Experimental Reconstruction of Primary Hot Fragment at Fermi Energy Heavy Ion collisions R. Wada, W. Lin, Z. Chen IMP, China – in JBN group IMP

Intermediate Heavy Ion Reaction – Central collisions Reaction time Experiments PrimarySecondary

Uncorrelated LP v n Kinematical focusing IMF Detector IMF Correlated LP

Black Histogram: Exp. Red: individual isotope Green : linear BG Blue: total Isotope 20 o64 Zn+ 112 Sn at 40 A 20 o 20 o

data Total Uncorr(kM n (Li)) Corr(M n ( 23 Na)) 4.5≤V IMF <5.5 cm/ns 3.5≤V IMF <4.5 cm/ns 5.5≤V IMF <6.5 cm/ns θ IMF-n =15 o 45 o 35o35o 25o25o Neutrons with 23 Na

Extracted Multiplicities Neutrons

A. Excitation energy of the primary fragments is reconstructed by (i =n,p,d,t,α) 1. = 2T, (surface type Maxwellian) 2.M i is generated by a Monte Carlo method, using the multiplicity distribution from GEMINI simulation. 3.E γ (energy carried away by gamma emissions) is evaluated by GEMINI simulation.

Ex(A MeV) Exp Reconstructed Ex (Exp.) and Ex of primary fragments (AMD,SMM) Be S A -1/3

A. Excitation energy of the primary fragments is reconstructed by (i =n,p,d,t,α) 1. = 2T, 2.M i is generated by Monte Carlo method, using the multiplicity distribution from GEMINI simulation. 3.E γ (energy carried away by gamma emission) is evaluated by GEMINI simulation. B. Mass and charge of the primary fragments is reconstructed by A hot = M i + A cold (i =n,p,d,t,α) AiAi Z hot = ZiZi M i + Z cold

Reconstructed multiplicity distribution Exp. Reconstructed AMD primary 64 Zn A MeV

64 Zn+ 112 Sn 64 Ni+ 124 Sn Predicted associated neutron multiplicity Z=10 0

Neutrons with 23 Na (5.5 <v IMF <6.5 ) 64 Ni+ 124 Sn 64 Zn+ 112 Sn 15 o 25 o 35 o 45 o -2

64 Zn+ 112 Sn 64 Ni+ 124 Sn Neutrons

Exp Reconstructed Ex (Exp.) and Ex of AMD primary fragments Ex (A MeV) 64 Zn+ 112 Sn

Coalescence technique : d 2 (I,j) = ν(r i -r j ) 2 + ((1/2Ћ) 2 /ν)(p i -p j ) 2 < Rc 2 ν = 0.16 fm -2 Z= Sn (MeV) A 0 0 Exp. AMD Ex (A MeV) 15 5 Z=10

Exp Ex (A MeV) 64 Zn+ 112 Sn C.W.Ma et al., CPL Vol. 29, No. 6 (2012)

Summary 1. Excitation energy and multiplicity of the primary hot fragments are reconstructed using a kinematical focusing technique. 2. Reconstructed Multiplicity distributions are well reproduced by the AMD primary isotope distributions. 3. Reconstructed excitation energies are not well reproduced by the AMD primary nor SMM prediction. Reconstructed excitation energy show a significant decrease as a function of isotope mass A for a given Z. 5. Very neutron rich isotopes may provide a good probe to study the hot nuclear matter in a point of least sequential decay disturbance. 4. Coalescence method may need to take into account the effect of neutron (or proton) separation energy for neutron rich ( or proton rich) isotopes.

