1. UIC – Physics Department Fast Timer Project Bob Dysert, Alan Bross - Fermilab November 18, 2005

2. f Fermilab MICE Simple in theory

3. f Fermilab MICE Muon cooling is needed to fit a beam into accelerator Need fast timing measurement to tag muons in RF bucket for acceleration Initial design: RF=805MHz required 10ps resolution Revised design: RF=201MHz requires only 50ps resolution

4. f Fermilab Fast Timer Operation f Fermilab Particles pass through radiator (MgF 2 ) Cerenkov light converted to electrons in photocathode (CsI) Electrons hit high gain MCPs Output of MCPs is collected on 50Ω anode Anode output is read out on fast oscilloscope or superconducting TDC TDC operation requires two detectors: one start, one stop

5. f Fermilab Fast Timer Readout Digital Tektronics oscilloscope 10GS/s, 3GHz, 4-Ch Superconducting TDC with 3-5ps per bin (never received)

6. f Fermilab Hardware Setup f MCP Stack MgF 2 Radiator CsI Photocathode UHV Enclosure 50Ω Anode SMA Feedthrough Particles

7. f Fermilab System Potentials Flange=GND Anode= -100V MCP Out= -1kV MCP In= -3.1kV PC = -4.1kV

8. f Fermilab MCP Performance G = 2E8 w/ Z-stack

9. f Fermilab Mechanical Setup f HV Feedthrough Baseplate Threaded Rod Ceramic Spacers HV Wings MCPs MgF 2 WindowSpring Loaded Top Plate Anode

10. f Fermilab Mechanical Setup - Baseplate

11. f Fermilab Mechanical Setup - Baseplate

12. f Fermilab Mechanical Setup - Anode

13. f Fermilab Mechanical Setup - Anode

14. f Fermilab Mechanical Setup – MCPs

15. f Fermilab Mechanical Setup – Photocathode

16. f Fermilab Mechanical Setup – Complete

17. f Fermilab Vacuum System Roughing Pump Leybold TMP50 Gate Valve Ceramic Isolation Vacuum Can Heat Tape Cold Cathode Gauge Quartz Window

18. f Fermilab Vacuum System Cold Cathode Readout Xenon Pulser APD for Trigger Scintillator Paddles PMTs Heating Tapes Detector HV Cables Bleed-up Valve

19. f Fermilab Problems Poor vacuum –Source: Quartz window leak –Source: MCPs outgassing –Source: Gas trapped? –Souce: Dirty components –Solutions: Plug leak, Bake out, Score screws, and clean.

20. f Fermilab Problems Arcing w/o MCPs in stack –Source: Wings arc to grounded threaded rod –Solution: PC potential = rod potential Arcing w/o MCPs in stack –Source: Threaded rod arcing to grounded vacuum flange –Solution: Solder threaded rod/nuts to prevent movement and eliminate sharp edges

21. f Fermilab Problems – Cont’d Breakdown w/ MCPs –Source: Resistance mismatch between MCPs in stack –Solution: Match MCPs No apparent signal –Source: Photocathode had degraded –Solution: Transport and assemble only in N 2 environment

22. f Fermilab Signals

23. Signals

24. Signals

25. Signals 1 st PE 2 nd PE Data from Xe UV Pulser (193 nm) G ≈ 2E7 1 st and 2 nd PE clearly visible

26. f Fermilab Questions? f bross@fnal.gov rdysert@fnal.gov

27. f Fermilab TDC Channel 2ps resolution with analog prescale

28. f Fermilab Thin MgF 2 radiator (Head-on as viewed by beam) –CsI Photocathode Fast Timing - Cerenkov Detector

29. f Fermilab Fast Timing Cerenkov Detector Wavelength region 120 - 200 nm –Cos  c = 1/  n –For 5 mm radiator  t = 3 ps ( not weighted for dn  /d ) –For CsI PC expect  70 pe Anderson, Kwan, Peskov - Solid CsI PC Lu, McDonald – Semi-Transparent PC