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Front End Electronic of
GCT camera for CTA
Andrea De Franco
Supervisor : Dr. Garret Cotter
PhD student: Jason Watson
This project has received funding from the European Union’s Seventh Framework Programme for research,
technological development and demonstration under grand agreement n° 317446
Today’s Talk
The Cherenkov Telescope Array
- How do we detect gamma rays with ground based telescope? (See Garret’s talk)
- Constraints on FEE
The Gamma Cherenkov Telescope
- A proposed design for the highest energies gamma-ray
Front End Electronic of GCT
- From optical photons to a stream of data
Status of GCT FEE
- Report on recent lab testing
GCT Milestone
- Towards completion of first prototype… (See Garret’s talk)
- …and simulating what’s beyond (See Jason’s talk)
Today’s Talk
The Cherenkov Telescope Array
- How do we detect gamma rays with ground based telescope? (See Garret’s talk)
- Constraints on FEE
The Gamma Cherenkov Telescope
- A proposed design for the highest energies gamma-ray
Front End Electronic of GCT
- From optical photons to a stream of data
Status of GCT FEE
- Report on recent lab testing
GCT Milestone
- Towards completion of first prototype… (See Garret’s talk)
- …and simulating what’s beyond (See Jason’s talk)
Cherenkov Telescope Array (CTA)
Artist’s impression of CTA
Proposed in 1985 the Imaging Atmoshperic Cherenkov Telescope technique to
detect high energy cosmic gamma-ray with ground based observatory
CTA is the next generation of IACTs:
● sensitivity X10 actual VHE ϒ-ray instr.
● energy range ~30 GeV - 300 TeV
● large (~8°) field of view for surveys
● improved angular and energy res.
● 2 sites in Northern and Southern emisphere
Imaging Atmospheric Cherenkov Telescope (IACT)
ϒ  e- + e+
e+/-  ϒ + e+/-
at 15-30 km a.s.l.
10 km in length
e+/- with v > c/n  Cherenkov light
Optical photons pool ~100m radius
Shape & Intensity of
the Image
Energy and Direction
of primary ϒ
IACT – The Challenge for FEE
(A. Bouvier et al. 2013)
Night Sky Background overlap with Cherenkov radiation spectrum at detection
level (after atmosphere self absorption)
 Observation time reduced to moonless nights.
Unless appropriate selection of photosensors
MAPM  SiPM
IACT – The Challenge for FEE
100 µs
(W. Hofmann, HESS)
Flash duration of individual shower ~ 10 ns
 Very fast trigger to reject NSB
10 ns
IACT – The Challenge for FEE
Gamma
Hadronic initiated shower
104 more frequent.
Proton
Background rejection
based on different image
shape
( due to inelastic scattering
hadron – nucleus )
(Bernlöhr K. 2007)
More Intelligent electronics
 EventSelection at FPGA level ?
Today’s Talk
The Cherenkov Telescope Array
- How do we detect gamma rays with ground based telescope? (See Garret’s talk)
- Constraints on FEE
The Gamma Cherenkov Telescope
- A proposed design for the highest energies gamma-ray
Front End Electronic of GCT
- From optical photons to a stream of data
Status of GCT FEE
- Report on recent lab testing
GCT Milestone
- Towards completion of first prototype… (See Garret’s talk)
- …and simulating what’s beyond (See Jason’s talk)
The Gamma Cherenkov Telescope
Dual Mirror
Schwarzschild-Couder
design
Mirror diameter:
4 meter primary
2 meter secondary
Total weight 7.8 t
Awesome RED
Cherenkov light is blue…
GCT Camera
Funding in place for 2 prototype cameras
- CHEC-M: Multi Anode Photo
Multipliers
- CHEC-S: Silicon Photo Multipliers
Design criterion:
- Low cost but high data quality
- Relatively fine pixellation
- Full waveform readout on all
channels
2048 pixels
32 x 64 pixel modules
GCT Camera - Mechanics
Lid
Pointing
LEDs
32 Photosensor
modules
Liquid cooling
GCT Camera - Electronics
FRONT
END
BACK
END
Today’s Talk
The Cherenkov Telescope Array
- How do we detect gamma rays with ground based telescope? (See Garret’s talk)
- Constraints on FEE
The Gamma Cherenkov Telescope
- A proposed design for the highest energies gamma-ray
Front End Electronic of GCT
- From optical photons to a stream of data
Status of GCT FEE
- Report on recent lab testing
GCT Milestone
- Towards completion of first prototype… (See Garret’s talk)
- …and simulating what’s beyond (See Jason’s talk)
Electronics
Amplification and
shaping
Buffering and
Serialisation
Digitisation and Trigger
16 x
16 x
Preamps
16 x
Preamps
Preamps
16 x Preamp
Target Asic
Target Asic
Target
Asic
TARGET
ASIC
FPGA
Data
Trigger
64 Pixel
Module
x 32
Backplane Board
Backplane
64 Pixel
Module
TARGET Module
DACQ
Board
Data Serialisation and
Control
Camera
Trigger
Peripherals
(calibration,
lid, etc)
Control,
Data
Electronics
Buffering and
Serialisation
16 x
16 x
Preamps
16 x
Preamps
Preamps
16 x Preamp
Target Asic
Target Asic
Target
Asic
TARGET
ASIC
Data
FPGA
Trigger
64 Pixel
Module
x 32
Amplification and
shaping
Digitisation and Trigger
Trigger:
4 neighbouring pixels
are summed, then
discriminated.
