Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Kahler, A. C.*; Talou, P.*; Plompen, A. J.*; Schillebeeckx, P.*; et al.
Nuclear Data Sheets, 148, p.189 - 213, 2018/02
The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - U, U, Pu, Fe, O and H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality. This report summarizes our results and outlines plans for the next phase of this collaboration.
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
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.
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
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.
Qian, J.*; Heinz, A.*; Khoo, T. L.*; Janssens, R. V. F.*; Peterson, D.*; Seweryniak, D.*; Ahmad, I.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; et al.
Physical Review C, 79(6), p.064319_1 - 064319_13, 2009/06
-, -, and conversion electron spectroscopy experiments for Rf have been performed using Fragment Mass Analyzer at Argonne National Laboratory. A new isomer with a half-life of 160 s has been discovered in Rf, and it is interpreted as a three-quasiparticle high- isomer. Neutron configurations of one-quasiparticle states in No, the -decay daughter of Rf, have been assigned on the basis of -decay hindrance factors. Excitation energies of the 1/2 states in =151 isotones indicate that the deformed shell gap at =152 increases with the atomic number.
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
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.
Ibrahim, K.*; Qian, H. J.*; Wu, X.*; Abbas, M. I.*; Wang, J. O.*; Hong, C. H.*; Su, R.*; Zhong, J.*; Dong, Y. H.*; Wu, Z. Y.*; et al.
Physical Review B, 70(22), p.224433_1 - 224433_9, 2004/12
no abstracts in English