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Secondary Emission Calorimetry R&D. Burak Bilki (for David Winn) University of Iowa Argonne National Laboratory. CHEF2013, Calorimetry for High Energy Frontier April 22-25, 2013 Paris, France. Why Secondary Emission Ionization Calorimeters?. - PowerPoint PPT Presentation
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Secondary Emission Calorimetry R&D
CHEF2013, Calorimetry for High Energy FrontierApril 22-25, 2013 Paris, France
Burak Bilki (for David Winn)
University of IowaArgonne National Laboratory
2
Why Secondary Emission Ionization Calorimeters?
• Secondary Emission (SE) signal: SE surfaces inside em/had showers:
– SE yield Scales with particle momentum
– e-: 3 < <100, per 0.05 <e-<100 keV (material dependent)
– ~ 0.05 - 0.1 SEe- per MIP
• SE is: Rad-Hard + Fast
– a) Metal-Oxide SE PMT Dynodes survive > 100 GigaRad
– b) SE Beam Monitors survive 1020 MIPs/cm2
Ex: ~60-240 SEe- per 100 GeV pion shower w/ MIPs aloneBUT SEe- Must be Amplified! Exactly like photoelectrons (p.e.)!
3
An SEe is statistically exactly like a p.e.
g~105–106 e per SEe (SEe as generated by shower particles) (just like p.e. gain from collected photons w/ g=105-6)
A) Muon MIP:~ 0.1 SEe- per sample module x 25 ModulesMIP Signal: We predict ~2.5 SEe/Muon (in 25 X0 EM module)
but we measure ~8x this in Test Beam!
B) EM Showers:~900 shower electrons/GeV yields 45-90 SEe/GeVNB: Lower Estimates! MIP SE, not true SE from particles
In CMS Hadron Forward Calorimeter Phase II Upgrade Framework
25 X0 Forward EM Calorimeter1 X0 W/Fe + SEe Sensor ~ 1.5 – 2.5 cm thick
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SEe Dynodes: a) Etched Metal Sheets
Hamamatsu Dynodes15 cm now ~50 cmAlready diced from largesheets
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Dn-Dn+1: 0.9 mmC-C mesh: 13 µmWire diameter: 5 µm
MESH DYNODE VARIANTS
SEe Dynodes: b) Metal Screen Dynodes: 15D - g~105
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Beam Tests of SE Sensor
We Expect ~500 Shower electrons to Cross Mesh ~25-50 SEe assuming all shower e = MIPs
Mesh PMT and BaseFacing DownstreamPhotocathode Reverse Bias
100 GeV e-
3 cm Pb
19 Stage Mesh
CERN SPS, Oct. 2011
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BEAM TEST: 100 GeV electrons 3 cm Pb ~ 5 X0 Radiator ~ Shower Maxdownstream the mesh PMT w/ photocathode turned off
Peak corresponds to ~40 SE electrons (mesh stack gain ~105)
PRELIMINARY!
Fluctuations High!- PMT Dia ~ Shower
Dia- Beam not centered
NOTE µ MIP:Detection Eff ~10%Response ~1-2 “SEe”
CERN SPS, Oct. 2011
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100 GeV Electrons – SE Mode
Charge > 160 fC cut applied. (1 pe ~ 160 fC) Scales with X0. Note: Shower not laterally contained!
~4 X0
CERN SPS, Oct. 2011
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80 GeV Electrons – SE Mode
Charge > 160 fC cut applied. (1 pe ~ 160 fC) Scales with X0 Note: Shower not laterally contained!
CERN SPS, Oct. 2011
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Muon Efficiency ~ 80%(1 pe ~ 160 fC)
Muons pass through the mesh dynodes (selected by the wire chambers)
Below Thresh.
SEe Efficiency with Muons CERN SPS, Oct. 2011
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SE Module Beam Test
51, … , 59: PMT IDs
Beam position(into the page)
2 datasets
Selected with Wire Chamber
515253
545556
575859
Using mesh dynodes from PMTsCERN SPS, Nov. 2012
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SE Module Beam Test
80 GeV e- Beam Variable absorbers
0 – 9 X0
SE SE SE SE
Shower not contained laterally or longitudinally Results require estimates and approximations
2-cm iron absorbers:
X0 = 1.75 cmMolière Radius: 1.72 cm
13
SE Module Beam Test
No upstream absorber80 GeV e- Beam hitting 1-51
Different measures of efficiency possible, here Charge > 45 fC (pedestal RMS) is chosen.
Efficiency ~ 41%
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SE Module Tests – Preliminary Results
Normalizing responses of different layers
Example: Normalization of Layer 3 response to Layer 2 response using 7X0 sampling
(Also works in the reverse order next slide)
Charge > 20 fC
15
SE Module Simulation
Geant4 simulation of the SE module test beam setup:80 GeV e- beam19 stage mesh dynodes generate SE electrons (dynodes ~ sheets)Gain is simulated offline (106)Landau fluctuations are implemented offlineSingle parameter to tune: Efficiency of SEe production(mesh dynodes are simulated as solid sheets) 0 - 0.35% flat random
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25 X0 sampling calorimeter1.75 cm Fe absorbers19-stage SE sensor ~ 2 cmLateral size 1 m x 1 m
SE Calorimeter SimulationUsing SE module MC tune
Landau fit MPVs and MPV errors
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Conclusions
Secondary Emission calorimeter is radiation-hard and fast.
Progressive beam test results are encouraging for better prototypes.
More beam test needed Next generation calorimeter prototype in preparation.
SE calorimetry is feasible for large-scale applications.
Large implementation options once the proof of concept is established (forward calorimetry for hadron/lepton colliders, beam monitors, Compton polarimetry for lepton colliders, etc. ).
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Backup Slides
SE: ionization e- random walk to surface oxide (10-50 nm thick), from ~1-2 µm in the underlying metal, escape into t vacuum under applied E-field = “secondary e-” = SEe.
SEYield gb -Semiempirical SternglassL = Escape Depth, Ep, Ap = particle energy, mass
Proton SE yield vs Ep
X200 peak-valley
Secondary Emission
20Shower +/- electron Energies
GEANT4: Cu Block, 1cm “plates”,100 GeV e incident. Shower e+/- that cross the 1 cm “gaps” arebinned in both energy and depth in Cu
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10 GeV e
100 GeV e
~900 e+-/GeVCross 1cm Cu gaps ~Indep of Einc
Yields 45-90 SEe/GeV generated.(assume all mips)
GEANT4: e’s in Cu1 cm absorber PlatesCount e+/- crossing gapsdNe/dE vs Shower e+- KE
Shower e+- energies crossing gaps
SEe Detector Module Concept -HCal
3D Stackable x,y,z
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Example SE: CERN LHC Beam Loss Monitor
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Al2O3,TiO2
~0.05 e- per MIP. Yet used as beam monitors:Rad Hard!
HadronShowers:Sub-mipCharged particles
Signal Generation from protons – DESY BPM
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