Noise from preamplifiers

Currently manufaetured hybrid PMTs have gains of the order of 10,000. Therefore eleetronie noise from the matching resistor and from the preamplifier impairs the time resolution of single photon detection. The relatively large distance between the photoeathode and diode chip may also cause transit-time spread. In praetieal applieations, the extremely high operating voltage also causes problems. Currently hybrid PMTs are not routinely used for TCSPC experiments. 

The first term is the broadening due to ionization statistics. The Fano factor F lies between 0.09 to 0.23 depending on the detector gas. Statistical fluctuations in the gas gain contribute through the second term Fa- Electronic noise from the preamplifier is accounted for in the term Fnoise. and the term Fp covers fluctuations due to variations in the counter design parameters over the dimensions of the... 

A basic radiation measuring system consists of the detector, a high-voltage power supply for bias voltage, a preamplifier, and a power supply for the preamplifier and signal amplifier. A pulse height discriminator is used to decrease the low-energy noise from the detector and the amplifier. 

Care was taken to minimize the coupling noise from adjacent channels. All input signal lines that connect the inputs of the preamplifiers to bonding pads were... 

The electronic instrumentation necessary for the operation of the proportional counter is shown in Figure 18.6. Pulses from the detector pass through a preamplifier and amplifier, where they are shaped and amplified. Emerging from the amplifier, the pulses go to a discriminator. The discriminator is set so as not to trip on noise pulses but rather to trip on radiation pulses of any larger size. The number of discriminator pulses produced is recorded by the scaler. 

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