Susan Olmsted
Advisor: Dr. John Kelley
ND Project Coordinator: Grace Sheu
Background
 Nuclear Data Evaluation
 The National Nuclear Data Center (NNDC)
 Isotope half-lives
 Applications
 Accuracy is important
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
Methods
 Literature review
 Data averaging software:
Visual Averaging Library
 Several averaging
techniques
Possible Averaging
Techniques
 Unweighted average
 Weighted average
 Limit of Statistical Weights
 Note: Be careful when
choosing the uncertainty
Outliers?
 Outliers usually marked by Chauvenet’s Criterion
 Deviation from the mean
 Does not take uncertainties into account
 Not always bad values
 Use 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 errors
 From 1964BI02:
Nitrogen-16 Recalculated
Chi-square: 0.48
(Critical Chi-square: 2.21)
Results
 Half-life values for several isotopes
 Website
 Tables for each beta decay isotope
Nuclide Method
Value
Quality
13O
Unweighted Average
8.73(12)
NA
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
Outliers?
No outliers
Recommended
8.58(7)
Future work
 Dealing with the more difficult isotopes
 Dealing with outliers
 Dealing with poor agreement
 Juggling averaging methods
 Activating the website completely
Source
 http://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?