Two- and multi-particle correlation studies

• Correlations as probes for spectroscopy and dynamics

[dynamics] [spectroscopy]Nuclear equation of state; Symmetry energy

Resonance decay/Invariant mass spectroscopy

Spectroscopic properties of unbound statesCollaboration:

INFN, CNRS (France), TAMU (USA)

Plans• Shorter term project:

– Correlation femtoscopy experiments with stable beams at GANIL and stable and exotic beams at LNS

• Physics (high priority on light particle detection, High statistics!)• Observables• Detector needs• Typical experiments• Possible proposals for campaigns in 2015-2016 (?)

• Longer term projects:– Inclusion of neutron correlations– Decay spectroscopy with magnetic spectrometers + correlators– Low energy reactions: CN decay femtoscopy and multi-

particle invariant mass spectroscopy in CN decay

ProjectileTarget

Pre-equilibrium, stopping, compression Expansion Fragmentation

Unbound states

Secondary decays and Spectroscopy tools

Equation of State

Dynamics:• Femtoscopy (HBT)• Correlation functions

Spectroscopic tools:• Primordial source

reconstruction• Resonance decays

A - Physical systems: HIC collision, particle emitting sources

B - Techniques and observables

C – Detector needs! Correlators (MUST2, FARCOS)+

4π event characterizer (Chimera, Indra)

TIME

“interdisciplinary research topic”• From low to relativistic energies: sharing of analysis techniques and

ideas

• WPCF-2013, Workshop on Particle Correlations and Femtoscopy, Catania, Nov 2013: large participation and exchanges with LHC and RHIC, www.ct.infn.it/wpcf2013– Interactions in three particle correlation studies (three-pion @ Alice Vs

Three-alphas @ Chimera, Birmingham, …)– Exchanges in projectile/target cluster structure effects on elliptic flow– Femtoscopy: energy-scan and studies over widely varying systems– 3D Vs. 1D imaging studies– Effects of collective motion on correlations– Resonance decays: in-medium effects on spectroscopy, recombination and

rescattering, …

• Relevance to multi-particle correlations in halo nuclei (exotic beam studies at Isol and In-Flight facilities

Building correlations

Final-state interactions

Coulomb anti-correlation (repulsion)

Resonances

• Detection needs/ requirements:

Shape of resonances: high angular and energy resolution

Low q-regions: high granularity and angular resolution

1+R

(q)

q (MeV/c)

deuteron-alpha

6Li

…can be extended to three- and multi-particle correlation functions…

r (fm)

S(r)

4 6 8 00

Source function

“Size”

Source funnction S(r): “Space-time” profile of decaying systemNeed high resolution in measuring the shape of peak!

20 40 60 800 100

q (MeV/c)

1+R(

q)

p-p

Data

Shape measurements of pp correlations

Input Output

G. Verde et al., PRC65, 069604 (2002)

Present challenge: symmetry energy

Asymmetry term

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

Many approaches… large uncertainties….

Microscopic many-body, phenomenological, variational, …ZH Li, U. Lombardo, PRC74 047304 (2006)

Fuchs and Wolter, EPJA 30, 5 (2006)

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

E sym

(MeV

)

E sym

(MeV

)Stiff

Soft

Need HIC at intermediate energies +Ranges of N/Z (δ2) enhance Esym effects

Symmetry energy and correlation functionsIBUU simulations 52Ca+48Ca E/A=80 MeV Central collisions

• Proton-proton correlation sensitive to Esym• nn and np also… but difficult… (later projects)

…meanwhile use: t-3He, t-t and 3He-3He

Correlation functions

neutron-neutron

proton-proton

0.0

0.5

1.0

1.5

1

2

3

4

1

3

5

7

q (MeV/c)1+

R(q)

proton-neutron

Lie-Wen Chen et al., PRL (2003), PRC(2005)

Stiff

Soft

First results from MSU on Ca+Ca – 80 MeV/u

MSU: HiRA + 4pi

Correlations + 4pi array

40Ca+40Ca Vs. 48Ca+48CaE/A = 80 MeV

1. Size effect or N/Z effect?2. What is the role of space-time

ambiguities?

