GBS Elektronik MCA 166 - Manual (Page 32)

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(Start) key needs to be pressed to start and automatically save a measurement.
Optionally a remark can be saved. For CANDU canister verification, the averaged
amplitude spectrum (512 channels) is being collected simultaneously in the background
for each scan. The corresponding spectrum file is optionally recorded together with the
time distribution. The following input options are available for multi channel scaling: cps
(MCS count proportional to input rate), ULD/ULD (MCS count proportional to the rate
between LLD and ULD) and TTL (MCS count proportional to rate of external TTL signal,
in this case no spectrum is recorded). The first option is used for canister scanning and
the last is used for criticality tests.
To use the MCS program:
1. Connect the detector and afterwards turn the MMCA module on (toggle switch at the
front side).
2. Turn on the computer (right upper corner of the keyboard, also used if the HP 200LX
went into the sleep mode). Start the program by pushing the corresponding numeric key
and reset the MMCA.
3. Read in the setup file for your detector ("Setup", "Read setup file", use arrow down key
to move the cursor bar to the setup file and press Enter twice).
4. Check the appearance of the file and turn on the high voltage ("Menu", "Setup",
"Detector high voltage", ENTER; verify that the HV value and sign correspond to what is
written on the detector and follow the instructions in the dialogue box.
5. Go to "File", "Autosave" to check or set the File saving options. Default settings are
"Autosave" no, "Save also ampl. spectrum" yes and "Remarks" yes. If Autosave is turned
on, a startup file name must be saved first, e.g., "mba-0001.spe". During the automated
measurement existing files will be overwritten without or after a warning. You can control
this by setting "Autosave", "Prompt before overwrite" yes or no. To avoid data losses, give
a new name, e.g., “MBA-0100.spe” to start a new series of measurements. The amplitude
spectrum information, if save is desired, is contained in the same file. The amplitude
spectrum is always acquired in 512 channels regardless of the number of time channels
used by the MCS.
6. Go to "Setup mcS" and check the input mode, the number of time channels and the
time/channel (=dwell time). The total measurement time will be calculated automatically
when you leave the input field. MCA and amplifier settings are not available if the external
TTL mode is chosen. If the cps or ULD/ULD input mode is chosen, check the MCA setup
parameters against your calibration sheet.
7. In case the amplifier or MCA is used (cps or LLD/ULD options of the MCS input) put a
source on the detector. Go to "Amplifier Setup" - "Switch to visual gain adjustment",
Enter. Use +/- keys to move the peak into the desired channel, Press ESC, Y to check
the PZC adjustment by minimizing the vertical bar on the left side of the screen using the
+/- keys. The source strength must be between 300 and 30000 cps and the spectrum
must reach at least 50% of the MCA range. Leave the dialogue box accepting all settings.
8. Go to "Data acquisition" - "Measurement" to start a MCS measurement.
Description of the MCS program in order of the commands
3.4.1 File menu
The file menu allows to open and to save files. Files contain MCS spectrum data with
setup information and may also contain amplitude spectrum data.