To compare the measured output of a detector in the Campbell mode with the predicted value, experimental values were applied in the following expression:

where

к = detector counting efficiency (with discriminator setting of zero),

Zjg = mid-bandpass transfer impedance,

Q2 = [the product of charge of either sign per pulse and fraction of applied

field through which it falls | 2 average,

Ы1Н = uPPer break frequency of bandpass of system, and = lower break frequency of bandpass of system.

An in-core counter (No. 1 assembly) was chosen for comparison because (a) the load impedance seen by the chamber can be expressed simply, being 5000 ohms; (b) a pulse height spectrum for determination of Q could be obtained from the detector in its actual operating condition (the Camp­bell detectors, having low internal gas pressure, do not provide pulses of adequate amplitude). For this counter, the ion collection time (0. 56 x 10’^ sec) and the bandpass of the system ( 8 to 10 kHz) result in an equivalent fraction of applied field through which the charge falls, of 3/4.

The experimentally determined values are:

2

Q is determined in the following manner. On a differential pulse height spectrum, the charge in a given pulse, q^, is related to the indicated pulse height, Pj, by a constant C.

(4-25)

where N is total number of pulses in the counting interval, and n is the number of pulse in the interval of average height Pj. .

The constant, C, can be evaluated from d-c sensitivity of the chamber.

where is the d-c sensitivity of the chamber. Hence,