Structure effects in the reactions 9,10,11 Be+ 64 Zn at the Coulomb barrier

Structure effects in the reactions Structure effects in the reactions 9,10,119,10,11Be+Be+6464Zn at Zn at the Coulomb barrierthe Coulomb barrier

Valentina ScuderiValentina Scuderi

10th International Spring Seminar on Nuclear Physics, New Quest 10th International Spring Seminar on Nuclear Physics, New Quest in Nuclear Structure, Vietri sul Mare, May 21-25, 2010in Nuclear Structure, Vietri sul Mare, May 21-25, 2010

Characteristics of the projectiles:Characteristics of the projectiles:Low break-up energy thresholds + Low break-up energy thresholds + long tail in long tail in

density distributiondensity distribution

Effects on direct reaction processes:Effects on direct reaction processes:Direct mechanisms, transfer and Direct mechanisms, transfer and

breakup, are favoured?breakup, are favoured?

Effects on fusion cross-section:Effects on fusion cross-section:Extended tailsExtended tails

enhancement of sub-barrier fusionenhancement of sub-barrier fusion

Reactions with neutron halo nuclei Reactions with neutron halo nuclei

Elastic scattering: a fundamental tool to investigateElastic scattering: a fundamental tool to investigate halo structurehalo structure

influence of break-up channel influence of break-up channel

nuclear potential between the colliding nuclei nuclear potential between the colliding nuclei

Which is the effect of the break-up couplings Which is the effect of the break-up couplings on other channels ? on other channels ?

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T+buT+bu ≈ 1.2b ≈ 1.2b

A. Di Pietro et al. Phys.Rev.C 69(2004)044613A. Di Pietro et al. Phys.Rev.C 69(2004)044613

tran+butran+bu//ReacReac 80% 80%

σσReacReac((66He) >> σHe) >> σReacReac((44He)He)

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4,64,6He+He+6464Zn Zn Elastic scattering a. d. @ EElastic scattering a. d. @ Ecmcm= 12.4 MeV= 12.4 MeV

66He+He+6464Zn Zn particle a. d. @ E particle a. d. @ Ecmcm=12.4 MeV=12.4 MeV

Some results with Some results with 66He beamHe beamSome results with Some results with 66He beamHe beam

Most of the experiments performed with Most of the experiments performed with 66He beamsHe beams (e.g. (e.g. 66He+He+209209Bi, Bi, 66He+He+238238U, U, 66He+He+6464Zn, Zn, 66He+He+6363Cu, Cu, 66He+He+197197Au,Au, 66He+He+208208PbPb) )

See also: See also: E.F. Aguilera Phys. Rev. C 63 (2001) 061603, E.F. Aguilera Phys. Rev. C 63 (2001) 061603, J.J. Kolata et al. Phys. Rev C 75 (2007)J.J. Kolata et al. Phys. Rev C 75 (2007) 031302031302 R, R, P. A. De Young et al. Phys. Rev. C 71 (2005) 051601(R), P. A. De Young et al. Phys. Rev. C 71 (2005) 051601(R), A. Chatterjee et al. PRL 101 (2008) 032701.A. Chatterjee et al. PRL 101 (2008) 032701.

1111Be + Be + 209209Bi elastic scattering angular distributionsBi elastic scattering angular distributions

Mazzocco et al. Eur. Phys. J. Special Topics 150 (2007) 37Mazzocco et al. Eur. Phys. J. Special Topics 150 (2007) 37

No effect on the reaction cross-section No effect on the reaction cross-section in in 1111Be case compared with Be case compared with 99Be. Be.

ReacReac99Be) ≈ Be) ≈ ReacReac 1111Be)Be)

Experiments with Experiments with 1111Be beamBe beamExperiments with Experiments with 1111Be beamBe beam

The The 9,10,119,10,11Be+Be+6464Zn experimentsZn experiments

Aims of the experiments:Aims of the experiments:

• Elastic scattering angular distribution Elastic scattering angular distribution

• 1111Be transfer/break-up angular distribution.Be transfer/break-up angular distribution.

1111Be ISOL beam @ EBe ISOL beam @ ELABLAB = 29.8 MeV = 29.8 MeV1010Be ISOL beam @ EBe ISOL beam @ ELAB LAB = 29.4 MeV= 29.4 MeV

99Be beam @ EBe beam @ ELABLAB = 29.0 MeV = 29.0 MeV

9,10,119,10,11Be + Be + 6464Zn @ same Zn @ same EEcmcm = 24.5 MeV = 24.5 MeV

99Be + Be + 6464Zn experiment @ LNS (Catania) Zn experiment @ LNS (Catania)

