sentences:  As soon as he arrived in Berlin, he became aware of the Bothe report (博特报告) relating to the emission of a new type of high-energy neutral radiation induced by the bombardment of beryllium with α particles from a radioactive polonium source, which was non-ionizing but even more penetrating than the strongest gamma rays derived from radium.These were (wrongly) presumed to be gamma rays.Wang suggested the use of a cloud chamber to study these particles.