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Search for time-dependent fluctuations in cosmic ray flux with the AMS-01 detector

Search for time-dependent fluctuations in cosmic ray flux with the AMS-01 detector. PhD Thesis Mercedes Paniccia Département de physique nucléaire et corpusculaire Université de Genève March 2008. SEP Dec. 2006. SEP Dec. 2006: PAMELA. Kinetic Energy ( ).

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Search for time-dependent fluctuations in cosmic ray flux with the AMS-01 detector

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  1. Search for time-dependent fluctuations in cosmic ray flux with the AMS-01 detector PhD Thesis Mercedes Paniccia Département de physique nucléaire et corpusculaire Université de Genève March 2008 Mercedes Paniccia - AMS Analysis Meeting

  2. SEP Dec. 2006 SEP Dec. 2006: PAMELA Kinetic Energy ( ) Short-term CR flux variations • Huge plasma emissions from the Sun (CMEs) + Magnetic reconnection at the Earth magnetosphere • Magnetic storms, Solar Energetic Particles, Ground Level Enhancements, Forbush decreases • Time scales from minutes to several days • Energy up to ~50 GeV/n • Disturbances to satellite operations • Geomagnetic and solar activity continously monitored Mercedes Paniccia - AMS Analysis Meeting

  3. June 2-12, 1998 Near Earth orbit: Altitude: 320-390 km Inclination: 51.7 Period: 90 min Attitude: variable AMS-01 Precursor Flight on Space Shuttle Discovery Mission STS-91 Mercedes Paniccia - AMS Analysis Meeting

  4. Searching for systematic fluctuations in cosmic ray fluxwith the AMS-01 data • Cosmic ray flux measurements: • Simplify flux measurement, enlarge acceptance • Verify by reproducing AMS-01 official cosmic ray flux measurements • Search for time-dependent cosmic ray flux fluctuations: • Determine mean and actual fluxes over all mission duration, eliminating effects related to variable: • detector attitude • geomagnetic position • Search for statistically significant deviation from mean flux • Correlate with solar activity Mercedes Paniccia - AMS Analysis Meeting

  5. Cosmic ray flux measurements Mercedes Paniccia - AMS Analysis Meeting

  6. Deuteron flux above cutoff 2% Secondary pions produced on top of AMS-01 1% below 0.5 GeV Cosmic ray flux measurementsAcceptance & Background Estimated from AMS-01 MonteCarlo simulation: Mercedes Paniccia - AMS Analysis Meeting

  7. Cosmic ray flux measurementsEvent Selection Event Selection I • Trigger • LVL1 • LVL3 (TOF + Tracker) • No reconstructed cluster in Anticoincidence Counter • At least one track in Tracker • At least one track in TOF • ≤40° • ChargeTOF=ChargeTracker • Signal in at least 3 TOF planes • |R/R |<0.4 • p, , Z compatibility: • Only downward going particles Mercedes Paniccia - AMS Analysis Meeting

  8. Cosmic ray flux measurementsEvent Selection Reduce contamination from misreconstructed pions to 10-4 Reduces contamination from misreconstructed deuterons and pions Track quality cut Event Selection II • Electron selection: • R<0 • Z=-1 • Isolated track • Ultrarelativistic  • Proton selection: • R>0 • Z=1 • |massmeas - massproton| < 3.5 mass • He nuclei selection: • R >0 • Z=2 • 4 2MSoff < 200 Mercedes Paniccia - AMS Analysis Meeting

  9. Cosmic ray flux measurements Acceptances • Systematics uncertainties included (taken from previous AMS01 analysis) • Bayesian unfolding method to correct for experimental resolution (AMSUnfold in AMS Root by J. Alcaraz) Mercedes Paniccia - AMS Analysis Meeting

  10. Cosmic ray flux measurements Background Estimation • Deuterons and pions contaminations reduced to negligible levels by selection cuts • Mutual e-, p and He contamination evaluated from MonteCarlo: Mercedes Paniccia - AMS Analysis Meeting

  11. Cosmic ray flux measurements Data set • Data collected during Zenith pointing period (~24 hours absolute time) • Only single particles propagating toward the Earth • Events collected when the Earth was in the AMS field of view excluded • South Atlantic Anomaly excluded: 85W-25E; 0-55S Mercedes Paniccia - AMS Analysis Meeting

  12. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  13. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  14. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  15. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  16. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  17. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  18. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  19. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  20. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  21. Cosmic ray flux measurementsProtons cutoff Proton fluxComparison to previous results • <40°: this analysis • <32°: previous AMS-01 results M.Aguilar et al. (AMS coll.), Physics Reports, 366:331-405 (2002) Mercedes Paniccia - AMS Analysis Meeting

  22. Cosmic ray flux measurements Reproduced previous AMS01 flux measurements (proton, electron and He nuclei ) Background contamination negligible: Mutual e-, p and He nucleicontaminations negligible given CR flux magnitude Deuterons and pions contaminations reduced by selection cuts Corrections for experimental resolution negligible because of large bin widths Use same event selection procedure to study systematic CR flux fluctuations possibly related to solar activity Mercedes Paniccia - AMS Analysis Meeting

