The Time History of 2.22 MeV Line Emission in Solar Flares

In this paper we examine the time dependence of 2.22 MeV emission using observations of the Solar Maximum Mission (SMM) gamma-ray spectrometer. We will determine the decay time constant for the 2.22 MeV emission process and from this derive implications concerning the density at which neutrons are captured and the value of the ^3He/H ratio. We will also set upper limits on the number of low energy neutrons produced in solar flares. The 2.22 MeV line provides a unique tool for probing the physics of the solar atmosphere since the neutrons which produce the line penetrate to depths exceeding the opacities at which optical observations can be made.