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Overview on H.E.S.S. camera designs

Explore camera designs for H.E.S.S. collaboration with low threshold, large dynamic range, and high trigger rate. Learn about image fine pixelation, photo-detector specifications, calibration, and acquisition speed. Get insights on large dynamic range and compact modular construction for easy maintenance and installation at the CTA meeting in Berlin on May 4-5.

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Overview on H.E.S.S. camera designs

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  1. Overview on H.E.S.S. camera designs P. Vincent for the HESS collaboration LPNHE – IN2P3/CNRS – Université Paris VI & VII H.E.S.S.-MAGIC-CTA meeting in Berlin, May 4-5

  2. Requirements • Low threshold (~ 0 GeV) • Large dynamic range and acceptance (∞) • Large FoV (~360o) • High trigger rate for minimal dead time (0%) • Good energy (ΔE/E -> 0) and angular resolution (ΔΦ -> 0”) and, all that for free CTA meeting - Berlin, May 4-5

  3. Some basic ideas developed on HESS cameras • Fine pixelisation ( < PSF) for 5o FoV (extended sources, survey, energy and angular resolution) • Redundant information for calibration purposes (for data quality) • Avoid delay line for data storage (also for data quality) • Fast readout with minimum dead time (to go to low energy). • Fast analogue trigger (to profit from timing information) • Should be easy to install and repair (for human life quality) • Not totally free but low cost (for our institutions) CTA meeting - Berlin, May 4-5

  4. Image of point source Fine pixelisation ( < PFS) for 5o FoV • Advantage : • Energy reconstruction • Angular resolution • Disadvantage : 960 pixels/camera have a cost CTA meeting - Berlin, May 4-5

  5. Standard PMTs from Photonis Co: QE ~ 20-25% rms ~ 40 % Time fall ~ 1.8ns FWHM ~ 3 ns @ 2.105 Dark current < 1 nA Unif. 20% for < 2.1 cm cone eff. ~ 70% DC-DC converters from ISEG Co : ΔU/U ~ 1.10-4 (< 0.1V @ 1000 V) 5V/ms Imax ≃154 μA 850 V < U < 1 300V ΔU/ΔT < 5.10-5 V per C0 ~250 mW per pixel Photo-multipliers About 180 €/channel CTA meeting - Berlin, May 4-5

  6. Photo-detector understanding • Single photo-electron at nominal HV value • 80 ADC channel @ 2.105 of gain Dispersion over a camera Checked every 2 days Stable on a period Rms ~ 6 ADC count CTA meeting - Berlin, May 4-5

  7. Calibration • Stability thanks to temperature control and monitoring : • 192 sensors • 92 fans • NSB monitoring : • HVI vs HV • Scalers • DCI CTA meeting - Berlin, May 4-5

  8. Calibration vs Acquisition • The single photo-electron @ 2.105 implies 2 gain channels to cover the dynamic range: • 2 data channels • 1 trigger channel CTA meeting - Berlin, May 4-5

  9. Large dynamic range HESS I Two gain channels • HESS I : • HG : from 1 to ~ 200 • LG : from 10 to ~ 1 600 From 100 GeV up to few tens of TeV • HESS II : • HG : from 1 to ~ 150 • LG : from 10 to > 5 000 ~20 GeV to few tens of TeV HESS II E. Delagnes, Y. Degerli,P. Goret (DAPNIA, CEA/Saclay) P. Nayman, F. Toussenel (IN2P3/LPNHE Paris) CTA meeting - Berlin, May 4-5

  10. Acquisition speed • HESS I: • Max speed 2.5 kHz (limited by the front end) • ~15% dead time @ 300 Hz • HESS II: • Max speed ≥ 3 kHz (limited by the network) • ~ 0.7% dead time @ 3kHz HESS II 0.7% dead time @ 3 kHz 2008 20?? 2004 CTA meeting - Berlin, May 4-5

  11. HESS I ARS0 : Analogue Memory built for ANTARES (SEI-Dapnia) 5 buffers/chip, 128 cells per channel. Sampling @ 1 GHz Dynamic range 9-10 bits Linearity (1 – 1,600 γe) Max readout ~ 15 KHz : Sampling (calibration) integrated charge (operation) HESS II SAM(Swift Analogue Memory) : 2 differential channels x 256 cells Max sampling freq : 2.5-3 GSps Analog input bandwidth ≤ 300 MHz Operate up to 400 kHz Dynamic range > 11.3 bits Cross-talk < 0.1% Linearity (1 – 5,000 γe) Low power consumption ~ 300 mW. Acquisition speed enhancement HESS I CTA meeting - Berlin, May 4-5

  12. Analogue sum of width of the signal pulse over a programmable threshold + multiplicity in a sector of 64 pixels. Answer in 70 ns and ~100 ns for HESS I and II respectively 38 overlapping sectors Use of analogue memories need fast trigger CTA meeting - Berlin, May 4-5

