1. E.Guschin (INR,Moscow) 9 December 2008LED system meeting CERN Plans: PS/SPD LED monitoring system tuning Online histograms. Presenter for group of 16(64) channels. The tuning procedure. The LEDTSB delay scan for SPD. Various HV sets for SPD tuning. Planning. Time schedule for tuning.

2. E.Guschin (INR,Moscow) 9 December 2008LED system meeting CERN DAQ + monitoring is required For effective tuning procedure the fast DAQ with (on-line) signal monitoring is required. From our experience the best possibility is to have on-line presenter of group of 16 histograms corresponding to LED driver tuned. In case of PS: It seems easier, just 16 2-D histograms of amplitude vs time slot. LEDTSB delay scan is optional. In case of SPD: LEDTSB scan is essential.

3. E.Guschin (INR,Moscow) 9 December 2008LED system meeting CERN Tuning procedure PS: Set HV value is equal to working one. V_LED is the same for inner and outer parts. For middle part is different (lower) because of different type of LED. Tuning of LED driver (group of 16 LED) can be done independently. At the first step the hottest channels are to be lowered (much bellow saturation). The second step is fine tuning of amplitude of each LED channel.

4. E.Guschin (INR,Moscow) 9 December 2008LED system meeting CERN Tuning procedure SPD: In case we have fast (on-line) presenter and fast (few seconds per scan) LEDTSB scan we can try to follow the same procedure as for PS. Very likely LEDTSB is rather slower, then the tuning method could be modified. Set the threshold to working value. At first step set the HV value equal to working one, then the very hot channels (pulse longer than 25 nsec) are to be lowered. Then all channels are tuned to be visible above the threshold for one 25 nsec cycle. The second step is to set HV lower by ~150V (gain is ~5-10 times), then the channels still visible are to be lowered. ….. Go to step 1 (in practice up to 5 iterations). The settings should be the same as for PS: V_LED is the same for inner and outer parts. For middle part is different (lower) because of different type of LED. Tuning of LED driver (group of 16 LED) can be done independently.

5. E.Guschin (INR,Moscow) 9 December 2008LED system meeting CERN Planning (1) 1.Prepare program presenter of online histograms. It should be ready and tested before January,26. Help of qualified people (Anatoly, Olivier …) is needed. 2.The pure tuning rate in case of PS is ~ 1 hour/PMT. If everything goes fine.. 3.For SPD it can be slower, because of iterations. The trading will be between time and tuning precision.

6. E.Guschin (INR,Moscow) 9 December 2008LED system meeting CERN Planning(2)+Comments The tuning efficiency and speed is very dependent on DAQ feedback: the online presenter of 16 LED signals is necessary. For SPD tuning fast LEDTSB delay scan or threshold scan can save time very much. Before start of tuning on Jan,26 all the procedure need to be tested on detector. We need few short accesses to do this. In December all preliminary studies, like V_LED settings, HV settings for tuning, and V_LED mapping for middle part have to be fixed.