Synthesis of elements 115 and 113 in the reaction {sup 243}Am+{sup 48}Ca

Journal Article · Thu Sep 01 04:00:00 EDT 2005 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.72.034611· OSTI ID:20698994

Oganessian, Yu Ts; Utyonkov, V K; Dmitriev, S N; Lobanov, Yu V; Itkis, M G; Polyakov, A N; Tsyganov, Yu S; Mezentsev, A N; Yeremin, A V; Voinov, A A; Sokol, E A; Gulbekian, G G; Bogomolov, S L; Iliev, S; Subbotin, V G; Sukhov, A M; Buklanov, G V; Shishkin, S V; Chepygin, V I; Vostokin, G K ^[1]

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1. Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation)

The results of two experiments designed to synthesize element 115 isotopes in the {sup 243}Am+{sup 48}Ca reaction are presented. Two new elements with atomic numbers 113 and 115 were observed for the first time. With 248-MeV {sup 48}Ca projectiles, we observed three similar decay chains consisting of five consecutive {alpha} decays, all detected in a total time interval of 30 s. Each chain was terminated by a spontaneous fission (SF) with a high-energy release and a lifetime of about a day. With 253-MeV {sup 48}Ca projectiles, we registered a different decay chain of consecutive {alpha} decays detected in a time interval of 0.5 s, also terminated by spontaneous fission, but after 1.8 h. The decay properties of the eleven new {alpha}- and SF-decaying nuclei are consistent with expectations for consecutive {alpha} decays originating from the parent isotopes {sup 288}115 and {sup 287}115, produced in the 3n- and 4n-evaporation channels, respectively. Support for the assignment of the atomic numbers of all of the nuclei in the {sup 288}115 decay chain was obtained in an independent experiment in which a long-lived spontaneous fission activity, {sup 268}Db (15 events), was found to be chemically consistent with the fifth group of the periodic table. The odd-odd isotope {sup 288}115 was observed with largest cross section of about 4 pb. In the SF decay of {sup 268}Db, a total kinetic energy of 230 MeV and a neutron multiplicity per fission of 4.2 were measured. The decay properties of the 11 new isotopes with Z=105-115 and the production cross sections are in agreement with modern concepts of the role of nuclear shells in the stability of superheavy nuclei. The experiments were carried out at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research.

• OSTI ID: 20698994
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 72; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA DECAY
AMERICIUM 243 TARGET
CALCIUM 48 REACTIONS
CROSS SECTIONS
ELEMENT 113
ELEMENT 115
HEAVY ION FUSION REACTIONS
JINR
KINETIC ENERGY
LIFETIME
MEV RANGE
MULTIPLICITY
NEUTRONS
SPONTANEOUS FISSION