George A. Souliotis Collaborators: M. Veselsky, G. Chubarian, L. Trache, A. Keksis, E. Martin, D.V. Shetty, S.J. Yennello Recent research results presented at: I The International Conference of Nucleon-Nucleon Collisions (NN03), Moscow, June 17-22, 2003, and The Institute of Nuclear Physics of NCSR ‘Demokritos’, Athens, Greece, June 24, 2003 a) Neutron-Rich Rare Isotope Production in the Fermi Energy Domain (Slides:1-12) b) Heavy Residue Properties, Isoscaling and N/Z Equilibration (Slides: 13-29)

Production of Neutron-Rich Nuclides (methods):  target, projectile fission  cold projectile fragmentation (medium to high energy)  deep inelastic collisions (low to medium energies)  multinucleon transfer reactions (around V b ) Present work: deep inelastic collisions at Fermi energies:  86 Kr(25MeV/nucleon) + 64 Ni, ( PLB (2002)  86 Kr Sn, 112 Sn (PRL in press, nucl-ex )  Heavy-Residue Yield Scaling (nucl-ex ) Findings:  Enhanced production of neutron-rich species, neutron skin effect  Heavy-Residue Yield Ratios probing N/Z equilibration Applications with RIB from TAMU upgrade and RIA Introduction

MARS Recoil Separator and Setup PPAC2 Stop T Silicon Telescope: ΔE 1, X,Y (Strips) ΔE 2, E residual PPAC1 Start T X,Y Production Target D1D2 D3 Wien Filter Q1 Q2 Q3 Q4 Q5 Dispersive Image Final Achromatic Image Rotatable Arm Reaction Angle: 0-12 o (selectable) MARS Acceptances: Anglular: 9 msr Momentum: 4 % Beam angle set to: 0 o ( o ) for Kr+Ni (  gr = 3.5 o ) 4 o ( o ) for Kr+Sn (  gr = 6.5 o )

Extracted physical quantities:  Velocity, Energy loss, Total Energy  Mass-to-charge ratio: A/Q B  ~ A/Q    Atomic Number Z Z ~  ΔE 1/2  Ionic charge Q Q ~ f(E,  )  Mass number A A = Q int  A/Q Yield distribution (Z,A,υ) Reactions studied:  86 Kr 22+ (25 MeV/u, 1-5 pnA) + 64 Ni (4 mg/cm 2 ) PLFs in o (  gr = 3.5 o )  86 Kr 22+ (25 MeV/u, 1-5 pnA) + 124,112 Sn (2 mg/cm 2 ) PLFs in o (  gr = 6.5 o ) Measured quantities:  ΔE 1, ΔΕ 2, Ε r, (x,y) strips  time of flight (START-STOP)  x-position at First Image (Bρ information) Experimental Details:

Gross Distributions: 86 Kr (25 MeV/u) + 64 Ni DIT/GEMINI DIT/GEMINI (filtered) DIT: L. Tassan-Got and C. Stephan, Nucl. Phys. A (1991) GEMINI: R. Chariy et al., Nucl. Phys. A (1988) EPAX: K. Summerer and B. Blank, Phys. Rev. C (2000). Isobaric Yield Distribution Z - A Distribution (relatice to Z  ) Velocity - A Distribution References:

Gross Distributions: 86 Kr (25 MeV/u) Sn -- DIT/GEMINI filtered (θ,Bρ) -- EPAX2 DIT: L. Tassan-Got and C. Stephan, Nucl. Phys. A (1991) GEMINI: R. Chariy et al., Nucl. Phys. A (1988) EPAX2: K. Summerer and B. Blank, Phys. Rev. C (2000). Isobaric Yield Distribution Z - A Distribution (relatice to Z  ) Velocity - A Distribution References:  Data  Data Corrected (θ, Bρ)

Resolutions (FWHM) : ΔZ = 0.5 ΔQ = 0.4 ΔA = 0.5 Z, Q, Α spectra (one run): 86 Kr (25 MeV/u) + 64 Ni

Mass distribution of Ge (Z=32) isotopes - 4p - 4p+1n - 4p+2n 86 Kr (25 MeV/u) + 64 Ni

