MCP Electrodes and End Spoiling

1
MCP Electrodes and End Spoiling

• Jeffrey Elam, Qing Peng, Anil Mane, Thomas
  Prolier, Joe Libera
• Argonne National Laboratory
• Large Area Photodetector Collaboration Meeting
• October 15, 2009

2
MCP Structure
pore

1. resistive coating (ALD)
2. emissive coating (ALD)
3. conductive coating (thermal evaporation or
   sputtering)

3
RF Magnetron Sputtering System, AJA International
ATC 2400 John Pearson, MSD
Sputtering system
Sample rotation
Deposition chamber
Load lock
Sample transfer Arm
4
RF Magnetron Sputtering on Au/Cr Electrodes
Were done, right?
No.
5
Electrodes and End-Spoiling in MCPs
Endspoiling hb/d
6
Importance of End Spoiling

• End spoiling output side
• increases spatial resolution
• decreases gain
• trade-off h1-2
• Input side
• h0.5-0.8

7
Effect of End Spoiling on Electron Energy
Distribution
8
Effect of End Spoiling on Electron Energy
Distribution

• N(E) narrows as end spoiling increases

9
Effect of End Spoiling on MCP Spatial Resolution

• small increase in spatial resolution (10) with
  1.5 end-spoiling

10
Effect of End Spoiling on MCP Spatial Resolution

• No systematic change in angle distribution with
  end-spoiling

11
Effect of End-Spoiling on MCP Gain
Gain (SEC) (L/z) SECsecondary electron
coefficient Lpore length zdistance between
collisions
Since E field gradient0 in electrode length h,
no gain there
Gain (SEC) (L/z) exp(-0.65h)

• Gain decreases with end-spoiling

12
Effect of End-Spoiling on MCP Gain
100
10
Gain
1
0.1
0.01
Voltage

• Gain decreases with end-spoiling

13
Controlling End-Spoiling
RF-magnetron sputtered Ti and Cu in high aspect
ratio trench
http//www.electroiq.com

• Sputtering is not line-of-site
• Need to use evaporation

14
Controlling End-Spoiling

• hatan(?)

15
Electrode Materials
Ossy suggests 200 nm Inconel 600, h1-2.
metal melting Point C Resistivity µO cm thermal conductivity W/mK Vickers Hardness 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
Inconel 600 Trademark of Special Metals
Corporation
Nichrome Brand name, range of compositions
Ni 72 Cr 17 Fe 10 Mn 1
Ni 80 Cr 20
16
Thermal Evaporation System, BOC Edwards AUTO
306 Hau Wang, MSD
17
Thermal Evaporation System, BOC Edwards AUTO
306 Hau Wang, MSD
sample rotation motor
200nm thermal evaporated NiCr on 33 mm ALD
MCP (end-spoiling not controlled)