Capintec CAPTUS 2000, Owner'S Manual

Page: 179 / 206

CAPINTEC, INC CAPTUS
®
2000
Figure 10-6
The Zero Offset, which sets the channel location of zero keV, ranges from a value of 0 to
255. To increase the Zero offset value, select the right arrow key from the arrow bar located
beneath the Zero Offset value. To decrease the Zero Offset, select the left arrow key from
the arrow bar. For large incremental changes, place the trackball indicator on the square
located in the middle of the arrow bar, and depress the left clicker. With the clicker
depressed, slide the box to the desired setting. Moving the box to the right increases the
Zero Offset value, moving the box to the left decreases the Zero Offset value.
The Threshold value acts as a coarse LLD control, and the LLD value acts as a fine LLD
control adjustment. Together, these values set the lower channel limit of detection for the
MCA board. Both may be adjusted from 0 to 255 by using the right arrow to increment, and
the left arrow to decrement. The LLD default is set to eliminate any extraneous electronic
noise yet allow counts of the lowest possible energy to be detected. The ULD control sets
the upper channel limit of detection. Similarly, the ULD ranges from 0 to 255, and is adjusted
by choosing the right arrow to increase the value and the left arrow to decrease the value.
For large incremental changes, place the trackball indicator on the square located in the
middle of the arrow bar, and depress the left clicker. With the clicker depressed, slide the
box to the desired setting. Moving the box to the right increases the value, moving the box to
the left decreases the value. When the Zero offset, LLD, and ULD values are correct, select
the
CLOSE button. This will cause the changes to be temporarily stored in the software
memory while in the MCA mode only, and exit the screen.
NOTE: WHEN YOU EXIT THE MCA PROGRAM, AND RETURN TO AN APPLICATIONS
PROGRAM (THYROID UPTAKE, BIOASSAY, WIPE TEST, LAB TESTS), THE
SOFTWARE WILL RESTORE THE HIGH VOLTAGE AND GAIN SETTINGS THAT WERE
DETERMINED IN AUTOCALIBRATE. THIS WILL RETURN THE CALIBRATION TO 2
keV/CHANNEL, AND ALLOW THE AUTOMATIC PEAK FINDING AND ROI PROGRAMS
TO OPERATE CORRECTLY.
Quick Calibration Restore
If changes have been made to any of the calibration parameters, voltage, gain, zero offset,
the automatic energy calibration settings can be quickly restored by selecting
Restore
Calibrated Settings from the Setup list. Figure 10-7 will appear.
July 00 MCA 10-5