Prospects for hard X-ray solar flare polarimetry with RHESSI


Designed primarily as a hard X-Ray imager and spectrometer the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is also capable of measuring the polarization of hard X-Rays (20–100 keV) from solar flares. These studies will provide the capability to probe the geometry of the acceleration process. Although not originally designed to study hard X-Ray polarization of solar flares, it was realized during the development of RHESSI that the essential ingredients for measuring the polarization, namely, an array of detectors in a rotating spacecraft, were already present. All that was needed was the addition of a strategically placed cylinder of Be in the cryostat to Compton scatter the hard X-Rays (20–100 keV) into the rear segments of the adjacent Ge detectors, since the direction of the scattering depends on the polarization of the incoming photon. Monte Carlo simulations indicate that a 20–100 keV polarization sensitivity of less than a few percent can be achieved for X-class flares, by comparing the counting rates of these rear segments.


Space Science Center, Physics

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COSPAR Colloquia Series



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Conference Proceeding


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