Atomic Mass Evaluations
Contributions of the Kaiser-Wilhelm-/Max-PlanckInstitut für Chemie
Dr. B. Pfeiffer
GSI Helmholtzzentrum für Schwerionenforschung
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Balances from “De re metallica, Liber Septem”
G. Agricola, 1556
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Motivation: scientific and personal
Importance of balances for rebirth
of atomic hypothesis around 1800
Prout‘s hypothesis
Isotopes
Contributions from Kaiser-WilhelmInstitut für Chemie
AMEs at Max-Planck-Institut
Future AME
Mass spectrograph built at
Kaiser-Wilhelm Institut für
Chemie in 1943
Seminar für Kern- und Kosmochemie (“K&K Seminar”)
MPI für Chemie, Mainz, Mittwoch, 10.2.2010, 17:15
1
Pre-history of talk, personal motivation
In summer during a „Nachsitzung“‡, Prof. Palme mentioned to have seen a mass spectrograph at the MPI. It had once been in the group of Mattauch. I remembered that he had
published mass evaluations together with A.H. Wapstra. It was proposed to ask G. Audi
to give a seminar on the collaboration of the Mainz group with Wapstra. But he got in
contact with Wapstra only 20 years later and so I was „made volunteer“ for a talk.
Some days later, I remembered my early days at the II. Physikalisches Institut in Gießen.
In a cellar, there had been a very old mass spectrograph built by the director Prof. Ewald
long ago. I vaguely had in mind that he had been in connection with Mattauch. Suddenly arose the suspicion that Prof. Palme might have seen this apparatus in Mainz.
So I started to search for clues to the history of this spectrograph and to the relation
between Ewald and Mattauch. Browsing through data bases as diverse as GOOGLE
and the NASA/Harvard Astrophysical Base I surprisingly found some publications of
Ewald together with Mattauch, Hahn, Strassmann going back to around 1940.
There were also hints to the wartime activities in the „Uranverein“, but I would like to
have more serious sources before discussing these topics.
Just in December, I was recalled that Ewald liked to put some students in his car when
he attended the early GSI seminars in Darmstadt-Wixhausen.
‡ C. Burkhard, 1.7.09
2
Very early days of GSI
In the December 2009 issue of target, the scientific magazine of
GSI, is displayed a picture from the early days of GSI (not yet at
the actual site). Prof. Ewald is easy to identify. I am not sure
who is the young guy at the left. It could be myself.
GSI 1972
?
3
Courtesy Prof. Rudolf Bock
“Prehistory” of atomic weights
For this audience, I need not explain the scientific motivation for determining atomic
masses. But the physicists in this field tend to oversee that the importance of mass did
not start with the detection of isotopes at the beginning of the 20th century!
The atomic hypothesis of Leukippos and Demokritos was never forgotten,
but the Four-Element theory of Empedokles was the mainstream for 2
millenia.
Alchemy was mainly concerned with qualitative attributes of substances,
quantitative analysis was performed by craftsmen in the mints or ore
mines (see, e.g. G. Agricola: De re metallica libri XII, 1556).
From Liber Septimus
Modern chemistry is interested in quantitative relations between elements:
Influenced by neoplatonic philosophy, J.B. Richter introduced 1792
„chymisches Rechnen“, in scientific notation
stoichiometry.
’Anfangsgründe der Stöchyometrie oder Meßkunst chymischer Elemente’.
To disprove his teacher Bertholet, J.L. Proust established 1799 the “Law of
Definite Proportions”, which was modified by J. Dalton’s “Law of Multiple
Proportions”.
In order to explain these chemical laws Dalton re-introduced the atomic hypothesis,
inspired by his studies of the physical laws of gases.
4
Alchemists and balances
Illustrations to various editions of Thomas Norton‘s Ordinall of Alchemy (ca. 1477)
I started the search reading that alchemists were
merely interested in „quality“ not quantity. Prof. H.
Gebelein, a modern alchemist, shows the figure at
the right side above.
He is convinced of the transmutation of elements
by alchemy, not only by atom smashers and neutrons.
