Study of small ADC spikes in BSMD 

Input:

•  all available events from fills 10399, 10402, 10403, 10404, 10407, 10412, 10415 added together
• pedestal residua for  NZS data captured on-line by Willie's daq reader  (Blue filled histo)
•  ZS data from L2W triggered events (Magenta line-only)

The following plots support those observation:

1. spikes are symmetric on both sides of pedestals peak, separated by 2^N ADC counts, narrower than pedestal peak, (Fig1)
2. spikes are correlated in even ID (or odd) strips the same plane, correlation is local, Fig 2 
3. spikes are correlated between P-plane & E-plane strips, Fig 3
4. energy deposit in BSMD increases probability of spikes, see peak/valley for blue vs. magenta in fig 1b.
5. bands are visible at larger ADC, as shown by Oleg, not sure what data and how many events, fig 4 
6. perhaps fig 1c shows yet another pathology, because it does not obey odd/even rule in fig 1a & 1b.

Fig 1a. Example of spikes delADC=16, in the vicinity of strip 1525-P, all strips from module 11 are shown in attachment A.

Fig 1b. Example of spikes delADC=32, in the vicinity of strip 1977-P, all strips from module 14 are shown in attachment B, module 22 looks similar.

Fig 1c. Example of spikes delADC=128, in the vicinity of strip 4562-P, all strips from module 31 are shown in attachment C, modules 51,52,57  look similar

Fig 2. Phi-Phi plane correlation of P-strip 1979 with (odd)  P-strips: 1977..1994. Attachment D contains correlation of P-strips [1977-80] with  24  strips in proximity. 

Fig 3. Phi-Eta plane correlation of P-strip 1979 with (odd)  E-strips: 1977..1994. Attachment E contains correlation of P-strips [1977-80] with  24  strips in proximity. 

Fig 4.Oleg observed this stripes in raw BSMD ADC spectrum, not sure what data.