Nuclear Data EvaluationSusan Olmsted

Advisor: Dr. John KelleyND Project Coordinator: Grace Sheu

BackgroundNuclear Data EvaluationThe National Nuclear Data Center (NNDC)Isotope half-lives

ApplicationsAccuracy is important

Our GoalsTo determine accurate half-life values for

A=3-20 nuclidesTo create an online

database that provides these values

This data will eventually be folded into the ENSDF (Evaluated Nuclear Structure Data File) database

MethodsLiterature reviewData averaging

software: Visual Averaging Library

Several averaging techniques

Possible Averaging TechniquesUnweighted averageWeighted averageLimit of Statistical

WeightsNote: Be careful when

choosing the uncertainty

Outliers?Outliers usually marked by Chauvenet’s

CriterionDeviation from the meanDoes not take uncertainties into account

Not always bad valuesUse caution

Intuitive Case: Carbon-17

Chi-square: 0.24(Critical Chi-square: 2.37)

More Complex Case: Nitrogen-16

Chi-square 21.77(Critical Chi-square: 1.88)

Nitrogen-16 Rearranged

Nitrogen-16 (cont.)Systematic errorsFrom 1964BI02:

Nitrogen-16 Recalculated

Chi-square: 0.48(Critical Chi-square: 2.21)

ResultsHalf-life values for several isotopesWebsiteTables for each beta decay isotope

Nuclide Method Value Quality Outliers? Recommended

13O Unweighted Average 8.73(12) NA No outliers 8.58(7)

Weighted Average 8.575(67) Chi: 1.93

Limit. of Stat. Weights 8.575(67) Chi: 1.93

Normalization Residuals 8.575(67) Chi: 1.93

Rajeval Technique 8.67(16) Chi: 0.53

MBR 8.65(16) 56.40%

Boostrap 8.72(20) Chi: 6.35

Mandel-Paule 8.66(14) Chi: 3.48

Future workDealing with the more difficult isotopes

Dealing with outliersDealing with poor agreementJuggling averaging methods

Activating the website completely

Sourcehttp://www.nndc.bnl.gov/J.K., Bienlein, and Kalsch Elsbeth. “The Half-life

of N16." Nuclear Physics 50: 202-08. Nuclear Science References. Web. 26 July 2015. <http://www.nndc.bnl.gov/nsr/>.

Questions?