5
Dokumastic in the Scripture?
Jeremias, 6
ca. 600 B.C.E.
29: The bellows are burned, the lead is consumed of the fire; the founder melteth in vain: for the
wicked are not plucked away.
30: Reprobate silver shall men call them, because the LORD hath rejected them.
Ezekiel, 22
ca. 580 B.C.E.
17: And the word of the LORD came unto me, saying,
18: Son of man, the house of Israel is to me become dross: all they are brass, and tin, and iron,
and lead, in the midst of the furnace; they are even the dross of silver.
19: Therefore thus saith the Lord GOD; Because ye are all become dross, behold, therefore I will
gather you into the midst of Jerusalem.
20: As they gather silver, and brass, and iron, and lead, and tin, into the midst of the furnace, to
blow the fire upon it, to melt it; so will I gather you in mine anger and in my fury, and I will leave
you there, and melt you.
21: Yea, I will gather you, and blow upon you in the fire of my wrath, and ye shall be melted in the
midst therof.
22: As silver is melted in the midst of the furnace, so shall ye be melted in the midst thereof; and
ye shall know that I the LORD have poured out my fury upon you.
Zechariah, 13
after 500 B.C.E.
9: And I will bring the third part through the fire, and will refine them as silver is refined, and will try
them as gold is tried: they shall call on my name, and I will hear them: I will say, It is my people:
and they shall say, The LORD is my God.
The first explicit reference to this analytical tool is in Pliny the Elder: Historia Naturalis.
6
Basis for the periodic system of the elements
Over time, the (al)chemists had discovered more than the 4 (5)
classical “elements“.
They were a “hermetically sealed” community and their cryptic
works are difficult to understand and often their names stand for
compounds or even more general principles:
• “antimony“ was Stibnit (Sb2S3),
• the element Sb was known as “antimony regulus“
The first task for modern chemistry was to find an unequivocal
definition of “element”, as already requested by Robert Boyle 1661.
Part of texts on astrology or alchemy?
The upcoming of a rudimentary chemical
„industry“ with the need of fixed procedures
instead of philosophical theories lead to
modern chemistry:
Decisive was the shift from “quality“ to
“quantity“,
the use of precise balances.
This led to stoichiometry and the proportional laws. Based on these principles, 1868/9
D.I. Mendeleev and L. Meyer developed
then the Periodic System of the Elements.
7
Table of the relative weights of the ultimate
particles of gaseous and other bodies
Appended to
J. Dalton
“On the Absorption of Gases by Water and
Other Liquids”
Memoirs and Proceedings of the Manchester
Literary and Philosophical Society, Manchester,
1805, vol. 6, pp. 271-287
This paper was already presented orally in 1803.
It contains the first steps to the atomic hypothesis
to explain the laws of definite and multiple proportions.
The first table of relative weights is appended
without explanation of the methods applied.
http://web.lemoyne.edu/~giunta/dalton52.html
8
John Dalton
A New System of Chemical Philosophy (1808)
http://www.archive.org/stream/newsystemofchemi01daltuoft
9
http://www.us.archive.org/GnuBook/?id=newsystemofchemi01daltuoft#010
New Table
of the relative weights of atoms
J. Dalton,
A New System of Chemical Philosophy,
Manchester,
printed by the executors of S. Russell for
George Wilson, London, 1827, vol. 2, p. 352
Remark:
Dalton, contrary to most fellow chemists,
was convinced that two atoms of the
same element cannot be part of a molecule.
Therefore, his reference mass for hydrogen
in reality is 0.5.
His formula for water is HO instead of
H2O, etc.
Avogadro obtained for
N 13.238
instead of
O 15.074
“
in units of H=1.
13.8964
15.8734
11
Prout-(Meinecke)-hypothesis
In 1816, the physician Prout (and the chemist L. Meinecke) put forward the
hypothesis that all relative weights of the elements are whole-number multiples of the
weight of hydrogen.
[It is generally assumed, that he did not base this assumption on contemporary
measurements, but on natural philosophy. He set the πρωτη νλη of the Greek
philosophers synonymous with H.]
