Observation of enhanced nuclear stability near the 162 neutron shell

In bombardments of {sup 248}Cm with {sup 22}Ne the authors discovered two new isotopes, {sup 265}106 and {sup 266}106, by establishing genetic links between {alpha} decays of the 106 nuclides and SF or {alpha} decays of the daughter (grand-daughter) nuclides. For {sup 266}106 they measured E{sub {alpha}}=8.62{+-}0.06 MeV followed by the SF decay of {sup 262}104 for which they measured a half-life value of 1.2{sup +1.0}{sub {minus}0.5} s. For {sup 265}106 they measured E{sub {alpha}}=8.82{+-}0.06 MeV. They estimated {alpha} half-lives of 10-30 s for {sup 266}106 and 2-30 s for {sup 265}106 with SF branches of {approximately}50% or less. The decay properties of {sup 266}106 indicate a large enhancement in the SF stability of this N=160 nuclide and confirm the existence of the predicted neutron-deformed shell N=162

Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions

The decay properties of {sup 290}116 and {sup 291}116, and the dependence of their production cross sections on the excitation energies of the compound nucleus, {sup 293}116, have been measured in the {sup 245}Cm({sup 48}Ca,xn){sup 293-x}116 reaction. These isotopes of element 116 are the decay daughters of element 118 isotopes, which are produced via the {sup 249}Cf+{sup 48}Ca reaction. They performed the element 118 experiment at two projectile energies, corresponding to {sup 297}118 compound nucleus excitation energies of E* = 29.2 {+-} 2.5 and 34.4 {+-} 2.3 MeV. During an irradiation with a total beam dose of 4.1 x 10{sup 19} {sup 48}Ca projectiles, three similar decay chains consisting of two or three consecutive {alpha} decays and terminated by a spontaneous fission (SF) with high total kinetic energy of about 230 MeV were observed. The three decay chains originated from the even-even isotope {sup 294}118 (E{sub {alpha}} = 11.65 {+-} 0.06 MeV, T{sub {alpha}} = 0.89{sub -0.31}{sup +1.07} ms) produced in the 3n-evaporation channel of the {sup 249}Cf+{sup 48}Ca reaction with a maximum cross section of 0.5{sub -0.3}{sup +1.6} pb

The Device to Measure Currents in External Beam Transportation Lines of the DC-72 Cyclotron

The present work is devoted to the development of a device to measure ion currents in external beam transportation lines of the DC-72 cyclotron, which is being created for the Cyclotron Centre of the Slovak Republic. The device is based on a Faraday cup. As possible constructive materials for the Faraday cup, Al, Cu, Fe, W and C were considered from the point of view of both the residual radiation and heating by the proton beam of the 3 kW power. Based on the calculations performed. It was suggested to use aluminium. The results of calculations of the temperature distribution in cylindrical and conic cups have been presented, both for a proton energy of 30 MeV at a beam power of 3 kW, and for a proton energy of 72 MeV at a beam power of 2.5 kW. Also presented are the results of calculation of the construction with permanent magnets that create sufficient magnetic field to eliminate the influence of secondary electrons emission on the current measurement accuracy. As a result, a sketch of the device construction with the moveable Faraday cup and bellows pneumatic drive has been suggested. On the basis of the Faraday cup has been developed

Proton induced fission of 232Th at intermediate energies

The mass-energy distributions and cross sections of proton-induced fission of Th-232 have been measured at the proton energies of 7, 10, 13, 20, 40, and 55 MeV. Experiments were carried out at the proton beam of the K-130 cyclotron of the JYFL Accelerator Laboratory of the University of Jyvakyla and U-150m cyclotron of the Institute of Nuclear Physics, Ministry of Energy of the Republic of Kazakhstan. The yields of fission fragments in the mass range A = 60- 170 a.m.u. have been measured up to the level of 10(-4)%. The three humped shape of the mass distribution up has been observed at higher proton energies. The contribution of the symmetric component grows up with increasing proton incident energy; although even at 55 MeV of proton energy the shoulders in the mass energy distribution clearly indicate the asymmetric fission peaks. Evolution of shell structure was observed in the fission fragment mass distributions even at high excitation energy

α\alpha decay of 273^{273}110: shell closure at N=162

In bombardments of Pu-244 with S-34 we discovered the alpha-decaying nuclide (273)110. We conducted an extensive off-line search of the raw data for event sequences which fit the expected pattern of implantation in a position-sensitive detector and subsequent decay of (273)110 and its descendants. We observed one three-member sequence of genetically linked alpha decays, resulting in E(alpha)=11.35 MeV, a half-life of 0.3(-0.2)(+1.3) ms, and a production cross section of about 0.4 pb for (273)110. Other possible (273)110 event chains were also observed. The measured a-particle energy for the N=163 nuclide (273)110 provides direct evidence for a neutron shell closure at N=162