Probing symmetry energy at high density

Betty Tsang, NSCL/MSU

CEE Pre-collaboration Workshop, Lanzhou, March 13, 2014

曾敏兒

SAMURAI p-Reconstruction

and Ion-tracker TPC

Collaboration

Nuclear Equation of State

Mathematical Relationship between energy, temperature, pressure, density in nuclear matter

E/A (,) = E/A (,0) + 2S() = (n- p)/ (n+ p) = (N-Z)/A

Nuclear Force – What is the nature of the nuclear force?

Nuclear Structure – What binds protons and neutrons into

stable nuclei and rare isotopes?

Nuclear Astrophysics – What is the nature of neutron stars

and dense nuclear matter?

Vcentral

Vtensor

r

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

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

Density dependence of symmetry energy

Equation of State of Asymmetric Nuclear Matter

Experimental Observables

@ < 0:

•Heavy Ion Collisions near

Fermi energy E/A~50 MeV

Isospin diffusions

•Comparison of constraints

to other observables from

nuclear masses and structure

•HIC is viable probe to study

the properties nuclear

matter.

Experimental Observables @ 20 :

•Challenges

•3n forces

•effective nucleon masses

•Observations from Neutron Star

•Heavy Ion Collisions in high

density; E/A>200 MeV

pi-/pi+ ratios and flow;

charge particles yield ratios

and flow – new detectors

•Status of SpRIT project

Summary and Outlook

Introduction

Probing symmetry energy at high density

知新溫故

Isospin Diffusion observable to study Esym with

Heavy Ion Collisions

Tsang, Shi et al., PRL92, 062701(2004)

S()=12.5(/o)2/3 +C (/o)

gi

Bao-An Li et al., Phys. Rep. 464, 113 (2008)

Tsang, Zhang et al., PRL122, 122701(2009)

Projectile

Target

124Sn

112Sn

Isospin Diffusion; low , Ebeam

Tsang et al., PRL 92 (2004) 062701

Large Esym

Small Esym

EoS of asymmetric matter -- Constraints from Heavy Ion

Collisions (HIC)

B.A

. Bro

wn,P

RL

85

(2000)5

296

Tsan

g et al,P

RL

10

2,1

2270

1(2

00

9)

...183

2

0

0

0

0

BsymB

osym

KLSE

E/A (,) = E/A (,0) + 2S(); = (n- p)/ (n+ p) = (N-Z)/A

Tsang et al. C 86, 015803 (2012)

heavy ion collisions

PRL 102,122701(2009)

p elastic scattering

PRC82,044611(2010)

Isobaric Analogue States

NPA 818, 36 (2009)

neutron-star radius

PRL108,01102(2012)

Pygmy Dipole Resonances

PRC 81, 041304 (2010)

Finite Droplet Range Model

PRL108,052501(2012)

...183

2

0

0

0

0

BsymB

osym

KLSE

Consistent Constraints on Symmetry Energy

from different experiments HIC is a viable probe

Constraints from nuclear structure and

reactions with credible uncertainties

NuSYM13 & ICNT2013

A Way Forward: Review paper from ICNT2013

Journal of Phys G (2014)

9

2

sym sym

*

if U U ,p

d Uaccel.

dt m

Momentum Dependence of Symmetry Energy

Central 124Sn+124Sn Collision

E/A = 120 MeV/AR

n/p

= Y

(n)/

Y(P

)

m*n<m*

p

neutrons more easily

accelerated to high

energies

m*p<m*

n

protons more easily

accelerated to high

energies

Y. Z

han

g, P

LB

(2014)

124Sn+124Sn;Y(nc)/Y(pc)112Sn+112Sn;Y(nc)/Y(pc)

Double Ratiominimize systematic errors

Data at high energy is consistent with mn*~<mp*

Thesis data :

Daniel Coupland

Michael Youngs

ImQMD05_sky张英逊 (Y. Zhang)

FOPI data not designed to

explore the symmetry energy

different codes give

contradictory interpretations

Theoretical & Experimental Challenges

Develop Reliable Transport Codes -- Code comparison

Workshop, Shanghai, Jan 8-12, 2014 + …

Design Better Experiments (SpRIT & CEE)

New observations of Neutron Stars (masses)

Lattimar & Prakash

Heavy Neutron Star masses rule out soft EOS

New observations of Neutron Stars (radius/Radii)

Lattimar & Prakash

SteinerS. Guillot, et al Astrophys. J.

772, 7 (2013), 1302.0023

Small Neutron Star radius rules out nearly all EOS

Suleimanov

SEP

Symmetry Energy @ 20 to explore neutron star radii(us)

SE@20 can only be explored on earth with Heavy Ion Collisions.

SE@>0 requires strong support from transport model community

Symmetry Energy science has high impact factors

See references in

PRC 86, 015803 (2012)

Importance of 3-body neutron-neutron force in the

Equation of State of pure neutron matter

Steiner et al., ApJ 722, 33 (2012)

Accuracies Needed: factor of 2

Hebler et al., PRL 105 161102, (2010)

Large uncertainties in the symmetry

energy beyond saturation density.

Successful Strategies used to study the symmetry energy

with Heavy Ion collisions with RIB Vary the N/Z compositions of

projectile and targets e.g.• 132Sn+124Sn, 132Sn+112Sn,

108Sn+124Sn, 108Sn+112Sn Measure isospin sensitive

observables such as isotope distributions (isospin diffusion), n/p, t/3He ratios, flow

Simulate collisions with transport theory

• Find the symmetry energy

density dependence that

describes the data.

• Constrain the relevant input

transport variables.

