CTA小口径望遠鏡用焦点面検出器の試作器開発
Hiro Tajima, Akira Okumura, Naoya Hidaka, Takanori Kawashima
Solar-Terrestrial Environment Laboratory, Nagoya University
Andrea Albert, Leonid Sapozhnikov, Luigi Tibaldo
SLAC National Accelerator Laboratory
Kavli Institute for Particle Astrophysics and Cosmology
Stefan Funk
University of Erlangen
Justin Vandenbroucke
University of Wisconsin, Madison
Richard White, Jim Hinton
Department of Physics and Astronomy, University of Leicester
Stephan Ohms
DESY
March 21, 2015
JPS meeting
Waseda University

Cherenkov Telescope Array❖ Observations of gamma rays in 20 GeV – 100 TeV band✤ Cherenkov light from electromagnetic shower produced by interaction ofgamma rays with atmosphere❖ Large collection area by placing many telescopes✤ x10 better sensitivity❖ Wide energy band coverage by three different sizes of telescopes✤ Large-sized telescope (LST): Φ = 23 m, 20 GeV – 1 TeV, 4 telescopes✤ Medium-sized telescope (MST): Φ = 10 – 12 m, 0.1 – 10 TeV, ~20 telescopes✤ Small-sized telescope (SST): Φ = 4 – 7 m, 1 – 100 TeV, 30 – 70 telescopes

LST23 m

SST4–7m

MST10 – 12 m
CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田2 /15

SST-2M Design Concept❖ Dual mirror design with small pixel photon sensor✤ Small pixel (~6 mm) photon sensor to reduce camera cost
๏ Multi-anode photomultiplier or SiPM
๏ High density readout electronics (ASIC)✤ Schwarzschild-Couder (SC) optics
๏ Short focal length to realize small plate scaleGCT• Technically challenging
camera1~100 TeV๏ Large field of view
• Longer telescope spacing(larger collection area)❖ Gamma-ray Cherenkov

Telescope (GCT)~4 m✤ Collaboration of Australia,France, Germany, Japan,Netherland, UK

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

3 /15

SST-2M Camera Design❖ SST-2M camera parameters
32 modFOV for 0.18°/pixel (36 mm/°)

8.6°

FOV for 0.28°/pixel (23 mm/°)

13.4°

Angular pixel size for FOV=10°

0.21°# of pixels per camera

2,048Power consumption per camera (FE)350 W

Weight per camera (FE+SiPM)

11 kg

Total cost (FE+SiPM) for 50 CAMs*$7.2M*Assuming $20/ch, which does not explicitly include laborfor mechanical module assembly and calibrations~31 cm
9°
32 modules
2048 channels

Front-End (FE) electronics module
CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

4 /15

Comparison with Single-Mirror Camera
SST-1M camera

SST-2M camera~31 cm
9°

88 cm
9.1°

32 modules
2048 channels
0.18° (6.2 mm)/pixel

108 modules
1296 pixels
0.25° (24 mm)/pixel

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

5 /15

GCT Camera Electronics
Camera module

Backplane

DAQ board
Trigger REQ

Front-end electronics
Photosensor•••

Trigger ACK× 16

Datastorage•••raw data,command(UDP)× 16

SPI control/monitor
Peripherals
LEDs, fans, temps

Peripheral board

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

6 /15

GCT Camera Electronics
Camera module

Backplane

DAQ board
Trigger REQ

Front-end electronics
Photosensor•••

Trigger ACK
× 16

Datastorage•••

raw data,command(UDP)× 16

SPI control/monitor
Peripherals
LEDs, fans, temps

Peripheral board

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

6 /15

GCT Camera Electronics
Camera module

Backplane

DAQ board
Trigger REQ

Front-end electronics
Photosensor•••

Trigger ACK
× 16

Data
storage•••raw data,command(UDP)× 16

SPI control/
monitor
Peripherals
LEDs, fans, temps

Peripheral board

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

6 /15

GCT Camera Electronics
Camera module

Backplane

DAQ board
Trigger REQ

Front-end electronics
Photosensor•••

Trigger ACK
× 16

Datastorage•••

raw data,command(UDP)× 16

SPI control/
monitor
Peripherals
LEDs, fans, temps

Peripheral board

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

6 /15

GCT Camera Electronics
Camera module

Backplane

DAQ board
Trigger REQ

Front-end electronics
Photosensor•••

Trigger ACK
× 16Datastorage•••

raw data,command(UDP)× 16

SPI control/
monitor
Peripherals
LEDs, fans, temps

Peripheral board

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

6 /15

GCT Camera FEE Function Diagram
GCT Camera Front-End Electronics (FEE)

