The above diagrams represent the P/E, RNG, and PEN logic as launched. The equations for P/E, RNG, and PEN events are:
Event type |
Coincidence equation |
P, E |
P1.P2.P4*.AL* |
RNG |
P1.P2.P4.AL* |
PEN |
P1.P2.P8 |
The buffers into which "orderly" events can fall are as follows:
Range |
No guards triggered |
Low, not high guard triggered |
High guard triggered |
P1 |
NONE |
NONE |
NONE |
P1 through P2 |
P/E |
NONE |
NONE |
P1 through P3 |
P/E |
NONE |
NONE |
P1 through P4, P5, P6, or P7 |
RNG |
NONE |
NONE |
P1 through P8 |
RNG, PEN |
PEN |
PEN |
Before launch, the PEN event buffer (PENE) failed. Thus it was disabled (the only change made to command word 3 so far) and the definition of RNG was changed to accept penetrating events by deletion of the P8* term. Thus a nominal penetrating event (P1 through P8, no guards) can be output in either the RNG or PEN buffers; since the RNG buffer is checked first, the PHA event will come out in this buffer unless it is already full (in which case the event will disappear because the PEN buffer is disabled). However, since the rate scalers are accumulated in the opposite order, such an event will always be counted in the PEN rate. Note, however, that a penetrating (P1 through P8) event which also triggers one or both guard thresholds will not be output in the PHA buffers (such events will be rejected from the RNG buffer, and the PEN buffer is disabled), but will still be counted in the PEN rate. Thus the PEN events extracted from the RNG buffer are not an unbiased sample of all events counted in the PEN rate, and fluxes calculated from them will be too high (in my experience, by about 20 to 25 percent).
new 6 August 1999