Photo sources

• This type of source uses the (g, n) reaction.
• An advantage of this type of source is that monoenergetic neutrons may be obtained.
  

  9Be + g ® 8Be + n	Q = -1.6 MeV
  d + g ® p + n	Q = -2.23 MeV

  
  
• The main disadvantage is the unavoidable g ray background.  They are also bulkier and give smaller yields than (a, n) sources.

See also: Radioactive sources