GBS Elektronik MCA 166 - Manual (Page 41)

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3.8 Example for Making a Measurement with a NaI
detector using the MCA program on the HP200LX
Assuming that the Mini MCA (with a positive HV module) is connected to the PC, and the
detector and the software is installed:
Step 1:
•
Turn the MCA on, and wait until the LED starts flashing. Start the MCA emulation
software (mca.exe) from the DOS-PROMPT (current directory must contain all software
components) by typing ”mca”. On the HP 200, just press “1” in the menu to start the MCA
program.
•
Press ”Y” when you are prompted with ”Reset MMCA to default setup and clear all
spectra (y/n) ?”.
Step 2:
•
Go to the Acquire menu, select ”Setup” (by using either letters or arrow keys)
and press ENTER. Move down to Channels and set the value to 512 (toggle Channel
value with the space bar) .
•
Press ESC and ENTER to store the Channel value.
Step 3:
•
Go to the Setup menu, select ”Detector high voltage setup” and press ENTER.
Type in 500 for the value, and press ESC and ENTER to turn the detector high voltage
on.
Step 4:
•
Now move on to ”Amplifier setup” and press ENTER. Use the space bar to
toggle the Coarse gain to a value suitable for the detector. Now move to ”Adjust
amplifier now” and press ENTER. You will now be prompted with a graphic screen. If the
radio active probe was placed near the detector, a growing spectrum will appear.
•
If you can not see the spectrum, change the coarse gain !
• You may adjust the fine gain to shift the peak by using the ”+” and ”-” keys. Once
you have finished press ESC and ”Y” to save the value.
Step 5:
•
Move on to ”Do PZC” and press ENTER. You will be prompted with the screen
”Manual PZC Adjustment” . Press ”+” or ”-” to minimize the zero offset (minimize the
deviations of the shaded bar on the left from the middle). Once the offset is equal or close
to 0, press ESC and ”Y” to save the value.
Step 6:
•
Press ESC and ENTER to accept the amplifier settings and quit the Setup menu
by pressing ESC again.
Step 7:
•
Go to the Acquire menu , select ”Start” and press ENTER. You will now see the
graphical ”Acquire” screen.
•
Press the F4 softkey to start the measurement. You will now see the growing
spectrum and other frequently updated values (such as elapsed time, dead time,
countrate in counts per second, etc.) .