In the following decades, chemists pushed the techniques to the limits in order to prove
or disprove Prout’s hypothesis (and advanced many ad-hoc “improvements”).
Around 1860, relative atomic weights for 57 elements had been determined and
they were one essential ingredient for the establishment of the “Periodic System”
by Mendeleev and Meyer.
“On the relation between the specific gravities of bodies in their gaseous state and the weights of
their atoms” Annals of Philosophy 6 (1815) 321
“Correction of a mistake in the essay on the relation between the specific gravities of bodies in their
gaseous state and the weights of their atoms” Annals of Philosophy 7 (1816) 111
http://web.lemoyne.edu/~giunta/PROUT.HTML#prout2
L. Meinecke, “Das specifische Gewicht der elastischen Flüssigkeiten” Annalen der Physik 24
(1816) 159
12
An ahead of time nucleosynthesis hypothesis?
Some scientists in the 19th century assumed that “atoms” were
composed of H atoms (and a glue).
Does anyone know, if someone may have speculated on
“nucleosynthesis” by adding H on atoms?
Or was their believe in the creation as described in Genesis
unshakeable?
Especially, as “atomists” were regarded as irreligious atheists. ‡
Physician William Prout
1785-1850
And was the discovery of natural radioactivity really so surprising at the end of a
century in which Prout‘s hypothesis had been discussed all time?
J.J. Thomson mentioned Prout when he presented his model of the atom: an about
1 Ǻ diameter elastic ball, in which electrons were imbedded.
‡
The referee for Gregor Mendel’s heredetary laws turned down the publication as he
regarded it as “atomistic”.
13
Platon’s influence on modern science
In the mid thirteenth century encyclopædia Liber de
proprietatibus rerum of Bartholomaeus Anglicus, Plato
is quoted as describing the hyle, πρωτη νλη ,the
“primary matter”, in the following terms:
“Hyle was without quantity, without quality, without colour,
without kind, without place, and without time,
something that was not matter and yet not absence
of matter”
The encyclopædist then continued:
“These words are not easy to fathom.”
Christ in midst of the 4 elements
First english print by
Wynken de Worde, Westminster,
1495
Platon influenced Prout, Crookes (prot(o)yle), Gamow
(hylem).
1919 Ernest Rutherford proved that nuclei of hydrogen are contained in other elements
as theorized by Prout. He named it „το πρωτον“ (the first), to honour Prout. Some
authors assume that he was influenced by Crookes’ “protyle”, other that it is coined after
“Prout”.
L.M. Celnikier: Find a hotter place! A History of Nuclear Astrophysics.
14
Testing Prout’s hypothesis
Prout’s hypothesis was accepted by
most scientists, and had followers
till the end of the century despite
contrary evidence.
More precise measurements were
performed as by J. J. Berzelius
(1828) or J.-B. Dumas. Most disconcerting was the value for chlorine:
~35.5.
Some proposed, that the basic unit
was ½ the weight of H (and then ¼
and 1/8 ….).
Jean-Charles-Galissard de Marignac
(1817-1894)
Jan Servais Stas (1813-1891)
Many casted doubt on the measurement techniques, especially the purity of the samples
(which often was correct). This forced the chemists to bring to perfection their methods.
Stas and de Marignac disproved the hypothesis. They determined the atomic weights
of 57 elements, laying the basis for the Periodic System of the Elements.
In 1861, Sir W. Crookes had discovered thallium with the spectroscopic method. In 1870
he undertook to determine the atomic weight with a carefully prepared measurement.
15
Against oll odds!
All instruments were specially produced for this measurement.
New technical developments were initiated, as for vacuum
pumps.
It seems to me that Sir Crookes was somehow “disappointed”
of the result:
The 2005 value for the element Tl is 204.383.300 ± 200 μu (in units of 12C/12).
Crookes applied Oelem/16 introduced by Stas.
His result in these units could be
203.650.000 ± 2.200 μM.E.
