probing symmetry energy at high density
TRANSCRIPT
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