Data on the pin-diode monitors in use at IMM-CAT
We have two different PIN diode types
EG&G VTS3085 (Newark part no 92F3665)
and
EG&G VTS3080 (Newark part no 95F9032)
A PIN diode with an intermediate size (3/8"x3/8") will be available soon:
EG&G VTS3082 (Newark part no 92F3666)
The VTS3085 (around $4) has an active area of 21 mm^2, and approximately
a 1/2 mm dead space around the outer edge. The Max Dark Current is 0.1
micro Amps and the Open Circuit Voltage is .33 V.
The VTS3080 (around $53) has an active area of 392 mm^2 a dark current
of 1.0 micro-amp and an open circuit voltage of .33V.
For both PIN diodes we usually assume that the Si thickness is 400 microns
and that it generates 1 charge pair for each 3.62 eV of deposited
energy. These numbers are not based on manufacturers values but tend to
give approximately correct flux measurements
Some data on the properties of the diode from PerkinElmer Optoelectronics
1.) The diffused junction is on the order of 0.5 microns.
2.) At zero reverse bias the depletion width is approximately 8 to 10
microns.
3.) The bulk material is on the 500 microns thick and has very high
minority carrier lifetimes (i.e. carriers generated deep in the bulk can
be collected by the junction).
Some callibration data on the PIN diodes,
Callibration for 10^6 gain and 10^5 counts/V gives 29537 photons/count at E=7.66 keV
Based on 3.62 eV per charge pair (from amptec manual e.g. ) and assuming 100% absorption.
Callibration for 10^6 gain and 10^5 counts/V gives 87535.7 photons/count at E=23 keV
This is based on a callibrated scatter crossover with the first harmonic. |