We have published our excellent understanding of the background in the XENON100 detector that comes from beta and gamma radiation:
E. Aprile et al. (XENON100), Study of the electromagnetic background in the XENON100 experiment, arXiv:1101.3866. The paper is also published in Physical Review D83 (2011), 082001, with an erratum ibid. D85 (2012), 029904.