1. B W Kennedy, RAL PPD VPT testing status Visual inspection of VPTs The RAL 1.8T test rig VPT testing at RAL High-field testing at Brunel Bruce Kennedy, RAL 7 March 2002

2. B W Kennedy, RAL PPD Visual inspection of VPTs Generally look well-finished 3 main concerns >Poor crimping of pins to leads >Off-centre anode grids >Uneven photocathode coverage

3. B W Kennedy, RAL PPD Faults seen in visual inspection Poor crimping >3% have obvious faults (mostly loose strands of wire; pins came off 3 VPTs during inspection or testing) Off-centre anode grids >4% have grids visibly off-centre Uneven photocathode coverage >7% have at least 10% of faceplate uncoated

4. B W Kennedy, RAL PPD The RAL 1.8T test rig

5. B W Kennedy, RAL PPD VPT testing in 1.8T rig Tested 119 VPTs so far >Response v field from 0T to 1.8T >Response v angle at 1.8T, -30  to 30  >3 drew excess current, tests incomplete Cross-calibrated for comparison with 2001 pre-production batch

6. B W Kennedy, RAL PPD Typical angle scan

7. B W Kennedy, RAL PPD Typical field scan Instability at low B field is typical

8. B W Kennedy, RAL PPD VPT response

9. B W Kennedy, RAL PPD High-field tests 20 VPTs tested at 4T at Brunel University >All performed satisfactorily >Samples of all batches will be tested at 4T

10. B W Kennedy, RAL PPD Conclusion A few minor problems found in visual inspection >Some VPTs already returned to RIE Test results so far are similar to 2001 pre-production batch Testing is continuing >More detailed report when whole batch has been tested