A coincidence window margin scan checks whether the time separation between two channels fits inside a fixed window, with zero margin as the boundary between pass and fail. With a 2-second window, channel B at times 4, 5, and 6 seconds gives separations 1, 2, and 3, yielding margins 1, 0, and -1 (pass, pass, fail) exactly for the stated toy timing ledger; real detector timing has clock calibration, jitter, dead time, and window-placement uncertainty.
Coincidence timing is a boundary comparison, including equality. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One-second separation is inside the window
Channel B time 4 seconds gives separation 1 second against a two-second window.
m=W−Δt=2−1=1,pass
Two-second separation is exactly on the boundary
Channel B time 5 seconds gives separation 2 seconds against a two-second window.
m=W−Δt=2−2=0,pass
Three-second separation misses the window
Channel B time 6 seconds gives separation 3 seconds against a two-second window.