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9th RHESSI Workshop |
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Genova, Italy, September 1-5 2009 |
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Participants |
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Leonty Miroshnichenko N.V. Pushkov Institute IZMIRAN, Moscow Region, Russia Email: leonty (at) izmiran.ru Group 2 Contribution: By the data on intensity-time profiles of the neutron capture line of 2.223 MeV we have studied some characteristics of two solar flares, 28 October 2003 and 20 January 2005 (INTEGRAL and CORONAS-F observations, respectively). The SINP code was applied making allowance for the main processes of neutron interactions and deceleration in the solar plasma, character of neutron source, losses of neutrons and density model of the solar atmosphere. Comparison of the computed time profiles of 2.223 MeV line with observed ones for the flare of 28 October 2003 confirms the results obtained earlier for three other flares. Namely, the effect of density enhancement (EDE) in the sub-flare region, as well as the variations (hardening) of accelerated particle spectrum in the course of the event have been confirmed. The usual modeling procedure by the SINP code, however, seems to be inapplicable to the event of 20 January 2005. Possible causes of density enhancements during some flares and peculiarities of the 20 January 2005 flare are discussed. Group 4 Contribution: Analysis of the intensity ratios between various gamma-lines produced by energetic solar particle in solar flares allows us to estimate the element abundances and other properties of surrounding medium in the region of particle interactions. In this paper we discuss the flux ratio between two lines with energies of 15.11 MeV and 4.44 MeV from excited states of 12C nuclei (f15.11/f4.44) and present our preliminary results of calculations for the intensity ratio between two lines with energies of 20.58 MeV and 2.223 MeV (f20.58/f2.233) produced by neutron capture on the nuclei of 3He and 1H, respectively. In particular, we consider a possibility to obtain 3He/1H ratio by the satellite data on high-energy gamma-emission of large solar flares. Some peculiar spectral features observed during the flare of 20 January 2005 are analyzed. Preliminary analysis of energy spectrum in the range of 2-21 MeV for this flare gives the value of 3He/1H ¡Ü 2¡Á10-4, i.e. ten times larger than widely accepted earlier ratio about 2¡Á10-5 in the photosphere. This conclusion is confirmed by numerical simulation of the intensity-time profile of the 2.223 MeV line by SINP code. Some other implications of the CORONAS-F and RHESSI data on gamma-lines are discussed.
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