Rare Isotope productions from Projectile Fragmentation. Ca + Be. Betty Tsang March 27, 2008

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1 Rare Isotope productions from Projectile Fragmentation 48 Ca + Be Betty Tsang March 27, 2008

2 Acknowledgement Collaborators: Michal Mocko (thesis) M. Andronenko, L. Andronenko, N. Aoi, J. Cook, F. Delaunay, M. Famiano, T. Ginter, M-J. van Goethem, H. Hua, N. Imai, H. Iwasaki, S. Lukyanov, W.G. Lynch, T. Motobayashi, M. Niikura, T. Ohnishi, D. Oostdy, A. Rogers, H. Sakurai, M. Steiner, A. Stolz, Z. Sun, U. Suzuki, E. Takeshita, S. Takeuchi, O. Tarasov, G. Verde, M. Wallace, A. Zalessov W. Friedman, S. Das Gupta, D. Lacroix, A. Ono, P. Danielewicz

3 Primary beams: 40 Ca, 48 Ca, 58 Ni, 64 Ni, 68 Ni, 69 Cu, 72 Zn, 86 Kr MeV/u and intensity 7 - pps Targets: 9 Be and 181 Ta Objectives: To better understand the fragmentation process How does it depend on the target? How does it depend on the asymmetry of the beam? Is there a difference between fragmentation of stable and unstable neutron rich beams? Modeling of the fragmentation process How do the data compare to EPAX? Can we understand the reaction mechanisms what are the important parameters for production of rare isotopes? Relationship between binding energy and cross-sections Extrapolations to rare isotopes & mass measurements ~2000 cross-section measurements

4 the NSCL v ~ 0.2c K500 cyclotron focal plane target I2 dispersive plane A1900 fragment separator v ~ 0.5c K1200 cyclotron Coupled Cyclotron Facility

CCF @ the NSCL+A1900 fragment separator v ~ 0.

5 the NSCL+A1900 fragment separator v ~ 0.2c K500 cyclotron focal plane target I2 dispersive plane I2 v ~ 0.5c K1200 cyclotron.2%

6 the NSCL+A1900 fragment separator v ~ 0.2c K500 cyclotron focal plane target I2 dispersive plane v ~ 0.5c K1200 cyclotron

7 Fragment identification: 58 Ni + Be Raw 45 Ca 40 Ar Calibrated Energy loss [channels] 50 Ti ToF [channels] N-Z dσ x dp = N Y x BEAM f n TRANSMISSION TARGET τ LIVE Δp [ mb /( MeV / c)]

8 Momentum distributions 58Ni+9Be 64Ni+9Be Modified gaussian p<p0 ( p0 p ) 2 N exp 2 2σ L Gaussian p p0 ( p0 p ) 2 N exp 2 2σ R ( p p) 2 N exp 0 2σ 2 Momentum distribution fitting Î total fragmentation cross sections Mocko et al: PRC 74 (2006)

9 Efficiency corrections -- Mocadi simulations 1. A1900 fragment transmission efficiency. σ = A ( A A A 1 ) σ ( A ( A 1) σ 1) 2 F P F 2 F F 2 trans 0 D P AP P R. Dayras et al. Nuclear Physics A460 (1986) A 2. Fragment angular distributions: Assumption of the transverse momentum distributions of fragments. Mocko et al: PRC 74 (2006)

10 Isotone Distributions Isotone distributions 64 Ni+Be 36

11 Mocko et al: PRC 74 (2006) Projectile Effects 8 extra neutrons in 48Ca produce nearly twice as many isotopes, most of which are neutron-rich. Gain in n-rich fragments is not as significant as the fragmentation of 48Ca versus 40Ca

12 R proj σ 48( A, Z) σ = = ; σ ( A, Z) σ 40 Projectile Dependence ( A, Z) ( A, Z) Isoscaling: R 21 =Y 2 / Y 1 e α ( Z ) N + β ( N explained in multifragmentation processes with the Grand Canonical assumption α~δμ n /T? ) Z

13 Effects on isoscaling from conservation of mass Statistical Multifragmentation Model Chaudhuri, Das Gupta, Mocko: arxiv:

