1. Aging tests of MCP PMTs and MAPMTs
Peter Križan
University of Ljubljana and J. Stefan Institute
SuperB meeting Perugia, June 17, 2009

2. Contents Aging tests of Photonis/Burle MCP PMT
Aging tests of Hamamatsu MAPMTs

3. Aging of MCP-PMTs
BURLE microchannel plate (MCP) PMT: multi-anode PMT with two MCP stages
degradation of the photocathode  lower QE
degradation of the MCP pore surface (secondary emission) lower amplification
Potential problem: residual molecules in the tube vacuum are ionized by secondary electrons  travel to the photocathode

4. MCP PMT aging test Idea: Uniformly illuminate MCP by LED
Monitor illumination by a reference PMT
Rate ~1 Mhz per channel
Record counting rate for 14 channels (out of 64) and total anode current
Regularly check:
the single photon pulse height distribution (by using pulsed laser) every hour
 quantum efficiency (by using a monochromator, normalize relative to a calibated PMT)

5. MCP PMT aging test status
Last week: measure QE across the surface
Illumination started last week with initial 50k per channel (~0.2 microA per tube)
Illumination increased this Monday (June 15) such that rate ~1 Mhz per channel (~3 microA per tube)
Total charge now: 20mC per cm2, no change in peformance
Plan: continue for the next three weeks, accumulate 0.2C per cm2

6. MCP PMT ageing – data from Burle/Photonis
Several discussions with Emile Schyns, Group Product Manager, Micro Channel Plates
Standard tube performance (without no Al protection layer):  50% drop of efficiency after 10-15C/tube = mC/cm2
Photonis: expect to improve the ageing by a factor >5 (use a different scrubbbing technique, deep UV  electrons)
Testing of new tube samples are underway right now, very encouraging, by mid July expect 0.5C/cm2

7. Multianode PMT aging test
Idea:
Use tubes that were used in the HERA-B experiment (Hamamatsu R channel PMTs with bialkali photocathode)
Compare the performance of tubes that were in a highly illuminated area (few MHz per channel) with tubes at the periphery (5-10x less).
Compare to the original QA measurements before the installation

8. Multianode PMT aging test- status
Measured the tubes from the periphery, in agreement with the initial response (before installation)
MA PMTs from the highly exposed region are waiting for the other aging test (MC PMT) to finish (they share the same set-up)  probably late July or even later