Status of NectarCAM camera project J-F. Glicenstein (IRFU) for the NectarCAM consortium
Outline NectarCAM Design and prototyping Focal plane instrumentation Readout and digitization Trigger Acquisition Mechanics Slow-control Camera integration Conclusion Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 2
NectarCAM Cameras for Imaging Atmospheric Cherenkov Telescopes Photons and charged cosmic rays produce atmospheric showers Electrons and positrons from the showers produce Cherenkov radia>on. The atmospheric shower is imaged at the focal plane of IACTs. Typical signal ~ 100 photons Typical longitudinal extension: 1 deg 2 Typical lateral extension: 0.2 deg 2 Photon signal very short: ~ a few ns Large background: Diffuse light + stars (~ 100 MHz on 0.1 deg 2 ) Charged cosmic rays (~a few khz) IACT IACT cameras at the focal plane of IACT Large field of view ( a few deg opening) Capture of the signal in a few ns. Atmospheric shower Focal plane Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 3
NectarCAM Components of NectarCAM Modular design similar to H.E.S.S. and MAGIC Each module reads 7 photomul>pliers ~250 modules in camera Analogue memory based read- out (1 GHz sampling) Several elements developed in common with other CTA telescopes: mechanics, trigger, power supply Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 4
NectarCAM NectarCAM consor>um Aim: build cameras for the MST telescopes of CTA 14 ins>tutes over 3 countries (France, Spain, Germany) ~50 ac>ve members Focal plane instrumenta>on: IPAG (Grenoble), IRAP (Toulouse), ICC- UB (Barcelona) Cooling and Mechanics: CIEMAT (Madrid), IRFU (Saclay), LLR (Palaiseau) Readout and digi>za>on: LPNHE (Paris), IRFU (Saclay), ICC- UB (Barcelona) Local trigger: IFAE (Barcelona), CIEMAT (Madrid), UCM- GAE (Madrid), DESY (Zeuthen) Global trigger/clock: UCM- GAE (Madrid), APC (Paris), DESY (Zeuthen) Control, safety, services: LAPP (Annecy), IFAE (Barcelona), LLR (Palaiseau) Integra>on: IRFU (Saclay) Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 5
Design and prototyping Focal plane instruments Focal plane equipped with 1.5 phototubes Possible candidate: R11922-100 from Hamamatsu Operated at low gain (4 10 4 ) Light concentrated with Winston cones Lenses also inves>gated Special purpose board (HVPA) with 2 func>onnali>es Crockog- Walton power supply+preamplifica>on Winston cone Lens HVPA V1 Rejec>on curves Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 6
Design and prototyping Signal acquisition: NECTAr module Readout and digi>za>on Focal plane Instrumenta>on Phototubes Backplane Ethernet Clock NECTAr module (version 0) Data Path Trigger Path Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 7
Design and prototyping Signal read-out and digitization 2 gain channels Data capture: NECTAr chip Dual analogue memory/12 bit ADC func>onnality Ac>ng as a circular buffer 1024 sample deep 0.5-3.2 GHz sampling rate Analogue bandwidth of full data channel: ~250 MHz Upon local trigger, readout in ALTERA FPGA «region of interest» readout (16-60 samples) Read- out dead>me: 2µs (20 samples) Charge in ROI/>me calculated in FPGA Transfered camera server through Ethernet Full waveform can be transfered Dynamic range: 0 - > 2000 photoelectrons Linearity bemer than 2% over whole dynamic range Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 8
Design and prototyping Performances of data path Linearity high gain channel (0-50 photoelectrons) Single photoelectron (PMT gain 4 10 4 ) Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 9
Design and prototyping Camera trigger Acquisi>on of data triggered by: 1. a significant energy deposit (several tens of photo- electrons) 2. in a compact region of the camera (~ 1 deg 2 ) 3. in a short >me interval (~4 ns) Mul>stage triggering scheme - level 0 (L0): module level - level 1 (L1): camera level - trigger latency ~ 400 ns << 1 µs length of analogue memory Several op>ons tested for the camera level trigger ("analogue" and "digital") Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 10
