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11th INTERNATIONAL SPRING SEMINAR ON NUCLEAR PHYSICS “Shell Model And Nuclear Structure: achievements of the past two decades” in honor of Aldo Covello ISCHIA, MAY 12-16, 2014. Isospin Physics by CHIMERA detector. Sara Pirrone EXOCHIM collaboration INFN-Sezione di Catania.

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11th INTERNATIONAL SPRING SEMINAR ON NUCLEAR PHYSICS “Shell Model And Nuclear Structure: achievements of the past two decades”

in honor of Aldo Covello

ISCHIA, MAY 12-16, 2014

Isospin Physics

by CHIMERA detector

Sara Pirrone

EXOCHIM collaboration

INFN-Sezione di Catania

The multifaceted influence of the nuclear symmetry energyA.W. Steiner, M. Prakash, J.M. Lattimer and P.J. Ellis, Phys. Rep. 411, 325 (2005).

EOS & Symmetry Energy



ρ0 = 0.16 fm-3

E(ρ,) = E(ρ,=0) + Esym(ρ)²

ρ  ρnρp

Esym() ≈ (/)

γ< 1 Asysoft,

γ≥ 1 Asystiff

I.Bombaci and U.Lombardo PRC 44,1892 (1991)

Example of Chimera coll. contribution to isospin physics studies

  • Study of the systems 124Sn+64Ni and 112Sn+58Ni @35 A.MeV. Neck emission, Time scale for fragment formation, fragment hierarchy, Dynamical fission(Chimera coll) LNS

  • Isospin dependence in the competition between incomplete fusion and dissipative binary reactions in 40Ca,48Ca + 40,48Ca, 46Ti @25 AMeV(Chimera coll.) LNS

  • Study of isospin diffusion in the reactions 124Sn+124Sn, 124Sn+112Sn, 112Sn+124Sn, 112Sn+112Sn @35 MeV.(MSU-Chimera coll.). LNS

  • Fast collinear partitioning of the 197Au + 197Au @15 A.MeV, system into three and four fragments of comparable size(Chimera coll.) LNS

  • Exploring the isospin dependence on decay from compound nucleus in the reactions 78,86Kr + 40,48Ca @10 A.MeV(Chimera-Indra coll.) LNS

  • Constraining the Symmetry Energy at Supra-Saturation Densities With Measurements of Neutron and Proton Elliptic Flow, Au+Au, 96Zr+96Zr and 96Ru+96Ru @400 A.MeV(AsyEos-Chimera coll.) GSI

    In progress…

CHIMERA studies

Charge Heavy Ion Mass and Energy Resolving Array



Identification A, Z, E – Recostruction of event

Dynamical range : from fusion, fusion-fission to multifragmentation reaction

Selected Chimera Experiment @INFN-LNS studies

on Reaction Dynamics & Isospin physics

  • TIMESCALE–DYNAMICAL FISSIONStudy of the systems124Sn+64Ni and 112Sn+58Ni (inverse) @ 35 A.MeV.Neck emission, Time scale for fragment formation, fragment hierarchy, Dynamical fission

  • ISODECExploring the isospin dependence on decay from compound nucleus in the reactions78,86Kr + 40,48Ca @10 A.MeV

Study of the systems studies

112Sn + 58Ni (n-poor), 124Sn + 64Ni (n-rich)@ 35 AMeV

Time scale for fragment formation, fragment hierarchy,

Neck Emission - Dynamical fission

n studies








Ternary and semiperipheral events selection

124,112Sn + 58,64Ni @ 35 AMeV





IMF , Z  3


Neck formation

E.De Filippo et al. PRC71,44602 (2005)

TIME SCALE: Emission Chronology by velocity correlation studies

124Sn+64Ni 35 MeV/A







Relative velocities are expressed in relationship with the Viola velocity (pure Coulomb repulsion)

Viola et al Nucl. Phys. A472, 318 (1987)

