William A. Fowler

William A. Fowler, Institute Professor of Physics Emeritus at the California Institute of Technology, died on 14 March 1995 in Pasadena, California, at the age of 83. In winning the 1983 Nobel Prize in Physics, with Subrahmanyan Chandrasekhar, Fowler was cited for his theoretical and experimental studies of the nuclear reactions of importance in the formation of the chemical elements in the universe

Robert V. Langmuir

Robert V. Langmuir, professor emeritus of electrical engineering at Caltech and a member of the team that first directly observed synchrotron radiation, died of cancer on 7 May 1992, at the age of 80. Langmuir had had a long and productive career as an educator, physicist, engineer and inventor

On the Origin of the Absorption Features in SS433

We present high-resolution optical spectroscopy of the X-ray binary system SS433, obtained over a wide range of orbital phases. The spectra display numerous weak absorption features, and include the clearest example seen to date of those features, resembling a mid-A type supergiant spectrum, that have previously been associated with the mass donor star. However, the new data preclude the hypothesis that these features originate solely within the photosphere of the putative mass donor, indicating that there may be more than one region within the system producing an A supergiant-like spectrum, probably an accretion disc wind. Indeed, whilst we cannot confirm the possibility that the companion star is visible at certain phase combinations, it is possible that all supergiant-like features observed thus far are produced solely in a wind. We conclude that great care must be taken when interpreting the behaviour of these weak features.Comment: Accepted for publication in MNRAS, 8 pages, 6 figure

4-Chloroacetophenone [1-(4-Methoxyphenyl)ethylidene]Hydrazone

The crystal structure of the title mixed azine, C17H17CIN2O, contains four independent molecules, A-D, and molecule B is disordered. All four molecules have an N-N gauche conformation, with C-N-N-C torsion angles of 136.5 (4), 137.0 (4), -134.7 (4) and -134.7 (4)°, respectively. The phenyl rings are also somewhat twisted with respect to the plane defined by Cipso and the imine bond. On average, the combined effect of these twists results in an angle of 64.7° between the best planes of the two phenyl rings. Arene-arene double T-contacts are the dominant intermolecular interaction. The methoxy-substituted phenyl ring of one azine molecule interacts to form a T-contact with the methoxy-substituted phenyl ring of an adjacent molecule and, similarly, two chloro-substituted phenyl rings of neighboring molecules interact to form another T-contact. The only exception is for molecule B, for which the disorder leads to the formation of T-contacts between methoxy- and chloro-substituted phenyl rings. The prevailing structural motif of T-contact formation between like-substituted arene rings results in a highly dipole-parallel-aligned crystal structure

Interview with Charles A. Barnes on cold fusion

An interview in two sessions in June 1989 with Charles Andrew Barnes, professor of physics (now emeritus) in the Division of Physics, Mathematics and Astronomy. Dr. Barnes discusses the March announcement of Drs. Stanley Pons and Martin Fleischmann of having produced “cold” nuclear fusion in a tabletop experiment at the University of Utah. Recalls his reaction and that of his Caltech colleagues; the paucity of information; coverage by the L.A. Times. Details his collaboration with Nathan Lewis, T. R. Wang, Stephen Kellogg, and Steven Koonin in vain attempts to replicate Pons–Fleischmann experiment. Growing skepticism in the scientific community; Steven Jones’s paper in Nature reporting neutron flux; claims of cold fusion by Texas A&M and Georgia Tech; Caltech’s Kellogg Radiation Laboratory colloquium in Beckman Auditorium. Discusses efforts by Pons, Fleischmann, and University of Utah officials to get money from Congress to establish cold fusion institute. Recalls May American Physical Society meeting in Baltimore and presentation of Caltech data; Koonin’s accusation of Pons and Fleischmann’s “incompetence and perhaps delusion;” Caltech president Thomas Everhart’s embargo of the word “fraud.” Pons and Fleischmann’s censoring of DOE’s visiting committee; committee’s June visit to Caltech. Possible motives of Pons, Fleischmann, and the University of Utah. Pons and Fleischmann’s paper in J. Electroanal. Chem., involvement of Cheves Walling and claim of production of helium-4; work of Harwell lab, Italians at Frascati, and group at Los Alamos. He concludes by noting that Kellogg lab continues to pursue aspects of the phenomenon while doubting it will prove a useful power source. Notes difficulties with a peer reviewer of Lewis et al.’s Nature paper on Caltech findings

