The National Superconducting Cyclotron Laboratory

Betty Tsang, Asy-EOS Slide 1

The National Superconducting

Cyclotron Laboratory@Michigan State University

U.S. flagship user facility for rare isotope research and education in nuclear science, astro-nuclear physics, accelerator physics, and societal applications


Michigan

State

University


Facility for Rare Isotope Beams (FRIB)

FRIB will provide intense beams of rare isotopes (that is, short-lived nuclei

not normally found on Earth). FRIB will enable scientists to make

discoveries about the properties of these rare isotopes in order to better

understand the physics of nuclei, nuclear astrophysics, fundamental

interactions, and applications for society.


282 employees, including 24 faculty, 46 graduate, and 51 undergraduate students.(as of March 05)

489 employees, including 40 faculty, 64 graduate and 70 undergraduate students

as of August 16, 2011


Facility for Rare Isotope Beams (FRIB)

FRIB will provide intense beams of rare isotopes (that is, short-lived nuclei

not normally found on Earth). FRIB will enable scientists to make

discoveries about the properties of these rare isotopes in order to better

understand the physics of nuclei, nuclear astrophysics, fundamental

interactions, and applications for society.


Graffiti Art, Dequindre Cut, Detroit, August, 2012

Artist: Kobie Solomon


Nuclear Structure – What is the nature of the nuclear force that binds protons and

neutrons into stable nuclei and rare isotopes?

Nuclear Astrophysics – What is the nature of neutron stars and dense nuclear

matter? What is the origin of elements heavier than iron in the cosmos? What are the

nuclear reactions that drive stars and stellar explosions?

Tests of Fundamental Symmetries – Why is there now more matter than antimatter

in the universe?

Research with rare isotope beams

Nuclear Equation of State

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

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


EoS of asymmetric matterE/A (, ) = E/A (,0) + 2S() = (n- p)/ (n+ p) = (N-Z)/A1

• The symmetry energy influences

many properties of neutron stars:

– Radii, moments of inertia

– Cooling rates

– Phase transitions in interior

• The symmetry energy dominates

the uncertainty in the n-matter EOS.

B.A

. Bro

wn

,PR

L8

5(2

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0)5

29

6

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et a

l,PR

L1

02

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(20

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...183

2

0

0

0

0

BsymB

osym

KLSE

Constraints from Heavy

Ion Collisions (HIC)


Tsang et al. C 86, 015803 (2012)

HIC: heavy ion collisions;

PRL 102,122701(2009)

p elastic scattering

PRC82,044611(2010)

Isobaric Analogue States

NPA 818, 36 (2009)

neutron-star radiusPRL108,01102(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


Neutron Number N

Pro

ton

Nu

mb

er

Z

3/2AaAaB SV 3/1

)1(

A

ZZaC

A

ZAasym

2)2(

EoS of asymmetric matterE/A (, ) = E/A (,0) + 2S() = (n- p)/ (n+ p) = (N-Z)/A1

Tsa

ng

et a

l,PR

L1

02

,12

27

01

(20

09

)

Constraints from Heavy

Ion Collisions (HIC)

Isospin degree of freedom

To improve experimental constraints:

: constraints mainly obtained from ID

: Increase the (A-2Z)2/A; RI beams

: Identify new observables

: remeasure n/p ratios


NSCL Experiment 07038: Precision

Measurement of Isospin Diffusion

Incoming Beam,

70 MeV/uBeam-like fragments

10<Z<50

Talk by J.R. Winkelbauer

• Investigates the density-dependence of the nuclear symmetry energy

using isospin diffusion from residues – new observable

• 112,118,124Sn+ 112,118,124Sn Collisions

• Combines the MSU Miniball, the LASSA Array,

& S800 Spectrograph


Isospin diffusion experiments with RIB


Isospin Diffusion Experimental Setup at RIKEN

BigRIPSZero Degree

Spectrometer

Target

15

WU microball


Physics at high density IB

.A. B

row

n,P

RL

85

(20

00

)529

6

Tsa

ng

et

al,P

RL

10

2,1

22

70

1(2

00

9)

??

Large uncertainties in the

symmetry energy high

density.

??