W. Crookes: "Research on the Atomic Weight of Thallium"
Proc. Roy. Soc. of London, Vol. 20 (1871-1872) pp. 475-483
16
Modern values
ATOMIC WEIGHTS OF THE ELEMENTS 2005
(IUPAC TECHNICAL REPORT)
Prepared for publication by M. E. WIESER
Pure Appl. Chem., Vol. 78, No. 11, pp. 2051–2066, 2006
Elem.
Isotop. compos.
Mass [u]
Multiples of H
H
99.9885%/0.0015%
1.000794(7)
C
98.9%/1.07%
12.0107(8)
12.0012
O
99.757%/0.038%/0.205%
15.9994(3)
15.9867
Tl
29.5%/70.5%
204.3833(2)
204.2212
Multiples of 1H
Isotope
Mass [μu]
1H
1008664.9157 ± 0.0006
203Tl
202972344.2 ± 1.4
201.2287
205Tl
204974427.5 ± 1.4
203.2136
http://www.iupac.org/publications/pac/2006/pdf/7811x2051.pdf
17
Can one save Prout’s hypothesis?
In the second half of the 19th century, the new analytical method of spectroscopy was
applied by some scientists to prove that atoms contained substructures. Leading
proponents were the chemist Crooke and the astrophysicist Norman Lockyer.
Their ideas did not survive further scrutiny. Faint spectral lines, which they took for
prove of substructures, were often indications to (trace) impurities in their samples.
Lockyer‘s concepts at least gave J.J. Thomson arguments for his theory that the atom
contained electrons.
In literature, Crooke is often cited as precursor of the concept of isotopes.
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Discovery of isotopes
Atomic masses
• The physician William Prout postulated in 1815 that all
atomic weights are multiples of hydrogen.
• Sir William Crookes hypothesized 1886 that deviations
from this rule indicate to “isotopes“.
• J.J. Thomson / F.W. Aston observed 1912 with cathode
rays, that Ne had two isotopes of mass 20 and 22.
• After the war, F.W. Aston measured isotopic masses
(1919).
• Based on these masses, Arthur Eddington explained
1926 the energy source of stars as fusion of H to He.
Hans Bethe
1906-2005
Many isotopes were not accessible to experiments so that
theoretical mass formulas were developed.
Based on the liquid drop model
C.F. v. Weizsäcker [Z. Physik 96 (1935) 431] and
H.A. Bethe and R.F. Bacher [Rev. Mod. Phys. 8 (1936) 82]
developed a semiempirical mass formula, that served as
basis for nucleosynthesis models for a long time, as
the CNO- or Bethe-Weizsäcker-cycle:
C.F. v. Weizsäcker, Z. Physik 39 (1938) 633 and
H. Bethe, Phys. Rev. 55 (1939) 434
Carl Friedrich von
Weizsäcker
1912 - 2007
19
Dempster’s mass spectrometer
This rather simple design with a 180° magnetic sector field was used
by many groups (but with important ameliorations!).
The theoretical resolution was100 (with d=10 cm, slits .5 mm). This
spectrum for Na and K had a resolution of 35 with 2 mm slit settings.
Arthur Jeffrey Dempster
(1886 - 1950)
Na and K with low resolution
Dempster's 1918 mass spectrometer
Dempster, A. J. (1918). "A New Method of Positive Ray Analysis". Phys. Rev. 11: 316–325.
20
Kaiser-Wilhelm-Institut für Chemie
Kaiser-Wilhelm-Institut für Chemie – heute
Otto-Hahn-Bau der Freien Universität Bild: FU
Inauguration 28.10.1913
From the beginning, the study of the new phenomenon radioactivity was
performed at the institute. In 1918, p.e., Hahn and Meitner codiscovered
231Pa. The nuclear chemistry culminated 20 years later in the discovery of
nuclear fission.
Many (all?) topics of interest at the MPI had already been studied in BerlinDahlem, as isotope geology including dating of rocks, isotopic abundances,
atomic weights, extinct radio-activity. Mass spectroscopy was applied as a
tool by the group of Mattauch, often in close collaboration with the nuclear
chemists.
Built 1943 for an accelerator
21
Isotopenberichte
The Kaiser-Wilhelm-Institut für Chemie published nearly every year “Isotopen-Berichte”
with relevant results from groups all over the world.
