A description is given of the mechanical gauge and electrical circuit employed for measuring millisecond pressure pulses in a liquid hydrogen bubble chamber, in a pulsed magnetic field region.
The pressure pulse produces a deflection of a diaphragm that acts as one electrode of a capacitor. The change in capacitance is measured in an electrical circuit by comparison with a reference capacitor.
A common source feeds two cables, one of which is terminated by the pressure‐measuring capacitor (``transducer''), the other by the adjustable comparison unit. Pulses from the common source are reflected from the two terminations, and their difference is amplified and displayed. The circuit employed is such that the distributed capacitance of the cables does not affect the sensitivity of the system. Hence, the interconnecting cables are not limited in length up to several thousand feet.
The frequency‐response limit is about 10 kc for units currently used, because of the diaphragm characteristics. Steady‐pressure calibration can be employed in order to determine the pressure and output relation.