Mass distributions: 86 Kr (25 MeV/u) + 64 Ni*  D ata ---- EPAX  DIT/GEMINI - 3p +1n +2n +3n -2p +1n +2n +3n +4n -1p +1n +2n +3n +4n -4p +1n +2n -5p +1n -6p Larger cross sections w.r.t. DIT/GEMINI or EPAX (Z=35-31) Cross sections similar to DIT/GEMINI or EPAX (Z  30) BrSe As ZnGa Ge * G.A. Souliotis et al., Phys. Lett. B 543, 163 (2002)

Mass distributions (cont.): 86 Kr (25 MeV/u) + 64 Ni Measured cross sections are similar to DIT/GEMINI and EPAX  Data ---- EPAX  DIT/GEMINI Cu Fe Mn Cr Ni Co

Mass distributions : 124 Sn (20 MeV/u) Sn Measured cross sections agree with DIT/GEMINI They are larger than EPAX predictions  Data ---- EPAX  DIT/GEMINI Cu Fe Mn Cr Ni Co ?

Estimates of Production Rates: 86 Kr+ 64 Ni 86 Kr beam (25MeV/u) 100 pnA 64 Ni target (20 mg/cm 2 ) * Use cross sections of this work, assume: * GSI data: M. Weber et al. Nucl. Phys. A 578 (1994) 659

Mass distributions: 86 Kr (25 MeV/u) Sn, 112 Sn*  86 Kr Sn  86 Kr Sn EPAX - 3p -2p -1p -4p -5p Larger cross sections with the n-rich 124 Sn target (Z=35-30) Se As ZnGa Ge * G.A. Souliotis et al., Phys. Rev. Lett. in press, nucl-ex/ Br

Neutron-Proton Density Calculations for 124 Sn, 112 Sn Thomas-Fermi : V.M. Kolomietz, A.I. Sanzhur et al., PRC 64, (2001) Skyrme-Hartree-Fock: J. Friedrich, P. Reinhard, PRC 33, 335 (1986) neutron skin n n p p

Mass Distribution of Germanium from 86 Kr(25MeV/u) Sn, 112 Sn, 64 Ni Ge Data using targets:  124 Sn  112 Sn  64 Ni EPAX2 Target N/Z Valley of stability 124 Sn 1.48 n-rich 118 Sn 112 Sn 1.24 n-poor 64 Ni 1.29 n-rich 60 Ni

Comparison: Data, Calculations: 86 Kr (25 MeV/u) Sn, 112 Sn*  Data DIT/GEMINI (standard) DIT/GEMINI with  (r) EPAX Calculation with neutron “skin” appears to account for the larger cross sections with the n-rich 64 Ni, 124 Sn targets * G.A. Souliotis et al., Phys. Rev. Lett. in press, nucl-ex/

Comparison: Data/EPAX : 86 Kr (25 MeV/u) + 64 Ni, 124 Sn For near-projectile fragments and above the projectile N/Z, the cross sections are larger. DIC between massive n-rich nuclei appear to be advantageous for very high N/Z RIB production

Velocity vs Z correlation 86 Kr Sn 86 Kr Sn 86 Kr + 64 Ni 86 Kr + 58 Ni  min E*/A = 2.2 MeV T = 5.3 MeV  mi n

N/Z vs Z correlation 86 Kr Sn 86 Kr Sn 86 Kr + 64 Ni 86 Kr + 58 Ni EAL: evaporation attractor line * SL: stability line * R. Charity, Phys. Rev. C 58, 1073 (1998) 86 Kr: Sn: Sn: Ni: Ni: 1.07 N/Z N/Z ~ constant

Scaling of Yield Ratios : 86 Kr+ 124 Sn, 112 Sn R 21 (N,Z) = Y 2 /Y 1 R 21 = C exp (  N ) R 21 = C´ exp (  Z )

Scaling of Yield Ratios : 86 Kr+ 64 Ni, 58 Ni R 21 (N,Z) = Y 2 /Y 1 R 21 = C exp (  N ) R 21 = C´ exp (  Z )

Isoscaling Parameters: ,  86 Kr+ 64 Ni, 58 Ni R 21 = C exp (  N ) R 21 = C´ exp (  Z ) 86 Kr+ 124 Sn, 112 Sn  =0.43  =0.27  = – 0.34  = – 0.51