Since 1940, the report was published also in Physikalische Zeitschrift, as the content had
shifted to physical methods.
Kernphysikalische Tabellen: mit einer Einführung in die Kernphysik
J. Mattauch, S. Flügge, 1942
This compilation includes tables of properties of isotopes as decay modes and masses. It was reprinted
several times, mostly without authorisation, even after superior data were available.
Isotopenbericht, Tabellarische Übersicht der Eigenschaften der Atomkerne,
soweit bis 1948 bekannt, von Prof. Dr. J. Mattauch und Doz. Dr. A. Flammersfeld.
Sonderheft der Zeitschrift für Naturforschung, Verlag der Z. Naturforschung,
Tübingen 1949, 243 S., 85 Abb., kartoniert DM 30.- (p 179)
G.T. Seaborg, I. Perlman: Table of Isotopes, Reviews of Modern Physics, vol. 20, Issue 4, pp. 585-667
were made available as manuscript and could be included.
22
Combined compilations / evaluations
The major part in reality is the Introduction into Nuclear Physics, the tables are an
appendix.
In the case of the masses of the (ground states) of isotopes, the results of two “groups”
are listed:
- on the one hand the mass spectroscopists and
- on the other the reaction people,
who had problems with each other.
As an example, Mattauch published in 1942
this booklet with lists of mass doublets and
reaction Q-values and estimated masses up to
the actinides.
In his Isotopic Report of 1949, masses are
only derived up to mass 41, he regarded the
reaction values as too uncertain.
Now, NUBASE combines masses of ground and long-lived isomeric states
23
with halflives, spins and parities.
Packing fraction curve 1938
Following Aston, nuclear structure effects were represented by the „Packing fraction
curve“.
f = 10000 * (M-A)/A
24
Packing fraction curve 1940
The „Berichte“ always contained the most
recent „Packungsanteilkurve“.
For the light
nuclides,
different
curves are
drawn for
even and odd
mass.
25
Isotopic ratios and elemental atomic weight of Cu
In 1944, no precision values for the isotope ratios
of Cu were known. Ewald not only measured the
ratio, but derived a new value for the atomic weight
of Cu from this ratio.
The 2005 value is 63.546(3) u or 63,566 M.E.
in agreement with the international value of 1944.
H. Ewald, ZfP 122 (1944) 487
26
Isotope geology, early Solar System
Zeitschrift für Physik 120 (1943) 598
Pollucit
(Cs,Na)2Al2Si4O12 • H2O
Walter August Wahl
(1879 - 1970)
Mattauch et al. repeated a measurement of W. Wahl from Helsingfors (Finland) and
attributed the M=132 line to C11, instead to 132Ba from extinct 132Cs.
Wahl insisted and Mattauch would have liked to invite Wahl to Berlin to repeat
the analysis with the original samples of Pollucit. But it was war time!
T1/2 of 132Cs was unknown in the early 1940‘s.
27
Ewald’s double-focusing spectrograph
Heinz Ewald
16.6.1914 –
5.2.1992
Heinz Ewald designed a double-focusing mass spectrograph at the Kaiser-WilhelmInstitut in the years 1942 – 1944. It accompanied him in all his career and ended at the
II. Physikalisches Institut in Gießen. There I saw it as a young student in a dark cellar.
Now it is displayed more openly.
Gottfried Münzenberg believes that it was once in Mainz. It had a mass resolution of
>30.000. The MPI wanted to build the “ultimate” machine with a resolution of 100.000,
but the design was flawed. Gottfried told me that parts for this instrument also had been
in the dark cellar in Gießen.
28
Partly personal remarks on Heinz Ewald
H. Ewald: Die Analyse und Deutung der Neodymsalzspektren
Annalen d. Physik. Folge 5, Bd 34, H. 3.; Göttingen, Math.-naturwiss. Diss., 1939
In war time, Ewald (+ Walcher + v. Ardenne) worked on electromagnetic isotope separators for 235U. The Ardenne/Ewald plasma sources were more efficient than the american
ones for the calutrons.
