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Neutron Capture Cross Sections from 1 MeV to 2 MeV by Activation Measurements

Neutron Capture Cross Sections from 1 MeV to 2 MeV by Activation Measurements. Korea Institutes of Geoscience and Mineral Resource. G.D.Kim, T.K.Yang, Y.S.Kim, H.J.Woo, H.W.Choi, and W. Hong. Korea Atomic Energy Research Institutes. J.H.Chang. Introduction.

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Neutron Capture Cross Sections from 1 MeV to 2 MeV by Activation Measurements

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  1. Neutron Capture Cross Sections from 1 MeV to 2 MeV by Activation Measurements Korea Institutes of Geoscience and Mineral Resource G.D.Kim, T.K.Yang, Y.S.Kim, H.J.Woo, H.W.Choi, and W. Hong Korea Atomic Energy Research Institutes J.H.Chang

  2. Introduction Activation method : Historically first means of measurement of NCCS in MeV range completely selective for a given nuclide in a mixture of target isotopes relatively simple to carry out In KIGAM NCCS are being measured by activation method Energies : 1 MeV to 2 MeV fusion reactor material research Material : 63Cu and 186W In KIGAM neutron facility Mono-energetic fast neutrons source : 3T(p,n)3He reaction. Proton energy stability of the used accelerator : within 1keV Producible maximum neutron energy : 2.6 MeV

  3. Target Analysis ERD RBS TiT target T : 4.6 x 1018 atoms/cm2 , Ti : 1.4 x 1019 atoms/cm2

  4. Neutron Energy Spread smeasured2 =sresonance2 + stithick2 , : NES 1.3 % at 2.1 MeV NES 1.7 % at 1.67 MeV

  5. Neutron Pulse Shape and Height Spectrum

  6. KIGAM neutron facility Cooling system monitor sample beam detector Target chamber

  7. Neutron Captured Cross Section Nof sact Dl = -lt1 -lt2 -lt3 (1-e e 1-e ) Rled )( )( l • Dl : gamma counts per unit time, No : areal density of sample • : neutron flux,sact : neutron captured cross section l : decay constant of activated sample t1 : neutron irradiation time t2 : elapsed time from irradiation to measurement t3 : measured time of gamma ray, Rl : transition probability ed : absolute gamma ray efficiency

  8. f(t) ;time dependence factor, subscript“o” refers to standard reaction Do = Nofoso Roeo fo/lo …… (1) D = N fs R e f/l …… (2) (1)/(2) D Nofo Roeo fol s = so Do N f R e f lo l =0.693/t ½ , fo/f = (pho/to)/(ph/t) , t :neutron irradiation time D No (ph)o t Roeo fo t 1/2 so s = Do N (ph) to R e f t1/2,0

  9. Characteristics of Sample Abundance : 63Cu = 69.2 %of Cu, 186W=28.6 % of W

  10. Absolute Efficiency of HPGe detector By MCNP code and standard mixed source

  11. Transition Probability By Table of Isotopes

  12. Gamma Spectrum of 198Au 411 keV

  13. Gamma Spectrum of 64Cu 511 keV

  14. Gamma Spectrum of 187W and Background 479 686

  15. Measured Data Table

  16. Neutron Captured Cross Sections of 63Cu

  17. Neutron Captured Cross Sections of 186W

  18. Total Cross Section Io I : neutron counts in sample–in Io : neutron counts in sample-out No: areal density of sample ln ( ) I st = No In scattering correction factor Dst = (p/4) (DL/L1L2)2 sn(0o) sn(0o)= (kR +1)4/4k2 : diffraction theory based on a continuum model R = 1.33 A1/3 10-13 cm, D is diameter of detector L is distance from target to detector, L1 is distance from target to sample L2 is distance from detector to sample

  19. Total Cross Sections of Cu

  20. Total Cross Sections of W

  21. Results Neutron capture cross sections of 63Cu and 186W Total scattering cross section of Cu and W Geometric Efficiency of HP Ge detector

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