Interview with Charles A. Barnes

Interview in six sessions, July and August 1987, with Charles A. Barnes, professor of physics, Caltech. He talks about his childhood and adolescence in Ontario, Canada; his early affinity for mathematics and science; undergraduate years at Canada’s McMaster University; wartime work in the British-Canadian atomic energy project at Chalk River, Montreal; and postwar PhD studies in physics at the University of Cambridge, working with O. Frisch and D. Wilkinson. The discussion of his 40-year career in Caltech's Kellogg Radiation Laboratory deals with many aspects of the lab’s history, personnel, and research contributions. Barnes talks about his nuclear physics collaborations with W. Fowler, T. Lauritsen, C. Lauritsen, and R. Christy. He gives a detailed account of his and Kellogg’s accelerator-based investigations into the nature of the weak nuclear interaction—a key focus of postwar work in quantum field theory and the development of grand unified theories—and describes research collaborations in this area with theorists M. Gell-Mann and R. P. Feynman. He talks about Kellogg’s social and scientific culture, the development of its accelerators and the chronology of its research, its groundbreaking investigations into stellar evolution and stellar nucleosynthesis, and the awarding of the 1983 Nobel Prize in physics to Fowler for his work in nucleosynthesis. Barnes describes his work with J. Bahcall on the solar neutrino flux and discusses the research contributions of K. Thorne, J. DuMond, F. Boehm, M. Schmidt, and G. J. Wasserburg, among others. The interview also covers Kellogg’s role in the physics and astrophysics community, both within and beyond Caltech, and the lab’s relationship with Caltech administration, including presidents and division chairs; Barnes’s work with students; and his views on current trends and future directions in physics and astrophysics

SeaWiFS technical report series. Volume 10: Modeling of the SeaWiFS solar and lunar observations

Post-launch stability monitoring of the Sea-viewing Wide Field-of-view Sensor (SeaWifs) will include periodic sweeps of both an onboard solar diffuser plate and the moon. The diffuser views will provide short-term checks and the lunar views will monitor long-term trends in the instrument's radiometric stability. Models of the expected sensor response to these observations were created on the SeaWiFS computer at the National Aeronautics and Space Administration's (NASA) Goddard Space Flight Center (GSFC) using the Interactive Data Language (IDL) utility with a graphical user interface (GUI). The solar model uses the area of intersecting circles to simulate the ramping of sensor response while viewing the diffuser. This model is compared with preflight laboratory scans of the solar diffuser. The lunar model reads a high-resolution lunar image as input. The observations of the moon are simulated with a bright target recovery algorithm that includes ramping and ringing functions. Tests using the lunar model indicate that the integrated radiance of the entire lunar surface provides a more stable quantity than the mean of radiances from centralized pixels. The lunar model is compared to ground-based scans by the SeaWiFS instrument of a full moon in December 1992. Quality assurance and trend analyses routines for calibration and for telemetry data are also discussed

4-Methoxybenzaldehyde Pentafluorophenyl-Methylidenehydrazone

The crystal structure of the mixed azine C15H9F5N2O is described. The molecule has a high degree of planarity. The two phenyl rings deviate from perfect planarity by less than 2° and the dihedral angles between the ipso-C atoms and the azine bridge also show a minute deviation from planarity of less than 2°. The only dihedral angle that indicates any significant twisting is the dihedral angle about the azine bridge [C1-N1-N2-C8 174.8 (6)°], and even this one is relatively small. Face-to-face arene-arene contacts are the dominant intermolecular interactions. There are double face-to-face contacts in which the two phenyl rings of one mixed azine interact with the two phenyl rings of another mixed azine. There are also single face-to-face contacts where one phenyl ring of one mixed azine interacts with a phenyl ring of another mixed azine. In the double face-to-face arene-arene contacts, the pentafluorinated phenyl ring of one mixed azine always interacts with the methoxy-substituted phenyl ring of another mixed azine. In the single face-to-face arene-arene contacts, the interactions are always between two pentafluorinated phenyl rings or two methoxy-substituted phenyl rings

SS433:the microquasar link with ULXs?

SS433 is the prototype microquasar in the Galaxy and may even be analogous to the ULX sources if the jets' kinetic energy is taken into account. However, in spite of 20 years of study, our constraints on the nature of the binary system are extremely limited as a result of the difficulty of locating spectral features that can reveal the nature and motion of the mass donor. Newly acquired, high resolution blue spectra taken when the (precessing) disc is edge-on suggest that the binary is close to a common-envelope phase, and hence providing kinematic constraints is extremely difficult. Nevertheless, we do find evidence for a massive donor, as expected for the inferred very high mass transfer rate, and we compare SS433's properties with those of Cyg X-3.Comment: 4 pages, 3 figures, to appear in "Compact binaries in the Galaxy and beyond

Structure formation in the Lemaitre-Tolman model

Structure formation within the Lemaitre-Tolman model is investigated in a general manner. We seek models such that the initial density perturbation within a homogeneous background has a smaller mass than the structure into which it will develop, and the perturbation then accretes more mass during evolution. This is a generalisation of the approach taken by Bonnor in 1956. It is proved that any two spherically symmetric density profiles specified on any two constant time slices can be joined by a Lemaitre-Tolman evolution, and exact implicit formulae for the arbitrary functions that determine the resulting L-T model are obtained. Examples of the process are investigated numerically.Comment: LaTeX 2e plus 14 .eps & .ps figure files. 33 pages including figures. Minor revisions of text and data make it more precise and consistent. Currently scheduled for Phys Rev D vol 64, December 15 issu