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We propose a new temperature compensation method for ball surface acoustic wave (SAW) devices using frequency dispersion. This method distinguishes the temperature effect independent of frequency and surface effects such as mass loading or elastic effects linearly dependent on frequency. After stating the principle of the method, we verify it by fabricating ball SAW devices with an interdigital transducer (IDT) that works at two frequencies, and apply them to the measurement of the coating of albumin on the surface of the device and on a hydrogen gas sensor with a surface-coated sensing film. Delay time measurements are carried out at two frequencies, and the difference in delay time is calculated to eliminate temperatureindependent effects. Because the results clearly show surface effects without temperature disturbance, it is a difficult to realize sensors using ball SAW devices.

We present a new analysis of Rossi X-Ray Timing Explorer observations of the 2002 outburst of the transient X-ray nova 4U 1543-47. We focus on observations in the high/soft state, and attempt to measure the "spin" of the black hole by simultaneously fitting the thermal disk continuum and by modeling the broadened iron k-shell emission lines and additional blurred reflection features. Previous works have found that use of these methods individually returns contradictory values for the dimensionless spin parameter a * = cJ/GM 2 . We find that when used in conjunction with each other, a moderate spin is obtained (a * = 0.43 +0.22 −0.31 ) that is actually consistent with both other values within errors. We discuss limitations of our analysis, systematic uncertainties, and implications of this measurement, and compare our result to those previously claimed for 4U 1543-47.

In environmental assessment and security, it is necessary to detect hazardous gases at low concentrations. The ball surface acoustic wave (SAW) sensor can have significantly improved sensitivity when the ultramultiple roundtrips (e.g., >100 turns) of the SAW is achieved. However, it is hindered by the thick and coarse organic sensitive film fabricated by the conventional spin-coating method. We propose an ''off-axis spin coating method'' in order to fabricate thin and highly uniform organic sensitive film with high reproducibility. Langasite ball SAW sensors were coated by polyisoprene, polyisobutylene, and polydimethylsiloxane sensitive films and were applied in detecting normal saturated hydrocarbons (pentane, hexane, heptane, octane, and nonane), a nerve gas simulant (dimethyl methylphosphonate: DMMP), and sick-house gases (benzene, toluene, and xylene). With the proposed method, we succeeded in realizing multiple roundtrips and in detecting DMMP at a sub-ppm concentration without preliminary condensation of the sample.