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Session 120 - The Sun.
Oral session, Saturday, January 10
International Ballroom East,

[120.07] Accelerated and Ambient He Abundances from Gamma-Ray Line Measurements of Flares

G. H. Share, R. J. Murphy (NRL)

The \gamma-ray lines from ^7Be and ^7Li produced when flare-accelerated He nuclei interact with ambient He have been found to be surprisingly intense from measurements made by \gamma-ray spectrometers on the SMM and COMPTON satellites (Share amp; Murphy 1997; Murphy et al. 1997). These high intensities suggest either accelerated \alpha/p ratios \small\stackrel>\sim\normalsize 0.5 and/or a He/H abundance >0.1 in the sub-coronal regions where the particles interact. Mandzhavidze, Ramaty, and Kozlovsky (1997) outline how the recently selected HESSI/SMEX high-resolution Ge spectrometer could distinguish between the two possibilities by resolving and comparing intensities of additional lines at 0.339, 1.00, 1.05 and 1.19 MeV produced by interactions of \alpha-particles on Fe with the intensity of the 0.847 MeV line produced by proton interactions on Fe. They also note that the ^16O(^3He,p)^18F reaction produces lines at 0.937, 1.040 and 1.080 MeV which complicates the analysis but offers the possibility of making an in-situ measurement of accelerated ^3He in flares. We report on detailed spectroscopic studies of data from the moderate-resolution \gamma-ray spectrometers on SMM and COMPTON to determine whether some constraints can already be placed on the accelerated and ambient He abundances. This work is supported by NASA DPR W-18895.

Mandzhavidze, N., Ramaty, R., amp; Kozlovsky, B. 1997, ApJ, 489, L99.

Murphy, R.J. amp; Share, G.H. 1997, ApJ, 490 (December).

Share, G.H. amp; Murphy, R.J. 1997, ApJ, 485, 409.

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