8.9. Electronics Noise 521
Problems
1.A semiconductor detector having a total capacitance of 1pFis connected to
a voltage sensitive preamplifier having a gain of 10. When the detector is
placed in a constant radiation field, it produces pulses of height 500mV at
the preamplifier’s output. Estimate the charge accumulated on the detector’s
capacitance corresponding to this voltage.
2.Suppose the temperature of the detector described in the previous exercise
can not be maintained at a fixed value and its variation can induce up to 10%
change in detector’s capacitance. Estimate the width of the charge distribution
corresponding to these fluctuations.3.Compute the voltage drop across a 20mlong copper wire having a cross
sectional area of 0.8mm^2 if a current of 0.5mAflows through it.4.Quantify the change in the response of a simple CR high pass filter with change
in frequency above the breakpoint offcutof f=1/ 2 πRC.5.A silicon based detection system has an inherent equivalent electronics noise
of 150 electrons. Compute the signal to noise ratio if the detector is placed in
a beam of 200keV photons such that 90% of the photons get absorbed in its
active volume.6.Determine the thermal noise currents of a 1MΩ resistor connected in parallel
at room temperature and at -10^0 C. Assume the system bandwidth to be 200
MHz.7.Determine the Johnson noise voltage at 27^0 Cif a 100 Ω resistor is connected
in series. The system bandwidth is from 100Hzto 500kHz.8.Calculate the shot noise in a silicon detector if a current of 15μAflows through
it. Assume the system bandwidth to be 1MHz.9.Compute the quantization noise of an 8-bit ADC having a conversion range
from -10V to +10V.