Quench in high temperature superconductor magnets

High field superconducting magnets using high temperature superconductors are being developed for high energy physics, nuclear magnetic resonance and energy storage applications. Although the conductor technology has progressed to the point where such large magnets can be readily envisioned, quench protection remains a key challenge. It is well-established that quench propagation in HTS magnets is very slow and this brings new challenges that must be addressed. In this paper, these challenges are discussed and potential solutions, driven by new technologies such as optical fiber based sensors and thermally conducting electrical insulators, are reviewed.Comment: 9 pages, Contribution to WAMSDO 2013: Workshop on Accelerator Magnet, Superconductor, Design and Optimization; 15 - 16 Jan 2013, CERN, Geneva, Switzerlan

Performance map of a heat pipe charged with ammonia

Test results are presented which describe dryout in type-304 stainless steel heat pipes when ammonia is the working fluid. Graph compares heat transfer capabilities of both ammonia and water. Heat pipe apparatus and performance are described

A voltage-tunable three-terminal Gunn device

Newly developed Gunn oscillator is three-terminal device which consists of piece of gallium arsenide with source, drain, and gate contacts. Voltage tunable three-terminal device does not require bulky resonant cavity and allows oscillation frequency to be rapidly tuned with simple circuitry

Evidence for Light Scalar Resonances in Charm Meson Decays from Fermilab E791

From Dalitz-plot analyses of $D^+\to\pi^-\pi^+\pi^+$ and $D^+\to K^-\pi^+\pi^+$ decays, we find evidence for light and broad scalar resonances sigma(500) and kappa(800). From a Dalitz-plot analysis of $D^+_s\to\pi^-\pi^+\pi^+$ decays, we measure the masses and decay widths of the scalar resonances f_0(980) and f_0(1370).Comment: References added. Contribution to 5th International Conference on Quark Confinement and the Hadron Spectrum, Gargnano, Italy, 10-14 Sep 200

Recent Charm Results from Fermilab Experiment E791

Fermilab experiment E791 studied weak decays of D+, D_s, and D^0 mesons produced in collisions of 500 GeV/c negative pions with Pt and C targets. The experiment collected over 200,000 fully reconstructed charm decays. Four recent results are discussed here: (a) measurement of the form factor ratios V/A_1, A_2/A_1, and A_3/A_1 in D->K*-l-nu and Ds->phi-l-nu decays; (b) measurement of the difference in decay widths $\Delta\Gamma$ between the two D^0/D^0-bar mass eigenstates; (c) search for rare and forbidden D decays to dilepton final states; and (d) search for a ``Pentaquark,'' a bound state of c-bar-suud.Comment: 8 pages, 2 figures, contribution to XXXIVth Rencontres de Moriond, Electroweak Interactions and Unified Theories, March, 199

The Crappies

The names: bachelor, campbellite, white bass, camp lighter, sac-a-lait, silver crappie, speckled bass, tinmouth, bar fish, Oswego bass, razorback, grassback, shiner, john demon, calico bass, strawberry bass and "crap'pee," along with 10-20 others, all refer to two rather than one species of fish. Most Maryland fishermen when applying these time honored names do not realize they are referring to two distinct species of fish. These species are the black crappie, Pornoxis nigromaculatus, and the white crappie, Pornoxis annulars. Contrary to common belief, the white crappie does not change into a black crappie during parts of the year nor are these two fish just color phases of one species. Crappies are members of the freshwater sunfish family of fishes, Centrarchidae. (PDF contains 4 pages