B. L

iu e

t al. P

RC

65

(20

02

)04

52

01

At <0 density, mass splitting

increase with density and

asymmetry


Use n/p spectral ratios and double

ratios to probe mn* and mp* and Esym

– 124Sn+124Sn;112Sn+112Sn,E/A=120 MeV

(Coupland, Youngs)

– 48Ca+124Sn; 40Ca112Sn,E/A=140 MeV

(Hodges, Rachel)

Zh

an

g, p

riva

te c

om

mu

nic

atio

ns

nucleon effective masses from n/p ratios

Coupland et al,

Sn+Sn,

E/A=120 MeV

09042

miniball

n-wall

LASSA


Experimental challenges in detecting n

and p

γ

Hn

Rejected

He

50 MeV

120 MeV

Many more particles detected by the neutron detectors in 124Sn+124Sn

reactions than n’s

Different coverage in geometry and energy for particles

protons

neutrons

Larg

e s

cin

tilla

tion a

rra

ys a

t gre

at

dis

tance

(TO

F)

Small Si-CsI arrays close to

target (DE-E)

TOF ECM (MeV)q

CM

(deg)

yie

ld


FAIRRIBF’12, FRIB’20,RISP? GSI’11

Symmetry Energy Project: International collaboration to

determine the symmetry energy over a range of densities


ASY-EOS experiment @GSI, May 2011Au+Au @ 400 AMeV

96Zr+96Zr @ 400 AMeV96Ru+96Ru @ 400 AMeV

~ 5x107 Events for each system

Beam Line

Shadow Bar

TofWall

Land

(not splitted)

target

Chimera

Krakow array

MicroBall

Russotto & Lemmon


124Sn+124Sn

Elab=120 MeV/A

b = 1fm

BU

U fro

m: D

an

iele

wic

z, N

PA

67

3, 3

75

(20

00

).

• New observables: p-/p+ ratio

• New detectors: SAMURARI- Time Projection Chamber Active Target -Time Projection Chamber

To probe symmetry energy at >0

with sub-threshold pions from HIC

Bic

kle

y e

t al., p

riva

te c

om

m. (2

00

9)

B.A

. Bro

wn

,PR

L8

5(2

000)5

296

Tsa

ng e

t al,P

RL1

02,1

22701

(200

9)


• Time-projection chamber (TPC) will sit within SAMURAI

dipole magnet

• Auxiliary detectors for heavy-ions and neutrons, and

trigger

Hodoscope

Nebula

(neutron array)

SAMURAI dipole

magnet and vacuum

chamber

SA

MU

RA

I-TP

Cbeam

Drawing courtesy of T. Isobe

SAMURAI-TPC


Heavy Ion Collisions at high density with RIB


Summary of 208Pb n-skin thickness constraints

Model calculations with

and without 3nn forces:

BHF: PRC80,045806 (2009)

Brueckner-Hartree-Fock

DBHF: arXiv:1111.0695

Dirac Brueckner-Hartree-Fock

CEFT :PRL105,161102(2010)

Chiral Effective Field Theory

QMC :PRC85,032801R(2012)

Quantum Monte Carlo

Importance of 3-body neutron-neutron force in the

Equation of State of pure neutron matter

Tsang et al.PRC (in print)

arXiv:1204.0466

neutron star


Study of Fission barriers of exotic nuclei

with AT-TPC & PAT-TPC•Provide constraints for fission cycling, beta-delayed and neutrino-induced fission

contributions to r-process yields

•Extrapolations of ground state and fission saddle point binding energies away from the

valley of stability

•Measurements of the excitation functions of fission cross-sections of exotic nuclei

•p+195Tlfission at E/A=75, 65, 55, 50, 40, 35 MeV (NSCL#12014)

•etc.

6He+4He

Cathode

Corona Ring

Beam Entrance

Voltage Feed-through

Field Cage

Micromegas

Endplate


Active Target -Time Projection ChamberLead PI :W. Mittig; Project leader: D. Bazin; Co-PI: W. Lynch

• AT-TPC will allow inverse kinematics studies in astrophysical, resonant, transfer,

breakup, fusion, fission reactions and to study the EOS using giant resonances

and heavy ion reactions.

• AT-TPC will make use of the full range of beam energies and intensities available

from the CCF and ReA3 and extend the scientific reach of both.

• Broad innovative scientific program.• Two alternate modes of operation

• Fixed Target Mode with solid target

inside chamber:

– 4p tracking of charged particles allows full event characterization

• Active Target Mode:– Chamber gas acts as both detector

and target (H2, D2, 3He, Ne, etc.)

– Provides a thick target for low intensity beams while retaining high resolution and efficiency


Summary

• HiRA provides capabilities to use transfer reactions to investigate single

particle levels in exotic nuclei from fast beams.

