1. Secondary Emission Ionization Calorimetry Detectors
David R Winn
for
Fairfield/Iowa/Mississippi

2. Secondary Emission Ionization
Calorimeters
Secondary Emission: Rad-Hard, Fast
Metal-Oxide/Cs Dynodes survive > 500 GigaRad
Signal from SE surface(s) in Hadron Showers:
SE yield  Scales with particle momentum ~dE/dx
e-: 3 <  <100, per 0.1 <e-<100 KeV (material depnt)
~ or SE e- per MIP
NB: This is a lower limit on hadron shower SE signals
4-6 MIP equiv per GeV sampling calorimeters
~50 SE e- per 100 GeV pi shower w/ MIPs alone
Achtung! SE e- Must be Amplified!

3. Signal Generation from e, pi Showers
Al2O3,TiO2
~0.05 e- per MIP.
Yet used as beam monitors:
Rad Hard!
Hadron
Showers:
Sub-mip
Charged particles

4. High SE Yield Materials
Peak Yields~5-10+; Alumina Easy
MgO
Electrons on MgO
Diamond
SE Yield
Stable in air!
Diamond Gain 300 V vs B Doping Level

5. SE Signal: MIP Equivs in Hadron Calorimeter
~5cm Fe Sampling HCal:
~4-6 mip equiv/GeV
The Lower Limit on Signal:
100 GeV Fe Hadron Cal:
Minimum of SE e-
…But need amplifier!

6. Digital Calorimetry: ~12 hits/GeV ->0.5-1 SEe/GeV (CALICE)
B.Bilki et al., 2009 JINST 4 P04006

7. ->800 SEe/GeV GEANT4: Cu, 1cm plates, 10 GeV e incident
Electrons counted as cross 1cm “gap”
->800 SEe/GeV
(100 events)
Showering e energy

8. Implies ~900 e/GeV Crossing gaps. > 45 SEe/GeV !
GEANT4 e’s in Cu
1 cm absorber Plates
Count shower e crossing gaps
Number shower e vs e energy
10 GeV e
Implies
~900 e/GeV
Crossing gaps.
> 45 SEe/GeV !
100 GeV e

9. ~740 Charged
Particles/GeV
More low E
than electron
->
~35-80 SEe/GeV

10. SE MIP Detector w/ 5 x 107 Gain
SE e-
Already
In Vacuum
Use Dynodes
To Amplify

11. Etched Metal Sheet Dynodes
SE e Detector Option A:
Etched Metal Sheet Dynodes
Hamamatsu Slat Dynodes
up to 6” now. Can be Scaled.
- Chemo-electro machined Metal “Mesh” Dynode Sheets
~1mm thick dynode layer - scale to µm
HV Vacuum: <10KV/mm -> 500V/0.2 mm ok.
Sheets can be up to square meters
Pressure + HV insulators: monotonous insulators
walls, posts, fibers (glass ceramics oxides)
Quasi Channelized: e- confined ->MCP operation
Metal cathode directly D1
B -> ~2T, as mesh dynode PMT

12. 5” wide PMT
Etched Dynodes

13. Metal Screen Dynodes: 15D: g~105, Bz~2 T
SE e Detector Option B:
Metal Screen Dynodes: 15D: g~105, Bz~2 T
fine mesh
distance between dynodes: 0.9 mm
step of the dynode mesh: 13 mm
mesh wires diameter: 0.5 mm

14. SE e Detector Option C:
MEMS Mesh Dynodes
µMachined Mesh Dynodes
Low Cost ~ 30 minute process
Channel Width ~200 mm
Offset layer layer helical channels
Insulator: Si3N4 or SiO2
Confined e- = High B
Can be taken to air repeatedly
~ microTorr operation ok

15. Alternative High-B SE e- Gain Mechanisms: MCP-Like Devices
A - El-Mul/A.Breskin
Sintered SE MicroSpheres ~ µm
Porous Plate: ~0.5-1 mm thick
Gain ~ 106 at G
B - Anodic Alumina ~ MCP-like?
~100 nm pores
Aspect ratio ~ :1

16. Anticipated Performance: SE 12 l Cu Hadron Calorimeter
Minimum Signal: muon MIP
~0.1 SE e- per module w/ g > 100,000 (delta rays~SE peak)
~ 40 Samples -> MIP Signal ~ 4 SE electrons/MIP
~ 2 “SE 105/SEe
Hadron Shower Signal:
Larger SE e per GeV - particles of lower momentum:
->SE ~1.5-6 compared with for MIP.
<E> ~ 60 MeV/2cm cube; Calice: ~23 “particles”/Hadron GeV
GEANT4 MC: ~740 charged hits/GeV ~35-75 SEe
-> 4-75 SEe/GeV hadron calorimeter showers
Electron Shower Signal:
GEANT4 MC: ~900 SEe/GeV ~45-90 SEe
N.B.: e/pi ~ possible compensation

17. Secondary Emission Calorimeter Sensor Basics:
- Top Metal Cathode, thin film SE inner Surface – Square/Hex/ –can be thick!
- Ceramic (Green Form) Edge Wall; HV feedthrus, supports; ~1cm high
Dynode Stack – mesh, MCP, slats, etc ~5-10 mm
- Bottom Metal Anode – thick/identical to Cathode/Vacuum pump tip; -

18. Schematic SEM Calorimeter Sensor Module - Plate Cathode/Anode Option
SLHC R&D technology –Secondary Emission Sensor Modules for Calorimeters
Schematic SEM Calorimeter Sensor Module - Plate Cathode/Anode Option

19. SE Calorimeter Manufacture Issues
- Similar to m2 Low Pressure Gas Plasma Display Technology
Proof of Principle/Manufacture - SE Calo sensor far simpler
Hermetic + Voltages similar to dynodes
Vacuum Supported by Ceramic walls or posts
-> thin metal windows
Ceramic Body 2.5” MCP-PMT

20. Basic Idea: Dynode/SE Stack is a High Gain Radiation Sensor
SE Calorimeter R&D technology Secondary Emission Sensors for Calorimeters
Basic Idea: Dynode/SE Stack is a High Gain Radiation Sensor
High Gain & OK Efficient (MgO yield ~0.1 e/mip per sample)
Energy Resolution: stochastic term ~10-50 SEe/GeV
Compact (micromachined metal ~0.3-1mm thick/stage)
Rad-Hard (PMT dynodes>100 GRads)
Uber-Fast
Potentially low cost/Non-Critical Assy
Simple Al oxide SEM monitors proven at accelerators
Rugged/Could be structural element
Easily integrated into large calorimeters/Arbitrary Shapes
~Minimal Dead Areas
Minimal services needed.
SE Detector Modules Are Applicable to:
- Energy-Flow Calorimeters (e+e-, µC, SLHC,….)
- Forward HiRad HiRate Calorimeters
- Compensation