Synthesis of the new neutron-deficient isotopes 250102, 242Fm, and 254Ku

Probing sub-barrier fusion and extra-push by measuring fermium evaporation residues in different heavy ion reactions

“…The listed values are experimental maximum cross sections if excitation functions were measured [15,17,29] or calculated maximum cross sections if only the average thick target production cross sections were measured [14,16,30]. In the latter cases the values listed in Table 2 were deduced from the target thickness and an assumed width of the corresponding excitation function.…”

“…The experimental techniques used to determine the cross sections summarized in Table 2 Table 2. Maximum cross sections for the production of fermium evaporation residues from the fusion reaction between argon and lead ; (14) ") this work b) unweighted average ~) spontaneous fission decay from 246Fm measured; assumed fission branch 8 ~o [26] otherwise detected by its c~-decay are, i) mechanical rotating wheel systems as used in this work which transport the reaction products continuously out of the beam into shielded positions where fission-track detectors register spontaneous fission decay [14][15][16]30], ii) a gas-jet system [293 which transports reaction products to collecting foils where the deposited activity is measured for c~-and spontaneous fission decay, iii) an in-beam detection system [31], where recoiling products were stopped in hydrogen gas and fission fragments detected by several ionisation chambers positioned around the stopping area, and iv) a velocity filter [32] able to separate in flight fusion products from the faster beam particles and the bulk of other reaction products [17]. Despite the very different techniques applied, the cross sections listed in Table 2 agree in general within about a factor of three.…”

Theoretical half-lives for the heaviest nuclei

“…The experimental data used for the comparison are collected in Table 1. They are taken from [17][18][19][20][21] given in the fourth and sixth columns of the table.…”

A study of fusion reactions between206, 207Pb nuclei and40Ar ions near the coulomb barrier

“…The final product of the reactions studied, Zg4Fm, undergoes spontaneous fission with a 100 ~o probability and has a half-life of about 4 ms [1, 71. These properties of 244Fm permitted its detection using a comparatively simple technique [3] as follows. Recoil nuclei knocked out from the target were stopped in a rotating disk and transported to mica detectors of spontaneous fission fragments.…”