14 Effects on isoscaling from conservation of mass Statistical Multifragmentation Model Chaudhuri, Das Gupta, Mocko: arxiv:

15 Fragmentation reaction mechanisms seem to be same for stable and unstable n-rich nuclei Lukyanov et al: in preparation Fragmentation of stable and unstable isotopes 58 Ni; N/Z= Ni; N/Z= Ni; N/Z= Ca Sc Ti -1 Ca Sc Ti -1 Ca Sc Ti Cross section (mb) 1-1 V Cr Mn Cross section (mb) 1-1 V Cr Mn Cross section (mb) 1-1 V Cr Mn Fe Co Ni 1 Fe Co Ni 1 Fe Co Ni Neutron excess N-Z Neutron excess N-Z Neutron excess N-Z 0 5

HOT-FRAGMENTS + Evaporation 2. Dynamical models: incorporate the full physical picture of nuclear collisions. AMD 3.

16 48 Ca+Be at 140 MeV/u, b = 4.23 fm t = 0 fm/c Transport models Ono et al: PRC 47,2652 Lacroix et al: PRC 69, t = 150 fm/c 1. HOT-FRAGMENTS + Evaporation 2. Dynamical models: incorporate the full physical picture of nuclear collisions. AMD 3. Hybrid models: statistical+dynamical model. HIPSE R tgt = σ σ Ta Be ( A, Z ) ( A, Z ) The differences between Be target and Ta targets are relatively small except for light charge particles and rare n-rich isotopes. Simulations mainly on 9 Be targets.

17 Excitation Energy Excitation energy rises steeply and saturates. Near the projectiles, excitation energy is higher in dynamical models than the Abrasion- Ablation model

18 Effects of reaction dynamics on detection efficiency corrections Comparisons to published cross-sections ε ex obtained from reasonable assumptions based on limited systematic data. AMD EPAX 48 Ca+ 9 Be HIPSE applied to published crosssections ε th = Y model /Y filtered HIPSE Correct comparisons AMD HIPSE AMD Comparisons to raw data

19 64 Ni+ 9 Be Comparison of (raw) data to (filtered results from) transport models HIPSE AMD The agreement is quite reasonable. In general, HIPSE predicts wider isotope distributions than AMD model. AMD results may provide constraints to transport model parameters. Impossible to predict rare isotope yields

20 How to predict rare isotope yields? 1. No fragmentation models can predict reliably on the yields of rare isotopes. 2. Global parameterization such as EPAX fails to predict accurate yields on nuclei far from stability. Two strategies: 1. Optimize EPAX fitting on individual reactions 2. Find a systematics that can give reliable relationship between mass (binding energy) and cross-sections.

21 EPAX--used for rate estimates global parameterization of the existing fragmentation data with little physics. N-N β 36 Z=25 86 Kr+ 9 Be 84 Se 82 Ga Cu 80 Zn 84 Se 79 Cu Standard parameterizations up to 25 fitting parameters based on fragmentations of 48Ca, 86Kr, 58Ni at E/A>500 MeV optimum parameterizations (up to 25 fitting parameters) Predictions for most n-rich still off. Mocko et al: PRC 76 (2007)

22 EPAX--used for rate estimates global parameterization of the existing fragmentation data with little physics. N-N β Ratio = Data/EPAX 36 Z=25 86 Kr+ 9 Be 84 Se 82 Ga 84 Se Cu 80 Zn Standard parameterizations up to 25 fitting parameters based on fragmentations of 48Ca, 86Kr, 58Ni at E/A>500 MeV optimum parameterizations 79 Cu Predictions for most n-rich nuclei are off due to lack of BE information Mocko et al: PRC 76 (2007)

23 How to predict rare isotope yields? A Si Study of production models suggests that sequential decays wash out the details of the prefragment stage of the reactions Use of statistical or phase space model to understand (systematize) the fragmentation crosssections. Mocko et al: EPL 79 (2007) 12001

