2. By Billy Mohr Advisor: Professor Daryl Hartley Sponsored by the National Science Foundation

3. Experiment at Gammasphere Heavy Ion Reaction Heavy Ion Fusion Reaction – 124 Sn( 51 V,4n) 171 Ta Experiment was designed to look for Triaxial Deformation

4. n n n n ProcessFusion Evaporation (4 neutrons) Statistical Gamma rays Discrete Gamma Rays Yrast Line

5. Data Analysis Necessary to Do: -Calibration of Detectors Need to account for Doppler shift of energies due to the moving target. Same Physics done in General Physics still applies: Ta- 171 is moving, thus detectors observes different frequencies. (Energy proportional to frequency) -Efficiency of Detectors Done with known sources with known energy states of gamma ray emmission. Important to account for relative efficiency since Gammasphere does not detect different energies equally. Then we can begin to analyze the spectrum

6. Eu-152 Spectrum Used for Calibration of Detectors since Energies were Known

7. Relative Efficiency Diagram Channel # (Correlates to Energy) Relative Efficiency Used 182 Ta, 152 Eu, 56 Co sources Low energy Full Range High Energy

8. Doppler Shift Correction E (Φ) =Eo(1+βcos(Φ)) β=(speed of Ta-171)/(speed of light) Φ=Angle at which detectors were relative to target 32° 70 ° 90 ° 110 ° 148 °

9. Data Analysis of Ta-171 It is possible to determine shape and behavior of a nucleus from the decay sequences and energy states at which it emits gamma rays. The energies that Gammasphere detected were sorted into a 3-D Coincidence Matrix All gamma rays being detected within 80ns were said to be coincidence with one another

10. Data Analysis of Ta-171 Sample Spectrum

11. d 5/2 h 9/2 g 7/2 d 3/2 h 11/2 i 13/2 J.C. Bacelar et al., Nucl. Phys. A 442, 54 (1985) (with only 6 detectors)

12. What does all this mean?? A Level Scheme is useful for:A Level Scheme is useful for: -Indications of deformations -Alignment -Trends in Energies -Band Structure -Backbending Backbending is a term used to describe significant gains in angular momentum that’s not due to rotation of the nucleus.

13. d 5/2 270450 g 7/2 280355 h 11/2 266 h 9/2 293 d 3/2 270346 Theory predicts crossings at 200 keV for the neutron alignments and 530 keV for the proton alignments Evidence of Backbending Predicted by Theory [d5/2] Unexplained by Current Theory [g7/2] keV keV ħ

14. Summary No evidence for triaxial deformation yet. Further research required Linked all bands together through transitioning gamma rays. Found approx. 130 new gamma rays. Interesting back bending properties Thanks to D.J. Hartley, M.K. Djongolov, F.G. Kondev, H. Amro, A. Aguilar, D.L. Balabanski, M.P. Carpenter, P. Chowdhury, W. Cluff, D.M. Cullen, M. Danchev, G.D. Dracoulis, G.B. Gagemann, A.M. Kishada, K. Lagergren, T. Lauritsen, E.F. Moore, E. Ngijoi-Yogo, S.W. Odegard, A. Pipidis, L.L. Riedinger, S.V. Rigby, M.A. Riley, D.T. Scholes, G. Sletten, S.K. Tandel, C. Teal, J.R. Vanhoy, P.M. Walker, and Jing-ye Zhang

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