  23. 1 M (rad) 0.5 0 -0.5 -1 -3 -2 -1 0 1 2 3 M (rad) Search for time-dependent cosmic ray flux fluctuations • DATA sample: all data collected after undocking from MIR ( from June 8 18h00 UT to June 12 2h36 UT) • For each pointing period measure average counting rate as function of geomagnetic position: M= ; M=0; 0.2; 0.3; 0.4 …. • Measure actual counting rate with ~1 min time sampling Shuttle geomagnetic latitude vs longitude Mercedes Paniccia - AMS Analysis Meeting

  24. Search for time-dependent cosmic ray flux fluctuationsProtons 0.1 GeV ≤ Ek < 0.3 GeV Actual vs Expected Counting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  25. Search for time-dependent cosmic ray flux fluctuationsProtons 0.3 GeV ≤ Ek < 1 GeV Actual vs Expected Counting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  26. Search for time-dependent cosmic ray flux fluctuationsProtons 1 GeV ≤ Ek < 3 GeV Actual vs ExpectedCounting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  27. Search for time-dependent cosmic ray flux fluctuationsProtons 3 GeV ≤ Ek < 10 GeV Actual vs ExpectedCounting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  28. Search for time-dependent cosmic ray flux fluctuationsProtons 10 GeV ≤ Ek < 30 GeV Actual vs ExpectedCounting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  29. Search for time-dependent cosmic ray flux fluctuationsProtons 30 GeV ≤ Ek < 100 GeV Actual vs ExpectedCounting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  30. Search for time-dependent cosmic ray flux fluctuationsProtons 100 GeV ≤ Ek < 200 GeV Actual vs ExpectedCounting rate • Actual counting rate time sampling ~1 min Ncounts/sec 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 flux variation (%) 1h40 2h00 2h20 2h40 3h00 3h20 3h40 4h00 4h20 Mercedes Paniccia - AMS Analysis Meeting

  31. Search for time-dependent cosmic ray flux fluctuations Selection Refinement • Observed flux variations near South Atlantic Anomaly region • Add refined South Atlantic Anomaly exclusion: • From Box (85°W-25°E; 0°-55°S) to geomagnetic field contour E. Fiandrini et al. (AMS coll.),J. Geophys. Res, 109, (2004) Mercedes Paniccia - AMS Analysis Meeting

  32. Search for time-dependent cosmic ray flux fluctuations Searching for fluctuation evidence: • Calculate deviation from Poisson distribution with mean value the expected counts: Flat for random deviations Mercedes Paniccia - AMS Analysis Meeting

  33. Search for time-dependent cosmic ray flux fluctuationsProtons 0.1 GeV ≤ Ek < 0.3 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  34. Search for time-dependent cosmic ray flux fluctuationsProtons 0.3 GeV ≤ Ek < 1 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  35. Search for time-dependent cosmic ray flux fluctuationsProtons 1 GeV ≤ Ek < 3 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  36. Search for time-dependent cosmic ray flux fluctuationsProtons 3 GeV ≤ Ek < 10 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  37. Search for time-dependent cosmic ray flux fluctuationsProtons 10 GeV ≤ Ek < 30 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  38. Search for time-dependent cosmic ray flux fluctuationsProtons 30 GeV ≤ Ek < 100 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  39. Search for time-dependent cosmic ray flux fluctuationsProtons 100 GeV ≤ Ek < 200 GeV Searching for fluctuation evidence: Prob(N≥Ncounts obs) Prob (N≤Ncounts obs ) Mercedes Paniccia - AMS Analysis Meeting

  40. Search for time-dependent cosmic ray flux fluctuations Systematic fluctuation frequency • Evidence for proton, electron and He nuclei flux fluctuation occurrence in the kinetic energy range from 0.1 GeV to 30 GeV • Systematic fluctuation if more than 3 deviation in at least three adiacent kinetic energy bins • Three-hour average fluctuation frequency: Positive and negative flux variations treated separately Time duration and intensity not taken into account Mercedes Paniccia - AMS Analysis Meeting

  41. Search for time-dependent cosmic ray flux fluctuations Geomagnetic activity • Planetary geomagnetic activity index Kp: • Three-hour average geomagnetic field perturbations • Data from 13 geomagnetic stations at subauroral latitudes (44°-60°) • Disturbance level: • from 0 (quiet) to 9 (highly perturbed) in 28 steps • Sensitive to solar particle effects Data retrieved from Space Physics Interactive Data Resource Mercedes Paniccia - AMS Analysis Meeting

  42. Search for time-dependent cosmic ray flux fluctuations Systematic fluctuation index • Three-hour average proton flux fluctuation index: Positive and negative flux variations summed together Time duration and intensity of systematic fluctuation considered Mercedes Paniccia - AMS Analysis Meeting

  43. Search for time-dependent cosmic ray flux fluctuations Systematic fluctuationsversus geomagnetic activity Proton fluctuation index versus planetary geomagnetic activity index • Spearman rank correlation coefficient -0.37 with 0.99 significance Mercedes Paniccia - AMS Analysis Meeting

  44. Conclusions • Observed systematic fluctuations in He, proton and electron flux in the kinetic energy range from 0.1 to 30 GeV/n • Biggest effects for protons • Both flux increases and decreases occurs during active periods • Systematic decreases correlated to geomagnetic disturbances of solar origin • Article in preparation Mercedes Paniccia - AMS Analysis Meeting

  45. THANK YOU Mercedes Paniccia - AMS Analysis Meeting

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