Delayed neutrons emitted from cooling water at high energy proton accelerator facility

At a high energy proton accelerator facility, cooling water passing through magnets along a primary proton beam line is exposed to high energy secondary particles and becomes activated. The radiation levels on the surface of the water pipe carrying the activated water may be quite high due to annihilation gamma rays of positron emitters. It is also probable that radionuclides (RNs) emitting delayed neutrons are produced in cooling water. Delayed neutrons released from cooling water have been successfully measured and 17N (T1/2 = 4.17 s) was identified as the RN responsible for the delayed neutrons by measuring the half-life. (Author)