6 mm
Photosensor
pixel
super pixel
Andrea De Franco
Camera Trigger
Peripherals
(calibration,
lid, etc)
Backplane Board
Backplane
64 Pixel
Module
TARGET Module
DACQ
Board
Data Serialisation and
Control
Control,
Data
Electronics
Buffering and
Serialisation
16 x
16 x
Preamps
16 x
Preamps
Preamps
16 x Preamp
Target Asic
Target Asic
Target
Asic
TARGET
ASIC
Data
FPGA
Trigger
x 32
Amplification and
shaping
Digitisation and Trigger
Camera Trigger
64 Pixel
Module
Any 2 neighbouring
super-pixels
Backplane Board
Backplane
64 Pixel
Module
TARGET Module
Following camera
trigger data read out
to central location
Peripherals
(calibration,
lid, etc)
DACQ
Board
Data Serialisation and
Control
Control,
Data
Today’s Talk
The Cherenkov Telescope Array
- How do we detect gamma rays with ground based telescope? (See Garret’s talk)
- Constraints on FEE
The Gamma Cherenkov Telescope
- A proposed design for the highest energies gamma-ray
Front End Electronic of GCT
- From optical photons to a stream of data
Status of GCT FEE
- Report on recent lab testing
GCT Milestone
- Towards completion of first prototype… (See Garret’s talk)
- …and simulating what’s beyond (See Jason’s talk)
GCT – MAPM Camera
Now under lab testing in UK.
Using TARGET 5 modules.
Backplane expected in the lab at the beginning of June for trigger testing.
A dummy backplane now fanning out external trigger signal to the modules
TARGET 7
Used in GCT – SiPM and pSCT(US Medium Size Telescope for CTA) prototype cameras.
First few modules produce and tested.
Design ready for production of camera prototype’s modules.
Improved dynamic range.
Better linearity.
TARGET-C & CCTV
Trigger moved to small ASIC companion to improve
trigger performance.
Cross talk reduced, expected improved performances:
Trigger noise < 1mV  trigger threshold < 4mV
TARGET-C: Designed specifically for CTA based on TARGET 7
– Buffer added to data path to reduce effects of digital activity
TARGET –CCTV : CTA Companion Trigger Variant
- 16 channels of T5 trigger
- Include pre-amp (can be bypassed in case of external pre-amp)
First modules to be produced soon
SiPMs
Order made of 35 Hamamatsu S126421616PA-50
Improvement of the product in the small
timeframe between order and delivery of
first batch
different coating to reduce cross-talk
Need for a window entrance for the
camera.
Today’s Talk
The Cherenkov Telescope Array
- How do we detect gamma rays with ground based telescope? (See Garret’s talk)
- Constraints on FEE
The Gamma Cherenkov Telescope
- A proposed design for the highest energies gamma-ray
Front End Electronic of GCT
- From optical photons to a stream of data
Status of GCT FEE
- Report on recent lab testing
GCT Milestone
- Towards completion of first prototype… (See Garret’s talk)
- …and simulating what’s beyond (See Jason’s talk)
GCT Camera - Commisioning
Robot Arm
Robot arm
(Photo – courtesy of A. Okumura)
See Garret’s talk
(Photo – courtesy of A. Okumura)
First results on lab test intended to be presented at ICRC 2015
( The first GCT camera for the Cherenkov Telescope Array.
A. De Franco, R. White et. al. for the CTA consortium)
GCT Camera – Towards SiPM
Robot Arm
Robot arm
See Jason’s talk
SiPM performance test and electronics design tuning undergoing at the moment for SiPM
based camera prototype.
Front End Electronic of
GCT camera for CTA
Thank you!!!
Andrea De Franco
Supervisor : Dr. Garret Cotter
PhD student: Jason Watson
This project has received funding from the European Union’s Seventh Framework Programme for
research, technological development and demonstration under grand agreement n° 317446