Measurement of Neutron Activation Cross Sections of Energy up to 40 MeV Using Semimonoenergetic p-Be Neutrons

An intense semimonoenergetic neutron field was made using a simple beryllium target system bombarded by protons of nine different energies between 20 and 40 MeV. Natural sodium, aluminum, vanadium, chromium, manganese, copper, zinc, and gold samples were irradiated at this field, and gamma rays from the samples were observed by a germanium detector. The production rates of 17 radionuclides were obtained for the nine different neutron fields, and the excitation functions of these 17 reaction channels of ²³Na(n,2n)²²Na, ²⁷Al(n, α)²⁴Na, ⁵¹V(n, α)⁴⁸Sc, ⁵¹V(n,p)⁵¹Ti, 50Cr(n,3n)⁴⁸Cr, ⁵⁰Cr(n,2n)⁴⁹Cr, ⁵⁵Mn(n,4n)⁵¹Ti, ⁵⁵Mn(n,4n)⁵²Mn, ⁵⁵Mn(n,2n)⁵⁴Mn, ⁶³Cu(n,3n) Cu, ⁶³Cu(n,2n)⁶²Cu, ⁶⁵Cu(n,p)⁶⁵Ni, ⁶⁴Zn(n,t)⁶² Cu, ⁶⁴Zn(n,3n)⁶²Zn, ⁶⁴Zn(n,2n)⁶³Zn, ¹⁹⁷Au(n,4n)¹⁹⁴Au, and ¹⁹⁷Au(n,2n)¹⁹⁶Au were obtained for neutron energies up to 40 MeV by using the SAND-II and the NEUPAC unfolding codes and also least-squares fitting. The initial guess value for these methods was obtained primarily from calculations of the ALICE/LIVERMORE82 code.