POSITRON-EMITTER PRODUCTION IN SOLAR FLARES FROM 3He REACTIONS
نویسندگان
چکیده
We treat in detail positron production from the decay of radioactive nuclei produced in nuclear reactions of accelerated 3He. Because of their large cross sections and low threshold energies, these reactions can significantly contribute to positron production in solar flares with accelerated-particle compositions enriched in 3He. The addition of these 3He reactions extends earlier calculations of positron production by accelerated protons and -particles. 3He reactions not only add significantly to the total positron yield in flares, but can also yield a positron depth distribution that peaks higher in the solar atmosphere. We discuss the impact these reactions have on the analysis of the annihilation line observed with RHESSI from the 2002 July 23 flare. A significant contribution from 3He reactions expands the utility of the annihilation line as a sensitive tool for investigating the structure of the flaring solar atmosphere. Subject headings: acceleration of particles — nuclear reactions, nucleosynthesis, abundances — Sun: flares — Sun: X-rays, gamma rays
منابع مشابه
The Physics of Positron Annihilation in the Solar Atmosphere
We compile the most recently measured and calculated cross sections for processes relevant to annihilation of positrons in solar flares and present the final evaluated cross sections. We calculate the 511 keV annihilation line spectrum and relative strength of the 3γ continuum for each of the annihilation processes, using a Monte Carlo code that simulates the thermalization of and positronium p...
متن کاملInvestigation of 50 Cr ( d , n ) 51 Mn and natCr ( p , x ) 51 Mn processes with respect to the production of the positron emitter 51 Mn
The positron emitter Mn (t1/2 5 46.2 min, Iβ1 5 97%) is of potential interest in positron emission tomography (PET). With a view to optimizing its production route, excitation functions for deuteron induced nuclear reactions on isotopically enriched (,95%) Cr were determined radiochemically over the energy range of 3 to 13 MeV and for proton induced nuclear reactions on Cr in the range of 18 to...
متن کاملWCSAR-TR-AR3-9311-1 Remote Sensing of Astrofuel [Prepared for Space 94, The 4th International Conference and Exposition on Engineering, Construction and Operations in Space, and The Conference and Exposition/Demonstration on Robotics for Challenging Environments, February 26 - March 3, 1994, Albuquerque NM]
A direct, high-resolution measurement from lunar orbit of the location of high concentrations of 3He in the lunar regolith is needed for the initiation of cost-effective mining operations on the moon. Gamma-ray spectroscopy has been successfully used to map the abundances and distributions of certain elements present in planetary regoliths. Helium-3 is unique among these elements since the gamm...
متن کاملSolar Latitudinal Distribution of Solar Flares around the Sun and Their Association with Forbush Decreases during the Period of 1986 to 2003
Solar flare events of high importance were utilised to study solar latitudinal frequency distribution of the solar flares in northern and southern hemisphere for the solar cycle 22 to recent solar cycle 23. A statistical analysis was performed to obtain their relationship with sudden storm commencement (SSCs) and Forbush decrease events (Fd) of cosmic ray intensity. An 11-year cyclic variation ...
متن کاملLithium-6 from Solar Flares
By introducing a hitherto ignored Li producing process, due to accelerated He reactions with He, we show that accelerated particle interactions in solar flares produce much more Li than Li. By normalizing our calculations to gamma-ray data we demonstrate that the Li produced in solar flares, combined with photospheric Li, can account for the recently determined solar wind lithium isotopic ratio...
متن کامل