Interlaboratory study of eddy-current measurement of excess-carrier recombination lifetime by Blum, A, Swirhun, J, Sinton, R, Yan, F, Herasimenka, S, Roth, T, Lauer, K, Haunschild, J, Lim, B, Bothe, K, Hameiri, Z, Seipel, B, Xiong, R, Dhamrin, M, Murphy, J