Need new experiments and better 4π characterization event-by event

Isolating particle at the early dynamical stage

112Sn+124Sn E/A=50 MeV bred=0-0.4

time (fm/c)

dN/d

t

PT/m > 0.2

PT/m > 0.3

Early

Late

Sn+Sn E/A=50 MeV bred=0-0.4

B. Barker et al.

Experimental data (preliminary)Xe+Au E/A=50 MeV MCP=36 (~bred<0.3)

Lassa@MSU

Proton energy spectra with pT > 0.15

pp correlations

No PT gate

PT/m > 0.2

Moving source fit: single-particle emitting source moving with v ~ vNN

E.V. Pagano

T. Minniti, G. Verde, et al., to be submitted

Source functions

Effects of pT gates on pp correlationsXe+Au E/A=50 MeVbred<0.3

(pT/m)min(pT/m)min

Fraction of dynamically emitted protons (%) - fdynamical

Source function size – r1/2

Sour

ce s

ize

f dyna

mic

al

• Consistent with increasing importance of dynamical sources at high PT

• Trend at high PT of source size need more understanding… Work in progress

Preliminary

T. Minniti, G. Verde, et al., in progress

Increasing relevance of dynamical emissions

Typical experimental setupCorrelators (FARCOS + MUST2)

4π detNeeds:• 4π for characterization of collision events: b, reaction plane, flow!• Correlators:

High resolution in (Theta, Phi, E) Large solid angle coverage: statistics AND changing kinematics with Ebeam

+ other physics cases in same experiment: Campaigns “a-la-indra”

Example: G. Verde and J. Natowitz –> comparisons femtoscopic radii vs coalescence radii (discussed briefly during last IWNDT meeting in College Station)

Must2: Mur à Strip

• Mostly used for direct reactions with exotic beams (GANIL, RIKEN)• Optimized for high energy and angular resolution detection of light particles: p,

d, t, 3He, 4He, 6He, …, Li isotopes… (dynamic range limited)• ASIC electronicsby the same team that develops GET electronics (similar ASIC

concepts, no digitalization, …)• In our project: best suited at large angles in the lab frame, dominated by light

particle emissions• Very flexible

Symmetry energy at very low densities? (TAMU)Pre-equilibrium emission Flow Multifragmentation

Central

ρ ≈ 0.01 ρ∙ 0

Clustering (~alphas) at small densities affects EsymC.J. Horowitz et al., NPA776, 55 (2006), G. Wanatabe et al., PRL103, 121101 (2009)Esym(ρ) not vanishing at very low ρ

64Zn+92Mo,197Au 40Ar, 64Zn+112,124Sn E/A=35 MeV

Emission volumes and densities from coalescence analyses of energy spectra!

NIMROD @ TAMU

E sym

(MeV

)

Density ρ(fm-3)

Symmetry Energy at very low densities

J.B. Natowitz et al, PRL 104 (2010) 202501

R. Wada et al., PRC85, 064618 (2012)Coalescence Vs. Femtoscopy? statisctial Vs. dynamical

Invariant mass spectroscopy: “gratuit” in the same experiment!

HIC and correlations as a spectroscopic tool• Cluster states, Hoyle states, BEC, …• Same experiment• Access to invariant masses, spin, branching ratios for simultaneous and

sequential decays• Compare direct reactions to HIC and in-medium decay

Expansion

Not only EoS…

Several unbound species in just one single experiment!

10C*

Spectroscopy Dynamics

p-p-16O correlation function

1+R

8Bep-7Li 8B p-7Be 10B α-6Li

12Cα+α+α 9Bp+α+α

18Nep+p+16O

Xe+Au E/A=50 MeV

Example: 8B unbound states in central HIC

States of 8B p+7Be

p+7Be

0.774

1.4 (?)

2.32

8B1+

3+

p-7Be correlations W.P. Tan et al. Phys. Rev. C69, 061304 (2004)

Xe+Au E/A50 MeV Central collisions

Relative height of resonances constraints the spin of states

Example: 2α-2p correlations : states in 10C*

Ek(MeV)

10C 6Be+α (2p+α)+α10C 8Be+p+p (α+α)++p10C 9B+p (p+α+α)+p

F. Grenier et al., Nucl. Phys. A811 (2008) 233 Constraining branching ratios for

sequential vs simultaneous decays

4-particle correlation functions: p-p-α-α

Direct and fragmentation reactions with exotic beams

12Be + p, 12C E/A = 50 MeV105 pps

HiRA @ MSU

Several new states studied

R.J. Charity et al., PRC76, 064313 (2007)

Projectile fragmentation beams

Opportunity: fast exotic beams @ LNSEx: Primary beam: 20Ne E/A=45 MeV/A Production target: 9Be (500 mm)Fragments transported and tagged event-by-event by E-ToF

DSSD Tagging detector

T (ns)

10Be

16C

13B12Be

9Li6He

17C

7Li

ΔE (M

eV) Bρ=2.71 Tm

11BeLight and medium mass isotopes for direct reactions in inverse kinematics: multi-particle correlations

Interplays dynamics-spectroscopy

• Femtoscopy (dynamics) with light particles (strongly interacting!) needs spectroscopy information: resonances, quantum statistical symmetries, etc.

