33mm MCP Testing at UC Berkeley Jason McPhate Experimental Astrophysics Group Space Sciences Laboratory University of California, Berkeley 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

MCP Testing Methodologies Phosphor screen imaging Single MCP imaging (uniformity of gain × QE, multi-fiber modulation) No simple gain measurement  Cannot separate gain and QE effects Photon counting imaging Requires more stack gain than single MCP Separates gain and QE effects Measure pulse height distribution (PHD) PHD characterization verses stacking scenarios 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Phosphor Screen Image Testing Interior Views Exposed Phosphor Screen Input Solid Edged MCP Loaded Output Glass Fiber Exterior View Phosphor screen readouts Imaging of single MCPs Characterize gain×QE variations Characterization of multi-fiber modulation Not photon counting  cannot separate gain and QE 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Example of Phosphor Screen Imaging (More Later) Older 6µm pore MCP – multi-fiber modulation evident Newer 6µm pore MCP – multi-fiber pattern completely gone. 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Flexible 33mm MCP Photon Counting Demountable Detector Design Top Clamp Plate Compression Spacers Compression Spring Φ33mm MCPs RT/Duroid Spacer PEEK Body Base Plate Pressure Pad Some piece parts have arrived (above) for 6 assemblies. We brought 2 assemblies to ANL. Awaiting other parts fabrication: RT/Duroid MCP spacers Pressure pads and springs Compression spacers 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Example of a Similar Demountable When complete the 33mm MCP demountable will be similar to this. Mounted on CF flange above a cross- delay anode readout. CF flange has feedthroughs for HV and anode signals. PEEK sandwiches base plate for rear field stand-off and hold down. Two more HV’s for MCP gap voltages (four total). This style detector is very useful for rapid MCP restacking and optimizing. 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Example of Photon Counting Imaging Photonis MCP “Z” stack (8µm top, 10µm mid/bot). Cross delay line readout. Counts image. Slight multi-fiber modulation visible, “dead” spots clear Gain map image (average gain per pixel). Multi-fiber modulation more evident 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Some Standard MCP Metrics MCP Stack Gain vs. Voltage Photon vs. Background PHDs Photon PHD vs. Voltage Stack PHD Width vs. Gain 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

Double Barrel 33mm MCP Test Station We are in the final stage of refurbishing a dedicated dual chamber vacuum station for 33mm MCP testing Separate chambers for phosphor screen detector and photon counting detector. Each chamber has independent roughing and hivac valves  uninterrupted testing of one detector while the other is swapped. 8” CF flanges for detector mounting  lots of room for feedthroughs. Will be using Viton gasket here for quick change out. Turbo pump system with a dry scroll pump for a clean reliable system. UV transmissive windows to illuminate detectors 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

ALD Coatings on 33mm Glass MCPs Two standard glass Photonis MCPs (R ~ 90MΩ) sent for Al2O3 ALD coating over approximately half the active area. 6nm and 12nm coatings. Resistances unchanged by coatings. Jig for ALD coatings on 33mm glass MCPs. Stainless plates and PTFE gaskets with matching half moon cutouts. ML201-B-1 – 6nm ALD on glass MCP, post-ALD, post-cleaning (similar both sides) ML201-B-2 – 12nm ALD on glass MCP, post-ALD, post-cleaning (similar both sides) 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

6nm Al2O3 ALD on Standard MCP Phosphor Screen Imaging Definite enhancement of brightness in ALD area. No degradation of image quality (except in boundary region). ML201-B-1: 86MΩ, UV flood illumination, 1050V MCP, 2900V screen. ML201-B-1: 86MΩ, UV flood illumination, 1150V MCP, 2800V screen. 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting

12nm Al2O3 ALD on Standard MCP Phosphor Screen Imaging Dramatic decrease of brightness in ALD area. Theory for 6nm/12nm Difference Brightness is product of QE × gain. Matt Wetstein’s testing indicates Al2O3 ALD increases gain (better SEE). NiCr electrode acts a photocathode on bare MCP. ALD covers the NiCr and has poorer UV response. All is explained if the 6nm ALD permits photoelectrons from the NiCr through, but the 12nm coating does not. In light of this, where the electrode layer is placed (above/below the SEE layer) has ramifications on tube processing. ML201-B-2: ~90MΩ, UV flood illumination, 1150V MCP, 2700V screen. 15 Oct 2009 J. McPhate – PSEC Collaboration Meeting