Mössbauer measurements of Fe57 were made on ferromagnetic Fe4N, which has a face-centered cubic arrangement of iron atoms with nitrogen at the body-center position. The hyperfine fields are 345 koe for the corner Fe and 215 koe for the three face-center Fe, approximately proportional to their magnetic moments, 3μB and 2μB. The isomer shifts, measured against a stainless steel source, are 0.30 mm/sec for the corner Fe and 0.45 mm/sec for the face-center Fe. These values are in line with their proposed electronic configurations of 3d74s and 3d84s, which are derived on the assumption that the nitrogen at the body-center position acts as an electron "donor" to the face-center Fe. The Mössbauer spectra of (Fe3.6,Ni0.4)N and (Fe3Ni)N are consistent with their ordered structures in which Ni replaces the corner Fe preferentially.
Garwin's dissertation was in beta-gamma angular correlation. He later consulted with Wu about the errors in the Rustad-Ruby experiment.
The beta-gamma angular correlation was investigated in the isotopes Na24, Co60, Ru103, Gd115, Ir192, and Au198. Measurements were made at ten angles between 45 to 180 degrees. No departure from spherical symmetry was found in any case, within the statistical error (standard deviation 1% or 2% in most cases). Tests and arguments are set forth to establish that the lack of correlation exists in fact at the atom and probably at the nucleus itself. The discrepancy between the results of this experiment and the predictions of the beta ray theory is discussed.
Readable history of Mossbauser science with numerous Stan Ruby mentions
This is the Golden Year, as we celebrate 50 Years of the Mössbauer Effect. Our approach to this issue of the Mössbauer Spectroscopy Newsletter is a bit non-traditional – included in this issue of the Newsletter is a modified version of the PowerPoint presentation given at the International Conference on the Applications of the Mössbauer Effect (ICAME) held in Kampur, India, in October 2007. Accompanying the slides is our selected commentary. Our approach to these significant 50 years is to consider as separate each of the five decades from 1958 to 2007, as we feel that each of those decades has a clear theme. These 50 years have been an incredible time in our scientific community with the birth and development of Mössbauer spectroscopy.
In the mid-1960s, a new phase began at Argonne when Michael Kalvius was recruited to the Solid State Science Division. By this time, Stan Hanna had left the Physics Division at Argonne and had been replaced by Stan Ruby. Ruby and Kalvius began working together and, during the next few years, their collaboration expanded to include two young solid-state physicists, Bobby Dunlap and Gopal Shenoy. Shenoy would remember later that they measured about 10,000 compounds during the Great Mössbauer Expansion period.
In the mid-60’s Stan Ruby approached Irwin Gruverman of NENC, the New England Nuclear Corporation, suggesting that NENC sponsor a one-day Mössbauer Effect Methodology conference (MEM) in association with the winter meeting of the APS. NENC had become a principal supplier of radionuclides and ME sources and absorbers here and abroad. The series began on January 26, 1965, in New York City with free registration for all 250 participants. The 15 papers were presented in an afternoon/evening format. As needed, NENC paid the expenses of the chosen speakers, who generally were from labs in the USA. A pre-Symposium dinner the night before the presentations became an effective vehicle for the speakers and the organizers to meet each other. Manuscripts were published in Mössbauer Effect Methodology Volume 1 (through Volume 10) by Plenum Press, New York, edited by I. Gruverman.
With the prodding and support of Stan Ruby, the Mössbauer Effect Data Center was established at the University of North Carolina at Asheville with a modest grant of $2,800 from the North Carolina Board of Science and Technology. The resources of Argonne National Laboratory were made available during these early years at the Center. Other funding during this time came from the National Bureau of Standards’s National Standard Reference Data Systems and the National Science Foundation, In 1969, MEDC developed one of the first databases used in the scientific community using IBM Assembler code.
The history of the flowering of the Columbia Physics Department under I. I. Rabi is recounted in Chapter 13.
Stan loved Christmas and he delighted in spoiling us kids. I guess it went back to his own father, but the Rubys always celebrated the joyous holiday, despite its Christian origin.
But if he would say "Merry Christmas" sincerely in late December, on occasion he used the expression the rest of the year in a sarcastic manner, suggesting perhaps that anti-Semitism could be at play in some situation.
Originally published in Chinese in 1996. Stan Ruby was interviewed and is cited as a source. Wu's involvement in the Rustad-Ruby affair is documented.
Narrating the well-lived life of the "Chinese Madame Curie" -- a recipient of the first Wolf Prize in Physics (1978), the first woman to receive an honorary doctorate from Princeton University, as well as the first female president of the American Physical Society -- this book provides a comprehensive and honest account of the life of Dr Wu Chien-Shiung, an outstanding and leading experimental physicist of the 20th century.
