BURLE update Peter Križan Friday meeting, Mar 24, 2006

Burle MCP-PMT BURLE MCP-PMT: ● multi-anode PMT with 2 MCPs ● 25  m pores ● bialkali photocathode ● gain ~ 0.6 x 10 6 ● collection efficiency ~ 60% ● box dimensions ~ 71mm square ● 64(8x8) anode pads ● pitch ~ 6.45mm, gap ~ 0.5mm ● active area fraction ~ 52%

Resolution and number of photons (clusters) Burle MCP PMT beam test ●  ~13 mrad (per cluster) ● number of clusters per track N ~ 4.5 ●  ~ 6 mrad (per track) -> ~ 4   /K separation at 4 GeV/c Operation in high magnetic field: ● the present tube with 25  m pores only works up to 0.8T, for 1.5T need ~10  m ● 10  m version with 4 channels available since June, tests done (J. Va’vra) Number of photons per ring: too small. Possible improvements: ● bare tubes (52%->63%) ● increase active area fraction (bare tube 63%->85%) ● increase the photo-electron collection efficiency (from 60% at present up to 70%) -> Extrapolation from the present data 4.5 ->8.5 clusters per ring  : 6 mrad -> 4.5 mrad (per track) -> >5  /K separation at 4 GeV/c Aging of MCP-PMTs ? Open questions

10micron pore tube The four pad 10 micron of the MCP PMT tube has finally arrived in Ljubljana (this Monday). It is still not clear to us what was the real reason for the trouble with shipping last summer...

Currently working on a 4-anode version of the Planacon with about 85% open-area-ratio (now 63%). It is currently only a custom product for one of the customers. They plan to finalize a general design in the next 2 months for the 4 and 64 anode versions. Working on a method to increase the QE of the photocathode from 23% (at ~400nm) to ~ 28%, hope to have the process worked out in the next few months. Plan to increase the angle of the MCP channels quite soon, which will increase the collection a little. The 10  m MCP option is not available as a standard option right now, but they expect it to be by the end of the summer. We will get the 85% open-area tube as soon as it is available. R+D report from the company

Aging: they do not use the protective Al foil. Typical aging tests show a lifetime of about C of extracted charge per tube ( C/cm2) before the output drops by 50%. Their highest priority item right now is to increase this value. They plan to implement a proven method (?) to significantly increase the lifetime in the next quarter. They will let us know the new lifetime figure when they have the initial results. N.B. Their results looks much better than for the HPK MCp tubes without the protective Al layer  R+D report from the company - 2