1. RHESSI Observations of Gamma- Ray Lines from Solar Flares Albert Y. Shih 1, David M. Smith 2, Robert P. Lin 1, Richard A. Schwartz 3, Gerald H. Share 4, Ronald J. Murphy 4 1 Department of Physics and Space Sciences Laboratory, UC Berkeley, Berkeley, CA 2 Department of Physics and Santa Cruz Institute for Particle Physics, UC Santa Cruz, Santa Cruz, CA 3 NASA Goddard Space Flight Center, Greenbelt, MD 4 E. O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, D.C.

2. Flare p nd e+e+ e-e- , p, ions , p, ions  p Nuclear de-excitation Positron annihilation 0.511 MeV Neutron capture 2.223 MeV Solar Gamma Rays Sun

3. RHESSI Observations RHESSI Gamma-Ray Flares DateGOES Class 2002 July 23X4.8 2003 June 17M6.8 2003 October 28X17 2003 October 29X10 2003 November 2X8.3 2003 November 3X3.9 2004 November 10X2.5 Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

4. Spectral Components 511 keV 2.2 MeVpower law narrow broad total model

5. Temporal Variability Analysis 00:27:20–00:32:56 UT00:32:56–00:43:20 UT

6. Low-FIP: Fe, Mg, Si High-FIP: Ne, C, O Temporal Variability Results 2002 July 232003 October 282003 November 2 0.29±0.080.80±0.14 Low-FIP/high-FIP ratios 0.36±0.050.74±0.20

7. Other Variability Analysis From the 20 Ne/( 12 C+ 16 O) ratio, there is no evidence for proton spectral variability in the 2003 October 28 or 2003 November 2 flares. There is weak evidence for temporal variation in the heavy ion/proton ratio based on broad to narrow line flux ratios (Share SH13A-1135).

8. Summed-Flare Spectra Sum together the three best flares Analyze weak lines such as the 339 keV  -Fe line or the 937 keV  - 3 He line

9. Line-Shape Analysis Sum together the Mg, Ne, and Si lines Use the line-shape to constrain the  /p ratio  -induced p-induced combined Assuming a spectral index of 3.75, the  /p ratio is

10. Summary RHESSI has observed several flares that exhibit temporal variability of line flux ratios. This variability may be due to variations in the ambient abundances, and in some flares the pattern of variation is consistent with low-FIP enhancement. Summed-flare analysis of the flares can be used to put constraints on the fluxes of weak lines and on the alpha-proton ratio.