E.De Filippo et al. PRC71,44602 (2005)

vrel/vviola =1 SEQUENTIAL DECAY OF IMF FROM PLF (or TLF), t ≥ 120 fm/c (2,3)

vrel/vviola≠ 1 NON-STATISTICAL EMISSION OF IMF , t ~ 40 fm/c (1 )

3 studies



1 40 fm/c

2 80 fm/c

3 120 fm/c

Emission chronology: light fragments are produced earlier (~40 fm/c) than heavier ones (~120 fm/c)

TIME SCALE: Emission Chronology by velocity correlation

124Sn+64Ni35 MeV/A

E.De Filippo et al, PRC86 014610 2012

Correlations with IMFs (Z studies 8) isotopic properties



124Sn + 64Ni 35 A.MeV









The correlation shows that the greatest neutron enrichment is linked to greater deviations from Viola systematics, that is to fast prompt emission of IMF.

We can select

Dynamical emission

Statistical emission


E.De Filippo et al. PRC71,44602 (2005)

Dynamical and Sequenzial emission of IMF studies

Dynamically emitted particles

Statistically emitted particles

Neutron rich system

Neutron poor system

n-rich system

- Entrance channel memory effect

- Reduction in staggering effect

E.De Filippo et al,

PRC86 014610 2012


124 studiesSn+64Ni 35 A.MeV

SMF - microscopic approach that describe the evolution of systems by Boltzmann- Nordheim-Vlasov transport equation.

The model includes nuclear mean field dynamics and effect of fluctuations.

V. Baran et al. Nucl. Phys. A730 329 (2004).





Stochastic Mean Field (SMF) + GEMINI calculation

Primary fragments

Dynamically emitted particles

Data consistent with γ ≈ 1

Calculations performed by: M. Colonna

E.De Filippo et al, PRC86 014610 2012

Study of the systems studies

112Sn + 58Ni (n-poor), 124Sn + 64Ni (n-rich)@ 35 AMeV

Time scale for fragment formation, fragment hierarchy,

Neck Emission - Dynamical fission

From early prompt neck fragmentation to PLF dynamical fission

Ternary events associated to the emission of heavy fragments coming from PLF break-up/fission and appearing at a longer time of emission




Binary break-up

  • The time-scale of the process is one of the the signature among different mechanisms:

  • Early neck fragmentation (40-120 fm/c)

  • Dynamical fission (120-300 fm/c)

  • Statistical fission (>1000 fm/c)

P. Russotto et. al. Phys. Rev. C81, 064605 (2010)

Dyn/Stat Fission components for fission124Sn+64Niand112Sn+58Ni

IMFs Cross-sections

Probability ratio of dynamical and statistical fission components

Dynamical component: enhanced in the n- rich system

Statistical component:

almost equal for n-rich, n-poor systems

P. Russotto et al. , submitted, PRC (2014)

The InKiIsSy (INverse KInematics ISobaric Systems-P.Russotto) Apr.2013

Size or Isospin effects?

124Xe+64Zn @ 35 AMeV

-same mass of the n-rich 124Sn+64Ni system, -N/Z near to the n-poor 112Sn+58Ni system

A new setup: the 4π CHIMERA + FARCOS 1° cluster prototype

4 telescopes 25 cm from the target

lab  16-44 deg,   45 deg

Analysis in progress…..

FARCOS project Systems-P.Russotto) Apr.2013

Femptoscope ARray for COrrelation and Spectroscopy

High energy and angular resolution (Δϑ<1°)

Low thresholds ( <1 MeV/A):

Pulse-shape on first Si layer for low energy experiments

High counting rate (1KHz)

Large Dynamic range (20MeV to 2GeV)

Flexibility, Modularity, Trasportability

Coupling to 4 detectors or spectrometers

Integrated Electronics (GET)

Study of the systems Systems-P.Russotto) Apr.2013

78,86Kr + 40,48Ca @10 AMeV

Isospin influence on the reaction and

emission mechanism of IMF (Z≥3)

ISODEC - Scientific Program Systems-P.Russotto) Apr.2013

ITA-FRA Collaboration

Lea - Colliga

  • “ Isospin dependence(N/Z) of theformation and emission mechanism

  • of complex fragments (IMF, Z≥3) from CN to get information on:

