Solar X-ray Spectroemters (SOXS) 

• The SOXS experimental payload has been proposed for Indian Geostationary Satellite (GSAT). The  experiment is primarily meant to study the disk integrated radiative flux from the Sun in the 2 keV-10 MeV energy range. The proposed instrumentation of SOXS payload consists of two types of detector modules viz. SOXS Low Energy Detector (SLD) Module and SOXS high Energy Detector (SHD) Module. The SLD module consists of state-of-the-art semiconductor device viz. Silicon P-intrinsic-N (PIN) detector for the low energy X-rays (2-15 keV) and Cadmium-Zinc-Telluride (CZT) detector for soft to medium hard X-rays in the energy range 4-50 keV, on the other hand, SHD module consists of a large phoswich scintillation detector for high energy X-rays and gamma rays (15 keV-10MeV). The SLD and SHD payload will work independently so as to observe the disk integrated radiative flux from the sun to enable to study the phenomenon of solar flare energy spectra. The responsibilities of design, development, fabrication and delivery of SLD and SHD payloads are shared between PRL, TIFR and Technical Physics Division (TPD), ISAC

• It is proposed to study the challenging and unanswered questions related to energy release processes and particle acceleration mechanisms in solar flares. The high spectral and time resolution observations in 2-300 keV energy range will address outstanding problems in solar physics such as (a) Solar flare energetics and dynamics, (b) Solar chromospheric and coronal heating, and (c) Interaction of magnetic field with plasma in active regions. This will also reveal, perhaps for the first time, the break in the energy spectrum at lower energies with sub-keV energy resolution to understand the thermal and non-thermal characteristics of solar flares as well as the nature of global contribution of micro and nano-flares which might be responsible for heating the solar chromosphere and corona. Further the comparison of the line and continuum spectra between SLD and SHD will reveal whether electrons and ions are accelerated simultaneously. The spectral resolution of SHD may be able to answer an important question viz. whether ions are accelerated in all flares or only in the more energetic ones. 

• The high energy observations during a solar flare will be a unique set of data not available so far. Also both the SLD and SHD measurements during the high solar activity period, are likely to produce high levels of solar research activity in the country.

• A meeting of SOXS PIs (of SLD and SHD payloads) along with a large number of solar astronomy groups in the country was held during January 19-20, 2000 at PRL, Ahmedabad. The participating solar physicists mentioned that multi-wavelength observations using ground based solar telescopes and development of suitable models would  be in-built into the space segment efforts.