TY - GEN

T1 - On the importance of a new formula for the double differential scattering kernel

AU - Dagan, R.

PY - 2004/12/1

Y1 - 2004/12/1

N2 - The original double differential scattering kernel developed by Rothenstein and Dagan for heavy isotopes, differs from the current NJOY solution procedure. The main difference is in the exclusion of the strong scattering resonances in the latter. The scattering kernel of many materials of interest like U238 is strongly dependent on the cross section profile, mainly in the vicinity of resonances, which leads to changes in the absorption and in the Doppler-effect. Moreover, former investigations and the current one indicate that the MCNP treatment in the epithermal region is questionable as the code applies unjustified approximations. New mathematical formalism by Rothenstein enabled the implementation of the modified kernel within the THERMR module of NJOY. The problematic of the existing kernel in NJOY is thus demonstrated and preliminary results emphasize the importance of using the new formula for the scattering kernel for nuclides with strongly energy dependent scattering cross-sections. The essential steps to improve the MCNP sampling methods are also discussed.

AB - The original double differential scattering kernel developed by Rothenstein and Dagan for heavy isotopes, differs from the current NJOY solution procedure. The main difference is in the exclusion of the strong scattering resonances in the latter. The scattering kernel of many materials of interest like U238 is strongly dependent on the cross section profile, mainly in the vicinity of resonances, which leads to changes in the absorption and in the Doppler-effect. Moreover, former investigations and the current one indicate that the MCNP treatment in the epithermal region is questionable as the code applies unjustified approximations. New mathematical formalism by Rothenstein enabled the implementation of the modified kernel within the THERMR module of NJOY. The problematic of the existing kernel in NJOY is thus demonstrated and preliminary results emphasize the importance of using the new formula for the scattering kernel for nuclides with strongly energy dependent scattering cross-sections. The essential steps to improve the MCNP sampling methods are also discussed.

KW - Double Differential Scattering

KW - Resonant absorption

KW - S(α, β)

UR - http://www.scopus.com/inward/record.url?scp=22344433359&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:22344433359

SN - 0894486837

T3 - Proceedings of the PHYSOR 2004: The Physics of Fuel Cycles and Advanced Nuclear Systems - Global Developments

SP - 2201

EP - 2207

BT - Proceedings of the PHYSOR 2004

T2 - PHYSOR 2004: The Physics of Fuel Cycles and Advanced Nuclear Systems - Global Developments

Y2 - 25 April 2004 through 29 April 2004

ER -