  • level density, (thermal properties, E*, meffective)

  • fission barrier, (Symmetry, congruence and Wigner E terms)

  • viscosity, ( coupling collective – intrinsic modes, Fermi level)”

  • Stable Beams

  • [email protected] , with INDRA (2007)

  • [email protected] , with CHIMERA (2010)

  • Next Exotic Beams

  • -Loi for [email protected]

  • -Next proposal for [email protected]

S. P. et al., Proc. of FUSION11, EPJ Web of Conf. 17, 16010 (2011)

G. Politi et al., Proc. of CNR11 EPJ Web of Conf. 21, 02003 (2012)

M.L.Commara et al., Proc. of IWM2011, EPJ Web of Conf. 11, 00022 (2012)

S. P. et al.,Proc of ICRTNP2012, AIP Conf. Proc. 1524, 7-10 (2013)

E475S INDRA @GANIL E Systems-P.Russotto) Apr.2013= 5.5 AMeV

78, 82 Kr + 40 Ca118,122Ba* (~ 100 MeV)



  • 3≤  ≤ 44° IC-Si-CsI

  • forward part

  • Energy, ang. Distr. RP

  • Charge distribution

  • Cross section decay mode

  • CN neutron rich (o)

  • 30% less fission (Z  14 )

  • Less even-odd staggering of IMF ( 6 ≤ Z ≤ 12 )

Comparisons with statistical and dynamical models don’t reproduce completely the data,

G. Ademard et al. PRC 83 (2011) 054619

  • Systems-P.Russotto) Apr.2013L.G. Moretto, Phys Rev. A247, 221 (1975).

  • R.J.Charity et al, Nucl.Phys.A483 (1988)

  • •D.Mancusi et al, PhysRev C 82 (2010)

Statistical Model

Fermi Gas model (level density)

Hauser-Feschbach for LCP’s

Trantion state model for IMF Z>2

FRLDM barrier from Sierk

Structure effect NOT considered

G. Ademard et al. PRC 83 (2011) 054619

G. Ademard et al. PRC Systems-P.Russotto) Apr.201383 (2011) 054619

Dynamical model

DNS in competition to CN

Quasi-fission phenomena

N/Z dependence not considered

DSN (di-nuclear system) -model

Statistical Model

Fermi Gas model (level density)

Hauser-Feschbach for LCP’s

Trantion state model for IMF Z>2

FRLDM barrier from Sierk

Structure effect NOT considered

Sh.A.Kalandarov et al.

PRC82 (2010)

Sh.A.Kalandarov et al.

PRC82 (2010)

ISODEC [email protected] E Systems-P.Russotto) Apr.2013= 10 AMeV

78Kr + 40Ca 118 Ba

86Kr + 48Ca 134Ba

  • Higher energy

  • Influence on the amplitude of the staggering, on the temperature of the emitting system.

  • Isotopic separation of IMF

  • to investigate the staggering effects looking at the isotopic distribution of IMF.

  • Exploration of a larger domain in N/Z of the system (stable beam!)

  • to study the dependence from the N/Z on the mechanism of complex fragment emission from CN

  • Exclusivemeasurements in a large angular range

IMF Isotopic Identification Systems-P.Russotto) Apr.2013

PSD in Silicon

ΔE-E , Si-CsI(Tl)

IMF Mass Distribution Systems-P.Russotto) Apr.2013

Li Be B C





Different isotopic compositions and relative enrichment for the same Z in the two systems

n-rich 86Kr + 48Ca 10 AMeV, ϑ=12°

n-poor 78Kr + 40Ca

Carbon Isotopes Energy Spectra (CM) Systems-P.Russotto) Apr.2013


Tesi B.Gnoffo 2013

Carbon Isotopes Energy Spectra (CM) Systems-P.Russotto) Apr.2013


Tesi B.Gnoffo 2013

  • - Influence of the Isospin (N/Z) Systems-P.Russotto) Apr.2013

  • influence of nuclear pairing force

  • influence of structure effects

  • (M. D’Agostino et al., NPA 861 (2011) 47 )

