04 BPRS sees beam background?

The pair of plots below demonstrates BPRS pedestal residua are very clean once peds for 128 caps are used and this 5% capID corruption is detected and fixed event by event.

 INPUT: run 9067013, st_phys events, stale BPRS data removed, all 38K events .

Fig 0. capID correction was enabled for the bottom plot. Soft ID is on the X-axis; rawAdc-ped(softID, capID) on the Y-axis.


Now you can believe me the BPRS pedestals are reasonable for this run. Look at the width of pedestal vs. softID, shown in Fig 1 below.

There are 2 regions with wider peds, marked by magenta(?) and red circle.

The individual spectra look fine (fig 2b, 2bb).

But the correlation of pedestal width with softID (fig 1a,1b) and phi-location of respective modules (fig 3a, 3b) suggest it could be due to the beam background at

~7 o'clock on the West and at 6-9 o'clock on the East.