• Spectroscopy information may be extracted from correlations with light complex particles (example: 10Cp+p+α+α)

Invariant mass spectroscopy: Direct (FRIBS) Vs. Multifragmentation

• Multifragmtation reactions: - Good: high statistics, “clean” stable beams - Bad: not clean states produced, distortions in medium (low density

nuclear matter), effects of reaction/production mechanism

• Direct reactions with exotic beams: - Good: clean states and analysis methods- Bad: low statistics, low beam quality (tracking required with resolution

and rate limitations, …)

Comparisons would be of mutual benefit:- Effects of reaction mechanism on extraction of spectroscopic properties

(important for exotic beam studies, structure reaction mechanism!)- In-medium effects on resonance formation and decay- Search for clusters in low density matter (Symmetry energy)- …

Experiments: scanning over widely varying systems

• Energy scan (E-scan): “wide” range of beam energies (intermediate) – understand space-time ambiguity in emitting source profiles– E/A<35 MeV @ LNS, TAMU(?)– E/A>35 MeV @ GANIL

• Mass scan Vs. Isospin scan (A-scan, N/Z-scan) – understand ambiguity in size effects Vs. symmetry energy effects– 40,48Ca+40,48Ca– 58,64Ni+58,64Ni– 112,124Sn+112,124Sn– …and inverse kinematics combinations (ex.: Sn+Ni, etc.), better

for coalescence studies

Shorter term campaigns –Fermi energies

Reaction systems at GANIL (> 2016?)N/Z-scan and A-scan:

• 40Ca + 40Ca, 48Ca + 48Ca• 58Ni + 58NiCa, 64Ni + 64Ni E/A=40 - 80 MeV• 112Sn + 112Sn, 124Sn + 124Sn• 58Ni + 40Ca, 64Ni + 48Ca (coalescence vs femtoscopy)

N/Z-scan:• 48Ca + 48Ca, 48Ti + 48Ti E/A=40 – 80MeV• 96Zr + 96Zr, 96Ru + 96Ru E/A=25 - 60 MeV

Reaction systems at LNS (<2017)N/Z-scan and A-scan:

• 40Ca + 40Ca, 48Ca + 48Ca• 58Ni + 58NiCa, 64Ni + 64Ni E/A=25 - 40 MeV• 112Sn+112Sn, 124Sn+124Sn• 58Ni + 40Ca, 64Ni + 48Ca (coalescence vs femtoscopy)• FRIBS beams: direct reactions and invariant mass spectroscopy

Spokesperson of Mus2 project

Group Leader NIMROD@TAMU

Longer term challenges: neutron-proton correlations

nn, np and pp correlation functions Symmetry energy

CorrelatorsProtons EDEN

Neutrons

Measuring pp, np, nn correlations:LNS: EDEN + MUST2/FARCOSGANIL: DEMON +

MUST2/FARCOS

neutron-proton correlations

G. Verde, Must2 meeting – 14 Nov 2013

Correlations at low energies16O+ 27Al @ E/A=8.8 MeV

1+R

(q)

q (MeV/c)

• Correlation femtoscopy: volumes, emission times, prompt vs evaporative decays, light particle emission chronology, etc.

• Multi-particle decay spectroscopy: emission of exotic nuclear systems (p-rich and n-rich) exploratory plans for SPES and Spiral2

Evaporative scenario

Explosive scenario

Start with stable beam experiments at LNS and GANIL: test experimental techniques in CN reactions (2015-2016?)

Documents under construction

• Scientific program• Logistics and Technical details• Manpower organization: students for data

analysis, organization of calibration tasks (“Indra-like” organization), technical tasks

• Letter of Agreement with international partners

• Milestones

Backup slides

Resonance decay (invariant mass) spectroscopy: direct and fragmentation reactions

New state in 8Be at E*~23 MeV --> sequential: 8Be 7Li + p

7Li t + α

R.J. Charity et al., PRC78, 054307 (2008)