DEVELOPMENT OF ACCELERATOR-DRIVEN COMPACT NEUTRON SOURCES

Abstract

Compact neutron sources are good tools for neutron sci- entist. In this paper we will present the current situation of compact accelerator-driven neutron source and the status of the facility of Nagoya University. SNS,andISIS.Thesetwomethodshavegoodneutronemis- sion efficiency. Photonuclear reaction and low energy pro- ton (or deuteron) reaction are using at compact neutron sources. The other neutron emission methods are fusion reaction and radioisotope. These two methods are lower neutron flux than the other methods in the laboratory use. In CANS, neutron emission efficiency is not so high and neutron flux is lower than that of large facilities. In order to compensate the neutron flux, these reactions require the incident beam intensity. One solution is increase duty ratio by using cyclotron or electro static accelerator. However, it is not suitable for the case of pulse imaging method, which need neutron TOF(time of flight) information. In this case, we have to try to increase the peak current by using linear accelerator. In these way, we have to select the suitable ac- celeration beam properties. The incident beam energy is also important for CANS. High incident beam energy increasing the accelerator and radiationshieldsize,andalsoincreasetheconstructioncost. Ontheotherside, thelowenergybeamdecreasetheneutron emission efficiency. The relation between incident beam energy and neutron emission is written in elsewhere (1). The selection of beam energy and target should be carried out carefully. In less than 2 MeV region, the deuteron beam is only useful for CANS. But the moderation efficiency in eq. (1) is not so good because of the emitted neutron av- erage energy is more than one MeV. In 2 - 5MeV region, proton beam and Li target is suitable for CANS, however Li target is difficult to use, and second solution is Be target (2). In more than 5 MeV region, Be target is suitable (3).