  • Esym connection (models)

Normalized Yields Comparison PRELIMINAR 10.5° ≤ϑ≤ 15.5°

New systems with higher N/Z would bring new insights

94Kr + 40,48Ca 10 AMeV132,140 Ba* E* ~ 320 MeV

LOI @ SPES- Second SPES Int. Workshop May 2014, LNL Italy

Fragmentation Beams @LNS Systems-P.Russotto) Apr.2013

Chimera group,since 2005, works to test the production of new beams and to realize new experiments @LNS with radioactive beams at intermediate energy.

In-Flight [email protected] Systems-P.Russotto) Apr.2013

Primary Beam by [email protected]

Stable Nuclei

A ~ 10 - 100

E ~ 20 - 60 MeV/A

Primary Beam



stable nuclei


Thin target

9Be 500µm- 2500µm

vF~ vP

RIB @ Intermediate Energy

In-flight fragmentation beams @ LNS Systems-P.Russotto) Apr.2013



CHIMERA beam line – tagging system Systems-P.Russotto) Apr.2013






17 Systems-P.Russotto) Apr.2013C

DE (MeV)








T (ns)

In-flight fragmentation beams @ LNS

Production Tests at the CHIMERA beam line

18O + 9Be (1.5 mm) at 55 MeV/A

Primary beam 88W, 5.5x1011 p/s


16C 40

17C 4

13B 23

11Be 6 Setting Bρ=2.71 Tm

10Be 21

8Li 11

E of secondary beam 40-50 MeV/A

Δ Systems-P.Russotto) Apr.2013E


36Ar + 9Be (0.5 mm) 42 MeV/A,

primary beam 25W - 1x1011 p/s


37K 14.0

36Ar 12.0

35Ar 8.5

34Ar 1.8 magnetic setting

33Cl 1.5

34Cl 6.5

31S 0.8

32S 10.0

28Si 5.0

29Si 6.5









Energy secondary beams 20-25 MeV/A

70 Systems-P.Russotto) Apr.2013Zn + 9Be (0.25 mm) 40 MeV/A,

primary beam 100W


Rate 20kHz

Energy 28 MeV/A

Search for iso-scalar excitation of

the PIGMY resonance in 68Ni nuclei

G.Cardella, E.G.Lanza

for the EXOCHIM coll.

Conclusion & Perspective Systems-P.Russotto) Apr.2013

Recent results were presented in the framework ofDynamics reaction and Isospin Physycsobtained from experiments with stable beams at intermediate and low energies and by using the 4 CHIMERA detector @INFN-LNS.

In preparation experiment at the new facility [email protected] and with detectors at high specialization, (as the FARCOS correlator).

In the meantime, It will be continued the activity of the CHIMERA group by using stable beams and Fragmentation beams @LNS.

This will make possible to refine and to improve our knowledge.

EXOCHIM – Collaboration Systems-P.Russotto) Apr.2013

F.Amorini6, L.Auditore7,8, C.Beck9, I.Berceanu10, E.Bonnet5, B.Borderie11, G.Cardella1, A. Chbihi5, M.Colonna6, A.D’Onofrio4,12, J.D.Frankland5, E.Geraci2,1, E.Henry13, E .LaGuidara1,14, G.Lanzalone15,6, P Lautesse16, D.Lebhertz5, N.LeNeindre 17, I.Lombardo4, M.LaCommara3,4, S.Pirrone1, G.Politi1,2, J.P.Wieleczko5, G.Ademard5, E.DeFilippo1, B.Gnoffo2, M.Vigilante3,4, K.Mazurek5, A.Pagano1, M.Papa1, E.Piasecki18, F.Porto2,6, M.Quinlann13, F.Rizzo2,6, E.Rosato3,4, P.Russotto2,6, W.U.Schroeder13, G.Spadaccini3,4, A.Trifirò7,8, J.Toke13, M.Trimarchi7,8, G.Verde1,L. Acosta,, V. Baran, L. Francalanza, S. T. Cap, G. Gianì, L. Grassi, A. Grzeszczuk, P. Guazzoni, J. Han, C. Maiolino, T. Minniti, E.V. Pagano, A. Pop, F. Porto, L.Quattrocchi, J. Wilczyński, L. Zetta.

