GBS Elektronik MCA 166 - Manual (Page 35)

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3.4.2.5 MCA Setup (only in LLD/ULD mode)
Allows to setup the acquire functions like MCA channels, Threshold, Upper and lower
Level discriminators (LLD, ULD) and ADC input
Channels
In the MCS program always 512.
Threshold
Allows to set a threshold value between 2% and 60% of the current MCA scale
.
Default is
2%. This analogue threshold cuts the pulses before they reach the ADC. Setting the
threshold high discriminates unwanted low energy pulses.
Do visual threshold adjustment
Allows to adjust the threshold using visual control of the spectrum.
LLD, ULD
LLD allows to set the lower level discriminator of the ADC. The value for LLD must be <
ULD. Default is 0.
ULD allows to set the upper level discriminator (ULD) of the ADC. The value for ULD must
be > LLD. Default is highest possible channel.
In LLD/ULD mode, only these counts are used for the MCS spectrum which are between
the LLD and the ULD limit. LLD and ULD do not affect the measured amplitude spectrum.
Do visual LLD/ULD adjustment
Starts acquiring a full spectrum, by pressing F5 and by not accepting the current values
you can enter new values by moving the cursor to LLD and ULD channel.
3.4.2.6 Setup Summary
This feature provides an overview on the MCA setup parameters. It does not allow any
editing. The MCS setup parameters can only be seen in the mcS setup menu.
3.4.3 Data acquisition menu
The acquire menu provides a start function to start data collection. The data gathering is
controlled from the graphic screen. It further provides an energy calibration menu.
3.4.3.1 Measurement
The first graphic screen is the ACQUIRE screen, which contains operative information like
actual counts per channel rate, real time preset for the measurement and which provides
a quickly updated live display of the spectrum. To start a measurement, press F4. During
a measurement only 256 channels (the width of the display) are transferred automatically
every 2 sec. from the Mini MCA to the (Palmtop-) PC.
If an intermediate evaluation is needed, a full spectrum (snap shot, not updated unless
requested) is presented on a second graphical screen (EVALUATION screen) showing
the evaluation information (integral counts, ect.) To enter the evaluation screen, press F2.