Summary of EOS working group

Z. Chajecki,B. Tsang

Additional contributions from: Garg, Brown, Pagano

Neutron starsHICs, Structure

Neutron skin

Tan Ahn

EOS working group - Summary 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

Equation of State of Nuclear Matter

3

E/A (,) = E/A (,0) + 2S()

= (n- p)/ (n+ p) = (N-Z)/A

adapted fromM.B. Tsang, PRL 102, 122701 (2009)

Brown, Phys. Rev. Lett. 85, 5296 (2001)

Stiff

Soft

Super soft

• 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 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

EOS working group - Summary 4

Updated constraints on Symmetry Energy

Updated from ICNT/NuSYM13

E/A (,) = E/A (,0) + 2S()

= (n- p)/ (n+ p) = (N-Z)/A

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

Observation:MNS ~ 2Msun

RNS ~ 9 km

Equation of Statestiff EoS at high softening EoS at ~20

Skyrme interactionsNeutron star

EOS working group - Summary 6

Astrophysics and Nuclear Physics

Neutron star

Equation of Statesoftening EoS at ~ 20

stiff EoS at high

HIC at FRIB

AV14+UVII Wiringa, Fiks, & Fabrocini 1988

Pions at ~20 (J. Hong and P. Danielewicz, pBUU)

0.8

0.9

1

1.1

1.2

1.3

0 20 40 60 80 100 120 140

Central Sn+Sn collisionsE/A = 300 MeV

=0.5=1.0=2.0

M(

- ,132

+124

)/M(- ,1

08+1

12)

KEcm

(MeV)

EOS working group - Summary 7

How to probe Sym En at ~20

Spirit TPC @ 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

AT-TPC @ 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

EOS working group - Summary 8

Improve constraints: GMR, GDRAT-TPC @ MSUGiant Monopole Resonances in

neutron-rich nuclei

Kt, Kcore and Kskin “soft GMR” akin to pigmy GDR’s.

Need inverse reactions2H, 4He, or 6Li targetsbeams 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

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

EOS working group - Summary

Establishing the mom-dependence of the Sym En

9

1. Isospin multiplet ratios in112Sn+112Sn and 124Sn+124Sn @ 50 and 120 MeV/A

E/A=120MeV

Protons (LASSA)

Neutrons (NW)

ΘC

M (d

eg)

Improvements for Neutron WallsVeto 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

EOS working group - Summary 10

Experiments to provide additional constraints

Isospin diffusions with RIBs• New observables: projectile-like residues• NSCL--112,118,124Sn+ 112,118,124Sn• RIKEN --109In+112Sn

Measuring time scale of N/Z equilibration• Pagano et al, INFN, Catania• S. Hudan, de Souza et al., Indiana University

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 nucleiPhysics Motivations: Neutron Star Crust Fusion Dynamics ⇒ EOSFusion 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 suggestsa softening of SE at ~20

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