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Precise Measurement of Internal Conversion in 197Pt

This study explores internal conversion theory in 197Pt through gamma decay and electron ejection, using ICCs for various analysis applications. The process involves nuclear reactor activation, spectral and impurity analysis, and K-shell calculation. Future work includes improving accuracy and acknowledgements of key contributors.

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Precise Measurement of Internal Conversion in 197Pt

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  1. Precise aK Measurement in 197Pt A Test of Internal Conversion Theory Mark Hernberg Advisor: Dr. John C. Hardy Mentor: Dr. Ninel Nica

  2. Internal Conversion • Atomic electron ejection • Followed by characteristic • X-ray emission Gamma Decay • Photon emission What Is Internal Conversion?

  3. Internal Conversion Coefficient ICCs are used in the study of: • Nuclear decay schemes • Spin and parity assignments, • Transition rates • Branching ratios • Detector efficiency calibration

  4. 346.5 M4 95.41 min 268.78 M1+E2 8.2% 199.44 M1+E2 15.4 ps 53.1 E2 16.58 ns 81.2% 77.35 M1+E2 10.6% 191. ns 19.89 hr stable 197mPt Decay CITATION: Nuclear Data Sheets (2005) From NNDC(BNL) Program ENSDAT

  5. Source Preparation • Homogeneous Layer of Sample • 0.7mg 196Pt dissolved in a solution of aqua-regia • 96% enriched sample, naturally occurring is only ~25% • Heated & dried to solidify • Placed on thin layer of Mylar • Thermal Neutron Activation • At TRIGA nuclear reactor here on campus • Activation time of ~4 hours

  6. Oops – Activation Problems • Long sample activation time resulted in an excessive level of both impurities and activity. 197mPt 197Pt

  7. Data Collection • 17 spectra collected from ~3 hours to 9 days after activation • Over 700 million counts • Average of over 900 counts/sec! • Relative photopeak efficiencies calibrated to 0.15%

  8. Detector Info Source • 3 Main Events in Detector: • Photoelectric Effect • Compton Scattering • Pair Production

  9. Spectral Analysis Spectrum 1: 8.28 minute run time, 55.4% live time, ~1.2 million total counts

  10. Spectral Analysis Spectrum 17: 22.1 hour run time, 97.6% live time, ~1 million total counts

  11. Impurity Analysis

  12. Impurity Analysis • Check known & common impurities- like 197Au • Make educated guesses: Known Gammas for 124Sb* Energy (keV) Ig(%) 602.7 98.2 722.78 10.8 1690.9 47.7 Found Gammas Energy (keV) Ig(%) 602.5 97.5 722.6 10.4 1691.4 47.1 *TORI Data from LBNL website (1999)

  13. Spectral Analysis

  14. Spectral Analysis 197Au 191m Hg 191m Hg

  15. Peak Analysis

  16. aK Calculation • Full Formula aK K-shell ICC wK fluorescence yield 0.959(4)* NK, Ng peak area eK, eg detector efficiency *E. Schönfeld, H. Jaben, NIM A 369 (1996) 527.

  17. Preliminary Results

  18. To Infinity and Beyond • Prepare another 196Pt sample, this time with the correct activation level. • Repeat data collection & analysis process • Determine aK to <1% uncertainty.

  19. Acknowledgements • Dr. John C. Hardy • Dr. Ninel Nica • Victor Iacob

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