  13. Compact & modular • 60 removable drawers HESS I By courtesy of P. Manigot - LLR HESS II By courtesy of P. Manigot - LLR CTA meeting - Berlin, May 4-5

  14. Compact & modular • Advantages: • Integrated electronics and local treatment is faster • Complete monitoring and slow control system • Minimal signal distortion • Compacity allow full construction and test in laboratory • Only power & network connection • Modularity facilitates the installation and maintenance • Constraints: • Weight (~1 ton for HESS I and ~3 for HESS II) • Modularity also has a cost CTA meeting - Berlin, May 4-5

  15. HESS I experience Assembly line : camera build and fully tested at the laboratory CTA meeting - Berlin, May 4-5

  16. Ready for usage Camera # 4 November 2003 CTA meeting - Berlin, May 4-5

  17. Plug & Play December 2nd • camera installation In the morning At noon afternoon CTA meeting - Berlin, May 4-5

  18. Plug & Play December, 3rd • Fill camera with drawers Very early in the morning CTA meeting - Berlin, May 4-5

  19. Plug & Play December 3rd • Install cone plate During night CTA meeting - Berlin, May 4-5

  20. Plug & Play December 4th Connect to the power, network and central trigger look if camera stay in place CTA meeting - Berlin, May 4-5

  21. Plug & Play December 11th After some more tests and the end of the moon period First event CTA meeting - Berlin, May 4-5

  22. HESS II • Other new features that I will not talk about : • New photo-tube studies (standard but new processes) • Auto-focus and unloading of the camera • Level 2 trigger (decision ~ 20μs) • …. see ICRC 2005 L2 trigger L1 trigger FPGA SAM FIFO SAM FIFO SAM FIFO SAM AM+ADC FIFO PMs < 400 kHz < 50 kHz CTA meeting - Berlin, May 4-5

  23. HESS I PMTs (960) 0.15 M€ Mechanics 0.16 M€ Electronics 0.34 M€ Camera 0.65 M€/unit HESS II PMTs (2048) 0.5 M€ Mechanics 0.8 M€ Electronics 1.2 M€ (x4 due to R&D and many test benches) Camera 2.5 M€/unit Cost } Industrialized process } Industrialized process CTA meeting - Berlin, May 4-5

  24. Summary • After 3 years of development 4 cameras were installed between June 2002 and end of 2003. • Performances reach expectations of five years ago. • HESS II camera profits from the first phase experiment with upgrades and additional features … • HESS cameras have proven their capability under operation … 32 k €/unit/(source/year). • Large scale production needs complete industrialization. It will induce extra cost but the R&D, already paid, can partially compensate … CTA meeting - Berlin, May 4-5

  25. That’s all folks MPI Kernphysik, Heidelberg Humboldt Univ. Berlin Ruhr-Univ. Bochum Univ. Hamburg Landessternwarte Heidelberg Univ. Kiel Univ. Tübingen, Germany LPNHE - Paris, Univ. Paris VI-VII LLR, Ecole Polytechnique, Palaiseau APC - College de France, Univ. Paris VII CEA - Saclay CESR - Toulouse LAOG - Grenoble LUTH - Observatoire de Paris LPTA - Montpelier LAPP - annecy Durham Univ. Charles Univ., Prag Dublin Inst. for Adv. Studies Yerewan Physics Inst. Univ. of Namibia, Windhoek Univ. Potchefstroom CTA meeting - Berlin, May 4-5

  26. DAS • Linux OS => pseudo-Real time OS are not quite free but profit from a large community of developers • cPCI bus. It is fast 64bits @ 33MHz + DMA transfer (HESS ~ 620 Mbits/s) • Independent remote control via terminal server for security. • … CTA meeting - Berlin, May 4-5

  27. HESS II Standalone 10-20 GeV HESS II Hybrid ~50 GeV ~100 GeV HESS I L1 standard trigger condition only HESS II expected performance • Trigger condition : • 4 PMs above 5γe • rate 2.5 kHz • dead time ~ 0.5% Stereoscopy H.E.S.S. Phase I Hybrid stereoscopy Phase II Monoscopy Phase II M. Ouchrif (IN2P3/LPNHE Paris) CTA meeting - Berlin, May 4-5

  28. M. Tluczykont (LLR/Ecole polytechnique) L1 (lower threshold) + L2(clustering) L1 (standard) Trigger Level 2 (under study): Binary information at the level of individual pixel. Decision must be taken in less than 20 s. Algorithm programmed on DSP or FPGA • Reject event without cluster • NSB and unclustered gamma • Reject High energy image amplitude • Pulsar study • Estimate second moment Hillas • Neural network • … CTA meeting - Berlin, May 4-5

  29. focusing Camera can moves by ~10 cm depending on elevation, to focus on shower image W. Hofmann, J.Phys. G27, 933(2001) CTA meeting - Berlin, May 4-5

  30. Autofocus CTA meeting - Berlin, May 4-5

  31. Implantation générale CTA meeting - Berlin, May 4-5

  32. Implantation générale CTA meeting - Berlin, May 4-5

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