H. Ewald u. H. Hintenberger: Methoden und Anwendungen der
Massenspektroskopie; Weinheim : Verl. Chemie, 1953
Later-on as director of II. Physik. Inst. in Gießen, he was engaged in the construction of
LOHENGRIN, OSTIS and SHIP.
29
Proposal of Ewald for an isotope separator 1942
Addendum 1:
Recently, R. Karlsch put forward the hypothesis that the
German scientists had made substantial progress on the
way to the atomic bomb.
In Ewald/Hintenberger is shown a proposal for an
isotope separator by Ewald 1942.
In M. Walker „German National Socialism and the Quest
for Nuclear Power 1939-1949“ is reported, that M. von
Ardenne picked-up the idea and constructed a prototype in his laboratory.
Prof. Schmidt-Rohr presumes that Ardenne built a fullfledged separator with the „Forschungsanstalt der
Deutschen Reichspost“ in a circular bunker near Bad
Saarow south of Berlin. This bunker corresponds to the
one constructed for a cyclotron at Miersdorf.
‡
http://www.petermann-heiko.de/index.php?option=com_content&view=article&id=83&Itemid=96&lang=de
‡
Recycling of a separator magnet
Addendum 2:
W. Walcher had built an isotope separator
at Kiel, which allowed to separate p.e.
some ten µgs of the stable Rb isotopes.
He was also involved in the „Uranverein“.
Around 1980, the magnet was used to
built the HELIOS-separator at the TRIGA reactor
in Mainz:
A. K. Mazumdar, H. Wagner, G. Kromer, W. Walcher,
M. Brügger, E. Stender, N. Trautmann and T. Lund;
Nucl. Instr. and Meth. 174 (1980) 183
Z. Phys. 108, 376 (1938)
Mattauch-Herzog type double-focusing spectrograph
32
Mass doublets
12CH
– 13C
4410
±8
μM.E.
4409
±9
μu
4470.185 ± 0.008 μu
AME03
12CH
3
– 15N
22317
± 15 μM.E.
23310
± 15 μu
23366.1979 ± 0.0017 μu AME03
M.E. 16O/16
12C/12
u
M.E./1.0003179 = u
33
Mass measurements for 13C and 15N
16O/16
13C
12C/12
13,0079
± 0,0002
(13,0038
± 0,0002)
Bainbridge 1936
13,00761
± 0,00015
(13,00348
± 0,00015)
Livingston 1937
13,00758
± 0,00006
(13,00345
± 0,00006)
Hahn 1940
13,007581 ± 0,000025
(13,003447
± 0,000025)
Ewald 1946
13,007478 ± 0,000005
(13,003344
± 0,000005)
Wapstra 1955
13,0074883 ± 0,0000007
13,0033543 ± 0,0000007
Everling 1960
13,00335483 ± 0,000000001 AME03
15N
15,0050
± 0,0003
(15,0002
± 0,003)
Bainbridge 1936
15,00489
± 0,00020
(15,00012
± 0,00020)
Livingston 1937
15,00494
± 0,00007
(15,00017
± 0,00007)
Hahn 1940
15,004934 ± 0,000030
(15,000165
± 0,000030)
Ewald 1946
15,004862 ± 0.000005
(15,000093
± 0,000005)
Wapstra 1955
15,0048769 ± 0,0000009
15,0001081 ± 0,0000009
Everling 1960
15,00010889 ± 0,000000007 AME03
34
Development of mass measurements
What happened
between 1948 and
1955?
35
Why differs the value for 13C from the modern value?
Ewald applied the expression below to derive the mass of 13C from 12CH. The masses
of the reference isotopes are taken from the fractional packing curve f.
fH
fC-12
1940
81,31
3,243
1946
81,30
3,218
1951
81,46
3,173
1955
81,45
3,169
2003
81,45
3,179
In units of 10-4 16O/16
The values since 1951 are
derived from a combination
of mass doublets and reaction
data.
