The above diagrams represent the P/E, RNG, and PEN logic with P and E equations modified to accept events that trigger the low guard threshold. The equations for P/E, RNG, and PEN events are:
Event type |
Coincidence equation |
P, E |
P1.P2.P4*.AH* |
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 |
P/E |
NONE |
P1 through P3 |
P/E |
P/E |
NONE |
P1 through P4, P5, P6, or P7 |
RNG |
NONE |
NONE |
P1 through P8 |
RNG, PEN |
PEN |
PEN |
This differs from the launch command state in that the P and E (and corresponding rate) equations were changed to accept events where the low guard threshold was triggered. This was because shortly after launch it was discovered that the centers and guards of P3 were subject to intermittent crosstalk, which sometimes caused valid (particle not entering the guard rings) PHI events to be vetoed because the crosstalk caused the guard to trigger. After another brief test, the instrument was returned to this state for most of 1993.
new 6 August 1999