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MCP MicroPitting and Performance Issues

MCP MicroPitting and Performance Issues. Latest 40µm pore 8” MCPs had some patchy discoloration Cleaning using standard techniques at SSL made no difference to the stains There were some features that can be identified as incomplete surface polish

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MCP MicroPitting and Performance Issues

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  1. MCP MicroPittingand Performance Issues • Latest 40µm pore 8” MCPs had some patchy discoloration • Cleaning using standard techniques at SSL made no difference to the stains • There were some features that can be identified as incomplete surface polish • Initial SEM/EDAX observations showed no composition variations, but did show micropitting of the glass surface and bulk. • Does the micropitting occur often? And does it contribute to the MCP performance issues we are seeing. • The performance issues we see, that have not already been explained, primarily relate to variations in background rate from MCP to MCP. • Further study of MCPs was done by Anil and Jeff using SEM • We are trying to correlate this with the INCOM batches and our MCP performance observations.

  2. 40µm Test Samples from 8” Substrate (6/11)

  3. MCP MicroPittingObservations (ANL) • SEM on a glass capillary, a multi draw and a cut substrate show no micropitting • MCP from scrap pile shows no micropitting • 40μm MCP #11874-249 Incom job # 524434 shows no micropitting • 20μm MCP #12317-114 Incom job # 523766 shows some micropitting • 20μm MCP B10320, PO# 1A-31445 IPN 300-2734-D shows no micropitting • 20μm MCP #11863-076 Incom job # 518627 shows no micropitting • How does this relate to our test data? • We are trying to correlate this with the INCOM batches and our MCP performance observations. • We have limited serial # traceability, stained 8” MCPs are 11874-215/216/218/219, like 11874-249? No pitting? • MCP 160 is 12317-113, so maybe like 12317-114 ---- pitting? • MCPs 161-168 are 11863-XXX, so like 11863-076 ------ no pitting?

  4. ALD 20µm Microchannel Plates #161-168 20 µm pores (8° bias). New substrate batch. All from INCOM 11863, job # 518627. All show comparable visual features – so same material batch. Visible light transmission for a 20 µm pore #168 ALD MCP . Surface photo for a 20 µm pore #168 ALD MCP with NiCr electrode .

  5. ALD 20µm Microchannel Plate #160, 12317-113, Has different construction 700v MCP Surface photo for a 20 µm pore #160 ALD MCP with NiCr electrode .

  6. ALD 33mm Microchannel Plates Earlier MCPs have different visual featuresApart from triple point voids and debris - which cause hotspots, there are no clear differences in background rate compared with the newest batch of MCPs other than #164.

  7. Imaging Performance of ALD MCPs, 33mm Early 2010 July 2011 20µm borosilicate MCP substrates, 60:1 L/d, 8 degree pore bias. ~1000v applied to each MCP. Single MCP tests in DC amplification mode show imaging and gain very similar to conventional MCPs. MCP pairs operated in photon counting mode also show imaging and gain very similar to conventional MCPs. Sample performance hasimproved dramatically overthe last 12 months due to process improvements. 1 MCP, Phosphor readout UV 184nm illumination 2 MCPs, Photon counting

  8. Arradiance ALD/Incom 20µm MCP Pair TestS000480 (#44) + S000476 (#40) Dark image, 2000 sec, ~2.8 event cm-2 sec-1, one hotspot, one hot patch. Gain-voltage for a 20µm, 60:1, 65% OAR Incom/Arradiance ALD MCP pair (44+40)

  9. Arradiance ALD/Incom 20µm MCP Pair Test S000376 (#27)+ S000372 (#23) Gain - pulse height histograms. Poor PHD due to poor gain in themultifiber edges. Needs slightly higher voltage than the 40µm 40:1 MCPs. Dark image, 300 sec, ~18 event cm-2 sec-1, mostly due to low gain hotspots, ~1 event cm-2 uniform background Gain-voltage for a 20µm, 60:1, 65% OAR Incom/ALD MCP pair

  10. Arradiance ALD/Incom 40µm MCP Pair Test Background image, ~1 event cm-2 sec-1, plus couple of hotspots UV gain/PHD for pair #32/31

  11. 33mm ALD-MCP #164 Background Rate MCP back to back pair (164-163), 20µm pores, 8° bias, 60:1 L/d, achieves <0.1 events cm-2 sec-1. Pulse amplitude distributions for UV145nm, and for background events, There may be excess background dueto detection of ion pump events. 1000 sec background, 496 counts, at 2.5 x 106 gain, 2600v total, with 400v on anode. Background rate is 0.095 events cm-2 sec-1.

  12. MCP Background Observations • Independent of Arradiance or ANL ALD processes most substrates have high background • Older 40μm MCPs, typically 2 to 5 events cm-2 sec-1 • Older 20μm MCPs, typically 2 to 5 events cm-2 sec-1 • MCPs 161-168 (11863-XXX) no pitting? Tested #168 #167 and #164 168, 167 both have 2 – 4 events cm-2 sec-1, but #164 has 0.095 events cm-2 sec-1. • It is not clear that pitting has anything to do with the majority of MCPs high background behavior • Need to test more of the current MCP batch to confirm • Cant yet find any spreadsheet datum that distinguishes MCP# 164, • we need to find out why it is so much better.

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