1. Update on 1 st Article Test of SiPMs Yi Qiang and Carl Zorn April 7, 2011

2. Overview 66 samples till April 6, 2011 ! Almost there … Suspecious samples discovered: –1 with very hot tile: #24 2 MHz@tile#1 –1 with abnormal Cross-Talk and PDE: #66 PDE < 10%

3. Ideas for Production Test DAQ Same LabVIEW controlled PC DAQ system: –V792 VME QDC: 32 Channels, 12 bits. ROOT analysis scripts: –1.5 Minutes to fit a single spectrum. Assume 16 SiPM samples per batch, two batches a day: –256 channels, 8 QDC modules needed. –If three levels of light input recorded: 40 hours of analysis: use batch farm. Question: Can we group signals from several channels while still getting uniformity of gain? –Maybe yes if we can identify individual photon peaks.

4. Some Studies by Summing Spectra Sample #58: signals from individual tiles Dark Spectrum: average NPE = 1.12

5. Some Studies by Summing Spectra Sample #58: Sum of all 16 tiles Dark Spectrum: average NPE = 1.12 Sum of 16 Tiles

6. Some Studies by Summing Spectra Sample #58: Sum of all 8 tiles Dark Spectrum: average NPE = 1.12 Sum of 8 Tiles

7. Some Studies by Summing Spectra Sample #58: Sum of all 4 tiles Dark Spectrum: average NPE = 1.12 Sum of 4 Tiles

8. Some Studies by Summing Spectra Sample #58: Sum of all 4 tiles 2% Filter: average NPE = 1.74 Sum of 4 Tiles

9. Some Studies by Summing Spectra Sample #58: Sum of all 4 tiles 6% Filter: average NPE = 2.90 Sum of 4 Tiles

10. Simulation of Gain Fluctuation To isolate the effect due to gain fluctuation Parameters from the measured samples –Gain: 60 channels –Width of Pedestal: 7 channels –Width of Single Photon Peak: 6 channels Variations of gains: –Single: vary the gain of one tile from 50% to 150% –Pair: vary the gains of a pair of tiles oppositely from 70% to 130% –All: vary the gains of all 4 tiles from 80% to 120% NPE: 0.5 – 3.0 pixels per tile

11. Sample Plots NPE = 0.5 NPE = 2.0

12. Impact on the Fitted Parameters NPE = 0.5 No significant change of  2 for small gain variation

13. Impact on the Fitted Parameters Same behavior holds for other NPE inputs NPE = 1.0NPE = 2.0

14. Our Sensitivity The standard deviation of the single photon signal from our measured samples ~ 8% Assume gain of 60 channel, intrinsic signal width 6, a 5% variation of 4 tiles brings: Very small margin to actually tell the deviation of gains.