Ca48+Bk249Fusion Reaction Leading to Element

J. Khuyagbaatar¹,

A. Yakushev²,

Ch. E. Düllmann³

et al.

Abstract

The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."

Statistical approaches to lifetime measurements with restricted observation times

“…This mathematical trick was then widely adopted by nuclear spectroscopists, in particular for super-heavy-nuclei data analyses (see, e.g., Refs. [7][8][9][10][11]). …”

How Many Chemical Elements are there in the Universe? A (not so) <i>Bohring</i> Question

“…The nuclear charge Z cannot exceed 137, i.e., the inverse of the value of the so called fine-structure constant, which is a dimensionless combination of three fundamental constants: e 2 /ħc, where e is the charge of the electron and ħ is the Plank constant h divided by 2π. The fact that ħc/e 2 is very close to an integer number (its approximate value is actually 137.04) 1 has in the past stimulated a great deal of speculation. Nevertheless, for students of Chemistry, who usually are not acquainted with the intricacies of QED, we note herein that the very same result can be arrived at by using the pioneering model proposed by Niels Bohr for the hydrogen atom: actually the first atomic model ever envisaging quantum conditions, and which is present in many textbooks.…”

“…To date, there are 118 elements in the PT: the most recent addition (accomplished in 2014) is the element having the atomic number Z = 117 (Ununseptium) [1], which filled a gap in the island of stability of super heavy elements predicted time ago. [2,3] Elements 116 and 118 had actually been added earlier, in 2006.…”

Desenvolvimento de conjuntos polarizados de funções de base relativísticas Gaussianas e aplicações

“…A busca de um uma ilha de estabilidade nuclear, com a possibilidade de síntese de um elemento super-pesado com considerável tempo de meia-vida, tem motivado o aumento no número de elementos artificiais incorporados à tabela periódica. Por exemplo, no começo de 2014, foi confirmada a síntese do elemento 117 Uus [17]. Tais elementos podem ser usados em sínteses moleculares, como ocorreu na obtenção de uma carbonila contendo um elemento transactinídeo, Sg(CO) 6 (Z Sg = 106), também realizada em 2014 [18].…”

“…Pelos resultados da Tabela 4.12, fica claro que o padrão notado para 13 Al e 18 Ar se mantém para os demais elementos do sub-bloco 3p: a função g 3 é a que resulta na maior variação de energia dentro desse bloco de momento angular; índices 3 e 4 retornam sempre as funções de momento angular f ideais (inclusive para 14 Si, onde o resultado destas funções em grupo concorda com os resultados individuais das mesmas); os índices que geram as funções d ideias se tornam uma unidade maior que aqueles para os elementos mais leves apenas a partir do 17 Cl.…”