Neutron Number N

Pro

ton

Nu

mb

er Z

3/2AaAaB SV 3/1

)1(

A

ZZaC

A

ZAasym

2)2(

Isospin degree of freedom

Hub

ble

ST

Crab Pulsar

B.A. Li et al., Phys. Rep. 464, 113 (2008)

Heavy Ion Collisions at high density with RIBOld data: Au+Au, E/A=150 to 1500 MeV

Proposed New Experiments at RIB facilities

Similar RIB reactions

can be used to study

isospin diffusions.

DjjID pn

ID Increase with

asymmetry gradient

6.5 days approved by

2013 June RIKEN PAC

124Sn+124Sn

Elab=120 MeV/A

b = 1fm

BU

U fro

m: D

anielew

icz, NP

A673

, 375 (2

000

).

To Probe Symmetry Energy at >0

with Sub-threshold Pions from HIC

• New observables: p-/p+ ratios

• New detectorsMSU: Active Target –Time Projection Chamber

RIKEN: SAMURAI – Time Projection Chamber

Bick

ley et al., p

rivate co

mm

. (20

09

)

S-TPC

S-TPC will be installed inside the SAMURAI

dipole magnet in RIKEN

chamber

Beam

x

y

Rigid Top PlatePrimary structural member,

reinforced with ribs.

Holds pad plane and wire planes.Front End ElectronicsLiquid Cooled

Pad Plane (108x112)

Used to measure particle

ionization tracks

Field CageDefines uniform electric field.

Contains detector gas.

Thin-Walled EnclosureProtects internal components,

seals insulation gas volume,

Supports pad pan while

allowing particles to continue

on to ancillary detectors.

Voltage Step-DownPrevent sparking from cathode

(20kV) to ground

Target Mechanism

Calibration Laser Optics

beam

SAMURAI TPC: Exploded View

RailsInserting TPC into

SAMURAI vacuum chamber

Beam

Thin-Walled EnclosureProtects internal

components, seals

insulation gas volume, and

supports pad plane while

allowing particles to continue

on to ancillary detectors.

Rigid Top PlatePrimary structural member,

reinforced with ribs.

Holds pad plane and wire

planes.

Pad PlaneMounted to bottom of

top plate. Used to measure

particle ionization tracks

Field CageDefines uniform electric field.

Contains detector gas.

Voltage Step-DownPrevent sparking from

cathode (20kV) to ground

Wire PlanesMounted below pad plane.

Provide signal multiplication

and gate for unwanted events

RailsFor inserting TPC into

SAMURAI vacuum

chamber

SAMURAI TPC: Exploded ViewFront End ElectronicsSTAR FEE for testing,

ultimately use GET

Target Mechanism

Calibration

Laser Optics

Construction status

Ship to RIKEN in February, 2014!

0.5m

1.5m1m

glued circuit

boards

Assembled for initial testing, May 2013

Four 17”x26”

PCBs

14 separate

circuit boards

on each side of

each wire plane

Gluing field cage together, Feb 2013

Pad and wire planes, March 2013

Pads that “see” cosmic ray

(108x226 mm^2)

Testing with state of the art -- GET

(General Electronics for TPC)

Figure courtesy of GET collaboration.

10.5 bit dynamic range

1KHz – 10Gb/s

Testing with 1024 channel GET (1 CoBo (Concentration

Board)+4AsAd (ASIC &ADC) at 1.2 GB/s taking 1000

four Magapixel digital photos per second.

Packing and shipping

2 PM Feb 25 2014 MSU

9AM Feb 28 2014

RIKEN

MilestonePlanned

Date

Actual

Date

Enclosure Conceptual design 3/15/11 3/15/11

Enclosure Detailed design (TAMU) 9/30/11 9/30/11

Detector Conceptual design 3/15/11 3/15/11

TPC parts Completed (MSU) 3/15/2012 3/30/2012

Enclosure Assembled (MSU) 5/31/2012 6/15/2012

MilestonePlanned

Date

Actual

Date

TPC construction Completed (MSU) 6/28/2013 5/15/2013

Deliverable, Hardware completed 9/30/2013 9/30/2013

TPC arrives at RIKEN 1/1/2014 2/28/2013

DOE Funding: 10/1/2010-9/31/2015

Schedule

February 2014 Shipment of TPC to RIKEN

Spring 2014 Setup and testing of TPC/electronics

Summer 2014 Installation into SAMURAI magnet

Spring 2015 Commissioning and first experiments

(13.5 days Sn+Sn approved in RIKEN)

Collaboration members

United States: J. Barney, Z. Chajecki, J. Estee, M. Famiano, W. Lynch, A. McIntosh, R. Shane,

M.B. Tsang, S. Tangwancharoen, G. Westfall, S. Yennello, M. Youngs

Japan: K. Ieki, T. Isobe, T. Murakami, J. Murata, Y. Nakai, N. Nakatsuka, S. Nishimura, H.

Sakurai, A. Taketani

China: F. Lu, R. Wang, Z. Xiao

United Kingdom: M. Chartier, R. Lemmon, W. Powell

France: E. Pollacco

Italy: G. Verde

Korea: B. Hong, G. Jhang

Poland: J. Lukasik Special thanks

NSCL staff: J. Yurkon, D. Bazin, J. Pline, and many others

HiRA group students: R. H. Showalter, J. Winkelbauer

TAMU staff: R. Olsen

Participating institutes in the TPC construction

Welcome collaboration

Summary

• The Equation of State is critical to our understanding on– Nuclear force;

– Nuclear structure;

– Neutron star properties

• Consistent constraints on the symmetry energy obtained

at sub-saturation densities implies that– Same strategies to use collisions of RIB to study the EoS

of asymmetric matter can be applied to high density.

• New observations of neutron star radius (~9Km) and

masses (2solar) suggest a softening of EoS ~20

– Unique opportunity at RIKEN & IMP