PASI 2013, 3 rd 5 th April 2013, RAL 03-Apr-2013Fergus Wilson,
STFC/RAL1 UK Silicon Digital Calorimetry
Slide 2
Digital Calorimeter (DECAL) 03-Apr-2013Fergus Wilson, STFC/RAL2
Make a pixellated calorimeter to count the particles. Binary
readout i.e. hit/no hit. Pixels need to be small enough to avoid
multiple particles passing through the same pixel. 100 particles/mm
2 leads to pixel sizes of 50 m 2. Higgs Factory ECAL would need 10
12 channels. Dead area and power consumption must be kept to a
minimum.
Slide 3
Silicon Pixel Detector Research SpiDer Created following demise
of Linear Collider R&D in the UK (~2007) Univ. of Birmingham,
Bristol, Oxford, Imperial College, Queen Mary, and RAL/STFC. Goal:
Develop monolithic active pixel CMOS sensors (MAPS) for future
experiments and to demonstrate their viability for vertexing,
tracking and calorimetry applications. Granularity, speed, power,
material budget, radiation hardness Still aimed at linear collider
(CALICE-UK) but with an eye on medical, nuclear and other particle
physics experiments. 3-yr, 9 FTE, 3M project request went in 2009.
Project informally approved 1 st April 2009 then formally cancelled
4 th April 2009 03-Apr-2013Fergus Wilson, STFC/RAL3
VertexingTrackingCalorimetry Pixel size (um)2025-5050 Spatial
occupancy (/mm 2 )1000.1-20.002 Material per layer (X0)< 0.1%5
bit analogueAnalogue or binarybinary Noise (MIP)
Monolithic Active Pixel Sensors (MAPS) Standard CMOS process
(=> low cost) 180 nm; 6 metal layers; Precision Components Low
leakage diodes; 5/12/18 m epitaxial layers. Very thin overall.
Additional Features developed: Deep p-well : improved charge
collection. High resistivity epitaxial layer : radiation hardness.
4T Structures : In-pixel double count sampling (DCS), low noise,
low power (
SPiDeR prototypes Build 3 chips: ISIS (vertexing), TPAC
(calorimetry), Cherwell (tracking). By time SpiDer cancelled all
chips made but only ISIS characterized. 03-Apr-2013Fergus Wilson,
STFC/RAL6 ISISTPACCherwell Charge CollectionPhotogate + CCD
register 4 diodes plus >100 transistors /pixel Pinned Photodiode
(4T) Pixel size (um)205025 (50) Time slicingX 20 in-situ storage
cells X 8192 time stampX10 rolling shutter Noise MinimisationRaw
charge storage and CDS signal shaping and pseudo-CDS CDS Power
Minimization Delayed slow readout (rolling shutter) Asynchronous
operation Rolling shutter Radiation ToleranceHigh resistivity study
to enhance tolerance Yield and costCustom CMOSStandard CMOS
Slide 7
Tera-Pixel Active Calorimeter Sensor (TPAC) 03-Apr-2013Fergus
Wilson, STFC/RAL7 1 cm
Slide 8
TPAC 55 Fe and IR laser results F B Pixel profiles Using 55 Fe
sources and IR lasers Using the test pixels (analog output) IR
laser shows impact of deep p-well implant 03-Apr-2013Fergus Wilson,
STFC/RAL8
TPAC Shower Multiplicity 03-Apr-2013Fergus Wilson, STFC/RAL11
Shows correct behaviour as function of energy. Demonstrates DECAL
concept validity
Slide 12
Out of the fire (2011) 03-Apr-2013Fergus Wilson, STFC/RAL12
Generic R&D program. Targetted: Flavour factories, ALICE
upgrade and T2K upgrade 1.25yr, 2 FTE, 500k requested. Awarded Dec
2011. Funding ends: April 6 th 2013
Slide 13
The Cherwell Chip 13 Cherwell Digital Calorimetry (DECAL) 4T
pixels with triggered global shutter and in-pixel CDS 25um pixel
pitch 2x2 pixel summing at column base [96x192 pixels] 50um pixel
pitch [48x96] Vertex Tracking Standard 4T pixels Reference pixel
array 12 bit ramp ADC implemented at column base [48x96] Strixel
array 12 bit ramp ADC in pixel array [48x96] 4 Blocks 3 Variants
03-Apr-2013Fergus Wilson, STFC/RAL
Slide 14
Maximising the fill factor 14 The efficiency of a detector is
dependent on how much of the surface area is occupied by dead
space. Core part of the design of Cherwell is to use islands of
electronics within the pixel array avoid having dead regions at the
edge of a sensor to maximise sensitive area. 4T4T SELECT COL RESET
COL 1x SR AM BIAS COL 4T4T 4T4T 4T4T 4T4T 4T4T 4T4T 4T4T 4T4T
03-Apr-2013Fergus Wilson, STFC/RAL
Slide 15
Laboratory Tests Cherwell Variants All the following results
are from the last month. Analysis is still on-going.
