1. Relative abundances of quiet-time suprathermal ions at 1 AU
K. Kecskeméty1, M.A. Zeldovich2, Yu.I. Logachev2
1 KFKI RMKI, Budapest, Hungary
2 Skobeltsyn Inst. of Nuclear Physics, Moscow State Univ., Russia
SH nd International Cosmic Ray Conference, Beijing, 15 August 2011

2. Suprathermal and energetic ions
Energy range 100 keV - 30 MeV: always present in interplanetary space, power-law tail of Maxwellian + pick-up
Mewaldt et al. (2001)

3. Quiet-time low-flux particles below ~1 MeV at 1 AU
What is their origin?
What are the seed populations?
What acceleration mechanisms operate?
look at the elemental composition
compare low and high FIP elements

4. Dayeh et al. (2009, ULEIS/ACE) C / O and Fe / O depend on the level of solar activity
80-640
keV/n
Fe/O
solar maximum: IP shock/SEP value, minimum: CIR

5. Selection criteria for quiet periods
Experimental data
ion fluxes
SOHO/EPHIN p, He 4-8 MeV/n
ACE/ULEIS C, Fe, Ne-S 40 keV/n MeV/nuc
WIND/STEP Fe, CNO
Selection criteria for quiet periods
no SEP event / active phenomena
J (p, 4-8 MeV) < 510-4 /(cm2 s sr MeV)
p/He (4-8 MeV/n) < 10 excludes SEP remnants
J (Fe, keV/n) < 510-2 /(cm2 s sr MeV)
51 periods grouped according to Fe/O, not summed up

6. Selection of quiet-time periods

7. Fe/O keV/n ACE/ULEIS

8. C/O keV/n ACE/ULEIS

9. WIND/STEP
ACE/ULEIS

10. Distributions

11. Energy spectra of ratios
low/high FIP ions: significant differences in 3 groups high/high FIP ions: small difference
averages for

12. Quiet-time energy spectra 1998-2010

13. Summary Fe/O, C/O, Ne-S/O ratio in suprathermal fluxes:
3 different groups: flare, corona, solar wind
Fe/O is near coronal value for 50% of time at solar max.
~ solar wind value for 90% of time at minimum
Fe, O, and C have different spectral forms ( MeV/n)
FIP bias in flare group (Fe/O)SEP/(Fe/O)ph = 14.8 ± 2.3 near solar upper atm. value in old active regions (15) 
SUA can contain the seed population in SEP background group, maybe in impulsive SEP events too (?)

14. backup slides

15. Fe average charge state and Fe/O
SEPICA / ACE Fe/O
Date <Q>
MeV MeV MeV
 1.03  
 0.94  
in most cases: SEP material, other periods: insufficient statistics

16. Quiet periods in o
 ,

17. C, O and Fe ion energy spectra

18. 34 quiet intervals selected
C/O values mixed
Fe/O: SEP, corona and sw periods well separated

19. Fe ion quiet-time energy spectra
=2.8
=1.9
=4.0
SEP sw
corona
solar wind + pickup:  = 1.5 (Fisk & Gloeckler, 2006)

20. Energy spectra of Fe/O and C/O

21. “quiet” intervals: contamination from SEP events
ACE SEPICA
“quiet” intervals: contamination from SEP events
SEPICA Fe charge state: very low statistics