Volume 77, Issue 7, July 2006
Index of content:
77(2006); http://dx.doi.org/10.1063/1.2219516View Description Hide Description
The transient hot-wire method is widely used to determine the thermal conductivity of various media. It has been improved through the addition of an insulation coating to the wire. However, this coating could affect the accuracy of the thermal conductivitymeasurement. The temperature rise for the insulation-coated wire was calculated as a function of time by a Laplace transformation along with the expansion method outlined by Carslaw and Jaeger [Conduction of Heat in Solids (Oxford University Press, Oxford, 1959)]. The results of numerical simulations and experimental tests show that, for most engineering applications, the relative measurement errors of the thermal conductivity caused by the insulation coating are very small if the slopes of the temperature rise-logarithmic time diagrams are calculated for large time values. No correction to the insulation coating is necessary even for the conditions that the insulation coating thickness is comparable to the wire radius, and that the thermal conductivity of the insulation coating is lower than that of the measured medium.
77(2006); http://dx.doi.org/10.1063/1.2219755View Description Hide Description
A room temperature high-energy sweeper had been designed, fabricated, and installed at the postacceleration section of the Tandem accelerator. The sweeper, a part of the new pulsing system, is being used to inject the bunched beam without dark current into the linear accelerator acting as a booster of the Tandem. The resonance frequency of the sweeper was set at and a quality factor of was achieved. During off-line testing of the sweeper, a deflector voltage of had been measured for an input power of . A pair of indigenously fabricated capacitors is used for fine-tuning of the resonance frequency. The silver plated coil of the tank circuit was fabricated with two concentric copper tubes. During the successful beam test of the sweeper, a peak to dark current ratio of 97% has been achieved.
77(2006); http://dx.doi.org/10.1063/1.2221543View Description Hide Description
The design and performance of a thin bakable in-line valve are described. The valve is designed for use in electron scatteringexperiments for efficient and minimal spatial separation of ultrahigh vacuum from a region containing metal vapors, base pressure of , or atmosphere. The simple compact design permits experiments with metal vapors and spin polarized electrons to be conducted with high efficiency and over months, without loss of emission from GaAs crystal or need for frequent bakeout of ultrahigh vacuum chamber.
77(2006); http://dx.doi.org/10.1063/1.2221545View Description Hide Description
A setup for measuringfemtosecond transient absorption in the gas phase is reported. The apparatus is based on a amplified Ti:sapphire laser system and measures gas-phase transient absorption using a shot-to-shot normalization scheme with background subtraction. We have used this setup to examine the wave packet dynamics of the state in the vapor phase as a benchmark. The results are consistent with those reported by other groups using indirect transient absorption techniques.
77(2006); http://dx.doi.org/10.1063/1.2227646View Description Hide Description
We report on a one-dimensional surface plasmon resonance imaging system that can measurereflectivity over a range of incident wavelengths on multiple samples in parallel. The design and operation of the instrument are described and two methods of quantification are demonstrated.