Transcript ppt - PPD - STFC Particle Physics Department

A MAPS-based readout of an
electromagnetic calorimeter for
the ILC
Nigel Watson
(Birmingham Univ.)
•Motivation
•Physics simulations
•Sensor simulations
•Testing
•Summary
For the CALICE MAPS group
J.P.Crooks, M.M.Stanitzki, K.D.Stefanov, R.Turchetta, M.Tyndel, E.G.Villani
(STFC-RAL)
Y.Mikami, O.D.Miller, V.Rajovic, NKW, J.A.Wilson (Birmingham)
J.A.Ballin, P.D.Dauncey, A.-M.Magnan, M.Noy (Imperial)
ILC: high performance calorimetry
Mass (jet3+jet4)
Mass (jet3+jet4)
 Essential to reconstruct jet-jet invariant masses in hadronic final
states, e.g. separation of W+W, Z0Z0, tth, Zhh, H
E/E =optimal
60%/E
E/E =flow
30%/E
 LEP/SLD:
jet reconstruction by energy
 Explicit association of tracks/clusters
 Replace poor calorimeter measurements with tracker
measurements – no “double counting”
Equivalent
best LEP
detector
Goal
ILC
Little benefit
from
beam energy constraint,
cf. at
LEP
Mass (jet1+jet2)
Nigel Watson / Birmingham
Mass (jet1+jet2)
EPS'07, 19-Jul-2007
ECAL design principles
 Shower containment in ECAL,  X0 large
 Small Rmoliere and X0 – compact and narrow showers
 int/X0 large,  EM showers early, hadronic showers late
 ECAL, HCAL inside coil
 Lateral separation of neutral/charged particles/’particle flow’
 Strong B field to suppresses large beam-related background in detector
 Compact ECAL (cost of coil)
 Tungsten passive absorber
 Silicon pixel readout, minimal interlayer gaps, stability
 “Swap-in” alternative to Si diode detector designs, e.g. in LDC, SiD
 CMOS process, more mainstream:
 Industry standard, multiple vendors (schedule, cost)
 (At least) as performant – ongoing studies
 Simpler assembly
 Power consumption larger – but better thermal properties
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Basic concept for MAPS
• How small?
• EM shower core density at
500GeV is ~100/mm2
• Pixels must be<100100mm2
• Our baseline is 5050mm2
• Gives ~1012 pixels for ECAL –
“Tera-pixel APS”
Nigel Watson / Birmingham
Weighted no. pixels/event
• Swap ~0.5x0.5 cm2 Si pads with small pixels
• “Small” := at most one particle/pixel
• 1-bit ADC/pixel, i.e. Digital ECAL
Effect of pixel size
50mm
100mm
>1 particle/
pixel
Incoming photon energy (GeV)
EPS'07, 19-Jul-2007
Tracking calorimeter
5050 μm2
MAPS pixels
ZOOM
SiD 16mm2 area cells
Physics simulation
 MAPS geometry implemented in Geant4 detector
model (Mokka) for LDC detector concept
 Peak of MIP Landau stable with energy
Geant4 energy of simulated hits
0.5 GeV
MPV = 3.4 keV
σ = 0.8 keV
 Definition of energy: E a Npixels
 Artefact of MIPS crossing boundaries
 Correct by clustering algorithm
s(E)/E
 Optimal threshold (and uniformity/stability)
important for binary readout
Ehit (keV)
5 GeV
MPV = 3.4 keV
σ = 0.8 keV
20 GeV photons
Ehit (keV)
200 GeV
MPV = 3.4 keV
σ = 0.8 keV
Nigel Watson / Birmingham
Threshold (keV)
Ehit (keV)
EPS'07, 19-Jul-2007
CALICE INMAPS ASIC1
First round, four architectures/chip
(common comparator+readout logic)
0.18mm feature size
INMAPS process: deep p-well
implant 1 μm thick under electronics
n-well, improves charge collection
4 diodes
Ø 1.8 mm
Architecture-specific
analogue circuitry
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Device level simulation
 Physics data rate low – noise
dominates
 Optimised diode for
 Signal over noise ratio
 Worst case scenario
charge collection
 Collection time
Nigel Watson / Birmingham
Signal/Noise
0.9 μm
1.8 μm
3.6 μm
Signal/noise
Distance to diode
(chargeEPS'07,
injection
point)
19-Jul-2007
Near future plans
3 July: 1st sensors
delivered to RAL
 Work ongoing on the set of PCBs holding,
controlling and reading the sensor.
