The study of the properties of spontaneously fissioning transfermium nuclei synthesized in the complete fusion reactions with heavy ions

International audienceThis report describes a series of experiments aimed on investigating characteristics of spontaneous fission of nuclei in the exotic region of short-lived neutron-deficient isotopes with Z ≥ 100. Unique data on the decay properties of neutron-deficient isotopes 244,246Fm, 250No, 252No, 254Rf and 256Rf produced in the complete fusion reactions with accelerated heavy ions 40Ar + 206,208Pb → 246,248Fm*, 48Ca + 204,206Pb → 252,254No*, 50Ti + 206,208Pb →256,258Rf* were obtained in experiments at the VASSILISSA (SHELS) separator combined with a neutron detector

Investigation of the Spontaneous Fission Properties of Neutron-Deficient Nobelium Isotopes

International audienceIn the last years we carried out several experiments aimed to investigate properties of short-lived SF isotopes. The neutron-deficient isotopes of nobelium were produced in fusion-evaporation reactions using 206,208Pb targets and an intense 48Ca-beam. Fusionevaporation residues were separated by the SHELS separator and implanted into a largearea double-sided 48×48 strip silicon detector surrounded by 3He-based neutron counters. Half-lives and decay branching ratios for 252,254No isotopes were measured. The average number of neutrons per spontaneous fission of 254No determined for the first time

Characteristics of spontaneous fission of 250^{250}No

International audienceThis study describes an experiment on investigating the properties of spontaneous fission of shortlived neutron-deficient nuclei synthesized in the reaction of complete fusion $^{48}$Ca +$^{204}$Pb = $^{252}$No*. The experiment is performed using the SHELS separator and the beam of multicharged ions at U-400 accelerator (LNR, JINR). Two activities undergoing spontaneous fission, which can be related to the ground and isomeric states of $^{250}$No nucleus, are registered. The half-lives, total kinetic energies of fission fragments, and neutron multiplicities are measured for the short-lived nuclei. The average number of neutrons per fission for the activity with t$_{1/2}$ = 5.1 ± 0.3 μs is = 4.38 ± 0.13 μs, and for nuclei with the half-life t$_{1/2}$ = 36 ± 3 μs it is xxxxx

New front and back-end electronics for the upgraded GABRIELA detection system

International audienceThe GABRIELA [1] set-up is used at the FLNR to perform detailed nuclear structure studies of transfermium nuclei. Following the modernization of the VASSILISSA separator (SHELS) [2] the GABRIELA detection system has also been upgraded. The characteristics of the upgraded detection system will be presented along with results from some recent electronics tests

Prompt Neutrons from Spontaneous 254^{254}Rf Fission

International audienceThe neutron yield from the spontaneous fission of the short-lived neutron-deficient$^{254}$Rf nucleus produced in the complete fusion reaction with the beam of multiply charged ions from the U400 accelerator at the Flerov Laboratory of Nuclear Reactions (FLNR), Joint Institute for Nuclear Research (JINR), is measured using the combined detection system of the SHELS velocity filter. The half-life and the branching ratio of$^{254}$Rf are also measured. The data on the multiplicity of prompt neutrons from spontaneous fission of$^{256}$Rf ($\bar {\nu }$ = 3.87 ± 0.34) are presented for the first time

Prompt Neutrons from Spontaneous 254Rf Fission

The neutron yield from the spontaneous fission of the short-lived neutron-deficient 254Rf nucleus produced in the complete fusion reaction with the beam of multiply charged ions from the U400 accelerator at the Flerov Laboratory of Nuclear Reactions (FLNR), Joint Institute for Nuclear Research (JINR), is measured using the combined detection system of the SHELS velocity filter. The half-life and the branching ratio of 254Rf are also measured. The data on the multiplicity of prompt neutrons from spontaneous fission of 256Rf ($$\bar {\nu }$$ = 3.87 ± 0.34) are presented for the first time.The neutron yield from the spontaneous fission of the short-lived neutron-deficient 254Rf nucleus produced in the complete fusion reaction with the beam of multiply charged ions from the U400 accelerator at the Flerov Laboratory of Nuclear Reactions (FLNR), Joint Institute for Nuclear Research (JINR), is measured using the combined detection system of the SHELS velocity filter. The half-life and the branching ratio of 254Rf are also measured. The data on the multiplicity of prompt neutrons from spontaneous fission of 256Rf ($$\bar {\nu }$$ = 3.87 ± 0.34) are presented for the first time.status: publishe

Short-Lived Isotopes of Transfermium Elements: Studying Characteristics of Spontaneous Fissioning

© 2018, Allerton Press, Inc. series of experiments performed in 2014–2015 using the SHELS separator and a beam of multicharged ions from the U-400 accelerator at the Flerov Laboratory of Nuclear Reactions (Joint Institute for Nuclear Research) in Dubna is described. In preparation for a large program of experiments with a beam of highly charged ions of 50Ti, an experiment is performed to study the spontaneous fissioning (SF) of short-lived neutron-deficient isotope 256Rf formed in complete fusion reaction50Ti + 208Pb = 256Rf + 2n. The half-life of 256Rf is measured along with the probability of its SF decay. The average number of neutrons per one event of 256Rf SF (v¯ = 4.47 ± 0.09) is obtained for the first time. The results from experiments to study the SF of short-lived neutron-deficient isotopes synthesized in complete fusion reaction 48Ca + 204Pb → 252No* are presented as well. Two short-lived activities attributed to the SF of the ground and isomeric states of 250No are revealed. The half-life, total kinetic energies of fission fragments, and neutron multiplicities are measured for the obtained short-lived nuclei. The average numbers of neutrons per one SF event are v¯ = 4.38 ± 0.13 and v¯ = 3.90 ± 0.20, respectively, for SF activity with t1/2 = 5.1 ± 0.3 and t1/2 = 36 ± 3 μs.status: publishe

Short-Lived Isotopes of Transfermium Elements: Studying Characteristics of Spontaneous Fissioning

International audienceseries of experiments performed in 2014–2015 using the SHELS separator and a beam of multicharged ions from the U-400 accelerator at the Flerov Laboratory of Nuclear Reactions (Joint Institute for Nuclear Research) in Dubna is described. In preparation for a large program of experiments with a beam of highly charged ions of$^{50}$Ti, an experiment is performed to study the spontaneous fissioning (SF) of short-lived neutron-deficient isotope$^{256}$Rf formed in complete fusion reaction$^{50}$Ti +$^{208}$Pb =$^{256}$Rf + 2n. The half-life of$^{256}$Rf is measured along with the probability of its SF decay. The average number of neutrons per one event of$^{256}$Rf SF ( $\bar v$ = 4.47 ± 0.09) is obtained for the first time. The results from experiments to study the SF of short-lived neutron-deficient isotopes synthesized in complete fusion reaction$^{48}$Ca +$^{204}$Pb →$^{252}$No* are presented as well. Two short-lived activities attributed to the SF of the ground and isomeric states of$^{250}$No are revealed. The half-life, total kinetic energies of fission fragments, and neutron multiplicities are measured for the obtained short-lived nuclei. The average numbers of neutrons per one SF event are $\bar v$ = 4.38 ± 0.13 and $\bar v$ = 3.90 ± 0.20, respectively, for SF activity with t$_{1/2}$ = 5.1 ± 0.3 and t$_{1/2}$ = 36 ± 3 μs