Editing Neutron activation analysis (section)

==Neutron sources==
A range of different sources can be used:
* A nuclear reactor
* An [[actinoid]] such as [[californium]] which emits neutrons through spontaneous fission
* An alpha source such as [[radium]] or [[americium]], mixed with [[beryllium]]; this generates neutrons by a (α,<sup>12</sup>C+n) reaction
* A D-T fusion reaction in a [[Neutron generator|gas discharge tube]]

===Reactors===
Some reactors are used for the neutron irradiation of samples for [[radioisotope]] production for a range of purposes. The sample can be placed in an irradiation container which is then placed in the reactor; if epithermal neutrons are required for the irradiation then [[cadmium]] can be used to filter out the thermal neutrons.

===Fusors===
A relatively simple [[Farnsworth–Hirsch fusor]] can be used to generate neutrons for NAA experiments. The advantages of this kind of apparatus is that it is compact, often benchtop-sized, and that it can simply be turned off and on. A disadvantage is that this type of source will not produce the neutron flux that can be obtained using a reactor.

===Isotope sources===
For many workers in the field, a reactor is an item which is too expensive; instead, it is common to use a neutron source which uses a combination of an alpha emitter and beryllium. These sources tend to be much weaker than reactors.

===Gas discharge tubes===
These can be used to create pulses of neutrons, they have been used for some activation work where the decay of the target isotope is very rapid. For instance in oil wells.<ref>[http://www.glossary.oilfield.slb.com/Display.cfm?Term=neutron+generator Search Results – Schlumberger Oilfield Glossary<!-- Bot generated title -->]</ref>