Phys.Rev. 82 (1951) 756
36
Mass measurements for 40A(r)
16O/16
12C/12
Year
39,971
39,958
1934/5
39,9754
39,9627
1937
39,97504
39,96234
1937
39,97555
39,96285
1940
39,9755
39,9628
1942
39,97551
39,96281
1949
39,97505
39,96235
1955
39,9750886
39,9623838
1960/2
39,9623842
1964
39,9623831
1977
39,9623837
1985
39,962383124
1993
39,962383130
1995/7
39,9623831225
2003
37
What is wrong with the measurements with mass spectrometers?
Last minute addendum:
38
Post-war activities - An early form of NUBASE?
The Kaiser-Wilhelm-Institut für Chemie had issued yearly progress reports on masses
since around 1934. After the war, J. Mattauch compiled a small booklet in honour of
Hahn’s 70th birthday. It comprised not only data on masses, but ,e.g., decay properties
as half-lives. Seaborg had made available war-time data by sending the “Table of
Isotopes” prior to publication.
In the following decades, mass evaluations normally contained only masses.39
55 years of modern mass evaluations (I)
The more recent history of nuclidic masses can be found in:
Georges Audi
“The history of nuclidic masses and of their evaluation”
International Journal of Mass Spectrometry 251 (2006) 85–94
An early (perhaps the first) attempt for a mass evaluation is
M.S. Livingston, H.A. Bethe, “Nuclear Physics, C. Nuclear dynamics, experimental”
Rev. Mod. Phys. 9 (1937) 245
XVIII. Nuclear masses; p. 366
The authors combined data from mass spectrometry and nuclear reaction and
decay data up to 40Ar.
In the early 1950’s it was found that the many relations (direct and indirect) between
nuclides overdetermined the mass value of many nuclides.
Aaldert H. Wapstra established a procedure using a least-squares method to solve the
problem of overdetermination.
The first table of atomic masses using this method is dated 1955.
40
55 years of modern mass evaluations (II)
A.H. Wapstra, Physica 21 (1955) 367 + 385; J.R. Huizenga, Physica 21 (1955) 410
F. Everling, L.A. König, J.H.E. Mattauch, A.H. Wapstra, Nucl. Phys. 18 (1960) 529
L.A. König, J.H.E. Mattauch, A.H. Wapstra, Nucl. Phys. 31 (1962) 18
R.R. Ries, R.A. Damerow, W.H. Johnson, Jr., Phys. Rev. 132 (1963) 1662 + 1673
J.H.E. Mattauch, W. Thiele, A.H. Wapstra, Nucl. Phys. A67 (1965) 1 + 32 + 73
After the retirement of Mattauch in 1965, all AMEs (as far as I know)
were directed by Aaldert H. Wapstra.
A.H. Wapstra & K. Bos, At. Data Nucl. Data Tables 19 (1977) 175
A.H. Wapstra, G. Audi & R. Hoekstra, Nucl. Phys. A432 (1985) 185
G. Audi & A.H. Wapstra, Nucl. Phys. A 565 (1993) 66
C. Borcea, G. Audi, A.H. Wapstra & P. Favaron, Nucl. Phys. A 565 (1993) 158
G. Audi, A.H. Wapstra & M. Dedieu, Nucl. Phys. A 565 (1993) 193
G. Audi & A.H. Wapstra, Nucl. Phys. A 595 (1995) 409
G. Audi, O. Bersillon, J. Blachot & A.H. Wapstra, Nucl. Phys. A 624 (1997) 1
G. Audi, O. Bersillon, J. Blachot & A.H. Wapstra, Nucl. Phys. A 729 (2003) 3
A.H. Wapstra, G. Audi & C. Thibault, Nucl. Phys. A 729 (2003) 129
G. Audi, A.H. Wapstra & C. Thibault, Nucl. Phys. A 729 (2003) 337
J. Mattauch
A.H. Wapstra
The Future AME (2013 ?) is prepared on a broader, international basis
including Orsay, GSI, ANL, the Institute for Modern Physics, Lhanzou.
