1. Photon Beam and Tagger working group status report Richard Jones Catholic University Glasgow University University of Connecticut University of Connecticut GlueX collaboration meeting, Newport News, Oct. 25-27, 2007

2. 2 Outline  Overview of progress in FY07  Diamond R&D  Tagger engineering design  Fixed counter array design  SiPM studies and microscope prototyping  Active collimator tests in Hall B  Goals for FY08  Manpower and budgets

3. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 3 Overview of progress in FY07  CLAS 20um thick diamond studied with using X-rays at CHESS (Cornell synchrotron source) data analyzed by Y. Guangliang large-scale warping hypothesis confirmed  Tagger 35% design completed by Protvino  Specification for 100% design under review  CAD drawings of tagging counters produced for Lehmann review, something like 35% design  Detailed measurements of SiPM response as function of V bias and temperature at UConn  SiPM readout electronics design underway at UConn  Successful test of active collimator during g8 run

4. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 4 Diamond R&D  6-day exploratory run at CHESS Nov. 1-6, 2006 Franz Klein Richard Jones Yang Guangliang Ken Finkelstein, CHESS staff

5. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 5 Diamond R&D CLAS target ladder Xray beam 4-circle goniometer beam shutter

6. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 6 Diamond R&D raw rocking curve image sequence extracted shape of diamond, analysis by Y. Guangliang X-ray images of 20m CLAS diamond taken at CHESS, November, 2006 peak/dip pair shallow depression

7. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 7 Diamond R&D  CLAS 20 micron diamond is badly warped Is this a general problem at 20 microns, or just one bad one? Did it happen during thinning between 50 microns and 20 or was this one warped earlier on? The curvature shows imprint of ink dots. Does the glue that ties it to the mounting wires contribute to this strain?  Further studies of thin diamonds are needed, but The CLAS diamond was shattered during a remounting attempt GlueX needs its own collection of diamonds for study several new stones obtained by Ken Livingston from Element 6 assessment of new stones planned at CHESS next week  Development at UConn (undergrad thesis) underway to enable surface topology measurements with laser interferometry – mounting tests without X-rays!

8. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 8 Tagger engineering design  35% design completed in May 2007 by IHEP  Some issues identified electron beam exit region alignment tolerances alignment plan and fixtures iron grade specification, relation to field uniformity support of hodoscope array on the “strongback” base stresses on vacuum chamber from internal motion

9. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 9 Fixed counter array design  detailed mechanical design (F. Klein) single support frame mounted on strongback remote controlled source moves on a rail along full length of support structure 9.0 – 11.4 GeV photon energy 3.0 – 9.0 GeV photon energy  no gaps  no overlaps  capable of tagging unpolarized beams at highest energy  gaps (samples spectrum)  mainly for monitoring crystal

10. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 10 SiPM studies and microscope prototyping  commercially available from Photonique (CPTA) and now Hamamatsu  intrinsic time resolution ~100 ps for 1 p.e. pulse

11. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 11 SiPM studies, cont. Measurements at UConn on Photonique 4mm 2 SiPM Gain and PDE vary with  V bias  temperature V bias referenced with respect to break- down voltage V bd  V bd varies ±0.5V between devices  individual control over V bias required, similar to case of PMT (but no HV).

12. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 12 SiPM studies, cont. Measurements at UConn on Photonique 4mm 2 SiPM measured using a fast LED pulser at 570 nm (yellow)

13. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 13 SiPM studies, cont. Measurements at UConn on Photonique 4mm 2 SiPM measured using a fast LED pulser at 570 nm (yellow)

14. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 14 SiPM studies, cont. Measurements at UConn on Photonique 4mm 2 SiPM measured with threshold set at 0.5 photoelectrons

15. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 15 Microscope readout + SiPM V b [0] E[0] SiPM... V b [4] cfd fadc[0] f1tdc[0] Energy Bins scint.clear Fibers: Bias voltages DetectorDAQ Rack + SiPM E[99] SiPM... V b [499]........... cfd fadc[119] f1tdc[119] 95 Echan @ 1 daqchan/Echan + 5 Echan @ 5 daqchan/Echan = 120 daqchan

16. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 16 Microscope readout dim box  digital electronics  external connections  moderately light tight dark box  scintillating fibers  PCB-mounted SiPMs  signal preamps and sum circuitry  V bias for each channel received from digital board interconnect plane PCB

17. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 17 Microscope assembly, cont. electrons microscope assembly, exploded

18. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 18 Active collimator tests in Hall B  Installed in alcove 4/2007  TAC motion controls permit sweep across the beam spot outer horizontal sectors inner horizontal sectors  2 sectors read out  either inner or outer sector pairs connected  record I[0], I[1] vs. x

19. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 19 Active collimator tests in Hall B  signal strength excellent, ~3 x MC estimate – low E processes  inner, outer peaks clearly seen, well matched  asymmetric artifact peaks also seen: readout cables, connectors? ? ?

20. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 20 Goals for FY08  Diamond R&D assess crystals on loan from Element 6, Mainz at CHESS order several slices cut and thinned for GlueX learn from BNL source group about chemical etching  Tagger engineering design send out 100% design package monitor design process at key stages  Microscope prototype complete electronics design construct prototype 5x5 fiber array for testing  Active collimator tests repeat with 4 channels read out measure bandwidth vs noise for feedback stabilization circuit

21. GlueX collaboration meeting, Newport News, Oct. 25-27, 2007 21 Manpower and budgets for FY08  University of Connecticut (student labor) one graduate student 2-3 undergraduates  Diamonds  Glasgow University (postdoc salary) Y. Guangliang possibility of technical help  IHEP Protvino (designers) engineering for tagger design  Yerphi Yerevan – (salary, travel) one physicist one tech for work on pair spectrometer $50,000 $80,000 $60,000 $10,000 $20,000 $220,000