抄録
In nuclear radiation measurement, pulse height discriminator (PHD) and single channel analyzer (SCA) are widely used to select pulses whose amplitude is within user's interesting range. PHD is derived from universal double voltage comparators by adding additional anti-coincidence circuits. Simple anti-coincidence method will generate false result, for the leading edge of upper comparator output falls behind that of lower comparator and pulse width of upper comparator output is narrower than that of lower comparator output. Anti-coincidence circuits in a conventional PHD and SCA often contain quite a few different circuits or components, such as monostable multivibrator and/or bistable flip-flop, NOR or NOT gate, etc. Such complex structure and manifold components deteriorate PHD's and SCA's response time and reliability. Great efforts have been made to simplify its structure and improve its reliability. Based on analyzing time sequence of the outputs of upper and lower voltage comparators, a novel, simple and practical structure is presented that contains only monolithic circuit (dual monostable multivibrator). Concrete circuits are fabricated and waveforms captured from digital storage oscilloscope (DSO) prove that it works properly and reliably till the input signal frequency increases up to 1MHz, regardless of sine wave, exponent falling or impulse signal. It can be utilized in the field of nuclear radiation measurement.
