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.

Propagation of surface acoustic waves (SAWs) was investigated on a single lithium niobate (LiNbO 3 ) ball of 1 inch diameter. We found ten specific routes, on which the roundtrips of SAWs are observed, and one or more specific routes, on which the multiple reflections of bulk waves are observed. Since the temperature coefficient is similar on each route of the SAW, one route can be used to correct the temperature dependency of all other routes, and the other routes can be used as multiple-gas sensors by coating various reactive thin films along each route.

In order to commonly use explosive H 2 gas as an energy source, fast, sensitive, and low-power consumption sensor is required. We developed a ball surface acoustic wave (SAW) sensor with porous PdPt alloy film to realize such a sensor. The sensor with 20% Pt alloying film was useful for the suppression of a phase transition of Pd and the detection of ppm order concentration at 35°C. The amplitude response was proportional to the square root of the concentration, which was demonstrated for the first time in the field of SAW sensor, resulting in the detection limit of 3.7 ppm at signal to noise ratio of 3. The response time decreased to 1/5, compared with those of pioneering H 2 sensors working at room temperature. From these results, it was shown that the fastest and most sensitive hydrogen sensor working at room temperature could be realized using the ball SAW sensor with porous Pd alloy film.

In order to improve the performance of ball surface acoustic wave (SAW) devices, we have developed an orientation control apparatus to find the Z axis of a quartz crystal ball by an optical birefringence measurement, and to find the X and Y axes by measuring the propagation characteristics of a SAW using an interdigital transducer (IDT), which is moved close to the ball using a translation stage. The soft spring of the vacuum chuck of the ball manipulator prevented damage to the ball or IDT during the contact. The concave shape of the ball holder of the chuck enabled repeatable alignment of the ball center and the manipulator axis. As a preliminary result, we confirmed that the SAW velocity variation had 60° periodicity and succeeded in identifying the -Y axis-equivalent direction on the quartz ball.