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197 A u at the End of the Dragon

197 A u at the End of the Dragon. Evan O’Connor University of PEI August 2 nd , 2006. Outline. Nuclear Astrophysics Dragon GEANT Testing Dragon’s Acceptance Summary.

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197 A u at the End of the Dragon

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  1. 197Au at the End of the Dragon Evan O’Connor University of PEI August 2nd, 2006

  2. Outline • Nuclear Astrophysics • Dragon • GEANT • Testing Dragon’s Acceptance • Summary 197Au at the End of the Dragon Evan O’Connor

  3. Nuclear Astrophysics… • …is the branch of physics that examines the formation of elements through nuclear reactions and the rates at which they occur. These rates determine the evolution and composition of stars and the makeup of solar systems 197Au at the End of the Dragon Evan O’Connor

  4. 15X 16Y Enter the Dragon… • Gas target, g array, electromagnetic mass separator • Uses inverse kinematics for radioactive beams 197Au at the End of the Dragon Evan O’Connor

  5. Selecting Mass 197Au at the End of the Dragon Evan O’Connor

  6. q 16Y Motivation • Important astrophysical reactions (12C(a,g)16O, 15O(a,g)19Ne) have maximum angles ~16 mrad (cone angle) • Dragon’s nominal cone angle is 20 mrad • When cone angles approach 20 mrad are all recoil particles transmitted fully through Dragon? If not, can we accurately predict the losses using computer software? 197Au at the End of the Dragon Evan O’Connor

  7. Geant • Computer simulation package specializing in simulating elementary particle trajectories • Upgrades were made to the simulated Dragon which include the addition of beam pipes and electrodes in dipoles • Source energy distribution model was re-evaluated to obtain an accurate fit to observed spectrum assuming detector efficiencies 197Au at the End of the Dragon Evan O’Connor

  8. Alpha Source Acceptance Studies • 148Gadolinium Alpha source in Dragon’s mouth • Double-Sided Silicon Strip Detector (DSSSD) • Previous Acceptance studies disagree with GEANT • Notched collimator to allow for ‘ray-tracing’ 20 mrad half angle 197Au at the End of the Dragon Evan O’Connor

  9. Detector locations Measurements Taken • Five orientations of collimator at three different locations + 1 measurement with no collimator 197Au at the End of the Dragon Evan O’Connor

  10. Measurements Taken • Transmission percentages between Detector location 1 and 2 for different orientations • This will raise a flagto allow for a more in-depthlook at Dragon Detector locations 197Au at the End of the Dragon Evan O’Connor

  11. Transmission 1-2 Percent transmission between detector position 1 and position 2 E (Experiment) S (Simulation) E: 93.4 +/- 0.5 S: 99.0 +/- 0.8 E: 62.9 +/- 0.6 S: 80.7 +/- 0.7 E: 88.7 +/- 0.9 S: 95.9 +/- 0.7 E: 96.4 +/- 0.4 S: 99.7 +/- 0.8 E: 98.7 +/- 1.0 S: 99.0 +/- 0.8 197Au at the End of the Dragon Evan O’Connor

  12. At Detector 2 Simulation: Experiment: Counts DSSSD Y Position (mm) 197Au at the End of the Dragon Evan O’Connor

  13. Moving first Quad1mm Up Simulation: Experiment: The same behaviour is seen when source is moved down ~2mm Counts DSSSD Y Position (mm) 197Au at the End of the Dragon Evan O’Connor

  14. Summary • A critical assumption in Dragon’s work is that all recoils are transmitted to the end. This is an issue with upcoming reactions approved for Dragon • To answer my two questions: Yes particles are lost in Dragon when cone angles are large Simulations show ‘agreement’ with experiment AND are probing problems observed with experiments 197Au at the End of the Dragon Evan O’Connor

  15. Thanks • Jonty Pearson, Dave Hutcheon • Dragon Collaboration • TRIUMF Student Summer Program • UPEI Co-op Program 197Au at the End of the Dragon Evan O’Connor

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