An upgraded external beam PIXE setup for multielemental analysis of atmospheric aerosol samples Xu, M. ; Chu, Y. J. ; Wang, G. F. ; Qiu, M. L. ; Zheng, L. Abstract Publication: X-ray Spectrometry Pub Date: January 2018 DOI: 10.1002/xrs.2814 Bibcode: 2018XRS....47...79X