MCP Electrodes and End Spoiling Jeffrey Elam, Qing Peng, Anil Mane, Thomas Prolier, Joe Libera...
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Transcript of MCP Electrodes and End Spoiling Jeffrey Elam, Qing Peng, Anil Mane, Thomas Prolier, Joe Libera...
MCP Electrodes and End Spoiling
Jeffrey Elam, Qing Peng, Anil Mane, Thomas Prolier, Joe LiberaArgonne National LaboratoryLarge Area Photodetector Collaboration MeetingOctober 15, 2009
MCP Structure
2
1) resistive coating (ALD)2) emissive coating (ALD)3) conductive coating (thermal
evaporation or sputtering)
pore
Sputtering system
Deposition chamber Load lock Sample transfer Arm
Sample rotation
RF Magnetron Sputtering System, AJA International ATC 2400John Pearson, MSD
Uncoated MCP
MCP100nm AZO
MCP+100nm AZO+Cr 5nm+Au 50nm
RF Magnetron Sputtering on Au/Cr Electrodes
We’re done, right?
No.
IEEE Trans Nucl. Sci. 19 (3) 74-84 1972 End spoiling output side:• increases spatial resolution• decreases gain• trade-off: h~1-2
Input side:• h~0.5-0.8
Importance of End Spoiling
A
AB
B(end spoiling)
• N(E) becomes more narrow as end spoiling increases
Effect of End Spoiling on Electron Energy Distribution
Effect of End Spoiling on Electron Energy Distribution
• N(E) narrows as end spoiling increases
Simulations:
h=0
h=0.5
h=1
h=3
• small increase in spatial resolution (10%) with 1.5 end-spoiling
Effect of End Spoiling on MCP Spatial Resolution
Effect of End Spoiling on MCP Spatial Resolution
• No systematic change in angle distribution with end-spoiling
Simulations:
h=0 h=0.5 h=1 h=3
Effect of End-Spoiling on MCP Gain
Gain ~ (SEC) (L/z)
SEC=secondary electron coefficientL=pore lengthz=distance between collisions
Since E field gradient=0 in electrode length h, no gain there
Gain ~ (SEC) (L/z) exp(-0.65h)
• Gain decreases with end-spoiling
IEEE Trans Nucl. Sci. 19 (3) 74-84 1972
Effect of End-Spoiling on MCP Gain
h=1.2
h=2.2
h=3
h=4
• Gain decreases with end-spoiling
Gai
n100
10
1
0.1
0.01
Voltage
13
Controlling End-Spoiling
RF-magnetron sputteredTi and Cu in high aspect ratio trench
http://www.electroiq.com
• Sputtering is not “line-of-site”• Need to use evaporation
Electrode Materials
Ni 72%Cr ~17%Fe ~10%Mn ~1%
Inconel 600: Trademark of Special Metals Corporation
metal melting Point°C
Resistivity µΩ cm
thermal conductivity
W/mK
VickersHardness
MPa
Adhesion Oxidation Resistance
Price to coat 8” square ($)
Inconel 600 1400 104 15 638 Great OK $0.3
Gold 1064 2.2 318 216 Terrible Best $6
Copper 1084 1.7 401 369 Poor Poor $0.06
Ossy suggests: 200 nm Inconel 600, h=1-2.
Ni ~80%Cr ~20%
Nichrome:Brand name, range of
compositions