1. Audrey Wright TUNL REU 2013 University of Texas at Austin Adviser: Dr. Calvin Howell Other Group Members: Dr. Alexander Crowell, Dr. Mitzi Boswell Evaluating the Cross Section of 9 Be Near Threshold

2. Supernovae: Elemental Crock Pots R-process: a rapid chain of nuclei capturing neutrons to produce a heavier nucleus Needs region with high neutron flux and appropriately high temperature Image: NASA, “Hot Topics |International Year of Astronomy”

3. R-Process Product plot 4 He(  n,  ) 9 Be( ,n) 12 C S.E. Woosley and R.D. Hoffman, Astrophys. J. 395, 202 (1992) Evaluated cross section (Evaluated cross section)*2

4. Scientific Motivation Blue elements come from r-process in supernovae …  +   8 Be 8 Be + n  9 Be +  9 Be +   12 C + n … Where r-process begins!! Image: Nerlich, Steve. "Astronomy Without A Telescope – Alchemy By Supernova."Universe Today Reverse Reaction: 9 Be +   8 Be + n

5. 9 Be Energy Levels Transitions from and their relative contributions to the reaction 9 Be +   8 Be + n Also the contribution of 9 Be +   5 He+   +n Image: TUNL Nuclear Data Evaluation, 2004

6. The Experiment Setup: (gamma beam goes into page) Tested at many  -energy levels Two possible reactions: 1: 9 Be +   8 Be+ n 2: 9 Be +    +  + n  Neutron Detector || Neutron Detector 9 Be Detector 2: θ =90°, Φ =90° Detector 1: θ =90°, Φ =0°

7. My purpose: Data Analysis Asymmetry N || and N  are the integrals beneath the main peaks Contributions from each channel Channel 1: 9 Be +   8 Be+n Channel 2: 9 Be +    +  + n Energy increases 

8. Data Analysis (cont.) First, we make cuts on the data. N-peak AmBe calibration source for n detection (Pulse Height) Pulse Height vs Pulse Shape Spectrum PH PSPH

9. Data Analysis (cont.) Energy increases  Counts

10. Preliminary Results Prediction from EM Multipole Analysis of 9 Be( ,n) Ex (MeV) J π EM Channel A(90°) 4.703/2+E1 8 Be + n-0.75 3.055/2+E1 8 Be + n+0.50 2.801/2-M1 8 Be + n 0.00 2.435/2-M1 E2 8 Be + n -0.50 +0.28 5/2+ 5/2- Asymmetry

11. Summary Next steps One step closer to understanding the world and how we came to be here! Acknowledgements

12. References Images: "Hot Topics | International Year of Astronomy 2009." NASA International Year of Astronomy 2009 - IYA - Events, Topics, and Discoveries. NASA, 1 May 2009. Web. 30 July 2013. http://astronomy2009.nasa.gov/topics_no v.htm, http://astronomy2009.nasa.gov/topics_no v.htm Nerlich, Steve. "Astronomy Without A Telescope – Alchemy By Supernova."Universe Today — Space and astronomy news. N.p., 14 Aug. 2010. Web. 30 July 2013.. "Energy Level Diagrams A=9." Triangle Universities Nuclear Laboratory : 2013. N.p., n.d. Web. 30 July 2013.. http://www.tunl.duke.edu/nucldata/figur es/09figs/menu09.shtml#1959 Cowan, John J., and Friedrich-Karl Thielemann. "R-Process Nucleosynthesis In Supernovae." Physics Today 57.10 (2004): 47. Print. “Cross-Section Measurement of 9 Be( ,b) 8 Be and implications for  +  + n  9 Be in the r process” C. W. Arnold, T. B. Clegg, C. Iliadis, H. J. Karwawski, G. C. Rich, J. R. Tompkins, C. R. Howell. Physical Review, c 85, 2012 “Measurement of the 9Be(g,n) Cross Section Near Threshold”;M. Boswell, A.E. Champagne, A.S. Crowell, C. R. Howell, H. J. Karwowski, A.P. Tonchev. TUNL Progress Report XLIII 2003-2004 p. 135, Section 9.4.1 TUNL Nuclear Data Evaluation Project: http://www.tunl.duke.edu/nucldata/ (Jill!) http://www.tunl.duke.edu/nucldata/

13. Thank you! Any Questions?