 Test device-level simulations using laser-based
charge diffusion measurements at RAL
 =1064, 532,355 nm,focusing < 2 μm, pulse
4ns, 50 Hz repetition, fully automated
 Cosmics and source setup, Birmingham and
Imperial, respectively.
 Potential for beam test at DESY end of 2007
 Expand work on physics simulations
 Test performance of MAPS ECAL in GLDC
and SiD detector concepts
 Emphasis on re-optimisation of particle flow
algorithms
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Summary
 Concept of CMOS MAPS digital ECAL for ILC
 Multi-vendors, cost/performance gains
 New INMAPS deep p-well process (optimise
charge collection)
 Four architectures for sensor on first chips,
delivered to RAL Jul 2007
 Tests of sensor performance, charge diffusion
to start in August
 Physics benchmark studies with MAPS ECAL to
evaluate performance relative to standard
analogue Si-W designs, for both SiD and LDC
detector concepts
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Backup slides…
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Architectures on ASIC1
Presampler
Preshaper
Type dependant area: capacitors, and big resistor or monostable
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Beam background studies
 Beam-Beam interaction by
GuineaPig
purple = innermost endcap radius
500 ns reset time  ~ 2‰ inactive pixels
 Detector: LDC01sc
 2 scenarios studied :
 500 GeV baseline,
 1 TeV high luminosity
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
The sensor test setup
1*1 cm² in total
2 capacitor arrangements
2 architectures
6 million transistors, 28224 pixels
7 * 6 bits pattern
per row
5 dead pixels
for logic :
-hits buffering
(SRAM)
- time stamp = BX
(13 bits)
- only part with
clock lines.
84 pixels
42 pixels
Nigel Watson / Birmingham
Row index
Data format
3 + 6 + 13 + 9 = 31 bits per hit
EPS'07, 19-Jul-2007
Impact of digitisation
 E initial : geant4 deposit
•What remains in the cell after
charge spread assuming perfect Pwell
•Neighbouring hit:
•hit ? Neighbour’s contribution
•no hit ? Creation of hit from charge
spread only
•All contributions added per pixel
•+ noise σ = 100 eV
•+ noise σ = 100 eV, minus dead areas
: 5 pixels every 42 pixels in one
direction
Nigel Watson / Birmingham
EPS'07, 19-Jul-2007
Device level simulation
 Physics data rate low – noise
dominates
 Optimised diode for
 Signal over noise ratio
 Worst case scenario
charge collection
 Collection time.
Using Centaurus TCAD for
sensor simulation + CADENCE
GDS file for pixel description
Collected charge
Signal/noise
0.9 μm
1.8 μm
3.6 μm
Distance to diode
Nigel Watson / Birmingham
Distance to diode
EPS'07, 19-Jul-2007
Digitisation procedure
Geant4 Einit
in 5x5 μm² cells
Apply charge spread
Eafter charge spread
%Einit
Einit
Register the position and the number
of hits above threshold
%Einit
+ noise only hits :
%Einit
proba 10-6  ~ 106 hits in the whole detector
BUT in
a 1.5*1.5 cm² tower : ~3 hits.
Add noise to signal hits
with σ = 100 eV
(1 e- ~ 3 eV  30 e- noise)
Nigel Watson / Birmingham
%Einit
%Einit
%Einit
%Einit
%Einit
Importance of the charge spread :
 Eneighbours ~ (50%  80%)  Einit
Sum energy in
50x50 μm² cells
Esum
EPS'07, 19-Jul-2007