21. Upon irradiation, a thermal neutron interacts with the target nucleus via a non-elastic collision, causing neutron capture. 22. Ancient and historic steel in Japan, India and Europe, a non-invasive comparative study using thermal neutron diffraction. 23. A Helium-3 ( He-3 ) filled proportional counter is the most common epithermal and thermal neutron detector. 24. Intermediate-energy neutrons have poorer fission / capture ratios than either fast or thermal neutrons for most fuels. 25. This detector shows good efficiency at detecting fast neutrons in a background of thermal neutrons and gamma radiation. 26. It will operate with thermal neutrons . 27. Even comparatively low speed thermal neutrons cause neutron activation ( in fact, they cause it more efficiently ). 28. The second most used fissile isotope plutonium-239 can also fission or not fission on absorbing a thermal neutron . 29. The hexaboride has a low coefficient of thermal expansion and a high nuclear cross section for thermal neutrons . 30. "This system uses a very simple technology, called thermal neutron analysis, " said Shea, the chief operating officer.
