我国的原子能科学技术在迅速地发展着,有越来越多的人要同放射綫打交道。人們为了工作的需要和保护人体安全,都需要测定放射綫。但是,放射綫是看不見的,应当怎样来測定呢?可以求助于一类专門的仪器——探測器。天然放射性物质,如鈾、钍等,能放出α China’s atomic energy science and technology are rapidly developing and more and more people are dealing with radiation. People need to measure radiation in order to work and protect human safety. However, radiation is invisible. How should we measure it? We can turn to a special kind of instrument - a detector. Natural radioactive substances, such as uranium, thorium, etc., can release alpha