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Catia Grimani and Michele Fabi Urbino University and INFN Florence

The potentialities of LISA as an observatory for solar and cosmic-ray physics at 1 AU far from Earth. Catia Grimani and Michele Fabi Urbino University and INFN Florence. Summary. LISA-PF & LISA missions & orbits Radiation monitors on LISA-PF Solar and Cosmic-ray Physics on board LISA

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Catia Grimani and Michele Fabi Urbino University and INFN Florence

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  1. The potentialities of LISA as an observatory for solar and cosmic-ray physics at 1 AU far from Earth Catia Grimani and Michele Fabi Urbino University and INFN Florence 21st European Cosmic Ray Symposium Kosice September 11th 2008

  2. Summary • LISA-PF & LISA missions & orbits • Radiation monitors on LISA-PF • Solar and Cosmic-ray Physics on board LISA • Conclusions 21st European Cosmic Ray Symposium Kosice September 11th 2008

  3. LISA Michelson Interferometer in space for gravitational wave detection down to 0.01 mHz: 3 S/C located at 5x106 km from each other near the ecliptic plane; 50x106 km behind the Earth Optical telescopes and inertial sensors Acceleration limit requirement: 3x10-15 m s -2 Hz-1/2 Launch expected in 2018- Duration 2-10 years LISA-PF Demonstration mission for LISA: two test masses placed at a distance of 30 cm L1 orbit One order of magnitude below the LISA requirements Launch expected in 2011 LISA & LISA-PF Km 21st European Cosmic Ray Symposium Kosice September 11th 2008

  4. LISA SCIENTIFIC GOALS 21st European Cosmic Ray Symposium Kosice September 11th 2008

  5. LISA-PF ORBIT 21st European Cosmic Ray Symposium Kosice September 11th 2008

  6. LISA IN SPACE 21st European Cosmic Ray Symposium Kosice September 11th 2008

  7. LISA orbitcharacteristics • Distance from the Sun 0.9933 - 1.0133 AU • Latitude off the ecliptic 0.7o - 1.0o • Longitude difference with respect to Earth 19o - 21o 21st European Cosmic Ray Symposium Kosice September 11th 2008

  8. VACT1 VAC 100 kHz L Csens1 VM Cp L Csens2 VACT2 Cp LISA Inertial sensor and test mass 21st European Cosmic Ray Symposium Kosice September 11th 2008

  9.  Radiation monitors (RM) will be placed on board the LISA spacecraft  RM design has been finalized for the PF only 21st European Cosmic Ray Symposium Kosice September 11th 2008

  10. SKETCH OF PARTICLE DETECTOR FOR LISA-PF 2 cm 1.05 cm 1.4 cm 2 layers of silicon detectors Dimensions: 1.05 x 1.4 cm2 Thickness: 300 m Lobo, 2004 Copper box 6.4 mm thick Geometrical factor: One layer - 9.24 cm2 sr Coincidence - 0.87 cm2 sr 21st European Cosmic Ray Symposium Kosice September 11th 2008

  11. Detector Positioning on LISA-PF Solar Panels Ecliptic Sun Earth to Earth to Sun Spacecraft Spacecraft Radiation Monitor front plane 21st European Cosmic Ray Symposium Kosice September 11th 2008

  12. Present RM characteristics • Galactic proton and helium nuclei (no 3He and 4He separation) in the whole energy range monitoring • SEPs above 70 MeV/n (p, He) monitoring • Overall countrate on each silicon detector • Ionization energy losses in the rear detector for coincidence events only (50 keV-5 MeV) • Maximum fluence 108particles/cm2 21st European Cosmic Ray Symposium Kosice September 11th 2008

  13. Galactic cosmic-ray variations and fluctuations • Long-term variations 11-year variation (Sun Spots) 22-year opposite Global Solar Magnetic Field (GSMF) Polarity change Quasi-biennial variations • Short-term fluctuations Forbush decreases 27-day variation Minutes - hours (Observed by two different experiments at the same time: HIST on POLAR and on INTEGRAL) seehttp://astro.ic.ac.uk/pwass/thesis/pjwThesis2 Shaul et al., 2006 21st European Cosmic Ray Symposium Kosice September 11th 2008

  14. Solar Modulation and Global Solar Magnetic Field Polarity Alanko-Huotari, Mursala, Usoskin and Kovaltsov, Solar Physics, 238, 391, 2006 21st European Cosmic Ray Symposium Kosice September 11th 2008

  15. Cosmic-ray proton observations during the last two solar cycles CG et al. 30th ICRC 2007 Merida Mexico 21st European Cosmic Ray Symposium Kosice September 11th 2008

  16. Solar Modulation of Galactic Cosmic Rays J(r,E,t) J(∞,E+) = E2-Eo2 (E+)2-Eo2 J: particle flux r: distance from Sun E: particle total energy t: time Eo= particle mass = particle energy loss from infinity (different for each species) Gleeson and Axford, Ap. J., 154, 1011, 1968 Ok for positive polarity epoch data only! 21st European Cosmic Ray Symposium Kosice September 11th 2008

