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On 16 August 2003, at the 42nd IUPAC General Assembly in Ottawa, Canada, the IUPAC Council officially approved the name for element of atomic number 110, to be known as darmstadtium, with symbol Ds. > View Press Release

The Questions and Answers below have been compiled from recent communications with Dr. Sigurd Hofmann from the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany, the laboratory where Ds has been discovered.

Q. The element was produced in 1995. Why did the naming take eight years? What was the name of the element in the interim period?

A. The relatively long period before a name for element 110 was officially accepted was not based on uncertainties or major objections from other laboratories. However, some clarification was needed concerning experimental work made in Dubna and Berkeley on element 110.

An IUPAC Technical Report on this subject was published by Karol et al. (the Joint Working Party, JWP) in Pure Appl. Chem., Vol 73, pp. 959-967, 2001. In that paper it was clearly stated that "Element 110 has been discovered by this (Hofmann et al., Z. Phys. A350, 277-280, 1995) collaboration. All other work was considered as insufficient to fulfill the criteria for the discovery of a new element.

After this report, IUPAC set November 2002 as a deadline for suggesting a name, which then, according to the rules, had to be made public for a period of five months.

Interim names for elements to be discovered are recommended by IUPAC.
For element 110 it was ununnilium, Uun.
However, in the laboratory jargon we simply used hundred ten, 110.

The first nucleus of 269Ds was produced on Nov. 9, 1994.
The publication was received by the editor on Nov. 14, 1994 and the paper appeared early 1995.

Q. How many of these nuclei have been produced to date?

A. By now a total of 48 nuclei of darmstadtium were measured at different laboratories. The nuclei were attributed to 6 different isotopes produced in different reactions. Some of the published data is subject to further investigation and confirmation.

62Ni + 208Pb --> 269Ds + 1 n, 1994, GSI Darmstadt, 3 atoms

64Ni + 208Pb --> 271Ds + 1 n, 1994, GSI Darmstadt, 9 atoms

64Ni + 208Pb --> 271Ds + 1 n, 2000, GSI Darmstadt, 4 atoms

64Ni + 208Pb --> 271Ds + 1 n, 2000, LBNL Berkeley, 2 atoms

64Ni + 208Pb --> 271Ds + 1 n, 2002, RIKEN Japan, 14 atoms

64Ni + 207Pb --> 270Ds + 1 n, 2000, GSI Darmstadt, 8 atoms

70Zn + 208Pb --> 277Uub + 1 n, --> 273Ds + 1 alpha, 1996, GSI Darmstadt, 1 atom

70Zn + 208Pb --> 277Uub + 1 n, --> 273Ds + 1 alpha, 2000, GSI Darmstadt, 1 atom

48Ca + 244Pu --> 289Uuq + 3 n, --> 281Ds + 2 alpha, 1998, FLNR Dubna, 1 atom

48Ca + 244Pu --> 288Uuq + 4 n, --> 280Ds + 2 alpha, 1999, FLNR Dubna, 2 atoms

48Ca + 248Cm --> 292Uuh + 4 n, --> 280Ds + 3 alpha, 2000, FLNR Dubna, 1 atom

48Ca + 248Cm --> 292Uuh + 4 n, --> 280Ds + 3 alpha, 2001, FLNR Dubna, 2 atoms

The half-lives range from 180 microseconds for 269Ds to 1.1 minute for 281Ds.

Q. Is there a scientific need to produce more of these nuclei? In what way, does this specific achievement help to produce other superheavy elements?

A. In order to better understand the synthesis of heavy elements, it is necessary to produce them in different reactions and at different beam energies, resulting in the so-called 'excitation functions' which are the yield as function of the beam energy. In these experiments one also increases the number of produced atoms.

A greater number of decays also exhibits more detailed information on nuclear structure, e.g. nuclear deformation, angular momentum, excited levels, decay modes like alpha or beta decay, or spontaneous fission.
It also increases the statistical accuracy of half-life and decay energy.

Q. Can you provide some story or episode of human interest associated with the production of the element?

A. Here I would like to refer to my book:

Hofmann, S., On Beyond Uranium - Journey to the end of the Periodic Table, Science Spectra Book Series, Volume 2, V. Moses, Series Editor, ISBN 0-415-28495-3 (hardback)
Taylor and Francis, London and New York, 2002, pp. 216
> link to publisher website or
> visit Taylor & Francis eBookstore ... from here visitors are able to use eSubscribe and ePrint/eCopy to access the sections of the book.

Q. What is the future plan in this expensive area of research?

A. In order to achieve a more detailed exploration of the structure and boundaries of the island of superheavy nuclei, technical improvements have to be performed. The aim is to get increased beam intensity, at least by a factor of 10, and to develop targets which can stand these high intensities.

The most urgent physical question to be solved is, where actually are the closed shells for the protons and neutrons located. Theory presently predicts 114, 120 or 126 for the protons and 172 or 184 for the neutrons as possible candidates.

Of great importance is also the question regarding the strength of these shells. Does only one major shell with strong shell effect for the protons and neutrons exist, or is the shell strength more equally distributed across a number of subshells?

These properties finally determine the production yield and the lifetime of superheavy nuclei. Both decide the possibilities for application of further techniques, like chemical separation to study the chemical properties or capture of the atoms in ion traps to perform high resolution mass spectroscopy and laser excitation of the atomic electron shells.

What is your question?

E-mail Sigurd Hofmann or/and visit <www.darmstadtium.com>

> link to FAQs about the Chemical Elements

Page last modified 22 October 2003.
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