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

ICNT—International Collaborations in Nuclear Theory EOS working group - Summary 2 MSU, GSI, & RIKEN directors contribute $50k/year to host 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 ): Symmetry energy at low nuclear densities Week II (July ): 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.

Equation of State of Nuclear Matter EOS working group - Summary 3 E/A ( ,  ) = E/A ( ,0) +  2  S(  )  = (  n -  p )/ (  n +  p ) = (N-Z)/A adapted from M.B. Tsang, PRL 102, (2009) Brown, Phys. Rev. Lett. 85, 5296 (2001) Stiff Soft Super soft Vary the N/Z compositions of projectile and targets e.g, 108,132 Sn+ 112,124 Sn, 52 Ca+ 48 Ca Measure N/Z compositions of emitted particles At low energies: isotopes yields  isospin diffusion Simulate collisions with transport theory Find the symmetry energy density dependence that describes the data. Constrain the relevant input transport variables. Strategies used to study the Symmetry Energy with HICs

Updated constraints on Symmetry Energy EOS working group - Summary 4 Updated from ICNT/NuSYM13 E/A ( ,  ) = E/A ( ,0) +  2  S(  )  = (  n -  p )/ (  n +  p ) = (N-Z)/A Consistent constraints establish HIC and structure as viable probe to study symmetry energy at supra-saturation density

Astrophysics and Nuclear Physics EOS working group - Summary 5 Observation: M NS ~ 2M sun R NS ~ 9 km Equation of State stiff EoS at high  softening EoS at   Skyrme interactionsNeutron star

Astrophysics and Nuclear Physics EOS working group - Summary 6 Neutron star Equation of State softening EoS at   stiff EoS at high  HIC at FRIB AV14+UVII Wiringa, Fiks, & Fabrocini 1988 Pions at  ~2  0 (J. Hong and P. Danielewicz, pBUU)

How to probe Sym En at  ~2   EOS working group - Summary 7 Spirit MSU (for RIKEN)  TPC and active target  4  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 MSU  Construction completed, electronics testing underway  To be shipped to RIKEN in Jan 2014  To be placed inside SAMURAI magnet  Commissioning and first experiment 2015 Cosmic tracks observed

Improve constraints: GMR, GDR EOS working group - Summary 8 MSU Giant Monopole Resonances in neutron-rich nuclei  K   K core and K skin “soft GMR” akin to pigmy GDR’s.  Need inverse reactions 2 H, 4 He, or 6 Li targets beams of 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 For ALL EoS measurements, we need to move AT-TPC to fast beam area  TPC as active target where TPC gas is the target  Provides good energy resolution for a thick target  4  acceptance of inelastically scattered target gas atoms  Will reside inside Twist solenoid magnet

Establishing the mom-dependence of the Sym En EOS working group - Summary 9 1.Isospin multiplet ratios in 112 Sn+ 112 Sn and 124 Sn and 120 MeV/A E/A=120MeV Protons (LASSA) Neutrons (NW) Θ CM (deg) 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) horizontal (or vertical) PV array

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

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

Sub-barrier fusion x-section of n-rich nuclei EOS working group - Summary 12 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

Summary EOS working group - Summary 13 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  ~2  0 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