W. Lin (IMP) R. Wada (IMP) M. Huang (IMP) Z. Chen (IMP) X. Liu (IMP) M. Rodorigus ( Instituto de Fisica, Universidade de São Paulo ) J. B. Natowitz (TAMU) K. Hagel (TAMU) A. Bonasera (TAMU) M. Barbui (TAMU) C. Bottosso (TAMU) K. J. Schmidt (Silesia Univ. Poland) S. Kowalski (Silesia Univ. Poland) Th. Keutgen (Univ. Cathoric de Louvain, Belgium) Thank you for your attention

64 Zn+ 58 Ni,

History to work with Joe Join JBN group – ANL : CN decay SARA- AMPHORA : Multifragmentation, Caloric curve TAMU K-500 : Reaction dynamics, Caloric Curve, Symmetry energy BRAHMS : RHIC physics publications in major journals : (BRAHMS) present IMP, LANZHOU

IMF n IMF Detector n LP Detectors Kinematical focusing

Correlated LP Kinematical focusing Correlated LP Uncorrelated LP v

Zn 47 A MeV Experiment IMF 20 o μm Projectiles: 64 Zn, 64 Ni, 70 Zn at 40 A MeV Target : 58,64 Ni, 112,124 Sn, 197 Au, 232 Th 64 Zn+ 112 Sn at 40 A MeV

Exp. vs AMD-Gemini Semi-violent collisions 16 O

N.Marie et al., PRC 58, 256, 1998 S.Hudan et al., PRC 67, , 2003 Gemini Exp p d t h α 32 A MeV 39 A MeV 45 A MeV 50 A MeV

data Total Uncorr(kM n (Li)) Corr(M n ( 23 Na)) 4.5≤V IMF <5.5 cm/ns 3.5≤V IMF <4.5 cm/ns 5.5≤V IMF <6.5 cm/ns 15 o 25 o 45 o 35o35o θ IMF-n

T (MeV)

64 Ni+ 124 Sm 64 Zn+ 112 Sm 64 Zn+ 112 Sn 64 Ni+ 124 Sn Exp. 64 Zn+ 112 Sn : 64 Ni+ 124 Sn

Isotope distribution at 300fm/c He Li Be B C O Ne Mg SiS Ar 17 C Note: All isotopes are generated in very neutron rich side 34 Mg

(μ n - μ p )/T a c /T Exp AMD Primary Reconstructed (0.40 ) 0.12 (μ n - μ p )/T and Coulomb parameters ln[R(1,-1,A)] = 2a c ·(Z-1)/A 1/3 /T + (μ n - μ p )/T I = ̶ 1 : even-odd: R(1,-1,A) = exp{ 2a c ·(Z-1)/A 1/3 /T } · exp[(μ n - μ p )/T] R(I+2,I,A) = exp{ [2a c ·(Z-1)/A 1/3 – a sym ·4(I+1)/A– δ(N+1,Z-1) + δ(N,Z)]/T } · exp[(μ n - μ p )/T]

a sym = c (V ) sym (1 − c (S) sym /c (V ) sym A 1/3 ): = c (V ) sym (1 − κ S/V /A 1/3 ) c (V ) sym c (V ) sym κ S/V AMD primary 7.9± ± (T=5) 39.5 MeV 40 MeV Reconstructed 4.4± ± ± 2.0 (T=5) 16.5 MeV g.s. BE 32± ± (H. Jiang et al. PRC85, (2012) )

Power law behavior of the reconstructed fragments

Summary 1. Excitation energy and multiplicity of the primary hot fragments are reconstructed using a kinematical focusing technique. 2. Reconstructed Multiplicity distributions are well reproduced by the AMD primary isotope distributions. 3. Reconstructed excitation energies are not well reproduced by the AMD primary nor SMM prediction. Reconstructed excitation energy show a significant decrease as a function of isotope mass A for a given Z. 4. Coalescence method may need to take into account the effect of neutron (or proton) separation energy for neutron rich ( or proton rich) isotopes. 5. Very neutron rich isotopes may be in a very low excitation energy when they are formed and less disturbed by the sequential decay effect. This suggests that neutron rich isotopes provide a good probe to study the hot nuclear matter in a point of least sequential decay disturbance.