  17. Reduction factors Solar minimum - negative polarity R1=1+(0.4/1.602)*logE+(0.4/1.602)-0.4 0.1<E<4.0 GeV(/n) High solar activity - negative polarity R2=0.61+1.41*E-1.2*E1.32+0.146*E1.95 0.1<E<1.6 GeV(/n) 21st European Cosmic Ray Symposium Kosice September 11th 2008

  18. Solar polarity effect on GCR p, He, e- and e+ CG et al. 30th ICRC 2007 Merida Mexico CG, A&A, 474, 339, 2007 p He Boella G. et al., J. Geophys. Res. 106:355 2001 21st European Cosmic Ray Symposium Kosice September 11th 2008

  19. Solar modulation during the next two solar cycles D. Hathaway and Dikpati M. http://science.nasa.gov/headlines/y2006/10may_lagrange.htm 21st European Cosmic Ray Symposium Kosice September 11th 2008

  20. Positive polarity cosmic-ray flux parameterization F[E(GeV)]=A(E+B)-EParticles/(m2 sr s GeV) (Papini, CG & Stephens, Il nuovo Cimento, 19, 367, 1996;CG et al., CQG,21,S629, 2004) 21st European Cosmic Ray Symposium Kosice September 11th 2008

  21. GCR p and He fluxes at the time of the LISA missions CG et al., XXX International Cosmic-Ray Conference, Merida, Mexico July 2007 CG et al., 7th Amaldi Conference Sidney Australia July 2007 presented by D. Tombolato CG and M. Fabi, Ionizing Radiation Detection and Data Exploitation Workshop, ESA/ESTEC, October 2007 21st European Cosmic Ray Symposium Kosice September 11th 2008

  22. Proton and Helium flux parameterization at the time of the LISA missions 21st European Cosmic Ray Symposium Kosice September 11th 2008

  23. Count rate and test-mass charging for the LISA missions (FLUKA Monte Carlo simulation) For absolute rates see Araujo et al. Astr. Phys., 22, 451, 2005 21st European Cosmic Ray Symposium Kosice September 11th 2008

  24. SOLAR FLARES (Reames, 1997) GRADUAL (CMEs) IMPULSIVE Electron rich 3He/4He =1 Fe/O = 1 H/He = 10 QFe = 20 Duration = hours Longitude = 40-70 Radio Type = III,V(II) X-rays = Impulsive Events/year = about 1000 Proton rich 3He/4He =0.0005 Fe/O = 0.1 H/He = 100 QFe = 14 Duration = days Longitude = more flat Radio Type = II,IV X-rays = Gradual Events/year = about 10 ONLY 1-2% of CMEs produce Solar Energetic Particles 21st European Cosmic Ray Symposium Kosice September 11th 2008

  25. ESTIMATE OF NUMBER OF YEARLY SEP EVENTS DURING THE NEXT DECADE Various methods are available in literature: Nymmik, 1999 We have estimated the yearly SEP-event number in the fluence range 106-1011 protons/cm2 above 30 MeV considering high and low solar cycle projections. Nymmik has found a correlation between the yearly number of SEP events and the number of yearly predicted solar spot number: NSEPs [NSSmin,NSSmax]=0.0694 NSS[min,max] Nymmik has found that the number of SEP events show a power-law trend as a function of fluence dNSEPs=C  e-  d Where =4x109 and C was determind on the basis of the total number of expected SEP events 21st European Cosmic Ray Symposium Kosice September 11th 2008

  26. Number of yearly expected solar spots during the next solar cycles Solar Cycle 24 Solar Cycle 25 21st European Cosmic Ray Symposium Kosice September 11th 2008

  27. During the LISA-PF mission (6 months) we expect 4.4 events in the fluence range 106-109 protons/cm2 21st European Cosmic Ray Symposium Kosice September 11th 2008

  28. Minimum number of SEP events expected during the next decade 106 - 107 p/cm2 107 - 108 p/cm2 108 - 109 p/cm2 109 - 1010 p/cm2 1010 - 1011 p/cm2 21st European Cosmic Ray Symposium Kosice September 11th 2008

  29. Maximum number of SEP events expected during the next decade 106 - 107 p/cm2 107 - 108 p/cm2 108 - 109 p/cm2 109 - 1010 p/cm2 1010 - 1011 p/cm2 21st European Cosmic Ray Symposium Kosice September 11th 2008

  30. Average number of SEP events expected during the solar cycle 25 106 - 107 p/cm2 107 - 108 p/cm2 108 - 109 p/cm2 109 - 1010 p/cm2 1010 - 1011 p/cm2 21st European Cosmic Ray Symposium Kosice September 11th 2008

  31. Gnevyshev gap in Sunspot Area Storini et al., 2008 21st European Cosmic Ray Symposium Kosice September 11th 2008

  32. Gnevyshev gap in SEP parameters Storini et al., 2008 21st European Cosmic Ray Symposium Kosice September 11th 2008

  33. Taking into account the Gnevishev Gap, the total number of expected SEP events might be reduced by 25% in the year(s) of the very solar maximum 21st European Cosmic Ray Symposium Kosice September 11th 2008