1) INFN - Catania, Italy

2) Dipartimento di Fisica e Astronomia, Università di Catania, Italy

3) Dipartimento di Scienze Fisiche, Università Federico II Napoli, Italy

4) INFN - Napoli, Italy

5) GANIL - Caen, France

6) INFN LNS - Catania, Italy

7) Dipartimento di Fisica, Università di Messina, Italy

8) INFN Gruppo Collegato di Messina, Italy

9) IN2P3 - IPHC Strasbourg, France

10) IPNE, Bucharest, Romania 11) IN2P3 - IPN Orsay, France

12) Dipartimento di Scienze Ambientali - Seconda Università di Napoli, Caserta, Italy

13) University of Rochester, USA

14) Centro Siciliano Fisica Nucleare e Struttura della Materia, Catania, Italy

15) Università Kore, Enna, Italy 16) IN2P3 - IPN Lyon, France

17) IN2P3 - LPC Caen, France 18) University of Warsaw, Poland

GET: General Electronics for TPC Systems-P.Russotto) Apr.2013

  • Especially designed for TPC (gas detectors) to be used with radioactive beams at E/A=5-350 MeV

  • Integrated and low power consuming

  • Wide dynamic range (LCP&HI)

  • Configurable

  • Digitalization of signals

  • Might work on photodiodes

    readout of CsI(Tl) crystals

    in Chimera and Farcos

INFN - Italy , GANIL, CEA-IN2P3, CNRS, IRFU France, Univ. Huelva-Spain

Dynamical Fission: in Systems-P.Russotto) Apr.2013124Sn+64Ni and 112Sn+58Ni @35 A.MeV

Separation axis


plane= fission angle on the reaction plane



Fission axis

Reaction plane


Statistical fission is characterized by isotropic fission fragment angular distribution,

Dynamical Fission is characterized by fast AL fragment emission preferentially backwards in the PLF reference system, i.e., towards the target nucleus

E. De Filippo et al., Isospin collaboration, Phys. Rev. C71, 064604 (2005)P. Russotto et al., Int. J. Mod. Physics E15 410 (2006)

P. Russotto et. al. Phys. Rev. C81, 064605 (2010)

Fission like fragments angular cross sections i
Fission-like fragments angular cross sections (I) Systems-P.Russotto) Apr.2013

 124Sn+64Ni


Forward peaked angular distributions Dynamical Fission Vs

Isotropic distributions  Statistical Fission

Dynamical Fission cross section is greater in the neutron rich system 

(a factor ~2) !

plane=fission angle in the reaction plane

P. Russotto et al., PRC 81 064605 (2010)

Activity of the GSS under the chair A.Covello Systems-P.Russotto) Apr.2013

Organization of the

First Spes Physics Workshop – LNL Oct. 2008

Formation of the subgroup Instrumentation - 2009

G. Casini, G. de Angelis, G. Pollarolo, G. La Rana

Organization of the

First SPES Int. Workshop and “Call for Letters of Intent”- LNL Nov. 2010

Organization of the (A.di Pietro-D.Napoli)

First Spes School on experimental techniques with radiactive beams - LNS 2011

Organization of the SPES-ONEDAY 2012 -2013 Systems-P.Russotto) Apr.2013

Transfer reactions with RiBs (Napoli, Apr.2012)

Coulomb excitations with RIBs (Firenze, Sept 2012)

Effects of Isospin in exotic nuclei (Catania, Oct 2013)

Collective excitations in exotic nuclei (Milano, Dec 2013)

Proposition of the organization of the

Second SPES International Workskop –

New Call for LOI - LNL May 2014

(realized by GSS with the new chair G.de Angelis)