5 Si –Si detector telescopes:5 Si –Si detector telescopes:

ΔE: 6-15 μm thick, Si Surface Barrier ΔE: 6-15 μm thick, Si Surface Barrier

detectorsdetectors

E : 90-130 μm thick, Si Surface Barrier E : 90-130 μm thick, Si Surface Barrier

detectorsdetectors

Angular distribution: 15°Angular distribution: 15° lablab 110°110°

Detectors inside the chamberDetectors inside the chamber

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10,1110,11Be + Be + 6464Zn experiment @ REX-ISOLDE (CERN)Zn experiment @ REX-ISOLDE (CERN)

BeamBeam

DSSDsDSSDsDetectors inside the chamberDetectors inside the chamberview from the topview from the top

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6 Si-Si detector telescopes:6 Si-Si detector telescopes:

ΔE: 50 μm thick, 50x50mmΔE: 50 μm thick, 50x50mm22 active area DSSDs detectors active area DSSDs detectors

16 +16 strips (256 pixels each detector)16 +16 strips (256 pixels each detector)

E : 1500 μm thick, 50x50mmE : 1500 μm thick, 50x50mm22 active area Si Single Pad detector active area Si Single Pad detector

Total covered angular range 10°Total covered angular range 10° lablab150°150°

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9,10,119,10,11Be + Be + 6464Zn Zn elastic scattering angular distributionselastic scattering angular distributions

99Be+Be+6464ZnZnOM FitOM Fit

1010Be+Be+6464ZnZnOM FitOM Fit

1111Be+Be+6464ZnZnOM FitOM Fit

Optical Model analysis: Optical Model analysis:

9,109,10Be: Wood-Saxon (W-S) form for real and imaginary volume potentialBe: Wood-Saxon (W-S) form for real and imaginary volume potential

1111Be: volume real and imaginary W-S potentials obtained from Be: volume real and imaginary W-S potentials obtained from 1010Be scattering Be scattering

++

surface imaginary termsurface imaginary term

a very large diffuseness (a very large diffuseness (aasisi=3.5fm) is needed to reproduce the elastic cross-section behaviour=3.5fm) is needed to reproduce the elastic cross-section behaviour

Reaction cross-section Reaction cross-section

ReacReac99Be) = Be) = 1090 ± 50 mb1090 ± 50 mb; ; ReacReac1010Be) = Be) = 1260 ± 280 mb 1260 ± 280 mb

ReacReac1111Be) = Be) = 2730 ± 300 mb2730 ± 300 mb

99Be+Be+6464ZnZnOM FitOM Fit

1010Be+Be+6464ZnZnOM FitOM Fit

1111Be+Be+6464ZnZnOM FitOM Fit

1010BeBe

1111BeBe1010BeBe

1010BeBe + + 6464Zn ∆E-E scatter plot @ 35°Zn ∆E-E scatter plot @ 35°

1111Be + Be + 6464Zn ∆E-E scatter plot @ 35°Zn ∆E-E scatter plot @ 35°

Which processes are contributing to the large reaction Which processes are contributing to the large reaction cross-section in the cross-section in the 1111Be case?Be case?

tran+butran+bu = = 1100 ± 110 mb1100 ± 110 mb

tran+butran+bu//ReacReac 0.4 0.4

1111Be+Be+6464Zn transfer+break-up angular distributionZn transfer+break-up angular distribution

ConclusionsConclusions

The collisions The collisions 9,10,119,10,11Be + Be + 6464Zn have been studied at EZn have been studied at Ecmcm = = 24.5 MeV by using post-24.5 MeV by using post-accelerated accelerated 10,1110,11Be beams at REX-ISOLDE.Be beams at REX-ISOLDE.

Damping of elastic cross-section for the reaction induced by the Damping of elastic cross-section for the reaction induced by the 1111Be nucleus when Be nucleus when compared with both compared with both 99Be (SBe (S

nn= 1.67 MeV) and = 1.67 MeV) and 1010Be (SBe (Snn= 6.8 MeV).= 6.8 MeV).

Surface term with large diffuseness needed to fit the Surface term with large diffuseness needed to fit the 1111Be data.Be data.

The reaction cross-section for The reaction cross-section for 1111Be induced collision is much larger than for the other Be induced collision is much larger than for the other

two Be isotopes σtwo Be isotopes σReacReac((1111Be) ~ 2 σBe) ~ 2 σReacReac((

9,109,10Be).Be).

Evidence for the presence of a large yield of transfer andEvidence for the presence of a large yield of transfer and//or breakup events in the or breakup events in the 1111Be induced collision with a corresponding cross section σBe induced collision with a corresponding cross section σ tran+butran+bu ~ 1 barn. ~ 1 barn.

