Summary of EOS working group Z. Chajecki,B . Tsang

1. Summary of EOS working groupZ. Chajecki,B. Tsang Neutron stars HICs, Structure Tan Ahn Additional contributions from:Garg, Brown, Pagano Neutron skin

2. ICNT—International Collaborations in Nuclear Theory http://frib.msu.edu/content/ICNT • MSU, GSI, & RIKEN directors contribute $50k/year to host 10-20 theorists’ get-together for 2-4 weeks. • ICNT2013 held at NSCL/FRIB- Symmetry-energy in the context of new radioactive beam facilities and astrophysics (Chuck Horowitz) • Week I (July 15 - 19): Symmetry energy at low nuclear densities • Week II (July 22 - 26): NuSYM13 • Week III (July 29 – Aug 2): Symmetry energy at high densities including astrophysical environment • Week IV (Aug 5 - 9): Future Directions • Deliverable: Write-up of a document after the ICNT ICNT reflected the international nature of EOS investigations. There are new results and initiatives from ICNT/NuSYM13. EOS working group - Summary

3. Equation of State of Nuclear Matter E/A (,) = E/A (,0) + d2S() d = (n- p)/ (n+ p) = (N-Z)/A Strategies used to study the Symmetry Energy with HICs • Vary the N/Z compositions of projectile and targets • e.g, 108,132Sn+112,124Sn,52Ca+48Ca • Measure N/Z compositions of emitted particles • At low energies: isotopes yields isospindiffusion • Simulate collisions with transport theory • Find the symmetry energy density dependence that describes the data. • Constrain the relevant input transport variables. adapted from M.B. Tsang, PRL 102, 122701 (2009) Brown, Phys. Rev. Lett. 85, 5296 (2001) Stiff Soft Super soft EOS working group - Summary

4. Updated constraints on Symmetry Energy E/A (,) = E/A (,0) + d2S() d = (n- p)/ (n+ p) = (N-Z)/A Updated from ICNT/NuSYM13 Consistent constraints establish HIC and structure as viable probe to study symmetry energy at supra-saturation density EOS working group - Summary

5. Astrophysics and Nuclear Physics Neutron star Skyrme interactions Observation: MNS ~ 2Msun RNS ~ 9 km Equation of State stiff EoS at high r softening EoS at r~2r0 EOS working group - Summary

6. Astrophysics and Nuclear Physics AV14+UVII Wiringa, Fiks, & Fabrocini 1988 Neutron star HIC at FRIB Equation of State softening EoS at r~ 2r0 stiff EoS at high r Pions at r~2r0(J. Hong and P. Danielewicz, pBUU) EOS working group - Summary

7. How to probe Sym En at r~2r0 AT-TPC @ MSU Spirit TPC @ MSU (for RIKEN) Cosmic tracks observed • TPC and active target • 4p acceptance of reaction products including pions • AT-TPC prototype successful • Final AT-TPC being assembled and electronics being tested. • Will reside inside Twist solenoid magnet • Construction completed, electronics testing underway • To be shipped to RIKEN in Jan 2014 • To be placed inside SAMURAI magnet • Commissioning and first experiment 2015 EOS working group - Summary

8. Improve constraints: GMR, GDR AT-TPC @ MSU • Giant Monopole Resonances in neutron-rich nuclei • Kt,Kcoreand Kskin “soft GMR” akin to pigmy GDR’s. • Need inverse reactions 2H, 4He, or 6Li targets beams of 35-100 MeV/A • TPC’s offer the best options for now. • AT-TPC (NSCL); CAT (CNS, Tokyo), MAYA (GANIL) • Experiments being planned/proposed at RIKEN and NSCL. U. Garg • TPC as active target where TPC gas is the target • Provides good energy resolution for a thick target • 4p acceptance of inelastically scattered target gas atoms • Will reside inside Twist solenoid magnet • For ALL EoS measurements, we need to move AT-TPC to fast beam area EOS working group - Summary

9. Establishing the mom-dependence of the Sym En Isospinmultiplet ratios in112Sn+112Sn and 124Sn+124Sn @ 50 and 120 MeV/A • Improvements for Neutron Walls • Veto charged particles directly in front of NW • Construct new PV scintillator array • Increase segmentation • Reduce scattering of charged particles through PV’s • Already have PMTs • Estimated cost: $50,000 (~$1,000/scintillator w/o PMTs) Protons (LASSA) ΘCM (deg) Neutrons (NW) E/A=120MeV horizontal(or vertical) PV array EOS working group - Summary

10. Experiments to provide additional constraints • Measuring time scale of N/Z equilibration • Pagano et al, INFN, Catania • S. Hudan, de Souza et al., Indiana University • Isospin diffusions with RIBs • New observables: projectile-like residues • NSCL--112,118,124Sn+112,118,124Sn • RIKEN --109In+112Sn EOS working group - Summary

11. New MONA-LISA Program • Use RIBs from NSCL; enhances sensitivityto Esym • Dedicated experiment approved (concept tested on previous data) • Couple with light fragment detection (HiRA?) EOS working group - Summary

12. Sub-barrier fusion x-section of n-rich nuclei Physics Motivations: Neutron Star Crust Fusion Dynamics ⇒ EOS Fusion of n-rich light nuclei may be important for heating the crust and to determine its chemical composition Need RIBs! Advantages: Relatively small floor space requirement (9ft x 3ft on beamline) Few days of beam time per isotope to measure the excitation function EOS working group - Summary

13. Summary • There is a rich program to constrain the symmetry energy at both low and high densities with RIBs • Next frontier is the high density region observation of small NS radius and high mass suggests a softening of SE at r~2r0 • Progress in theory is important – transport model workshop scheduled in Jan, 2014 in China (ICNT) • Future needs: • Moving AT-TPC to the fast beam area for both giant resonances and pion measurements • Neutron wall veto detector to improve the identifications of charge particles • Chamber for charge particle detection with MONA-LISA • General beam line for fusion measurements at REA3 EOS working group - Summary