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Solar Modulation Davide Grandi AMS Group-INFN Milano-Bicocca.

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Presentazione sul tema: "Solar Modulation Davide Grandi AMS Group-INFN Milano-Bicocca."— Transcript della presentazione:

1 Solar Modulation Davide Grandi AMS Group-INFN Milano-Bicocca

2 Outline The heliosphere Suns Magnetic Field, Polarity and Activity Solar Wind and Neutral Sheet Solar modulation of GCR Diffusion, Convection, Energy Loss, Drift The basic: Parker Model Force Field Approx. Our 2D Stochastic Monte Carlo JK modif. of polar field Drift model: WNS & PM Dynamic parameters Comparison with data & Prediction for AMS-02 Conclusions La physique d'AMS, Annecy 9-10 March 2010

3 The heliosphere the region of influence of the solar magnetic field th ICATPP, Como 5-9 October 2009

4 The heliosphere the region of influence of the solar magnetic field... La physique d'AMS, Annecy 9-10 March 2010

5 Field polarity Configuration for A>0Configuration for A<0 Solar cycle period is approx 11 years 11 th ICATPP, Como 5-9 October 2009

6 Magnetic field generated from the Sun Field lines frozen in the plasma created by the solar corona adiabatic expansion 11 th ICATPP, Como 5-9 October 2009

7 Solar Activity The solar activity is related to: - Sunspot number ( 100 maximum) - Wavy Neutral Sheet opening/tilt angle (10° minimum ; >75° maximum) A<0 A>0 A<0A>0 11 th ICATPP, Como 5-9 October 2009

8 Latitudinal Dependence Solar Wind and Magnetic Field Wavy Neutral Sheet 11 th ICATPP, Como 5-9 October 2009

9 Solar Wind High Solar Activity Low Solar Activity

10 Modulazione solare dei RCG Leffetto del trasporto dei RC è una DIMINUZIONE del flusso di RC dallesterno verso linterno della eliosfera

11

12 Introduzione Mod. ParkerPropag. RCNostro ModelloRisultati & Conclusioni Modulazione Solare Il Flusso Integrale dei Raggi Comici diminuisce avvicinandosi al Sole Flusso integrale misurato dalle sonde Voyager 1 (V1) Voyager 2 (V2) e Pioneer 10 (P10)

13 Introduzione Mod. ParkerPropag. RCNostro ModelloRisultati & Conclusioni Campo Magnetico Interplanetario Il Sole Ruota Le linee di campo si deformano secondo una spirale di Archimede La rotazione del sole è differenziale Leliosfera si divide in due emisferi a polarità opposta divisi a uno strato neutro di corrente

14 Introduzione Mod. ParkerPropag. RCNostro ModelloRisultati & Conclusioni Propagazione di RC in Eliosfera Force Field Nymmik Risoluzione analitica dellequazione di Parker monodimensionale. Ha come unico parametro il fattore di modulazione Modello empirico, richiede come unico parametro il numero di smoothed sunspot number per calcolare il potenziale effettivo modulazione nei mesi precedenti la data di osservazione

15 The global effect on CR si given by: Diffusion Magnetic irregularities on a small scale Magnetic Drift Magnetic field gradients on larger domains Convection Solar Wind expansion Parkers FP Equation 11 th ICATPP, Como 5-9 October 2009

16 CR propagation in the heliosphere is decribed by: Parkers Equation Is essentially a Fokker-Planck equation Diffusive Term Convective/Drift Term U is density number of CR for unit interval of energy 31st ICRC Lodz 7-15 July 2009

17 Diffusione e Moti di Deriva Interazione della particella cosmica con il mezzo interplanetario Continui URTI che causano una variazione del percorso Processo di Random Walk

18 Stochastic 2D Montecarlo Parkers equation, in the 2D (radius and co-latitude) approximation, is mathematically equivalent to the following set of stochastic differential equations Diffusive term Convective/Drift term 11 th ICATPP, Como 5-9 October 2009

19 Magnetic Drift using the Guiding Center approximation 11 th ICATPP, Como 5-9 October 2009

20 Introduzione Mod. ParkerPropag. RCNostro ModelloRisultati & Conclusioni Deriva Magnetica La deriva magnetica è legata alla componente anti-simmetrica del tensore di diffusione

21 Different Solar polarities th ICATPP, Como 5-9 October 2009

22 Drift model: WNS vs. PM Massimo Solare Minimo Solare Potgieter Moraal model (1985) Wavy Neutral Sheet Model (1995) Transition function, is 0 on the ecliptic plane and ± 1 at the poles NS term, is maximum on the ecliptic Magnetic drift equation is solved for the approximation <<1 rad 30° 31st ICRC Lodz 7-15 July 2009

