Summary and Outlook for 9th International Symposium on Heavy Flavor Physics

This is the summary talk of a meeting held at the California Institute of Technology Sept 10-13, 2001. I do not attempt to summarize all the beautiful experimental results we have seen this week, nor to repeat the lively theoretical discussions that have occurred. Rather I will present my own biased perspective on what we have learned, and on the important tasks that need our attention as we work to make the most of the rapidly accumulating data in this field.Comment: Talk presented at 9th International Symposium on Heavy Flavor Physics, California Institute of Technology, September 10-13, 200

Resonant isolator for maser amplifier

An isolator is described for use in a low noise maser amplifier, which provides low loss across a wide bandwidth and which can be constructed at moderate cost. The isolator includes a train of garnet or ferrite elements extending along the length of a microwave channel parallel to the slow wave structure, with the elements being of staggered height, so that the thin elements which are resonant to the microwaves are separated by much thicker elements. The thick garnet or ferrite elements reduce the magnetic flux passing through the thin elements to permit altering of the shape of the thin elements so as to facilitate their fabrication and to provide better isolation with reduced loss, by increasing the thickness of the thin elements and decreasing their length and width

Improved masers for X-band and Ku band

Slow-wave structure of traveling-wave maser utilizes comb system which is comprised of ruby on one side and alumina on other; alumina also supports isolator material. Radiation at pump frequency is coupled to ruby through shaped alumina strips. Contact between ruby bars and comb completes conductance path for heat transfer

In-flight boundary-layer measurements on a hollow cylinder at a Mach number of 3.0

Skin temperatures, shear forces, surface static pressures, boundary layer pitot pressures, and boundary layer total temperatures were measured on the external surface of a hollow cylinder that was 3.04 meters long and 0.437 meter in diameter and was mounted beneath the fuselage of the YF-12A airplane. The data were obtained at a nominal free stream Mach number of 3.0 (a local Mach number of 2.9) and at wall to recovery temperature ratios of 0.66 to 0.91. The local Reynolds number had a nominal value of 4,300,000 per meter. Heat transfer coefficients and skin friction coefficients were derived from skin temperature time histories and shear force measurements, respectively. In addition, boundary layer velocity profiles were derived from pitot pressure measurements, and a Reynolds analogy factor was obtained from the heat transfer and skin friction measurements. The measured data are compared with several boundary layer prediction methods

A 2.3-GHz maser at Usuda, Japan, for TDRSS-orbiting VLBI experiment

A 2.3 GHz traveling-wave maser/closed-cycle refrigerator (TWM/CCR) that is used in the DSN was installed and successfully operated on the 64 m antenna at Usuda, Japan. The TWM/CCR supported the first very long baseline interferometry (VLBI) experiment to use an orbiting spacecraft as one of the receiving antennas. The experiment required a 15 K receiving system over a 2271 to 2285 MHz bandwidth. The maser installation was made during June 1986, and successful VLBI measurements were made during July and August 1986 and again in January 1987

Study of storm time fluxes of heavy ions

Ion composition data sets from Lockheed instruments on a variety of spacecraft were used in combination with each other and with data from other instruments to address a variety of problems regarding plasma sources, energization and transport within the magnetosphere. The availability of data from several differing orbits has given a highly flexible approach to attacking the continually evolving questions of magnetospheric physics. This approach is very successful and should be continued in the future

Dual-polarization 8.45 GHz traveling-wave maser

An 8.5 GHz dual-channel, dual-polarization traveling-wave maser (TWM) amplifier was installed in the XKR solar system radar cone at DSS 14. The TWM is based on the Blk IIA 8.45 GHz maser structure, with two of the four maser stages being used for each channel, and each maser half then followed by a high-performance GaAs FET amplifier to achieve the desired net gain. A shortened low-noise input waveguide and an orthogonal-mode junction which is cooled to 4.5 K feeds each amplifier chain. The rotation of an external polarizer permits the polarization of each channel to be defined as either linear or circular. A circular waveguide switch was also developed to provide for noise calibration and to protect the maser from incident transmitter power

Off the Beaten Path: A New Approach to Realistically Model The Orbital Decay of Supermassive Black Holes in Galaxy Formation Simulations

We introduce a force correction term to better model the dynamical friction (DF) experienced by a supermassive black hole (SMBH) as it orbits within its host galaxy. This new approach accurately follows the orbital decay of a SMBH and drastically improves over commonly used advection methods. The force correction introduced here naturally scales with the force resolution of the simulation and converges as resolution is increased. In controlled experiments we show how the orbital decay of the SMBH closely follows analytical predictions when particle masses are significantly smaller than that of the SMBH. In a cosmological simulation of the assembly of a small galaxy, we show how our method allows for realistic black hole orbits. This approach overcomes the limitations of the advection scheme, where black holes are rapidly and artificially pushed toward the halo center and then forced to merge, regardless of their orbits. We find that SMBHs from merging dwarf galaxies can spend significant time away from the center of the remnant galaxy. Improving the modeling of SMBH orbital decay will help in making robust predictions of the growth, detectability, and merger rates of SMBHs, especially at low galaxy masses or at high redshift.Comment: 8 pages, 4 figure, Accepted by MNRA