts in the fusion-evaporation reaction. The initial distribution is extracted from measured
-ray multiplicity and total
-ray energy. This paper describes the details of the entry distribution method, and reports the first determination of the fission barrier heights of
No, which is the heaviest nucleus whose fission barrier has been measured.
Robinson, A. P.*; Khoo, T. L.*; Seweryniak, D.*; Ahmad, I.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; Davids, C. N.*; Greene, J.*; et al.
Physical Review C, 83(6), p.064311_1 - 064311_7, 2011/06
Times Cited Count:33 Percentile:84.74(Physics, Nuclear)We have identified an isomer with a half-life of 17 s in
Rf through a calorimetric conversion electron measurement tagged with implanted
Rf nuclei using the fragment mass analyzer at Argonne National Laboratory. The low population yield for this isomer suggests that this isomer should not be a 2-quasiparticle high-
isomer which is typically observed in the N = 152 isotones, but should be a 4-quasiparticle one. Possible reasons of the non-observation of a 2-quasiparticle isomer are this isomer decays by fission with a half-life similar to that of the ground state of
Rf. Another possibility, that there is no 2-quasiparticle isomer at all, would imply an abrupt termination of axially symmetric deformed shape at Z=104.
Villard, L.*; Bottino, A.*; Brunner, S.*; Casati, A.*; Chowdhury, J.*; Dannert, T.*; Ganesh, R.*; Garbet, X.*; Grler, T.*; Grandgirard, V.*; et al.
Plasma Physics and Controlled Fusion, 52(12), p.124038_1 - 124038_18, 2010/11
Times Cited Count:21 Percentile:60.74(Physics, Fluids & Plasmas)Seweryniak, D.*; Khoo, T. L.*; Ahmad, I.*; Kondev, F. G.*; Robinson, A.*; Tandel, S. K.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; et al.
Nuclear Physics A, 834(1-4), p.357c - 361c, 2010/03
Times Cited Count:7 Percentile:46.98(Physics, Nuclear)Experimental data on single-particle energies in nuclei around Z=100 and N=152 play an important role to test validity of theoretical predictions for shell structure of superheavy nuclei. We found high-K two-quasiparticle isomers in No and
No, and evaluated energies of proton single-particle orbitals around Z=100. We also found a new high-K three quasiparticle isomer in
Rf. Energies of neutron single-particle orbitals were also evaluated from experimental data of the
decay of
Rf. Comparisons between the present experimental data and various theoretical calculations for the proton single-particle orbitals indicate that the calculation by using the Woods-Saxon potential gives the best agreement with the data.
Robinson, A. P.*; Khoo, T. L.*; Ahmad, I.*; Tandel, S. K.*; Kondev, F. G.*; Nakatsukasa, Takashi*; Seweryniak, D.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; et al.
Physical Review C, 78(3), p.034308_1 - 034308_6, 2008/09
Times Cited Count:52 Percentile:91.09(Physics, Nuclear)Isomers have been identified in Cm and
No with quantum number
, which decay through
rotational bands built on octupole vibrational states. For
isotones with atomic number
102, the
and 2
states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2
energy at
Cm, due to the additional role of proton configurations.