If you are using a Canberra Model 2101 preamplifier, disable the Reset Delay using
these three steps:
1.
Remove all signal and power connections from the preamp.
2.
Remove the preamp cover and change jumper plug W1 from position A to
position B. Jumper plug W1 is located on the main PC board next to RV1.
3.
When done, reinstall the preamp cover an reconnect the preamp to the 9660
as before or as indicated in “Spectroscopy System Setup” on page 34 and in
Figure 19.
For additional information on the Reset Delay feature and jumper plug W1, please re-
fer to the
Model 2101 User’s Manual
.
Pole/Zero Setting for Reset Preamps
Since the Reset Preamp output signal is a step function instead of the classical tail
pulse, with exponential decay, Pole/Zero compensation is not required. For this appli-
cation, the Pole/Zero should be set off or to infinity. On the 9660, this is accomplished
by setting the preamp type to RESET. The preamp type can be changed in the Filter
Device MID Editor. If RESET is selected, the Pole/Zero is automatically set to a value
of zero, corresponding to a fall time of infinity, and no further adjustment is required.
If RC is selected, the pole zero value in the Filter Device Adjust screen must be manu-
ally set to zero.
Using the Reset Inhibit
During the preamp reset interval, the preamp reset event produces a large signal to the
9660 driving it into severe overload. The 9660 automatically senses preamplifier reset
events and gates off pulse processing during the associated overload event. However,
to obtain optimum performance, especially at high count rates, it is recommended the
preamplifier’s Inhibit signal be connected to the Inhibit Input on the 9660. Figure 35
below shows Trapezoid Signal, Preamp Output and Inhibit Signals.
The 9660 system inhibit is initiated or derived from the preamp inhibit signal. The op-
timum system inhibit time can be set automatically by the 9660 or adjusted manually.
For automatic inhibit, set the Inhibit Mode, Gain Device Adjust screen, to “Reset”.
When using the RESET mode of operation, the correct system inhibit time is automati-
cally set. It is not necessary to make critical adjustments of the inhibit signal at the
preamp. However, the preamp inhibit signal should be set to its minimum value.
Please consult the Detector/Preamp Operator manual for this adjustment.
User’s Manual - ICN 9231014G
73
Operation with Reset Preamps and Selecting Inhibit Mode