Origin of Isotopic Scaling: Grand Canonical Ensemble (equilibrium limit): Fragment Yield: * Y(N,Z) = F(N,Z) exp{B(N,Z)/T} exp { (N  n +Z  p )/T } R 21 (N,Z) = Y 2 (N,Z) / Y 1 (N,Z) = C exp (  N +  Z) (Isoscaling) with:  =  n /T  =  p /T  n   S n  p   S p  = 4 C sym /T ( (Z 1 /A 1 ) 2 – (Z 2 /A 2 ) 2 ) * J. Randrup and S. Koonin, Nucl. Phys. A 356, 223 (1981) M. B. Tsang et al. Phys. Rev. C 64, (2001) A.S. Botvina et al. Phys. Rev. C 65, (2002) Extracted Parameters:

Heavy Residue Isoscaling and N/Z equilibration R 21 ~ exp (  N ) N/Z 86 Kr+ 124 Sn => [ 210 Rn] Kr+ 112 Sn => [ 198 Rn] 1.30  (N/Z) = 0.14 N/Z equilibrated quasi-projectile  = 4 C sym /T ( (Z 1 /A 1 ) 2 – (Z 2 /A 2 ) 2 ) *  = 8 C sym /T (Z/A) 3 ave  (N/Z) * M. B. Tsang et al. Phys. Rev. C 64, (2001) A.S. Botvina et al. Phys. Rev. C 65, (2002) 86 Kr+ 124 Sn, 112 Sn Evolution towards N/Z equilibration of quasi-projectile** ** G.A. Souliotis et al., nucl-ex/ , Phys. Rev. C submitted

Velocity and E* vs mass correlations 86 Kr Sn 86 Kr Sn  min E*/A = 2.2 MeV T = 5.3 MeV E*/A max observed

Isobaric Scaling of Yield Ratios : R 21 (N,Z) = Y 2 /Y 1 R 21 = C exp (  N +  Z) Rearrange with  ´= (  +  )/2 *  ´= (  -  )/2 R 21 = C exp {  ´A +  ´(N  Z)} = C exp (  ´A + 2  ´t z ) 86 Kr+ 124 Sn, 112 Sn data   =0.47 * A.S. Botvina et al. Phys. Rev. C 65, (2002)  = 0.47

Heavy Residue Isobaric Scaling and N/Z equilibration R 21 ~ exp{  (N  Z)} N/Z 86 Kr+ 124 Sn => [ 210 Rn] Kr+ 112 Sn => [ 198 Rn] 1.30  = 4C sym /T (Z/A) 2 ave  (N/Z) qp ** 86 Kr+ 124 Sn, 112 Sn  Isobaric approach  Isotopic approach Evolution towards N/Z equilibration of quasi-projectile**  (N/Z) = 0.14 N/Z equilibrated quasi-projectile N/Z equilibration : continuous process strongly correlated with E* Intermediate Energy: S.J. Yennello et al, Phys. Lett. B 321, 15 (1994) (IMF yield ratios) B.A. Lee and S.J. Yennello, Phys. Rev. C 52, 1746 (1995) H. Johnston et al., Phys. Lett. B 371, 186 (1996) ** G.A. Souliotis et al., nucl-ex/ , Phys. Lett. B, submitted

Early N/Z equilibration studies N/Z equilibrated quasi-projectiles Evolution towards N/Z equilibration 58 Ni, 64 Ni (8.5MeV/u) U (2) 92 Mo(15MeV/u) U, 154 Sm (1) N/Z 58 Ni measured derived 64 Ni measured derived Derived from data using evap. code (1) M. Petrovici et al., Nucl. Phys. A 477, 277 (1988) (2) R. Planeta et al., Phys. Rev. C 38, 195 (1988) DIC Model (Randrup)

Measured charge, mass, velocity distributions of residues from: 86 Kr (25 MeV/u) + 64 Ni, 124 Sn, 112 Sn, Studies inside  gr Reaction simulations: DIT/Gemini: reasonable description, Effect of the Neutron Skin (very n-rich products) Scaling of Heavy-Residue Yields: N/Z Equilibration Plans for future work :  Investigate reactions with heavier targets: 208 Pb, 238 U (look ~  gr )  Study the process of N/Z equilibration, E/A dependence * TAMU Cyclotron White Paper in : Tools at Texas A&M:  Superconducting Solenoid Rare Isotope Line (Large Acceptance)  MARS Line (High Resolution)  Future: Re-accelerated beams via a Gas-Cell based ISOL concept* Summary and Outlook Application in studies using high-N/Z beams from RIA