1. RHESSI/NESSIE, June 2003 H.S. Hudson Gamma-ray event statistics H. Hudson, R. Lin, D. Smith

2. RHESSI/NESSIE, June 2003 H.S. Hudson Background Most extensive properties of solar flares follow a flat power law, ~W -1.8 Most extensive properties of solar flares correlate well if loosely with each other (hence the “Big Flare Syndrome”) Solar proton fluences are an exception (Hudson, Solar Phys. 57, 237, 1978)

3. RHESSI/NESSIE, June 2003 H.S. Hudson The RHESSI  -ray Event

4. RHESSI/NESSIE, June 2003 H.S. Hudson Upper limits from other events Have ~75 well-covered M and X flares For each take the GOES time range as the likeliest 2.223-MeV emission interval Determine upper limit using July 23 observation as a template

5. RHESSI/NESSIE, June 2003 H.S. Hudson Representative upper limit

6. RHESSI/NESSIE, June 2003 H.S. Hudson Non-RHESSI observations OSO-3 (first observations) HEAO-A4 (one event) HEAO-C3 (one event, Ge) SMM CGRO

7. RHESSI/NESSIE, June 2003 H.S. Hudson Observations and limits

8. RHESSI/NESSIE, June 2003 H.S. Hudson Summed-epoch analysis

9. RHESSI/NESSIE, June 2003 H.S. Hudson

10. RHESSI/NESSIE, June 2003 H.S. Hudson Conclusions RHESSI has not seen 2.223-MeV emission in any flare except for the July 23 event The upper limits lie outside the bounds of the “big flare syndrome” expectations Observations with other instruments are consistent Proton acceleration in flares is not part of the main flare process.