Preamp
Photo sensors

SiPM bias
Peltier control

TARGETFPGATrigger ACK
Slow control

DC/DC

PreAmp/Powerboard

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

Trigger REQ x16
Data

Backplane

12 V

Signal Processing
board

7 /15

GCT Camera FEE Design~28 cm
DC/DCFPGATARGET ASIC

Preampdesigned by G. Varner (Hawaii)
CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田~29.5 cm
Peltier
ControlPreamp
ADC

8 /15

GCT Camera FEE Specifications❖ Requirements✤ Waveform sampling at ~ 1 GSa/s✤ Signal bandwidth > 380 MHz✤ Cross-talk < 1%
✤ Look-back time: > 12 µs
๏ For coincidence between telescopes✤ Dynamic range: > 9 bits
✤ Readout (dead) time: < 30 µs✤ Trigger timing: < 4 ns
✤ Trigger segment: 0.1° x 0.1° ~ 0.2° x 0.2°
❖ TARGET ASIC
✤ Switched capacitor array for high speed waveform sampling✤ Integrated digitization circuits and trigger circuits
๏ Reduction of components and cost, increase reliability✤ Internal bias generator
๏ All digital interface✤ Low power consumption: ~70 mW/channel including FPGACTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

9 /15

TARGET ASIC Development❖ TARGET ASIC is required to minimize cost and PCB space✤ while realizing GHz sampling and digitization, and trigger❖ Current status of development✤ Waveform recording and digitization satisfy requirements✤ Trigger performance needs improvements due to interference
from waveform recording
TARGET ASIC
๏ Separate ASIC for trigger
Dataand preamp
Waveform
recording
Photo sensors

Preamp

Digitization

L0 trigger

Trigger

New TARGET ASIC

Waveform
recording

Data

Digitization

New Trigger ASIC

Photo sensors

Preamp

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

Trigger

L0 trigger

10 /15TARGET Performance
200
Goal
Requirement
Nonlinearity (NL)NL+Dispersion (before calibration)
NL+Dispersion (after calibration)

ΔV (mV)

150

100

Waveform recording resolution

50— linear response
00250

500

750

10001250

1500

Waveform recording linearity

Trigger Effiency

Pulse Voltage (mV)

1.4
1.2

Trigger performance with sampling OFF

10.8
0.6

Minimum detectable pulse:
3.1 mVσ = 0.6 mV

0.4
0.2
00
CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

2468

101214pulse height (mV)
11 /15Development of Photo sensor

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

50Crosstalk (%)❖ Silicon photomultiplier✤ High photon detection efficiency (PDE)✤ Low bias voltage (50–70 V)✤ Robust compared with phototubes✤ Crosstalk needs improvement
๏ Trade off with PDE
๏ Factor of >10 improvementwith 10-15% loss of PDE✤ Packaging density is getting betterwith Through Via Silicon technology
๏ 4-side buttable๏ 200 µm gap between pixels✤ It is a default choice for all dual-mirror
telescopes in CTA❖ R&D is almost over✤ 6 mm sensor is being evaluated✤ Prototype with correct pixel size
(6.3–6.7 mm) will be fabricated and tested4030— original (HPK)— LCT2— LCT3— LCT4— LCT520100010203040 50
PDE (%)

12 /15

DAQ and Slow Control Software❖ libTARGET (2013 –)✤ C++ and Python libraries for lab tests of TARGET ASICs✤ Was not designed for multiple modules or high trigger rates❖ libCHEC (2014 –)✤ Based on libTARGET, but fast DAQ, slow control, and event
display functionality was written from scratch✤ C++ and Python libraries✤ Makes use of C++11, CMake, Boost, CFITSIO, ROOT6, SWIG,
Google Protocol Buffer, and ZMQ✤ 32 UDP sockets are connected to 32 camera modules
๏ For raw data transfer and slow control of camera modules✤ Still under development, being tested with CHEC-M in a lab

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

13 /15

Camera Commissioning❖ First GCT camera prototype is assembled and being tested✤ FEE module level tests completed✤ Integrated camera test in progress
Test bench output

FEE modules

Camera prototype(back side)

FEE module test bench

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

Camera prototype
full scaleside view

14 /15

Camera Commissioning❖ First GCT camera prototype is assembled and being tested✤ FEE module level tests completed✤ Integrated camera test in progress
Test bench output

FEE modules

Photon pulse
from cameraprototype
Camera prototype(back side)

FEE module test bench

CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

Camera prototype
full scaleside view

14 /15

Summary and Plans❖ Waveform sampling capability of TARGET-7 is satisfactory✤ Trigger performance will be fixed by CCTV
❖ Characterization and improvement of SiPM ongoing✤ R&D is almost over❖ System test ongoing for the first camera prototype❖ Plans✤ CCTV is out of fab and will be tested soon
✤ Prototype sensor will be fabricated after
completion of 6 mm sensor testing✤ Prototype production of complete
GCT telescope ongoing
GCT telescope structure
CTA小口径望遠鏡用焦点面検出器の試作器開発
JPS meeting, MAR 21, 2015, 早稲田

15 /15