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问题 问答题 简答题

绝对探测效率和本征探测效率的区别是什么？

答案

参考答案：

绝对探测效率考虑的是对每一个源发射出的粒子，探测器测量到的计数值；

本征探测效率考虑的是对每一个射入探测器的粒子，探测器测量到的计数值；

绝对探测效率是整个探测系统中所有环节的综合表现；而本征探测效率则主要反映了探测器的特性；

填空题

根据短文内容，用方框中所给单词的适当形式填空，每词限用一次。

Scientists would like to put a huge mirror in space above the earth. It might be sixty miles wide. It would be   小题1:to catch the rays of the sun. it would direct the sun’s rays on the earth as a child might do to make sunlight   小题2: on the wall with a hand mirror.

Why do they want to do this? The sun’s rays could be   小题3:  in many ways. They could light up   小题4:  by night. The warm rays could stop frosts(霜冻) which might come at night and hurt fruit and crops. They could melt（融化) 小题5: icebergs in the ocean. Perhaps they could change cloud movements and bring rain where it is needed.
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单项选择题

X线的韧致辐射的产生是由于()

A．高速运动的电子作用于靶原子的内层电子 

B．高速运动的电子作用于靶原子的外层电子 

C．高速运动的电子作用于靶原子的原子核 

D．高速运动的电子作用于靶原子的内层电子和原子核 

E．高速运动的电子作用于靶原子的内层电子层电子 
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