24 Relation between cross-sections sections and average binding energy (B/A) Study of production model suggests that sequential decays wash out the details of the prefragment stage of the reactions Use of statistical or phase space model to understand (systematize) the fragmentation crosssections. Mocko et al: EPL 79 (2007) 12001

25 Relation between cross- sections and average binding energy (BE/A) Mocko et al: EPL 79 (2007) σ=cexp(<b> /τ) Statistical model Y(Z, N) = ca 3/2 exp[(nμ n +Zμ p -F)/T] Statistical Multifragmentation Model Chaudhuri, et al Phys. Rev. C 76, (2007)

26 Mass measurements of neutron rich rare isotopes with cross-sections sections Mass of 75 Cu AW03: ± 0.98 MeV

27 Mass measurements of neutron rich rare isotopes with cross-sections sections Mass of 75 Cu AW03: ± 0.98 MeV Compared to ± 0.40 MeV Experimental Uncertainties ~15% σ corresponds to 200 kev; comparable to TOF method Tsang et al: PRC 76 (2007) (R)

Extrapolation of cross-sections sections of drip-line nuclei Existence of 40 Mg but non-existence of 39 Na establishes the n-drip line at N=28 Mocko et al: EPL 79 (2007) 12001 40 Predicted

28 Extrapolation of cross-sections sections of drip-line nuclei Existence of 40 Mg but non-existence of 39 Na establishes the n-drip line at N=28 Mocko et al: EPL 79 (2007) Predicted cross-sections: σ( 40 Mg)~4-8x -11 mb σ( 39 Na)~0.4-6x -11 mb 39 Na Predictions in arxiv: changed from σ( 40 Mg)~4+1x - mb to 4+x -11 mb 40 Mg σ=cexp(<b >/τ) Y(Z, N) = ca 3/2 exp[(nμ n +Zμ p -F)/T]

29 Extrapolation of cross-sections sections of drip-line nuclei Mocko et al: EPL 79 (2007) Predicted cross-sections: σ( 40 Mg)~4-8x -11 mb σ( 39 Na)~0.4-6x -11 mb After our publication, the predicted number of σ( 40 Mg)~ in arxiv: : 4+1x - mb was changed to PRC 75, :4+1x -11 mb This set of data was taken from our thesis data without authorization.

30 Summary Systematic data with ( 58,64,68 Ni, 40,48 Ca, 86 Kr) + (Be, Ta) Benchmark quality data to test fragmentation models; to understand production mechanisms, safety shielding calcs. Fragmentation mechanism of stable and unstable n-rich nuclei are similar Study of Dynamical models suggests that Good agreement with data even though the models are not originally developed to describe fragmentation data. Data can be used to explore the dynamics of the fragmentation reactions. Customary efficiency corrections (based on phase space) may not agree with the reaction dynamics predicted by transport models. Fragments furthest away from stability cannot be predicted accurately by models or EPAX. Exponential relationship between cross-sections and average binding energy established: Binding energy measurements ~ 200 kev -- comparable to TOF method. Extrapolation to cross-sections of rare isotopes

31 Acknowledgement Collaborators: Michal Mocko (thesis) M. Andronenko, L. Andronenko, N. Aoi, J. Cook, F. Delaunay, M. Famiano, T. Ginter, M-J. van Goethem, H. Hua, N. Imai, H. Iwasaki, S. Lukyanov, W.G. Lynch, T. Motobayashi, M. Niikura, T. Ohnishi, D. Oostdy, A. Rogers, H. Sakurai, M. Steiner, A. Stolz, Z. Sun, U. Suzuki, E. Takeshita, S. Takeuchi, O. Tarasov, G. Verde, M. Wallace, A. Zalessov W. Friedman, S. Das Gupta, D. Lacroix, A. Ono, P. Danielewicz

Extrapolation of neutron-rich isotope cross-sections from projectile fragmentation

July 2007 EPL, 79 (2007) 12001 doi: 10.1209/0295-5075/79/12001 www.epljournal.org Extrapolation of neutron-rich isotope cross-sections from projectile fragmentation M. Mocko 1,M.B.Tsang 1(a),Z.Y.Sun 1,2,