Regensburg 2007 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 10: Poster

EP 10.19: Poster

Wednesday, March 28, 2007, 18:00–20:00, H46

Analysis of SOHO/EPHIN data using regularization techniques — •Robert Wimmer-Schweingurber, Eckart Boehm, Alexander Kharytonov, Reinhold Mueller-Mellin, Raul Gomez-Herrero, and Bernd Heber — Extraterrestrial Physics, Institute for Experimental and Applied Physics,*Christian-Albrechts-University Kiel, Germany

We analyze data from the Solar and Heliospheric Observatory (SOHO) instrument EPHIN by full deconvolution of the measured data with the instrument response function. We show how regularization methods can be applied to energetic particle measurements to derive unambiguously the original particle spectrum - devoid of any assumptions made about its functional behaviour. This inversion technique still requires knowledge of the instrument response function, however, it is an improvement upon normal least-squares or maximum-likelihood fitting procedures because it does not require any a priori knowledge of the underlying particle spectra. Given the instrument response function in matrix form (derived by Monte Carlo techniques), the original Fredholm integral equation reduces to a system of algebraic equations that can be solved by regularization methods, such as singular value decomposition (SVD) or the Tikhonov method with constraints (non-negative count rates). We apply the methods to measured data from SOHO/EPHIN. The derived results agree well with those of other methods that rely on a priori knowledge of the spectral shape of the particle distribution function, demonstrating the power of the method for more general cases.