1. TB analysis update Gwen & Alessandra VELO Group Meeting, Monday October 6 th first fits of the landaus header correction algorithms irradiated RD50: status by Carl

2. 2 Tell1 8 n-in-p Tell1 5 n-in-n Beam high irr low irr high irr Position of irradiation spots lars config run over 20000 events Voltages: 500V on each sensor 300V on irradiated and 500V on non-irr Bottom Top

3. 3 Cluster Parameters Search Parameters “Loose” –Seed : 6 ADC –Low: 3 ADC Event Selection Only events with one single- strip cluster on each sensor Cluster Matching –Clusters closer than 100 um (same as Karol)

4. 4 Beam @ top of module Tell1 5 / 500 V / Fit Landau * Gauss [10;60]Tell1 8 / 500 V / Fit Landau * Gauss [10;40] Tell1 5 / 300 V / Fit Landau * Gauss [10;60]Tell1 8 / 300 V / Fit Landau [11;40] Top position : Tell1 8 to irradiated sensor

5. 5 Beam @ bottom of module Tell1 5 / 500 V / Fit Landau * Gauss [10;50]Tell1 8 / 500 V / Fit Landau * Gauss [16;60] Tell1 5 / 300 V / Fit Landau [11;50]Tell1 8 / 300 V / Fit Landau * Gauss [16;80] Bottom position : Tell1 5 to irradiated sensor

6. 6 Comments on fits First fits, functions will be improved (e.g. add large Gaussian) but ideas are welcomed ! Landau * Gauss prepared by VELO people, we simply used it. When fit was really bad, tried a simple Landau. Clear correlation between quality of fit and irradiated sensor at lower voltage.

7. 7 Header Correction, JC’s version Idea: the first data channel (Ch0) will be modified by a fixed quantity depending on the states of the last two header bits (H2 and H3) Thought that Karol made the study to calculate the parameters δ 1 and δ 2 … but not exactly H3Ch0 0- δ 1 1+ δ 1 First Order H2H3Ch0 00- δ 1 +/- δ 2 11+ δ 1 -/+ δ 2 Second Order

8. 8 Header Correction, Liverpool’s version see Themis’ ppt @ http://indico.cern.ch/conferenceDisplay.py?confId=37795 http://indico.cern.ch/conferenceDisplay.py?confId=37795 Idea: the first two data bits (ch0 & ch1) will be affected by the last two header bits (h2 & h3) –For each event, calculate the 4 couples {h2, h3} for the 4 links –For all events and for each combination {h2, h3}, make the average of each data channel. This is what they a new pedestal. –Subtract this pedestal from the data (for the first two bits)