Covariance Propagation in R-Matrix Model Fitting

CHEN Zhen-Peng; SUN Ye-Ying; ZHANG Rui; LIU Ting-Jin

Chinese Physics C> 2004, Vol. 28> Issue(1) : 42-47

Covariance Propagation in R-Matrix Model Fitting

Department of Physics,Tsinghua University,Beijing 100084,China2 China Nuclear Data Center,Beijing 102413,China

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Abstract：
This work is done for improving the current international standard cross section of nuclear reaction. The features of covariance propagation in R-matrix model fitting for ⁷Li,¹¹B and ¹⁶O systems are researched systematically with Code RAC, and the results about propagation of non-diagonal elements of covariance matrix are presented. It is found that in R-matrix model fitting, short-energy-range parameters result in relatively smaller covariance propagation coefficient (CPC), medium and long-energy-range parameters produce relatively larger CPC. Especially the medium-energy-range component of systematic error plays very important role in propagation of covariance. In the evaluation procedure of nuclear data both long-energy-range component (LERC) and medium-energy-range component (MERC) of systematic error should be considered in experimental data-base file. Furthermore, these conclusions are suitable for the similar model fitting in other science fields.

References

[1]

.Carlson A D,Muir D W,Pronyaev V G.2001,IAEA,INDC (NDS)24252.ZHANG Feng,KONG Xiang-Zhong.High Energy Phys.and Nucl.Phys.,2003,27 (1):28 (in Chinese)(张锋,孔祥忠.高能物理与核物理,2003,27(1):28)3.CHEN Zhen-Peng,ZHANG Rui,SUN Ye2Ying et al.Science in China,2003,G46(3):2554.Smith D L.Probability.Statistics and Data Uncertainties in NuclearScience and Technology,American Nuclear Society,Inc.1991,229 —2325.CHEN Zhen-Peng,SUN Ye-Ying.IAEA,2003,INDC(NDS)2438:626.Lane A M,Thomas R G.Reviews of Modern Physics,1958,30 (2):257

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CHEN Zhen-Peng, SUN Ye-Ying, ZHANG Rui and LIU Ting-Jin. Covariance Propagation in R-Matrix Model Fitting[J]. Chinese Physics C, 2004, 28(1): 42-47.

CHEN Zhen-Peng, SUN Ye-Ying, ZHANG Rui and LIU Ting-Jin. Covariance Propagation in R-Matrix Model Fitting[J]. Chinese Physics C, 2004, 28(1): 42-47. shu

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Received: 2003-05-26
Revised: 1900-01-01

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沈阳化工大学材料科学与工程学院沈阳 110142

Covariance Propagation in R-Matrix Model Fitting

Corresponding author: CHEN Zhen-Peng,

Department of Physics,Tsinghua University,Beijing 100084,China2 China Nuclear Data Center,Beijing 102413,China

Received Date: 2003-05-26
Accepted Date: 1900-01-01
Available Online: 2004-01-05

Abstract: This work is done for improving the current international standard cross section of nuclear reaction. The features of covariance propagation in R-matrix model fitting for ⁷Li,¹¹B and ¹⁶O systems are researched systematically with Code RAC, and the results about propagation of non-diagonal elements of covariance matrix are presented. It is found that in R-matrix model fitting, short-energy-range parameters result in relatively smaller covariance propagation coefficient (CPC), medium and long-energy-range parameters produce relatively larger CPC. Especially the medium-energy-range component of systematic error plays very important role in propagation of covariance. In the evaluation procedure of nuclear data both long-energy-range component (LERC) and medium-energy-range component (MERC) of systematic error should be considered in experimental data-base file. Furthermore, these conclusions are suitable for the similar model fitting in other science fields.