Presentation on theme: "1 Dr. B. Pfeiffer GSI Helmholtzzentrum für Schwerionenforschung Seminar für Kern- und Kosmochemie (“K&K Seminar”) MPI für Chemie, Mainz, Mittwoch, 10.2.2010,"— Presentation transcript:
1 Dr. B. Pfeiffer GSI Helmholtzzentrum für Schwerionenforschung Seminar für Kern- und Kosmochemie (“K&K Seminar”) MPI für Chemie, Mainz, Mittwoch, , 17:15 Balances from “De re me- tallica, Liber Septem” G. Agricola, 1556 Atomic Mass Evaluations Contributions of the Kaiser-Wilhelm-/Max-Planck- Institut für Chemie Mass spectrograph built at Kaiser-Wilhelm Institut für Chemie in 1943 Motivation: scientific and personal Importance of balances for rebirth of atomic hypothesis around 1800 Prout‘s hypothesis Isotopes Contributions from Kaiser-Wilhelm- Institut für Chemie AMEs at Max-Planck-Institut Future AME
2 Pre-history of talk, personal motivation In summer during a „Nachsitzung“ ‡, Prof. Palme mentioned to have seen a mass spectro- graph 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. Sudden- ly 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 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,
3 GSI 1972 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. Courtesy Prof. Rudolf Bock
4 “Prehistory” of atomic weights 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). 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. From Liber Septimus 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 20 th century!
5 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. Alchemists and balances
66 Dokumastic in the Scripture? Jeremias, 6 ca. 600 B.C.E. Zechariah, 13 after 500 B.C.E. Ezekiel, 22 ca. 580 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. 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. 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. The first explicit reference to this analytical tool is in Pliny the Elder: Historia Naturalis.
7 This led to stoichiometry and the proportio- nal laws. Based on these principles, 1868/9 D.I. Mendeleev and L. Meyer developed then 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 (Sb 2 S 3 ), 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 Decisive was the shift from “quality“ to “quantity“, the use of precise balances. Part of texts on astrology or alchemy? Basis for the periodic system of the elements The upcoming of a rudimentary chemical „industry“ with the need of fixed procedures instead of philosophical theories lead to modern chemistry:
8 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 This paper was already presented orally in It contains the first steps to the atomic hypothesis to explain the laws of definite and multiple pro- portions. The first table of relative weights is appended without explanation of the methods applied.
9 John Dalton A New System of Chemical Philosophy (1808)
11 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 mole- cule. Therefore, his reference mass for hydrogen in reality is 0.5. His formula for water is HO instead of H 2 O, etc. Avogadro obtained for N instead of O “ in units of H=1.
12 “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 L. Meinecke, “Das specifische Gewicht der elastischen Flüssigkeiten” Annalen der Physik 24 (1816) 159 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.
13 An ahead of time nucleosynthesis hypothesis? Some scientists in the 19 th 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 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”.
14 Platon influenced Prout, Crookes (prot(o)yle), Gamow (hylem) Ernest Rutherford proved that nuclei of hydrogen are contained in other elements as theorized by Prout. He named it to honour Prout. Some authors assume that he was influenced by Crookes’ “protyle”, other that it is coined after “Prout”. In the mid thirteenth century encyclopædia Liber de proprietatibus rerum of Bartholomaeus Anglicus, Plato is quoted as describing the hyle,,the “primary matter”, in the following terms: Platon’s influence on modern science “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.” L.M. Celnikier: Find a hotter place! A History of Nuclear Astrophysics. Christ in midst of the 4 elements First english print by Wynken de Worde, Westminster, 1495 πρωτη νλη „το πρωτον“ (the first),
15 Testing Prout’s hypothesis Jan Servais Stas ( ) Jean-Charles-Galissard de Marignac ( ) 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 discon- certing 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 ….). 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.
16 Against oll odds! W. Crookes: "Research on the Atomic Weight of Thallium" Proc. Roy. Soc. of London, Vol. 20 ( ) pp The 2005 value for the element Tl is ± 200 μu (in units of 12 C/12). Crookes applied O elem /16 introduced by Stas. His result in these units could be ± μM.E. 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:
17 Modern values IsotopeMass [μu]Multiples of 1 H 1H1H ± Tl ± Tl ± Elem.Isotop. compos.Mass [u]Multiples of H H %/0.0015% (7) C98.9%/1.07% (8) O99.757%/0.038%/0.205% (3) Tl29.5%/70.5% (2) 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
18 Can one save Prout’s hypothesis? In the second half of the 19 th 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.
19 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. Atomic masses 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 Hans Bethe Carl Friedrich von Weizsäcker Discovery of isotopes
20 Dempster’s mass spectrometer Dempster's 1918 mass spectrometer Dempster, A. J. (1918). "A New Method of Positive Ray Analysis". Phys. Rev. 11: 316–325.A New Method of Positive Ray Analysis Arthur Jeffrey Dempster ( ) Na and K with low resolution 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.
21 From the beginning, the study of the new phenomenon radioactivity was performed at the institute. In 1918, p.e., Hahn and Meitner codiscovered 231 Pa. 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 Berlin- Dahlem, 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. Kaiser-Wilhelm-Institut für Chemie Kaiser-Wilhelm-Institut für Chemie – heute Otto-Hahn-Bau der Freien Universität Bild: FU Inauguration Built 1943 for an accelerator
22 Isotopenberichte 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) 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. The Kaiser-Wilhelm-Institut für Chemie published nearly every year “Isotopen-Berichte” with relevant results from groups all over the world. G.T. Seaborg, I. Perlman: Table of Isotopes, Reviews of Modern Physics, vol. 20, Issue 4, pp were made available as manuscript and could be included. Since 1940, the report was published also in Physikalische Zeitschrift, as the content had shifted to physical methods.
