9 research outputs found
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 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 Ca +Pb = 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 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 = 5.1 ± 0.3 μs is = 4.38 ± 0.13 μs, and for nuclei with the half-life t = 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 Rf Fission
International audienceThe neutron yield from the spontaneous fission of the short-lived neutron-deficientRf 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 ofRf are also measured. The data on the multiplicity of prompt neutrons from spontaneous fission ofRf ( = 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 ( = 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 ( = 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 ofTi, an experiment is performed to study the spontaneous fissioning (SF) of short-lived neutron-deficient isotopeRf formed in complete fusion reactionTi +Pb =Rf + 2n. The half-life ofRf is measured along with the probability of its SF decay. The average number of neutrons per one event ofRf SF ( = 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 reactionCa +Pb →No* are presented as well. Two short-lived activities attributed to the SF of the ground and isomeric states ofNo 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 = 4.38 ± 0.13 and = 3.90 ± 0.20, respectively, for SF activity with t = 5.1 ± 0.3 and t = 36 ± 3 μs