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R.R. Ries et al., “Atomic Masses from Ga to Mo”, Phys. Rev. 132 (1963) 1662
R.A. Damerow et al.:”Atomic Masses from Ru to Xe”, Phys. Rev. 132 (1963) 1673
Local evaluations done in Minneapolis
Backbone of evaluation:
Mass doublets measured with doublefocusing mass spectrometers
Nuclear reaction and β-decay
data are then combined with
the masses of stable isotopes
from the mass spectrometers.
Some mass doublet values from
these papers are still listed in the
2003 Mass Evaluation!
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Progress in mass measurements and evaluations
A=120
?
1u = 16O/16
AME 1955
1u = 12C/12
AME 1977
AME 2003
43
Atomic Mass Evaluation & NuBASE
AME 2003
November 18, 2003
3504 masses
3179 - ground-state masses
2228 experimental
951 estimations
325 - isomers
201 experimental
122 estimations
From the 2228 experimental masses
have uncertainties
• 192 < 1 keV
• 1020 < 10 kev
• 231 < 100 keV
• 785 > 100 keV
Based on 7773 data, 374 not accepted:
6169 valid input data
4373 after compression by pre-averaging
887 added from systematic trends
“Primary” data:
• 1381 data representing 967 reactions
and decays
• 414 mass spectrometric data
Backbone from least-square calculation:
System of 1381 equations for 847
parameters (“primary” masses)
This sample represents about half of the expected nuclides between the drip-lines.
44
Progress in AME
AME2003
2009
(approximate values)
Masses
3504
3555
Data points (total)
7773
13080
Mass-doublets
4390
Mass-triplets
220
Reaction data
8470
Not used
After preaveraging
374
7130‡
4373
4760
Mass adjustment
“Primaries”
equ. / unknowns
1381 / 847
1570 / 988
“secondaries
2770
2800
systematics
890
850
‡ The new precise values (as, e.g., from trap measurements) in general
supersede older ones.
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Long-range and multiple connections
The mass evaluations up till now
contain mostly connections between
2 (or a few) close lying neighbours.
The future AMEs will in addition be
characterised by long-range relations
and complex connectivities between
multiple isotopes:
• In the traps, nuclides are typically
compared to easily ionisable reference masses as 133Cs. The isotope
229Rn is 96 mass units distant from
the reference mass.
• Direct mass measurements by TOF
in storage rings as ESR at GSI
observe many nuclides simultaneously. The masses are derived from
correlation matrices which may contain up to 100.000 relations. This
plenty of information is not (yet) taken
into account in the actual AME.
133Cs
Connections of input data for AME200346
Future precision mass measurements
The project to build a mass spectrograph with a resolving power of 100.000 failed at
the MPI. Nowadays even higher precision measurements can be performed with
Penning traps. One such instrument is connected to the velocity filter SHIP (which was
built with the participation of Prof. Ewald). The work which once started at Berlin
is now continued by the scientific off-spring.
SHIPTRAP at GSI
TRIGATRAP for reactor in Mainz
And also at the Mainz TRIGA reactor (which is a legacy of Fritz Strassmann) a Penning
trap will continue the study of fission products.
47
Atomic Mass Evaluations
Contributions of the Kaiser-Wilhelm-/Max-PlanckInstitut für Chemie
• For a long time, the KWI / MPI had been at the forefront of work dedicated to the study
of radioactivity.
• Also from the early days on, radioactive (and stable) isotopes have been applied
in other fields as geology.
• And there had always been a fruitful collaboration between scientists from
neighbouring fields (as the very long interchange between the chemist Otto Hahn and
the physicist Lise Meitner).
• The work on atomic masses shifted in the course of the 1930‘s from chemistry to
physics, but there remained close ties between the groups.
• Influenced by my personal scientific background (as a „grandson“ of Ewald), I
have presented in this seminar talk mainly work performed with mass spectrographs.
• My actual work with the Atomic Mass Evaluation can be regarded as a return to
the roots layed by Mattauch / Ewald in Dahlem, Tailfingen, Mainz, München.
Seminar für Kern- und Kosmochemie (“K&K Seminar”)
MPI für Chemie, Mainz, Mittwoch, 10.2.2010, 17:15
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