23 Neutral Sheet Drift Potgieter & Moraal (1985) Burger & Potgieter (1989) Wavy Neutral Sheet - Hattingh & Burger (1995) Ordinary Drift NS drift Transition Function that emulate the effect of a wavy neutral sheet 2D Approximation erer N S

24 Drift model: PM Massimo Solare Minimo Solare Potgieter Moraal model (1985) Transition function, is 0 on the ecliptic plane and ± 1 at the poles NS term, is maximum on the ecliptic where the term f(θ), is 11 th ICATPP, Como 5-9 October 2009

25 Ulysses (orbita polare solare) IMP8 (1AU) Counting rate (1/s) ~16% [Heber 1998] Polar field corrections 11 th ICATPP, Como 5-9 October 2009

26 Polar field corrections 11 th ICATPP, Como 5-9 October 2009

27 Polar field corrections 31st ICRC Lodz 7-15 July 2009

28 Dynamic parameters 100 AU Magnetic perturbations move with the solar wind Sun magnetic field in not constant in the Heliosphere 11 th ICATPP, Como 5-9 October 2009

29 Dynamic parameters At a first approximation we can divide the heliosphere in different regions In every sector we consider solar condition of a period x-months before the data taking The time needed for a magnetic perturbation to reach the external limit of the heliosphere (100AU) is roughly: months 11 th ICATPP, Como 5-9 October 2009

30 Cosmic Rays moduated spectra 30° A>0 A<0 BESS High Solar Activity AMS-01 Low SOlar ACtivity IMAX Medium Solar Activity CAPRICE Low Solar Activity 11 th ICATPP, Como 5-9 October 2009

31 Cosmic Rays moduated spectra -IMAX 11 th ICATPP, Como 5-9 October 2009 Menn et al. 2000

32 Cosmic Rays moduated spectra - BESS 11 th ICATPP, Como 5-9 October 2009 Shikaze et al.2007

33 Cosmic Rays moduated spectra - Caprice 11 th ICATPP, Como 5-9 October 2009 Boezio et. al. 1999

34 Cosmic Rays moduated spectra – AMS th ICATPP, Como 5-9 October 2009 Alcaraz et. al. 1998

35 Cosmic Rays moduated spectra 31st ICRC Lodz 7-15 July th ICATPP, Como 5-9 October 2009

36 Cosmic Rays moduated spectra 31st ICRC Lodz 7-15 July th ICATPP, Como 5-9 October 2009

37 Cosmic Rays moduated spectra 31st ICRC Lodz 7-15 July th ICATPP, Como 5-9 October 2009

38 Cosmic Rays moduated spectra 31st ICRC Lodz 7-15 July th ICATPP, Como 5-9 October 2009

39 We estimated the expected GCR flux for the AMS-02 mission Estimated Sunspot Numbers A<0 A>0 A<0 AMS-02 measurements 11 th ICATPP, Como 5-9 October 2009

40 Predictions for AMS th ICATPP, Como 5-9 October 2009

41 Relation between Solar Activity and Tilt angle 11 th ICATPP, Como 5-9 October 2009

42 Relation between Solar Activity and Tilt angle 11 th ICATPP, Como 5-9 October 2009

43 Conclusions We realized a 2D Stochastic Montecarlo to evaluate the CR modulation in the Heliosphere We introduced the JK modification for the polar field and used the PM as NS Drift models, suitable for different solar conditions We introduced a dynamic approach to the use of parameters in order to reproduce the real physical process different experiments We reproduced the proton CR flux for different experiments (AMS, Caprice, BESS and IMAX) in different solar polarities for medium, high and low solar activity We used our 2D Montecarlo to predict the CR flux that AMS-02 will measure on the ISS from 2010 to 2012 (maximum), this will also help a better tuning and small corrections We are able to modulate different kind of particles (antiprotons, nuclei, electrons etc.) We are investigating also a more strict connection between the tilt angle and the solar activity

44 Thank you for your attention!

45 Polarity/Charge dependence 31st ICRC Lodz 7-15 July 2009

46 Boella et. Al Modulation There is a strong dependence of the modulation from the polarity of the field Variation between two consecutive minimum (it change the Field polarity) Rate of flux in two consecutive period with similar solar activity

47 Raggi Cosmici in Eliosfera Lo strato neutro di corrente oscilla entro un certo angolo con leclittica Angolo di Tilt La rotazione differenziale del Sole causa una divisione delleliosfera in 2 regioni divise da uno strato neutro di corrente

48 Raggi Cosmici in Eliosfera Il modello comprende Deriva magnetica dovuta a curvatura e gradiente dellIMF Deriva dovuta a allo strato neutro di corrente Il modello dipende dalla polarità del campo magnetico solare e dalla carica delle particelle (in figura positive)


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