TTF - ECAL Plenary in CMS week ECAL Stability Contacts: Marc Dejardin, Julie Malcles (laser) nfId= nfId= /1/2016

Laser Stability: context 2/1/20162  APD/PN corrected for (see CMS DN-2008/001 for more detail): PN linearity Laser pulse variation  Selection criteria: 100 < number of events < < laser FWHM < ADC < amplitude < 4000 ADC 3 < signal maximum sample < 8 max amplitude r.m.s.: 10% max amplitude m3: 40% max amplitude/PN r.m.s.: 3% max amplitude/PN m3: 40% 0.8(0.7) < laser pulse correction < 0.9(0.95) for barrel(endcap)  Two periods have been considered on 2010 data (only the second period shown in this talk, results are comparable): ! , 500 h, 500 sequences, red laser and blue laser ! , 350 h, 800 sequences, blue laser only

Blue laser APD/PN stability: barrel 2/1/20163 Stability of the ECAL laser monitoring system. RMS deviation of the quantity APD/PN for the blue laser for EB channels with nominal data quality cuts applied. The most stable of the two reference PNs was used in each light monitoring region.

Blue laser VPT/PN stability: endcap 2/1/20164 Stability of the ECAL laser monitoring system. RMS deviation of the quantity VPT/PN for the blue laser for EE channels with nominal data quality cuts applied. The most stable of the two reference PNs was used in each light monitoring region. Right half of EE+ has only 1 active PN (instead of 2) for the considered period, this is why there are less stable regions (also seen in PN stability)

Red laser APD/PN stability: barrel (only) 2/1/20165 Stability of the ECAL laser monitoring system. RMS deviation of the quantity APD/PN for the red laser for EB channels with nominal data quality cuts applied. The most stable of the two reference PNs was used in each light monitoring region.

Test pulse stability: APD 2/1/20166 Stability of the APD electronics response to a fixed charge injection. RMS deviation of the response for EB channels with nominal data quality cuts applied.

Test pulse stability: PN 2/1/20167 Barrel approval pendind: need to understand PN regions which do not seem to correlate to the APD/PN stability map Stability of the PN electronics response to a calibrated charge injection. RMS deviation of the response with nominal data quality cuts applied.

History plot for one typical channel 2/1/20168 History plot of the quantity APD/PN for the blue laser and one typical channel.

Laser pulse correction for one typical channel 2/1/20169 Due to different shaping time of the APD and PN, the APD/PN ratio depends on the laser signal variations. With the information of the laser pulse shape and the SPR signal response we can calculate a correction factor exactly correlated with APD/PN ratio. The colour of the points gives their time ordering. Correlation between the measured variation of the quantity APD/PN with the expected correction factor computed using the electronics Single Pulse Response and the laser pulse shape information. The colour of the points indicate their time ordering.