Design and prototyping Options for camera trigger "Analogue" trigger: - analogue values are aligned in >me, summed, then compared to a threshold at module level (L0) - realized on the front- end board with an ASIC - camera level trigger (L1): several adjacent modules send a trigger within a short (a few ns) >me- window - realized on the "backplane" of the module "Digital" trigger: - every channel from the module is digi>zed on the front- end board (L0). - data from 7 adjacent modules give a L1 trigger if enough energy is present - realized on the "backplane" of modules - camera level trigger if several modules send a trigger within a short >me- window Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 11
Design and prototyping Camera trigger tests 3 pixels in the same module 3 pixels in different modules Trigger tests are undergoing with analogue and digital op>on Performed with a 5- module setup Preliminary with 3 modules and digital trigger: Trigger if 3 nearest neighbors (3NN) Trigger latency: ~ 134 ns Coincidences with >meshigs ΔT up to 4 ns Trigger latency measurement! Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 12
Design and prototyping Overview of data acquisi>on 3 x 10 Gbit/s 1 Gbit/s Embedded in camera box Transfer to ground with Ethernet (UDP protocol) Data from modules (1.5 Mb/s charge, 90 Mb/s waveform) concentrated in 6 switches (maximum trigger rate 9 KHz) Transfer to camera server: 400 Mb/s (charge), 23 Gbit/s (waveform) Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 13
Design and Prototyping Basic mechanical design Camera in enclosed in aluminium box Front sealed to avoid dust contamina>on Modules in a module holder in front, slow- control, power in rack in rear Mechanical design driven by cooling system Main proper>es: Camera needs proper Cooling! Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 14
Design and Prototyping Mechanical design: module holder Mechanics of a single module Module Holder Back Front Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 15
Design and prototyping Cooling and temperature control Humidity control: avoids electronics failure and sta>c build- up Temperature control: increase of electronics life>me, control of electronics response (calibra>on of analogue memories, gain stability of phototubes). Temperature gradient required to be no more than 10 o C in module holder 2 independant cooling loops for the front (modules) and rear (slow- control, power crates) Front cooling with cooling plates (phototubes)+forced convec>on (front end electronics) extensive simula>ons Simula>ons being checked with a thermal demonstrator simulated flow in module holder Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 16
Design and prototyping Thermal demonstrator Half module- holder Dummy PCB Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 17
Design and prototyping Thermal tests: preliminary results Temperature difference less than 10 o C in all channels - > validates cooling concept Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 18
Design and prototyping Slow control, safety Temperature Light ECC: Compact RIO + BeagleBone OPCUA based sofware Sensors on I2C buses Home- made mul>purpose sensor boards Pressure Humidity Accelera>on Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 19
Camera integration Prototyping strategy Early stage (2010-2014) - All subcomponents are designed and tested independently. 5- module demonstrator (2013-2014): - allows to test the trigger and the interface to DAQ. Thermal demonstrator (2014): test of cooling. - 19- module (133- pixel) demonstrator (2014-2015) - True mini- camera with slow- control, DAQ, cooling, mechanics. 5- module demonstrator Future integra>on hall of NectarCAM Qualifica>on model (2015-2016) - Pre- produc>on (industrial test benches and processes) Produc>on (ager 2016) Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 20
Camera integration NectarCAM schedule Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 21
Conclusion and outlook NectarCAM is a modular camera for Cherenkov Astronomy, designed by a consor>um of fourteen labs for CTA, mostly from France and Spain. It is based on 7- pixel NECTAr modules. The Cherenkov light signal is captured by phototubes, sampled at 1 GHz, then digi>zed and sent through Ethernet to a camera server. The prototyping strategy is: Subcomponent design and test (well advanced) Thermal demonstrator and 5- module prototype tests (2013-2014) Installa>on of a mini- camera with full mechanics, cooling, slow- control, DAQ and 19 modules (en 2014-2015) Qualifica>on camera (2015-2016) Status of the NectarCAM project Astrophysique des très Hautes Energies et perspectives pour CTA 22