23 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 with halflives, spins and parities.
24 Packing fraction curve 1938 Following Aston, nuclear structure effects were represented by the „Packing fraction curve“. f = * (M-A)/A
25 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.
26 Isotopic ratios and elemental atomic weight of Cu H. Ewald, ZfP 122 (1944) 487 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 (3) u or 63,566 M.E. in agreement with the international value of 1944.
27 Isotope geology, early Solar System Zeitschrift für Physik 120 (1943) 598 Mattauch et al. repeated a measurement of W. Wahl from Helsingfors (Finland) and attributed the M=132 line to C 11, instead to 132 Ba from extinct 132 Cs. 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! Walter August Wahl ( ) Pollucit (Cs,Na) 2 Al 2 Si 4 O 12 H 2 O T 1/2 of 132 Cs was unknown in the early 1940‘s.
28 Ewald’s double-focusing spectrograph Heinz Ewald designed a double-focusing mass spectrograph at the Kaiser-Wilhelm- Institut in the years 1942 – 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 > The MPI wanted to build the “ultimate” machine with a resolution of , but the design was flawed. Gottfried told me that parts for this instrument also had been in the dark cellar in Gießen. Heinz Ewald –
29 Partly personal remarks on Heinz Ewald H. Ewald u. H. Hintenberger: Methoden und Anwendungen derMethodenundAnwendungender MassenspektroskopieMassenspektroskopie; Weinheim : Verl. Chemie, 1953 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 separa- tors for 235 U. The Ardenne/Ewald plasma sources were more efficient than the american ones for the calutrons. Later-on as director of II. Physik. Inst. in Gießen, he was engaged in the construction of LOHENGRIN, OSTIS and SHIP.
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 In M. Walker „German National Socialism and the Quest for Nuclear Power “ is reported, that M. von Ardenne picked-up the idea and constructed a proto- type in his laboratory. Prof. Schmidt-Rohr presumes that Ardenne built a full- fledged 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.
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“. Recycling of a separator magnet Z. Phys. 108, 376 (1938) 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
32 Mattauch-Herzog type double-focusing spectrograph
33 Mass doublets 12 CH – 13 C 12 CH 3 – 15 N 4410 ± 8 μM.E ± 9 μu ± μu AME ± 15 μM.E ± 15 μu ± μu AME03 M.E. 16 O/16 u 12 C/12 M.E./ = u
35 Development of mass measurements What happened between 1948 and 1955?
36 Why differs the value for 13 C from the modern value? fHfH f C ,313, ,303, ,463, ,453, ,453,179 In units of O/16 Ewald applied the expression below to derive the mass of 13 C from 12 CH. The masses of the reference isotopes are taken from the fractional packing curve f. The values since 1951 are derived from a combination of mass doublets and reaction data. Phys.Rev. 82 (1951) 756
38 What is wrong with the measurements with mass spectrometers? Last minute addendum:
39 Post-war activities - An early form of NUBASE? The Kaiser-Wilhelm-Institut für Chemie had issued yearly progress reports on masses since around After the war, J. Mattauch compiled a small booklet in honour of Hahn’s 70 th 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.
40 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 55 years of modern mass evaluations (I) 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 40 Ar. 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.
41 A.H. Wapstra, Physica 21 (1955) ; 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) J.H.E. Mattauch, W. Thiele, A.H. Wapstra, Nucl. Phys. A67 (1965) 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 The Future AME (2013 ?) is prepared on a broader, international basis including Orsay, GSI, ANL, the Institute for Modern Physics, Lhanzou. 55 years of modern mass evaluations (II) J. Mattauch A.H. Wapstra
42 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 double- focusing 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!
43 Progress in mass measurements and evaluations AME 1955 AME 1977 AME 2003 A=120 ? 1u = 16 O/16 1u = 12 C/12
44 Atomic Mass Evaluation & NuBASE AME 2003 November 18, masses ground-state masses 2228 experimental 951 estimations isomers 201 experimental 122 estimations 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 From the 2228 experimental masses have uncertainties 192 < 1 keV 1020 < 10 kev 231 < 100 keV 785 > 100 keV This sample represents about half of the expected nuclides between the drip-lines. Backbone from least-square calculation: System of 1381 equations for 847 parameters (“primary” masses)
45 AME (approximate values) Masses Data points (total) Mass-doublets4390 Mass-triplets220 Reaction data8470 Not used ‡ After preaveraging Mass adjustment “Primaries” equ. / unknowns 1381 / / 988 “secondaries systematics Progress in AME ‡ The new precise values (as, e.g., from trap measurements) in general supersede older ones.
46 Long-range and multiple connections Connections of input data for AME Cs 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 refe- rence masses as 133 Cs. The isotope 229 Rn is 96 mass units distant from the reference mass. Direct mass measurements by TOF in storage rings as ESR at GSI observe many nuclides simultane- ously. The masses are derived from correlation matrices which may con- tain up to relations. This plenty of information is not (yet) taken into account in the actual AME.
47 Future precision mass measurements SHIPTRAP at GSITRIGATRAP for reactor in Mainz The project to build a mass spectrograph with a resolving power of 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. And also at the Mainz TRIGA reactor (which is a legacy of Fritz Strassmann) a Penning trap will continue the study of fission products.
48 Seminar für Kern- und Kosmochemie (“K&K Seminar”) MPI für Chemie, Mainz, Mittwoch, , 17:15 Atomic Mass Evaluations Contributions of the Kaiser-Wilhelm-/Max-Planck- Institut 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.