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Calorimetry in space with PAMELA Valter Bonvicini INFN – Trieste

Calorimetry in space with PAMELA Valter Bonvicini INFN – Trieste On behalf of the PAMELA Collaboration OUTLINE : Scientific goals of PAMELA Overview of the PAMELA instrument 3. The Si-W imaging calorimeter: description and design details 4 . Scientific results 5 . Conclusions. Italy:.

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Calorimetry in space with PAMELA Valter Bonvicini INFN – Trieste

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  1. Calorimetry in space with PAMELA • ValterBonvicini • INFN – Trieste • On behalf of the PAMELA Collaboration • OUTLINE: • Scientific goals of PAMELA • Overview of the PAMELA instrument • 3. The Si-W imaging calorimeter: description and design details • 4. Scientific results • 5. Conclusions Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  2. Italy: CNR, Florence Bari Florence Frascati Naples Rome Trieste Russia: Moscow St. Petersburg Germany: Sweden: Siegen KTH, Stockholm The PAMELA Collaboration Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  3. PAMELA scientific objectives (A Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) PAMELA design performance • Study antiparticles in cosmic rays • Search for antimatter • Search for dark matter • Study cosmic-ray propagation • Study solar physics and solar modulation • Study the electron spectrum (local sources?) • energy rangeparticles in 3 years • Antiprotons 80 MeV - 190 GeV O(104) • Positrons 50 MeV - 270 GeV O(105) • Electrons up to 500 GeV O(106) • Protons up to 700 GeV O(108) • Electrons+positrons up to 2 TeV (from calorimeter) • Light Nuclei up to 200 GeV/n He/Be/C: O(107/4/5) • AntiNuclei search sensitivity of 3x10-8 in He/He Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  4. Resurs-DK1 satellite + orbit • Resurs-DK1: multi-spectral imaging of earth’s surface. • PAMELA mounted inside a pressurized container. • Launch from Baikonur on June 15th, 2006 at 0800 UTC with a Soyuz-U rocket. • As of now, ~ 1013 triggers, > 30 TB of data downloaded. Lifetime extended till end of satellite operations. • Data transmitted to NTsOMZ, Moscow, via high-speed radio downlink, ~16 GB per day. • Quasi-polar (70.0°) and elliptical orbit (350 km - 610 km) – from 2010 circular orbit (70.0°, 600 km). • Traverses the South Atlantic Anomaly. • Crosses the outer (electron) Van Allen belt at south pole. PAMELA Resurs-DK1 Mass: 6.7 tonnes Height: 7.4 m Solar array area: 36 m2 350 km 70o SAA 610 km Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  5. The PAMELA instrument 21.5 cm2sr • Time-of-flight • Trigger / Albedo rejection / Particle identification (up to 1 GeV/c) / dE/dx • 3 double-layer scintillator paddles • Timing resolution: • (paddle)  110 ps • (ToF)  330 ps (MIPs) • Anticoincidence system • Rejection of events with particles • interacting with the apparatus • Plastic scintillator paddles • MIP efficiency > 99.9% • Si Tracker + magnet • Measures rigidity • 5 Nd-B-Fe modules (0.43T) • 6 planes of double-sided Si microstrip detectors • ~3 µm resolution (bending view) •  MDR  1.2 TV Mass: 470 kg Power: ~ 360 W Size: 130x70x70 cm3 Si-W Imaging Calorimeter • Shower-tail catcher (S4) • Plastic scintillator paddle, 1 cm thick • Main task: ND trigger • Neutron detector • 36 3He counters • e/h discrimination at high energies Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  6. The PAMELA Imaging Calorimeter - 1 • Main tasks: • lepton/hadron discrimination • e+/- energy measurement • Characteristics: • 22 W plates (2.6 mm / 0.74 X0) • 44 Si layers (X-Y), 380 µm thick • Total depth: 16.3 X0 / 0.6 lI • 4224 channels • Self-triggering mode option • (> 300 GeV; GF~600 cm2 sr) • Mass: 110 kg • Power Consumption: 48 W • Design performance: • p,e+ selection efficiency ~ 90% • p rejection factor ~ 105 • e rejection factor > 104 • Energy resolution ~ 3% @ 200 GeV Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  7. The PAMELA Imaging Calorimeter - 2 • 44 Si detector views (22X and 22Y) • 8x8 cm2 detectors arranged in a • 3x3 matrix • 32 strips/detector, 2.4 mm pitch • Strips of detectors in the same row • (column) are bonded together • (ladder)  24 cm long strips • Each ladder (32 channels) is read • out by 2 CR1.4P front-end chips •  6 front-end chips/view • In total: • 396 silicon detectors • 264 CR1.4P chips • 4224 channels Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  8. The PAMELA Imaging Calorimeter - 3 • Front-endCR1.4P ASIC (full custom design) • Design characteristics: • - 16 channels/chip • - channel structure: CSA, shaper, T/H, out. mux. • - input-selectable calibration circuit • - integrated self-trigger circuit • - shaping time = 1 µs • - sensitivity = 5 mV/MIP • - wide dynamic range: 7.1 pC = 1400 MIP (1 MIP = • 4.9 fC) • - ENC ≈ 2700 e- rms + 5 e- /pF • ADC: • - 1 16-bit ADC/view  44 ADCs (AD977A) • - total calorimeter proc. time ~ 700 µs • Readout: • - Calorimeter divided into 4 sections: • Odd_X, Odd_Y, Even_X, Even_Y • - 1 DSP/section (ADSP2187)  4 DSPs • on-line calibration • data compression • - 1 FPGA/section (A54SX72)  4 FPGAs Architecture of one channel of the CR1.4P 1-MIP signal distribution (S/N ~ 10) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  9. 84 GeV/c interacting antiproton(flight data) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  10. 