• Charged particle decay spectroscopy reveals structure and decay modes

at the proton drip-line.

• Consistent constraints on the symmetry energy at sub-saturation densities

with different experiments suggest that heavy ion collisions provide a good

probe at high density..

• Experiments to measure constraints on the symmetry energy above

saturation densities have started with n/p ratios and will continue with pion

and flow measurements with the AT-TPC

• The AT-TPC and its prototype have a broad science program to study

fission barriers of exotic nuclei, transfer reactions, isobaric analog and

cluster states and giant resonanes.

• The AT-TPC will be ready for experiments with ReA3.


Nuclear Structure studies with Transfer Reactions

single partilcle structure of unstable nuclei – pf shell

H(46Ar,d)45ArH(56Ni,d)55Ni

(Sanetullaev,

PhD, 2011)

2p3/2

1d3/2

1f7/2

N=28 gap

2s1/2

N=20 gap

1f7/2

2p3/2

2s1/2 1d3/2

Spectroscopy of N=27 isotones


Nuclear ReactionsTo study nuclear structure and the equation state of nuclear matter

• Transfer reactions:

– What are the properties of single particle orbits?

• Decay spectroscopy of Nuclei at the drip-lines:

– What is their structure and how do they decay?

• Fission Barriers of exotic nuclei:

– How to extrapolate the Fission Barriers for nuclei relevant to the r-process?

• What is the EoS of Asymmetric Matter?

– Sub-saturation densities

– Supra-saturation densities

Faculty: Lynch, Mittig, Tsang, Westfall

Detectors: HiRA, neutron wall, AT-TPC & its prototype


Looking forward to the AT-TPC at ReA3

•Prototype (½ scale) AT-TPC

•NIMA660,64(2011)

•NIMA, (2012)

6He+4He

Cathode

Corona Ring

Beam EntranceEndplate

Field Cage

Micromegas

• Transfer Reactions to measure

SF’s, ANC’s

– Neutron particle states in neutron

rich exotic nuclei using (d,p).

– Proton particle states in proton-

rich nuclei using (3He,d).

• Isobaric Analog Resonances: AZ(p,p)

– Probe structure of states in A+1Z: determine E*, J, L, SF’s

• Cluster states in the continuum.

• Fission Barriers of exotic nuclei

• etc.

Scientific programs for AT-

TPC and its prototype:



Experiments with AT-TPC Prototype

Prototype (½ scale) AT-TPC

NIMA660,64(2011)

NIMA (in print)

Experiments at Notre Dame:

-6He+4He (10Be decay spectroscopy)

-10Be+4He (14C decay spectroscopy)

-6He+40Ar (complete and incomplete

fusion)

a+6He a + 6He*

a+6He a + 6He

6He+4He

Cathode

Corona Ring

Beam Entrance


Field Cage

Micromegas

Endplate a+2n


Decay spectroscopy for dripline nuclei

Decay of proton unbound nuclei – explosive hydrogen burning in X-ray bursts

69Br p+68Se waiting point. (Rogers, PhD 2009; PRL106, 252503 (2011) )

73Rb p+72Kr, (NSCL#10015)

Other programs:8Cg.s.2p+2p+a8BIAS2p+6LiIAS +

(NSCL#10001)16Ne and 16FIAS,

(NSCL#11001)


Strategies used to study the symmetry energy

with Heavy Ion collisions below E/A=100 MeV Vary the N/Z compositions of

projectile and targets• 124Sn+124Sn, 124Sn+112Sn,

112Sn+124Sn, 112Sn+112Sn Measure N/Z compositions

of emitted particles• n & p yields• 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.

Neutron Number N

Pro

ton

Nu

mb

er

Z

3/2AaAaB SV 3/1

)1(

A

ZZaC

A

ZAasym

2)2(


Hubble

ST

Crab

Pulsar


Microball from WU

2. Proposed Experimental Set up

Chamber from

RIKEN

Scintillator &

degrader foil

ladder


Heavy Ion Collisions at high density with RIBB

.A. B

row

n,P

RL

85

(20

00

)529

6

Tsa

ng

et a

l,PR

L1

02

,12

27

01

(20

09

)

At <0 density, consistent

constraints Effect of mass

splitting increase with density

and asymmetry

??

Large uncertainties in the

symmetry energy high

density.

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

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

??

B. L

iu e

t al. P

RC

65

(20

02

)04

52

01

The National Superconducting Cyclotron Laboratory

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