These results show a strong effect on nuclear reaction mechanisms around These results show a strong effect on nuclear reaction mechanisms around the Coulomb barrier due to the halo structure and its weak bindingthe Coulomb barrier due to the halo structure and its weak binding

L. Acosta, F. Amorini, M.J.G. Borge, A. Di Pietro, P. Figuera, M. Fisichella, L. Acosta, F. Amorini, M.J.G. Borge, A. Di Pietro, P. Figuera, M. Fisichella, L.M. Fraile, J. Gòmez-Camacho, H. Jeppesen, M. Lattuada, I. Martel, M. L.M. Fraile, J. Gòmez-Camacho, H. Jeppesen, M. Lattuada, I. Martel, M. Milin, A. Musumarra, M. Papa, M.G. Pellegriti, R.Raabe, G.Randisi, F. Milin, A. Musumarra, M. Papa, M.G. Pellegriti, R.Raabe, G.Randisi, F. Rizzo, D. Santonocito, E.M.R. Sanchez, G. Scalia, V. Scuderi, O. Tengblad, Rizzo, D. Santonocito, E.M.R. Sanchez, G. Scalia, V. Scuderi, O. Tengblad, D. Torresi, A.M. Vidal, M. ZadroD. Torresi, A.M. Vidal, M. Zadro

•INFN- Laboratori Nazionali del Sud and sezione di Catania, Catania, Italy•Dipartimento di Fisica ed Astronomia, Università di Catania, Catania, Italy

•Departamento de Física Aplicada, Universidad de Huelva, Huelva, Spain•Insto. de Estructura de la Materia, CSIC, Madrid, Spain• CERN, Geneva, Switzerland•Departamento de Física Atómica, Moleculary Nuclear, Universidad de Sevilla, Spain•Ruđer Boŝković Institute, Zagreb, Croatia•Dipartimento di Metodologie Fisiche e Chimiche per l’Ingegneria, Università di Catania, Catania, Italy•DAPNIA/SPhN, CE Saclay, Gif-sur-Yvette •LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France

Collaboration Collaboration

Thank youThank you

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9,10,119,10,11Be+Be+6464Zn optical potentialsZn optical potentials

ReactionReaction V(MeV)V(MeV) a(fm)a(fm) RR00(fm)(fm) VVii(MeV)(MeV) aaii(fm)(fm) RRi0i0(fm)(fm) VVSiSi(MeV)(MeV) aaSiSi(fm)(fm) RRSiSi(fm)(fm)

99Be+Be+6464ZnZn 126126 0.60.6 1.11.1 17.317.3 0.750.75 1.21.2

1010Be+Be+6464ZnZn 86.286.2 0.70.7 1.11.1 43.443.4 0.60.6 1.21.2

1111Be+Be+6464ZnZn 86.286.2 0.70.7 1.11.1 43.443.4 0.60.6 1.21.2 0.1510.151 3.53.5 1.31.3

Rutherford scattering for Rutherford scattering for 1212C + C + 197197Au @ 28 MeV and Au @ 28 MeV and 1010Be + Be + 197197Au Au

@ 29.4 MeV to cross check the geometry determination.@ 29.4 MeV to cross check the geometry determination.

Detector geometry determinationDetector geometry determination

0.10.1

1111Be+Be+6464Zn quasi-elastic angular distributionZn quasi-elastic angular distribution

inelastic inelastic = 275 = 275 76 mb 76 mb

Work is in progress to extract Work is in progress to extract fusfus(E) for the (E) for the 1010Be+Be+6464Zn systemsZn systems

Fusion cross-section measurement for Fusion cross-section measurement for 10,1110,11Be+Be+6464Zn using the Zn using the activation techniqueactivation technique

1010Be+Be+6464Zn X-ray spectra analysis Zn X-ray spectra analysis

Ge isotope activity curve Ge isotope activity curve shortly after shortly after the end of the the end of the irradiationirradiation

E.R.E.R. TT1/21/2

7272SeSe 8.4d8.4d7171SeSe 4.7m4.7m7272AsAs 25h25h7171AsAs 65.28h65.28h7171GeGe 11.43d11.43d6969GeGe 39.05h39.05h6868GeGe 270.8d270.8d6868GaGa 67.61m67.61m

1010Be+Be+6464ZnZn

Fragmentation beam degraded to Fragmentation beam degraded to barrier energiesbarrier energies

E(MeV)

Cou

nts

11Be11Be beam energy profile

large beam energy spread large beam energy spread

1111Be + Be + 209209Bi quasi-elastic scattering angular distributionsBi quasi-elastic scattering angular distributions

Mazzocco et al. Eur. Phys. J. Special Topics 150 (2007) Mazzocco et al. Eur. Phys. J. Special Topics 150 (2007) 3737

No effect on the total reaction No effect on the total reaction cross-section in cross-section in 1111Be case Be case compared with compared with 99Be. Be.

RR 99Be) ≈ Be) ≈ RR 1111Be)Be)

Experiments with Experiments with 1111Be beamBe beamExperiments with Experiments with 1111Be beamBe beam