92 GeV/c positron (flight data) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  11. Flight data: 36 GeV/c interacting proton Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  12. Flight data: 32.3 GeV/c positron Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  13. Antiprotonresults Ptuskin et al. (ApJ 642 (2006) 902) Simon et al. (ApJ 499 (1998) 250) Donato et al. (PRL 102 (2009) 071301) O. Adriani et al., PRL 102, 051101 (2009); O. Adriani et al., PRL 105, 121101 (2010) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  14. p (non-int) p (int) Positron selection with the calorimeter - 1 Rigidity: 20-30 GV e- Events Events (x 103) p (non-int) e+ p (int) Fraction of charge released along the calorimeter track (left, hit, right) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  15. Positron selection with the calorimeter - 2 Rigidity: 20-30 GV e- Events e+ Events p Fraction of charge released along the calorimeter track (left, hit, right) + Energy-momentum match Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  16. Positron selection with the calorimeter - 3 Rigidity: 20-30 GV e- Events Events e+ p • Energy-momentum match • Starting point of shower • Longitudinal profile Fraction of charge released along the calorimeter track (left, hit, right) + Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  17. Positron-to-electron fraction - 1 O. Adriani et al., Nature 458 (2009) 607-609. O. Adriani et al, Astropart. Phys. 34 (2010) 1-11. Moskalenko and Strong, Astrophys. J.493, 694-707 (1998) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  18. Positron-to-electron fraction - 2 Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  19. Summary • PAMELA has been in orbit and studying cosmic rays for ~ 7 years. ~1013 triggers • and > 30 TB of data have been downlinked. • The Imaging Calorimeter has been performing nominally throughout this period: • basic performance (noise, signal, baseline...) are nominal and stable; • science performance (energy resolution, particle id., etc.) are consistent with • design specifications; • no degradations/failures/functionality loss observed so far; • the calorimeter proved to be a key instrument to achieve the scientific • results of PAMELA. • Antiproton-to-proton flux ratio and antiproton energy spectrum (~100 MeV - 200 GeV) • show no significant deviations from secondary production expectations. • High energy positron fraction (>10 GeV) increases significantly (and unexpectedly!) • withenergy (recent confirmation by AMS). Primary source? • The proton and helium nuclei spectra have been measured up to 1.2 TV. The • observations challenge the current paradigm of cosmic ray acceleration and • propagation. • Waiting for other AMS results to compare contemporary measurements. Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  20. ~ Spare slides ~ Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  21. Orbital environment and in-flight operation • Particle rate: • max. at the poles (cutoff <100 MV) • min. at the equator (cutoff ~15 GV) • Calorimeter operation: • Calibration performed every 95 min. (at • the ascending node) • Data acquisition: • - special run after calibration (“full mode”) •  ~ 10 kByte/ev. • - normal physics runs (“compressed • mode”)  ~ 1 kByte/ev. • Slow control: • Temperatures • Detector leakage currents • Calibration & supply voltages ~ 25 Hz Calibration @ ascending node Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  22. ~24.3 Calorimeter in-flight performance - 2 ~24.0 GROUND (muons) FLIGHT (relativistic particles) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  23. Calorimeter in-flight performance - 1 January 2008 July 2006 Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  24. Calorimeter in-flight performance - 2 January 2008 July 2006 Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  25. H and He absolutefluxes @ high energy O. Adriani et al., Science 332 (2011) 69 Deviations from single power law (SPL): • Spectra gradually soften in the range 30÷230GV • Spectral hardening @ R~235GV ~0.2÷0.3 SPL is rejected at 98% CL Origin of the structures? - At the sources: multi-populations, etc.? - Propagation effects? (e.g. P. Blasi et al., Phys.Rev.Lett. 109 (2012) 061101 2.77 Spectral index 2.85 2.48 2.67 243 GV 232 GV He H Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  26. Flight data: 11.6 GeV/c interacting anti-proton Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  27. Flight data: 18 GeV/c non-interacting anti-proton Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  28. Flight data: 14.7 GV Interacting nucleus (Z = 8)‏ Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  29. calorimeter self-trigger (m.p. electron) Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  30. 13 GV Interacting He Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  31. CALO SELF TRIGGER EVENT: 167103 MIP RELEASED 279 MIP in S4 26 Neutrons in ND Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  32. Charge identification with the Calorimeter Truncated mean of multiple dE/dx measurements in different silicon planes Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

  33. Energy-momentum match Preliminary e- e+ ‘Electron’ ‘Hadron’ p, d p Valter Bonvicini - CHEF2013, Paris, 22-25 April 2013

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