1. Susan Olmsted Advisor: Dr. John Kelley ND Project Coordinator: Grace Sheu

2. Background Nuclear Data Evaluation The National Nuclear Data Center (NNDC) Isotope half-lives Applications Accuracy is important

3. Our Goals To determine accurate half-life values for A=3-20 nuclides To create an online database that provides these values This data will eventually be folded into the ENSDF (Evaluated Nuclear Structure Data File) database

4. Methods Literature review Data averaging software: Visual Averaging Library Several averaging techniques

5. Possible Averaging Techniques Unweighted average Weighted average Limit of Statistical Weights Note: Be careful when choosing the uncertainty

6. Outliers? Outliers usually marked by Chauvenet’s Criterion Deviation from the mean Does not take uncertainties into account Not always bad values Use caution

7. Intuitive Case: Carbon-17 Chi-square: 0.24 (Critical Chi-square: 2.37)

8. More Complex Case: Nitrogen-16 Chi-square 21.77 (Critical Chi-square: 1.88)

9. Nitrogen-16 Rearranged

10. Nitrogen-16 (cont.) Systematic errors From 1964BI02:

11. Nitrogen-16 Recalculated Chi-square: 0.48 (Critical Chi-square: 2.21)

12. Results Half-life values for several isotopes Website Tables for each beta decay isotope NuclideMethodValueQualityOutliers?Recommended 13OUnweighted Average8.73(12)NANo outliers8.58(7) Weighted Average8.575(67)Chi: 1.93 Limit. of Stat. Weights8.575(67)Chi: 1.93 Normalization Residuals8.575(67)Chi: 1.93 Rajeval Technique8.67(16)Chi: 0.53 MBR8.65(16)56.40% Boostrap8.72(20)Chi: 6.35 Mandel-Paule8.66(14)Chi: 3.48

13. Future work Dealing with the more difficult isotopes Dealing with outliers Dealing with poor agreement Juggling averaging methods Activating the website completely

14. Source http://www.nndc.bnl.gov/ J.K., Bienlein, and Kalsch Elsbeth. “The Half-life of N 16." Nuclear Physics 50: 202-08. Nuclear Science References. Web. 26 July 2015.. Questions?