US CMS HCAL Meeting Boston University

1. US CMS HCAL MeetingBoston University Vasken Hagopian Florida State University US CMS HCAL at BU

2. HPD QE & K27 Spectrum US CMS HCAL at BU

3. Test Beam results US CMS HCAL at BU

4. QE x K27 Spectrum US CMS HCAL at BU

5. Conclusions • The test beam measurements are not compatible with the QE of the HPD’s. • The HPD QE provided by DEP are not standard bi-alkali nor green extended bi-alkali. • We need to find out what DEP is actually measuring. US CMS HCAL at BU

6. HB/HE LED and Laser From Test Beam at CERN in 2002 • Nichia blue LED barely excites K27 fluor. • The LED light to HPD is mostly scattered blue light. • Easy to correct so LED light to HPD should be very similar to megatile. Use greenLED that is 2.5 times brighter. (See K. Johnson talk). • Green LED at 5 volt and 25 nsec should correspond to over 1 TeV. US CMS HCAL at BU

7. HB/HE LED and Laser • Basic calibration module design is good. • Laser distribution has been measured in the lab with splitters and the correct length of quartz fibers. Measurements with Pin Diodes and corrected for HPD. • QE of Pin Diode 80%, QE of HPD ~10% with a gain of 2000. US CMS HCAL at BU

8. Laser system • Laser to Calorimeter sector (e.g HB+) to Calibration box to HPD. • 337 nm UV. Pin1 = 25pC. Pin2 = 3pC, HPD = 30 pC. • 380 nm with dye laser. Pin1 = 50pC, Pin2 = 6pC, HPD = 60 pC. • UV laser to megatile 4 pC. • Dye Laser to megatile 0.3 pC. US CMS HCAL at BU

9. Progress • HB Calibration box on hold waiting for VECSEL connection determination. Most optical parts completed. • HE Calibration box, first prototype under construction (just completed). • HO Calibration box – box dimensions not yet specified. US CMS HCAL at BU