Khuyagbaatar, J.*; Heberger, F. P.*; Hofmann, S.*; Ackermann, D.*; Burkhard, H. G.*; Heinz, S.*; Kindler, B.*; Kojouharov, I.*; Lommel, B.*; Mann, R.*; et al.
Physical Review C, 102(4), p.044312_1 - 044312_8, 2020/10
Nuclear structure of Fm, Fm, and their daughter nuclei were investigated via detection of their radioactive decays, , , and spontaneous fission. Measured -decay energies, half-lives, and branching ratios improve the literature data significantly. A signature for detection of the hitherto unknown Cm was found in the -decay chains from Fm. Two groups of events with average energies of 6.69(2) MeV and 7.01(2) MeV and with a half-life of = 300, s are suggested to originate from Cm. Tentative decay schemes for Fm, Cf, Cm, and Fm, Cf isotopes are suggested based on the present experimental data. Systematical trends of single-particle states in =141 isotones of = 92-98 nuclei are discussed.
Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; Mnzenberg, G.*; Antalic, S.*; Barth, W.*; Burkhard, K. G.*; Dahl, L.*; Eberhardt, K.*; et al.
European Physical Journal A, 52(6), p.180_1 - 180_34, 2016/06
The reaction Cr+Cm was investigated at the velocity filter SHIP at GSI with the intention to study production and decay properties of isotopes of element 120. Three correlated signals were measured, which occurred within a period of 279 ms. The heights of the signals correspond with the expectations for a decay sequence starting with an isotope of element 120. However, a complete decay chain cannot be established, since a signal from the implantation of the evaporation residue cannot be identified unambiguously. Measured properties of the event chain are discussed in detail. The result is compared with theoretical predictions. Previously measured decay properties of even element super-heavy nuclei were compiled in order to find arguments for an assignment from the systematics of experimental data. In the course of this review, a few tentatively assigned data could be corrected. New interpretations are given for results which could not be assigned definitely in previous studies. The discussion revealed that the cross-section for production of element 120 could be high enough so that a successful experiment seems possible with presently available techniques. However, a continuation of the experiment at SHIP for a necessary confirmation of the results obtained in a relatively short irradiation of five weeks is not possible at GSI presently. In the summary and outlook section we also present concepts for the continuation of research in the field of super-heavy nuclei.
Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; Khuyagbaatar, J.*; Ackermann, D.*; Antalic, S.*; Barth, B.*; Block, M.*; Burkhard, H. G.*; et al.
European Physical Journal A, 48(5), p.62_1 - 62_23, 2012/05
The synthesis of element 116 in the reactions of Ca+Cm was studied at the GSI-SHIP. Four decay chains from the isotope 116 and one decay 116 were detected at the reaction leading to the excitation energy of 40.9 MeV. The cross sections were 3.4 and 0.9 pb, respectively. The decay character reproduced the reported data at FLNR, Russia. In the decay chain, we observed the higher -particle energy in the decay of 114, which suggested the population and the decay of a quasiparitcle state.
Heinz, S.*; Comas, V.*; Heberger, F. P.*; Hofmann, S.*; Ackermann, D.*; Burkhard, H. G.*; Gan, Z.*; Heredia, J.*; Khuyagbaatar, J.*; Kindler, B.*; et al.
European Physical Journal A, 38(2), p.227 - 232, 2008/11
Various nuclear reactions like quasi-fission, fusion-fission or particle and cluster evaporation from excited compound nuclei were studied in heavy-ion reactions by using the velocity filter SHIP of GSI. The velocity distributions were measured for the heavier nuclei produced by bombarding Mg, Ni to the target nuclei Pb at energies of 5.9 MeV/A and 8.7 MeV/A. In addition to the evaporation residues produced in the fusion reactions, we found evidence for rotation and quasi-fission of nuclear molecules. The break-up of the systems showed a preferred clustering leading to isotopes in the region 84 88 and 122 127.
Khuyagbaatar, J.*; Hofmann, S.*; Heberger, F. P.*; Ackermann, D.*; Burkhard, H. G.*; Heinz, S.*; Kindler, B.*; Kojouharov, I.*; Lommel, B.*; Mann, R.*; et al.
European Physical Journal A, 37(2), p.177 - 183, 2008/08
Spontaneous fission of neutron-deficient fermium isotopes with neutron number N144 was investigated. The nuclei were produced in fusion-evaporation reactions of Ar beams with Pb targets. The new isotope Fm was identified, and the half-life 0.73 ms was determined. The half-life was significantly longer than the neighboring even-even isotopes Fm, and the hindrance factor were calculated by the to be 1.110 for Fm and 5.210 for Fm, being associated with the lower tunneing probability for nuclei having nuclear spins. The result suggests also the possible production and detection of Fm becalsue of the stabilization against spontaneous fission.
Khuyagbaatar, J.*; Hofmann, S.*; Heberger, F. P.*; Ackermann, D.*; Antalic, S.*; Burkhard, H. G.*; Heinz, S.*; Kindler, B.*; Lisetskiy, A. F.*; Lommel, B.*; et al.
European Physical Journal A, 34(4), p.355 - 361, 2007/12
Isomeric states in Th and Th were produced in the fusion-evaporation reactions of Cr + Dy and identified by means of -rays from the isomeric states. The life-times were determined by measureing the time difference between the signals of the implanted evaporation residues (Th) and the -rays signals, and were obtained to be 1.24 s for Th and 1.4 s for Th. The proton configuration betweens the orbitals of 1h and 2f was assigned to the isomeric states in Th.
Hofmann, S.*; Ackermann, D.*; Antalic, S.*; Burkhard, H. G.*; Comas, V. F.*; Dressler, R.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; Heberger, F. P.*; et al.
European Physical Journal A, 32(3), p.251 - 260, 2007/06
The fusion reaction of Ca projectiles withU target nuclei was studied at the velocity filter SHIP of GSI. Two decay chains were measured, which fully confirm data that were previously assigned to the isotope 112 in experiments at the Flerov Laboratory in Dubna. Two other events are consistent with a 50% spontaneous fission (SF) branch of this isotope. The mean value obtained for the half-life of 112 is (6.9) s, the energy is (9.5200.015) MeV, and the total kinetic energy (TKE) of SF is (23814) MeV. The half-life of the decay daughter nucleus Ds is (0.18) s, and the TKE of SF is (210) MeV. The cross-section deduced from all four events is (0.72) pb, measured at an excitation energy of 34.6 MeV of the compound nucleus 112.