Initial Tests Of The Pion Beta Decay Detector

4.5 Summary

Data taken using the tomography apparatus at PSI yields an effective attenuation length for the staves of 39.6 ± 1.3 cm. The measured attenuation length of the PV staves is four times smaller than the nominal attenuation length quoted by Bicron for BC-400 material.

Figure 4.7: Scatter plots of distance along stave (mm) vs. signal time (0.1 x ns). The slope of these plots is the signal velocity along the direction of the stave.

The effective signal velocity in PV staves was measured to be (7.7 ± 1.0) × 10⁷ m/s. This is about 2.6 times slower than speed of light in BC-400 material as reported by the manufacturer. Using a TDC with 0.25 ns resolution, the position along the stave at which a signal originates can be determined to within ~2 cm via signal timing.