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Title: Neutron activation cross-section measurements from 16 to 20 MeV for isotopes of F, Na, Mg, Al, Si, P, Cl, Ti, V, Mn, Fe, Nb, Sn, and Ba

Journal Article · · Nuclear Science and Engineering
DOI:https://doi.org/10.13182/NSE99-14· OSTI ID:20014327

Cross sections have been measured with the activation technique at various neutron energies in the range of 16.0 to 20.5 MeV for the following 22 reactions: {sup 19}F(n,p){sup 19}O, {sup 23}Na(n,p){sup 23}Ne, {sup 23}Na(n,{alpha}){sup 20}F, {sup 25}Mg(n,p){sup 25}Na, {sup 27}Al(n,p){sup 27}Mg, {sup 28}Si(n,p){sup 28}Al, {sup 29}Si(n,p){sup 29}Al, {sup 29}Si(n,np + pn + d){sup 28}Al, {sup 31}P(n,{alpha}){sup 28}Al, {sup 35}Cl(n,2n){sup 34m}Cl, {sup 37}Cl(n,p){sup 37}S, {sup 46}Ti(n,p){sup 46m}Sc, {sup 50}Ti(n,p){sup 50g+m}Sc, {sup 51}V(n,p){sup 51}Ti, {sup 55}Mn(n,{alpha}){sup 52}V, {sup 56}Fe(n,p){sup 56}Mn, {sup 57}Fe(n,np + pm + d){sup 56}Mn, {sup 57}Fe(n,p){sup 57}Mn, {sup 93}Nb(n,{alpha}){sup 90m}Y, {sup 93}Nb(n,2n){sup 92m}Nb, {sup 119}Sn(n,p){sup 119g}In, and {sup 138}Ba(n,2n){sup 137m}Ba. The half-lives for the reaction products range from 11 s to 10.15 days. Quasi-monoenergetic neutrons were produced via the {sup 3}H(d,n){sup 4}He reaction. In some cases isotopically enriched materials were used to enhance the reaction yield or to facilitate correction for interfering reactions leading to the same product. The gamma rays emitted from the irradiated samples were measured with a high-purity germanium detector. A pneumatic sample transport system was used to limit the decay of the radioactive products between neutron irradiation and gamma-ray counting. All cross sections were obtained as ratios to the standard reaction {sup 27}Al(n{alpha}){sup 24}Na, using as secondary neutron fluence references the {sup 27}Al(n,p){sup 27}Mg reaction as well as a calibrated Bonner sphere. Corrections have been applied for sample-irradiation and counting environment geometric effects, neutron absorption and multiple scattering, time variation of neutron-source strength, neutron-source angular distributions, secondary neutrons from the target, gamma-ray absorption, and gamma-ray sum coincidences. A detailed analysis of the uncertainty sources was performed. The present results are compared with other measurements and evaluated data. For seven reactions, measured cross sections have been obtained for the first time beyond 15 MeV. These new data help appreciably to resolve discrepancies in evaluated data files.

Research Organization:
Commission of the European Communities, Geel (BE)
Sponsoring Organization:
USDOE
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
20014327
Journal Information:
Nuclear Science and Engineering, Vol. 134, Issue 2; Other Information: PBD: Feb 2000; ISSN 0029-5639
Country of Publication:
United States
Language:
English