User Guide
- 15 -
Vertilon Corporation, 66 Tadmuck Road, Westford, MA 01886
/
Tel: (978) 692-7070
/
Fax: (978) 692-7010
/
www.vertilon.com
Coincidence Detector
The coincidence detector uses the outputs from discriminators A and B to determine coincidence between particle events
on SPMArray2 devices A and B. As shown in Figure 7, events occurring within a user-defined coincidence time window
(t
CW
) result in the generation of a trigger signal on connector J6. This signal can be used to trigger the capture of the 32
SiPM detector signals by a data acquisition system or other electronics. Two LEDs are used to indicate that the
coincidence detector has determined a coincidence condition. When coincidence occurs due to an event on
SPMArray2 A followed by an event on SPMArray2 B, LED LD3 flashes green. In the reverse condition when an event on
SPMArray2 A follows an event on SPMArray2 B, LED LD4 flashes green. Generally both LEDs will flash equally when
events occur near simultaneously. If however a particle event on one array continually precedes an event on the other
array, then the LED associated with the array that detected the later event will flash red instead of green. When an event
is detected on a particular SPMArray2 but with no coincidence, then the LED associated with the SPMArray2 that
detected the event will flash red. The coincidence detector LEDs can be quite useful for system setup, diagnostics, and
timing alignment.
Figure 7: Coincidence Detector Timing
For applications requiring simple energy threshold triggering instead of event coincidence triggering, the coincidence
detector can be configured to generate a trigger signal if a threshold-crossing event is detected on either SPMArray2.
This is done by setting Trigger Type in the dialog box to Level.
t
cw
TRIGGER
OUTPUT
SPMArray A
DISCRIMINATOR
SPMArray B
DISCRIMINATOR
t
CW
= Coincidence Window Time
Summary of Contents for SIB2316
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