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 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)

MCP MicroPitting Observations (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 # Incom job # shows no micropitting 20μm MCP # Incom job # shows some micropitting 20μm MCP B10320, PO# 1A IPN D shows no micropitting 20μm MCP # Incom job # 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 /216/218/219, like ? No pitting? MCP 160 is , so maybe like pitting? MCPs are XXX, so like no pitting?

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

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

Earlier MCPs have different visual features Apart 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 # ALD 33mm Microchannel Plates

Imaging Performance of ALD MCPs, 33mm 1 MCP, Phosphor readout 2 MCPs, Photon counting Early 2010July µm 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 has improved dramatically over the last 12 months due to process improvements. UV 184nm illumination

Gain-voltage for a 20µm, 60:1, 65% OAR Incom/Arradiance ALD MCP pair (44+40) Arradiance ALD/Incom 20µm MCP Pair Test S (#44) + S (#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/ALD MCP pair Arradiance ALD/Incom 20µm MCP Pair Test Dark image, 300 sec, ~18 event cm -2 sec -1, mostly due to low gain hotspots, ~1 event cm -2 uniform background Gain - pulse height histograms. Poor PHD due to poor gain in the multifiber edges. Needs slightly higher voltage than the 40µm 40:1 MCPs. S (#27)+ S (#23)

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

33mm ALD-MCP #164 Background Rate Pulse amplitude distributions for UV 145nm, and for background events, There may be excess background due to detection of ion pump events sec background, 496 counts, at 2.5 x 10 6 gain, 2600v total, with 400v on anode. Background rate is events cm -2 sec -1. MCP back to back pair ( ), 20µm pores, 8° bias, 60:1 L/d, achieves <0.1 events cm -2 sec -1.

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 (11863-XXX) no pitting? Tested #168 #167 and # , 167 both have 2 – 4 events cm -2 sec -1, but #164 has 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.