In the early 1950s, two of Wu's students, S. Ruby and B. Rustad, performed an experiment to investigate the beta decay in the transition from radioactive helium (He-6) to lithium (Li-6).
Wu held discussions with the students during the experimental process. The students published a short article in Physical Review Letters in 1952, followed by a long article in the Physical Review in 1955. They determined that the Fermi theory had a scalar (S) transition matrix, and the Gamow-Teller theory had a tensor (T) transition matrix.
As their experiment had Wu's endorsement, and she had a long record of precision, the Ruby-Rustad papers initially carried a lot of credibility. Later experiments, however, showed conflicting results.
Richard Feynman, M. Gell-Mannn (who won the Nobel Prize for a proposal of "quarks" and their interactions), R. Marshak and his student E. Sudarshan, and another physicist, J. Sakurai, all argued that the transition matrices in begta decay were vector (V) and axial vector (A). Before this was settled, some said that Marshak must be mad. How could the He-6 experiment be wrong?
Not long afterward, Maurice Goldhaber and two collaborators did an elegant experiment and proved that the V-A theory was correct. That settled the dispute.
Wu was very unhappy about the mistake made in the experiment of Ruby and Rustad. Ruby discussed the experiment in the Plaza Hotel (a landmark in New York City where Chiang Ching=Kuo, then Vice-Premier and later President of Taiwan, was shot while visiting the US) in January 1990, and regretted that he was so careless. He did not finish his Ph.D. degree, worked for IBM for some time, and resumed research work at Stanford University. Rustad died in the early 1960s.
The incident bothered Wu, She later built a larger experimental setup at Columbia, and did a similar experiment with He-6/ She and her collaborator Arthur Schwarzchild wrote a paper in 1958 pointing out the factors causing the mistake in the earlier experiment.
This bad mark did not change very much the position of authority in the field of beta decay that Wu enjoyed. Her reputation as the most precise experimentalist was intact. The saying in the physics circle was: “If the experiment was done by Wu, it must be correct.” [H. Schopper]
Danish beta decay experts review the likely coupling constants, citing RR as determining tensor coupling in GT transitions.
Recent experimental data on superallowed transitions are used in a redetermination of the decay coupling constants. It is suggested that the β-decay interaction may contain an admixture of vector coupling besides the usually adopted scalar and tensor interactions.
The improved accuracy in the experimental data on superallowed β-transitions as well as the determination of several new ft-values for superallowed 0 —> 0 transitions permit a higher accuracy in the determination of the coupling constants in β-decay. We shall follow the same procedure as applied earlier. In the first section, we assume that no cross terms are present, which, according to recent recoil investigations, means that the β-interaction is a mixture of scalar and tensor coupling only. In the second part, we consider the evidence on the possible admixture of axial vector and, especially, vector interaction.
The phenomenon of nucleear beta decay reflects the workings of interactions which are very weak on the cale of those forces which determine the structure of the nucleus itself. Precisely for this reason beta decay provides an admirable probe for the study of nuclear structure. On the other hand, for those whose interest lies with the weak interactions in themselves, nuclei are admirable objects only insofar as they undergo beta disintegration. A generation ago, weak-interaction physics was coextensive with nuclear beta-decay physics; today the subject ranges over a much wider domain.
The Theory of Beta Radioactivity. E. J. Konopinski. Oxford University Press, New York, 1966. 413 pp., illus. $12.; Beta Decay. C. S. Wu and S. A. Moszkowski. Interscience (Wiley), New York, 1966. 410 pp., illus. $16.
The entire book, from the first chapter's historical introduction to the detailed mathematical exercises in the appendices, radiates a warmth and excitement that are not very often found in such a technical and specialized volume.
Franklin's study of the K-U modification of the Fermi theory, and its eventual reversal—a theoretical error that preceded the RR experimental error in the history of beta decay research.
In 1934, Enrico Fermi proposed a theory of beta decay. Although it was supported by existing experimental evidence, a more detailed examination revealed discrepancies. Emil Konopinski and George Uhlenbeck proposed an alternative theory that better fit the results and was accepted by the physics community. It was later realized that both the experimental results and the experiment-theory comparison were incorrect. When both problems were corrected, in part by the work of Konopinski and Uhlenbeck themselves, Fermi’s theory was supported. As Konopinski publicly stated in a 1943 review article, “Thus, the evidence of the spectra, which has previously comprised the sole support for the K-U theory, now definitely fails to support it.