DEM Distributions for Short and Long Duration Flares as Determined from RESIK Soft X-ray Spectra

Title:		DEM Distributions for Short and Long Duration Flares as Determined from RESIK Soft X-ray Spectra
Authors:		A. Kepa, J. Sylwester, B. Sylwester, M. Siarkowski and V. Kuznetsov
Abstract:		RESIK bent crystal spectra (3.3 Å - 6.1 Å) constitute a unique database to study the distribution of plasma with temperature in solar flares. A convenient way to describe this is based on the interpretation of so-called differential emission measure (DEM) distributions. DEM shape contains important information for investigations of the energy transport processes and studies of flare energy balance. From many methods available for determination of DEM shape we selected to use the "Withbroe - Sylwester" multiplicative iterative algorithm, in order to interpret of RESIK line and continuum fluxes. The respective emission functions were calculated based on the CHIANTI spectral code. The nineteen independent input fluxes as measured throughout a number of selected flares have been used for DEM determinations. In the present study, we compare and discuss the DEM shapes as obtained for two groups of flares - short and long duration - in order to check for presence of any noticeable differences.