  34. LONGITUDE DEPENDENCE OF SOLAR EVENTS • Large CME shocks might cause flat longitude profiles • In the western flank of the shock the event is more • dynamic than the rest of the CME • For central and eastern SEP events invariance begins after • shock passage Figure from Reames, 2002 21st European Cosmic Ray Symposium Kosice September 11th 2008

  35. RADIATION MONITOR EXPECTED PERFORMANCE 21st European Cosmic Ray Symposium Kosice September 11th 2008

  36. SEP FLUX AT SMALL STEPS IN LONGITUDE ABOVE 100 MeV We expect a SEP flux difference among the LISA satellites associated with the same event ranging between 5 and 10%. This estimate was carried out on the basis of observed, energetic, proton fluxes related to gradual events differing by a few degrees in solar longitude. Further investigation is needed in order to take into account the role of different boundary conditions for each event. 21st European Cosmic Ray Symposium Kosice September 11th 2008

  37. Expected count rate variation on each silicon wafer Central-eastern event Western event 21st European Cosmic Ray Symposium Kosice September 11th 2008

  38. Flare May 7th 1978 SOLAR ENERGETIC PARTICLES Flare February 16th 1984 Figures from Grimani&Vocca PHOEBUS Proposal; 2004 Flare September 29th 1989 21st European Cosmic Ray Symposium Kosice September 11th 2008

  39. Expected count rate on one silicon layer Count rate GPm:galactic protons at solar minimum GPM:galactic protons at solar maximum F1: Flare 7 May 1978 F2: Flare 16 February 1984 F3: Flare 29 September 1989 Flux numbers are those reported in previous pictures 21st European Cosmic Ray Symposium Kosice September 11th 2008

  40. Expected count rate on both silicon layers Count rate GPm:galactic protons at solar minimum GPM:galactic protons at solar maximum F1: Flare 7 May 1978 F2: Flare 16 February 1984 F3: Flare 29 September 1989 Flux numbers are those reported in previous pictures 21st European Cosmic Ray Symposium Kosice September 11th 2008

  41. GALACTIC AND SOLAR PARTICLE IONIZATION ENERGY LOSSES IN PARTICLE MONITORS 21st European Cosmic Ray Symposium Kosice September 11th 2008

  42. ROLE OF ELECTRONS ON BOARD LISA 21st European Cosmic Ray Symposium Kosice September 11th 2008

  43. BEST-LINE FIT TO THE INTERPLANETARY ELECTRON SPECTRUM DURING A POSITIVE POLARITY PERIOD Jovian maximum Jovian minimum CG et al., in preparation 21st European Cosmic Ray Symposium Kosice September 11th 2008

  44. BEST-LINE FIT TO THE INTERPLANETARY ELECTRON SPECTRUM DURING A NEGATIVE POLARITY PERIOD Solar electron fluxes Flare September 7th 1973 Flare November 3rd 1973 Jovian maximum Jovian minimum 21st European Cosmic Ray Symposium Kosice September 11th 2008

  45. INTERPLANETARY ELECTRONS, INCLUDING SOLAR, ACCOUNT FOR 5% AND 13%, RESPECTIVELY, OF PROTONS AT SOLAR MINIMUM AND MAXIMUM RESPECTIVELY ON THE RM COUNT RATE AND REDUCE 15% THE NET TEST-MASS CHARGING WHILE INCREASE OF 8% THE SHOT NOISE AT SOLAR MINIMUM, TWICE THIS VALUE AT SOLAR MAXIMUM … MORE THAN THIS… ELECTRONS ALLOW… SEP FORECAST Posner (2007) has developed a method for SEP event forecasting. Electron fluxes of solar origin in the energy range between 0.3 and 1.2 MeV reach 1 AU always BEFORE energetic protons in the energy range <50 MeV. 21st European Cosmic Ray Symposium Kosice September 11th 2008

  46. (*) The intensity increase of both electrons and protons are correlated (*) Both are correlated to the longitude between the observer and the flare (*) Timescales of electron intensity increase are of tens of minutes. (*) Protons above 100 MeV can be forecasted through the detection of 1 MeV electrons. Delay time of protons with respect to electrons range between 10 minutes and 1 hour. 21st European Cosmic Ray Symposium Kosice September 11th 2008

  47. Time delay between solar electrons and protons 21st European Cosmic Ray Symposium Kosice September 11th 2008

  48. Conclusions • Particle monitors on board LISA missions will provide precious clues on solar and cosmic-ray physics • LISA will allow us to map SEP fluxes above 100 MeV(/n) as a function of time at small steps in longitude. • An electron monitor for SEP forecasting would be recommended on LISA. 21st European Cosmic Ray Symposium Kosice September 11th 2008

  49. From the talk by E. Daly (ESA space environment specialist, Head of Space Environment Effects Analysis Section): ESA and Space Weather One man’s noise is another man data III Space Weather Week Brussels - Belgium November 13th-17th 2006 Our proposition to use LISA RM for solar physics and space weather investigations is now officially part of the ESA program for future space weather investigations. 21st European Cosmic Ray Symposium Kosice September 11th 2008

  50. Thank you for your attention! 21st European Cosmic Ray Symposium Kosice September 11th 2008

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