Table Of ContentOn Beyond Uranium
Science Spectra Book Series
Series Editor: Vivian Moses, King’s College, London, UK
Volume 1
The Key to the Future
by John Cater
Volume 2
On Beyond Uranium
Journey to the end of the Periodic Table
by Sigurd Hofmann
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which may be cancelled at any time and which provide for automatic billing
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On Beyond Uranium
Journey to the end of the
Periodic Table
Sigurd Hofmann
London and New York
First published 2002
by Taylor & Francis
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Simultaneously published in the USA and Canada
by Taylow & Francis Inc,
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This edition published in the Taylor & Francis e-Library, 2003.
© 2002 Taylor & Francis
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Contents
Page
Preface vii
Acknowledgements viii
Chapter 1 The landscape 1
Chapter 2 Elements created in stars 21
Chapter 3 Synthetic elements 27
Chapter 4 Elements made with light ion beams from ‘small’
cyclotrons 37
Chapter 5 Hot fusion and controversial discoveries:
elements 102 to 106 43
Chapter 6 Cold fusion and ‘big’ cyclotrons 49
Chapter 7 The dream: uranium beams 65
Chapter 8 Models, cross-section and fusion 79
Chapter 9 New techniques – kinematic separators and
position-sensitive detectors 89
Chapter 10 New elements and other stories: from bohrium to
meitnerium 119
Chapter 11 The year 1988: a new beginning 151
Chapter 12 Three more elements: 110, 111 and 112 163
Chapter 13 Names mean more than numbers 175
Chapter 14 Attack on the domain of superheavies:
elements 114, 116 and 118 183
Chapter 15 Epilogue 207
Bibliography 209
Name index 211
Subject index 213
Element index 216
Preface
The nineteenth-century chemists did a marvellous job. From no more than a
primitive understanding of chemistry and the nature of the elements in 1800,
ten decades later chemical science knew of the probable existence of 92 ele-
ments, from hydrogen the lightest to uranium the heaviest (although a few
were so rare that they had not yet actually been identified). For nigh on 40
years we thought we knew what the Earth and everything on it and in it was
made of.
Then things started to change. Towards the end of the 1930s chemists
and physicists began tentatively to discover elements beyond uranium, the
‘transuranics’. After World War II, with its startling developments in atomic
physics leading both to atomic bombs and nuclear power stations, the pace
began to quicken. When I started to study physics at the University of Darm-
stadt in 1963, there were 103 elements known; now there are 116 and the
number is still rising, albeit slowly. Looking for new elements is one of the
strangest treasure hunts ever.
You don’t find them in the rocks or in the sea or even in the stars. Most
probably they really are not found in Nature at all except, perhaps, in a most
transitory sense – here one moment, gone the next. In the sense that they do
‘exist’, they are to be found only in very carefully and precisely designed
experiments in powerful nuclear tools of various sorts. Everything has to be
set up all ready to detect them the instant they are formed because, for some
of them, their survival time is to be measured in fractions of a second.
Looking for new superheavy elements is what I spend my time doing –
and I cannot imagine a more exciting branch of science. It is every bit as
enthralling as it once was to explore an unknown continent but without mos-
quitoes and hard camp beds. This book is about the search for elements
never before known to humankind. The story takes a bit of telling; some of
the concepts will be unfamiliar and the terminology new for you. But stick
with it through the more difficult parts; it is worth staying the course until the
end to find out why I remain so enthusiastic!
Acknowledgements
Extracts on pages 28, 31, 32, 33, 34, 39, 40, 41, 42 are taken from
Seaborg, G.T. and Loveland, W.D. (1990) The elements beyond uranium.
John Wiley and Sons, Inc., New York. This material is used by permission
ofJohn Wiley and Sons, Inc.
1
The landscape
Our world of elements is a landscape of minute particles, of protons and
neutrons, of electrons and their counterpart, neutrinos. From that set of four
sub-atomic particles a whole world is made, a world of planets and moun-
tains, of rivers, lakes, shores and oceans, of flowers and trees and animals –
and also of ourselves, we the thinking people.
How is this possible – four tiny pieces and such a variety of con-
sequences? Because the particles carry three secrets: the forces acting
between them (which determine how the particles attract and repel each
other, how they combine, and how they separate), the radiation which can
be emitted from them when they move (this is the way we get the light from
our sun), and the huge numbers of bricks available and how tiny each one is.
Nowadays, many people have some understanding of chemistry and
know about the existence of atoms and protons, and neutrons and electrons,
although neutrinos remain something for specialists. Chemistry grew from
alchemy; the alchemists, who, you will remember, were forever looking for
the philosopher’s stone which would turn base metals into gold, with which
their rulers never seemed to become sated. One of those alchemists, Johann
Friedrich Böttger of Dresden, found porcelain instead of gold and was kept a
prisoner in his laboratory so as not to betray the secret. All that looking at
natural substances and experimenting with the ways in which they interacted
with one another did, in the course of time, throw up a vast amount of
empirical information which eventually demanded explanation. So chemistry
became a modern experimental science, unlike the attempt at magic which
had been the basis of the alchemy which had gone before. At about the same
time, in the seventeenth century, the quality of astronomy reached a high
standard. Sir Isaac Newton identified the universal law of gravitational force.
Light and gases were investigated and answers sought to such apparently
simple questions as the nature of air.
The nineteenth century was the century of electromagnetic force, the
force which acts between the charges of the fundamental particles. Michael
Faraday in London coined the term ion for charged particles moving in an
