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Isospin Diffusion Experiment(s) at RIKEN

Isospin Diffusion Experiment(s) at RIKEN. Betty Tsang August 22, 2012. O utline. Introduction – MSU expeirment Experimental Setup in RIKEN Status of RIKEN isospin expeirments Proposed reaction 132Sn+112Sn, 124Sn. HIC constraints on symmetry energy.

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Isospin Diffusion Experiment(s) at RIKEN

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  1. Isospin Diffusion Experiment(s) at RIKEN Betty Tsang August 22, 2012

  2. Outline • Introduction – MSU expeirment • Experimental Setup in RIKEN • Status of RIKEN isospinexpeirments • Proposed reaction 132Sn+112Sn, 124Sn

  3. HIC constraints on symmetry energy Current constraints from HIC weigh heavily on isospin diffusion. (The n/p ratios are more for consistency checks due to large error bars at high nucleon energy.

  4. Isospin Diffusion with Neck Fragments Liu et al.PRC 76, 034603 (2007). Ri(α)=Ri(d) assumingd=mα+b d (residue asymmetry) α (isoscaling parameter) This can be described by the isoscaling parameters  and :

  5. Confirm the assumed Linearity of α on δ • α depends linearly on the asymmetry according to statistical and dynamic models. • Experimentally verified in central collisions. • Measure 118Sn on 118Sn to add a data point to 112Sn + 112Sn and 124Sn + 124Sn. Ri(α)=Ri(d) assumingd=mα+b d (residue asymmetry, BUU) α (isoscalingparameter, expt)

  6. IsospinTransport in Residues • Different amount of isospin diffusion for heavy residues. • provide another isospin observable and impact parameter selection

  7. Experiment 07038: Precision Measurement of Isospin Diffusion • Investigates the density-dependence of the nuclear symmetry energy • 112,118,124Sn+ 112,118,124Sn Collisions • Combines the MSU Miniball, the LASSA Array, and the S800 Spectrograph Incoming Beam, 70 MeV/u Beam-like fragments 10<Z<50 J.R.Winkelbauer,7

  8. Experiment 07038: Precision Measurement of Isospin Diffusion Motions: Targets Downstream scintillator/degrader (deflect beam away from focal plane) Detectors miniball—b selection LASSA – detect Z<8 S800 – detect residues 20<Z<45 J.R.Winkelbauer,8

  9. 1. Introduction 1.1 Data taken at MSU (Ex07038) • 112,118,124Sn + 112,118,124Sn • ~5 mg/cm2 Targets • 70 MeV/u beam energy • Event rates 200-300/s • Beam Rate 2*107/s to 6*107/s • Millions of events:

  10. 1.2 RIKEN Experiment Primary beam: 124Xe (10-30 pnA) No 124Sn beam because there is no 132Xe primary beam 124Sn Beam is not available Proposed beams : 108Sn and 112Sn Proposed reactions: • 108Sn + 112Sn • 108Sn + 124Sn • 112Sn + 112Sn (referenced to MSU) • 112Sn + 124Sn (referenced to MSU) Calculations use beam intensities in the proposal based on 100 pnA of 124Xe beams

  11. 2. Proposed Experimental Set up Microball from WU Scintillator & degrader foil ladder Chamber from RIKEN

  12. Experimental Setup (It turns out that the beam intensity is only 20% of what is written in the proposal and here) Zero Degree Spectrometer BigRIPS Target Slits Fast Plastic Scintillator with a hole in the center: Polystyrene ,C8H8, 1.06g/cm3, 125 micron

  13. 6. Beam Charge States Measurement (With target, With Fast Plastic hole) 108Sn: 112Sn:

  14. 3. Brho “Safe” Region Avoid the beam Consider different reactions at the same time. (In current setting, the same fragments from different reactions have the similar Brho. ) Conclusion: choose the Brho region smaller than 2.58.

  15. 7. Al Degrader (For Plan A) Use the Al to replace the target to tune the beam into the fragments Brho region. (No target, No Fast Plastic) 108Sn: 112Sn:

  16. 5.2* Summary of the measured isotopes (for Plan B) Press here to directly go back to Slide 16

  17. Status • Xe beam cancelled for December, 2012 • Rachel Hodges will travel to RIKEN in week of Sept 10 and work on the chamber design & beam calculations. • Transport microball to RIKEN in Dec (Betty?) • Pursuing a separate set of electronics (loan from ORNL?) • Propose132Sn+ 112, 124Sn; 124Sn+124Sn (match to MSU) to Dec PAC • Run the proposed experiment as a campaign to the 108,112Sn + 112, 124Sn isospindiffusion expt.

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