SOLAR ENERGETIC PARTICLE SPECTRUM ON 2006 DECEMBER 13 DETERMINED BY IceTop by Abbasi, R, Ackermann, M, Adams, J, Ahlers, M, Ahrens, J, Andeen, K, Auffenberg, J, Bai, X, Baker, M, Baret, B, Barwick, S, Bay, R, Alba, J, Beattie, K, Becka, T, Becker, J, Becker, K, Berghaus, P, Berley, D, Bernardini, E, Bertrand, D, Besson, D, Bieber, J, Blaufuss, E, Boersma, D