1. HEP2001, Budapest, July 2001 R M Brown - RAL 1

2. HEP2001, Budapest, July 2001 R M Brown - RAL 2

3. HEP2001, Budapest, July 2001 R M Brown - RAL 3

4. HEP2001, Budapest, July 2001 R M Brown - RAL 4

5. HEP2001, Budapest, July 2001 R M Brown - RAL 5

6. HEP2001, Budapest, July 2001 R M Brown - RAL 6

7. HEP2001, Budapest, July 2001 R M Brown - RAL 7

8. HEP2001, Budapest, July 2001 R M Brown - RAL 8

9. HEP2001, Budapest, July 2001 R M Brown - RAL 9

10. HEP2001, Budapest, July 2001 R M Brown - RAL 10

11. Characterisation of VPTs
Detail of RAL test Cell
4.0T Solenoid at Brunel
1.8T Dipole Magnet at RAL
All VPTs are measured at 0  B  1.8T and -30o    30o at RAL
Sample VPTs are measured at B =4.0T and  = 15o at Brunel
Perspex diffuser plate with LEDs at corners. (Red circle indicates effective VPT diameter)
500 ‘Preproduction’ VPTs delivered by RIE (St Petersburg)
HEP2001, Budapest, July R M Brown - RAL

12. Response vs Angle at B=1.8T
Arrows indicate angular regions of end caps
HEP2001, Budapest, July R M Brown - RAL

13. Response vs B-Field Strength
VPT Axis at 15o w.r.t. Magnetic Field
HEP2001, Budapest, July R M Brown - RAL

14. Distributions of Gain (B=0) and Quantum Efficiency
(%)
Taken from the ‘passport’ supplied with each tube by the manufacturer
Gain and quantum efficiency are uncorrelated
HEP2001, Budapest, July R M Brown - RAL

15. Anode Response Distribution
B=1.8T
=15o
Spread in anode response  Some sorting of VPTs necessary
HEP2001, Budapest, July R M Brown - RAL

16. Test beam:Energy Resolution
No preshower detector
With preshower detector
HEP2001, Budapest, July R M Brown - RAL

17. Faceplate optical transmission Post-irradiation
Loss in optical transmission of 2 faceplate samples
after 25 kGy 60Co irradiation (380Gy/hour)
(approx 10 yrs LHC at  = 2.6)
HEP2001, Budapest, July R M Brown - RAL

18. VPT Behaviour Under Irradiation
60Co Irradiation (58 Gy/hr)
Photocurrent produced by Cerenkov light in VPT window.
(Vertical lines correspond to pauses in irradiation)
VA=1000 VD= 800
HEP2001, Budapest, July R M Brown - RAL

19. VPT Summary
A new generation of fine-mesh VPTs has been developed to satisfy the high magnetic field/radiation hardness requirements of CMS
An automated characterisation facility has been commissioned to handle devices
The performance of 500 pre-production VPTs from RIE meets CMS requirements
HEP2001, Budapest, July R M Brown - RAL