03-Apr-2013Fergus Wilson, STFC/RAL15 Noise per pixelFull well per
pixel New Implant = low noise variant
Slide 16
Temperature variation 16 Performance of the pixels changes as a
function of temperature: Want to understand how things vary over a
sufficient range for a viable system: T = [-50, +50] C. Believe we
can go lower. Have gone down to 77K without problem. More tests in
the Summer 2013. Could be useful for cryogenic detectors. High Res
Epitaxial Layer Expected behaviour up to ~50C Good operating range
03-Apr-2013Fergus Wilson, STFC/RAL Stable
Slide 17
Cherwell PTC Characterisation work 17 RMS Noise(e) per
pixelGain (ADCs/e) per pixel Signal Log(Signal) Log(Noise 2 ) Noise
2 Good Uniformity
Slide 18
18 Cherwell Test beam CERN Nov. 2012 T4 beamline at H6 at CERN
1 week of 120 GeV beam time Aim: understand resolution, charge
sharing, and efficiency of Cherwell. p ~ 120 GeV/c p/p ~1.5%
03-Apr-2013Fergus Wilson, STFC/RAL
Slide 19
Cherwell Correlation Plots Fergus Wilson, STFC/RAL19 S1:S2
S3:S4 S5:S6 S2:S3 S4:S5 S1:S6 Row Number 03-Apr-2013 Position
resolution analysis still on-going Hoping for < 8m
resolution.
Slide 20
Cherwell initial Cluster analysis Seagull plot showing where
charge is added to a hit Shows that charge is spread between more
clusters in standard resistivity sensors Looking at the size of
clusters (lower plot) charge is also more often in larger clusters
03-Apr-2013Fergus Wilson, STFC/RAL20
Slide 21
MAPS exploitation from STFC 03-Apr-2013Fergus Wilson,
STFC/RAL21 Rad tolerant, low noise Highly Miniaturised Radiation
Monitor (HMRM) for ESA Achilles : Rad hard 16M pixels for
Transmission Electron Microscopy (TEM). Lassena : 6M pixels for
X-ray imaging. 3-side buttable Kirana: >10 6 frames per
second
Slide 22
Near Future : Cherwell 2 and ALICE 03-Apr-2013Fergus Wilson,
STFC/RAL22 Using the Arachnid project expertise and funding,
developed a new sensor prototype at RAL for use on ALICE Inner
Tracker System upgrade. Out for production: 12 th March 2013.
Testing at DESY: June-July. Technology decision : Fall. TDR :
Winter. Our participation depends on receiving STFC funding in 2013
(and beyond). ALICE ITS requirements surprisingly similar to CLIC
vertex detector specifications.
Slide 23
UK MAPS Near Future 2013 DAQ/Test bench setup Our current
system is too slow and out of date. Looking at Commercial
development systems: (e.g. Xilinx SP605). LHC system : ATCA/TCA +
GLIB card + Connector board. Digital ECAL MAPS (Cherwell 1 / DECAL)
Have the chips in hand. Needs some tuning/FPGA work. Hope to test
at DESY June. Hope to fund from STFC Particle Physics Department
New Detector Initiatives. ALICE MAPS sensor (Cherwell 2) Out for
production: 12 th March 2013. Testing at DESY: June-July.
Technology decision : Fall. TDR : Winter. 03-Apr-2013Fergus Wilson,
STFC/RAL23
Slide 24
UK and STFC facilities/interest Interest from UK universities
in the technology for multiple purposes: nuclear, dark matter,
medical, astronomy, commercial,. STFC in-house facilities Sensor
Design Technology Division (TD) Good relationship with CMOS foundry
(TD) Wire bonding facilities, etc DAQ / Test bench (PPD) Testing
facilities 55 Fe irradiation, X-ray radiation, IR laser. Good
relationship with DESY/CERN for test beams. 03-Apr-2013Fergus
Wilson, STFC/RAL24
Slide 25
Conclusion MAPS has shown itself to be: Versatile; fast;
radiation hard; temperature tolerant; low power (passive cooling);
low noise; potentially cheap to produce. Characterisation of
Cherwell 1 on-going. We hope to test Cherwell 1 Digital Calorimeter
block DECAL at DESY in Summer 2013. We hope to be involved in
testing of ALICE Cherwell 2 chip. We hope to get funding to develop
sensor for ITS ALICE => could be first large scale pixel
detector using this technology. Particle Flow algorithms continue
to be maintained and developed at Universities. Weve kept the work
going by being generic and then producing spin-offs (e.g. ALICE).
Open to other MAPS exploitation proposals. MAPS is no longer the
technology of tomorrow. 03-Apr-2013Fergus Wilson, STFC/RAL25