SPECTRAL SHAPE OF

SOLAR PARTICLE EVENTS AT ENERGIES

ABOVE

Catia Grimani

University of Urbino – INFN Florence

Italy

In collaboration with:

M. Fabi, N. Finetti, M. Laurenza, M. Storini

ECRS 2012 Moskow July 5th 2012

100 MeV/n

Outline

• LISA-PF• GCR projections and SEP occurrence in

2015• SEP differential flux trend above 100

MeV/n• Conclusions

LISA-PF MISSION

LISA-PF inertial sensor and test mass V

AC

T1

V

AC

T2

V

M

Csens

1Csens

2

VAC

100 kHz

L

L

C

p

C

p

LISA-PF TEST MASSES AND RADIATION MONITORS

2 silicon wafersof 1.4 x 1.05 cm2 areaplaced 2 cm apart. Courtesy by A. Lobo

SUNSPOT PROJECTIONS IN 2015

Predicted Sunspotsin 2015: 595 and 95 percentile levels: 33 and 84

Solar modulation parameter expectedvariation:350 MV/c - 800 MV/c

Usoskin et al.,2005, 2011

LISA-PF data taking

http://solarscience.msfc.nasa.gov/predict.shtml

CG et al., CQG, 2012

GCR PROJECTIONS IN 2015

GC et al., CQG, 2012 and references therein= 350 f MV/c – 800 MV/c

SEP EVENTS DURING LISA-PF

We consider here SEP events associated with a peak flux equal or larger than the minimum GCR background expected in 2015.

Nymmik’s model (Nymmik, 1999 a,b) allows us to predict SEP occurrence (NSEPS) in terms of both event fluence and peak fluxes on the basis of expected yearly SS (NSS):

NSEPS=0.0694 NSS

SEP fluence distribution is assumed to follow a power-law trend with an exponential decrease for large fluences.

SEP PROJECTIONS IN 2015

The number of expected SEP events at the time of LISA-PF is: 1.1 min – 2.0 avg – 2.9 max with fluences above 106 protons/cm2

> 30 MeV

SEPS OF DIFFERENT INTENSITIES February 23rd 1956: N24W74 May 7th 1978: N23W72 September 29th 1989: S27W90 July 14th 2000: N22W07 April 15th 2001: S20W85 January 20th 2005: N14W61 December 13th and 14th 2006: S06W23

and S06W46

GCR IN 2015 AND SEP EVENTS SEP Event February 23rd 1956

SEP Event December 13th andDecember 14th2006

Adriani et al., 2011

Vashenyuk et al., 2007

SEP FLUX INTERPOLATION FUNCTIONS

(1) F(E)= A e-E/b Particles/[m2 sr s GeV(/n)]

(2) F(E)= A E- g Particles/[m2 sr s GeV(/n)]

(3) F(E)= A e-E/b E- g Particles/[m2 sr s GeV(/n)]

Ellison and Ramaty, 1985

SEP FLUX INTERPOLATIONS

SEP FLUX INTERPOLATIONS

SEP FLUX INTERPOLATIONS

CONCLUSIONS

SEP energy differential flux interpolation during the whole evolution of various intensity events above 100 MeV/n indicates (on average) that:

the initial phase of SEP events is

sometimes better represented by an exponential trend, however, in general, a power-law modulated by an exponential or power-laws and/or broken power-laws basically represent all phases of the events.