The Anticoincidence System of the PAMELA Satellite Experiment Johan Lundquist

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The Anticoincidence System of the PAMELA
Satellite ExperimentJohan Lundquist

• Cosmic Rays, history
• PAMELA physics highlights
• PAMELA satellite and detector
• Need for Anticoincidence system
• Challenges for space experiments

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Cosmic Rays

• Cosmic Rays discovered in 1912 balloon
  experiment.
• Many important discoveries
• Positron (first observation of anti-matter)
• Strange particles
• Flux measured by many experiments but many
  mysteries remain
• Where do they come from?
• Who ordered the highest energy cosmic rays (1020
  ev baseball at 100 km/hour!).
• anti particles in the primary Cosmic rays?

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Cosmic Ray Spectrum

• What is the acceleration mechanism? Models exist
  but no conclusive experiments.
• How come there are Cosmic Rays above the GZK
  cut-off???

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Astro-Particle Physics

• Experiments on Cosmic rays might make new
  discoveries in fundamental physics.
• E.g. Supersymmetry most promising theory for new
  physics predicts new sources for anti-particles
  (neutralino annihilation).
• Some models predict observable effects for
  anti-protons and positrons (? transparencies)

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Anti Protons

• If Big Bang created equal numbers of particles
  and anti-particles, how come there are so few
  anti-particles?
• Effect of heavy neutralino (946 GeV) easily
  observable.

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Positrons

• Positrons appear to be mainly secondary
  particles.
• Is there an excess of high energy positrons?
• What is the sensitivity of PAMELA?

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PAMELA
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SOYEZ Rocket

• Health warning 3.2 of flights fail!

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Need for AntiCoincidence Detector

• Want to measure spectrum of particles with the
  spectrometer.
• Look at rare anti-matter particles ? need clean
  events.
• Veto all events which didnt have a track going
  cleanly through the spectrometer ? AC detector.

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CLEAN MUON IN PAMELA
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FALSE TRIGGERS
Interactions in material ? not a track going
cleanly through the spectrometer
Gives hits in AC detector ? use AC to veto false
triggers
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AntiCoincidence Detector
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Challenges for Satellite Experiment

• Pamela is like a conventional particle physics
  detector but space environment is difficult
• Reliability most work for 3 years with no
  possibility of maintenance.
• Mechanically robust must survive up to 16g
  during launch.
• Radiation levels much higher than on Earth ?
  electronics can fail catastrophically.
• Must be very light for launch.
• Very low power consumption.
• Limited data rates ? improved trigger.

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Johans Contribution

• Design of the Data Acquisition System
• Performance Studies
• Study of a Second Level Trigger.
• I would like to ask Johan to tell us more about
  the physics and the technical work and how he
  addressed the challenge of putting a particle
  physics detector into space