The optical potential of light exotic nuclei

Transcription

1 Angela Bonaccorso The optical potential of light exotic nuclei in collaboration with F. Carstoiu, RJ Charity [Bucharest, St Louis, Pisa] Trento 15 th May 2015

2 2

3 More or less in the same period (early 80 s) 3

4 Nowadays 4

5 Determine ANC and/or spectroscopic factor for SP states (can give reaction rates directly) Ab-initio (Nollett-Wiringa) or HF wfs 5

6 β 1 β 2 c 6

7 One-neutron knock-out to study 7

8 9 Cà 8 C (α+4p). α... n. b c 8

9 Core P // spectra 9

10 r s =1.4 à R s = (fm) 10

11 11

12 transfer and 12 AB&F.Carstoiu, NPA706 (2002) 322 AB&A.Ibraheem, NPA748 (2005) 414

13 Study sensitivity to S ct 2 comparing to σ R data A target used very often is 9 Be 13

14 14

15 A.B & R. J. Charity, PRC89, (2014) 15

16 AB & F. Carstoiu, PRC61, (2000) (mb) Finlay n+ 9 Be eikonal eikonal eikonal JLM E n (MeV) 16

17 Resonances,)trojan)horse) knockout) 3 2 data p reaction data n reaction data total data elastic react eik elastic eik tot eik σ(barn) E_lab(MeV)

18 n+ 9 Be, 40MeV WHMeVL 20. Single Folding BW density & σ pp from Eq. (7) AB DOM rhfml 18

19 Status of the Art Reaction cross sections of unstable nuclei See for example A. Ozawa (University of Tsukuba)

20 1800 Results in RIBLL A.Ozawa et al., NIMB in press σ I (mb) Be Predictions by phenomenological formulae Energy (A MeV) B B σ I (mb) σ I (mb) Energy (A MeV) Energy ( A MeV) They obtained only interaction cross sections (σ I ) with large error bars

21 14 C D.Q.Fang et al., PRC 69 (2004) Pure p 15 Pure s 1/2 C 1/2 RIPS data RIPS data T.Zheng et al., NPA709(2002) C Pure s 1/2 C.Wu et al., NPA 739 (2004) C RIPS data RIPS data

22 NORMAL NUCLEI PRC22 (1980)

23 A test case: results for 9 C+ 9 Be σ R data D. Nishimura et al., unpublished PD density 9C BW density DOM HF density scaled n-9be reaction calc AB pot 9C Nishimura data FLO JLM no renorm. 9C YK-E density 9C YK-E density +5% 9C FC(HF) density σ R (mb) r s (fm) 1.2 E(AMeV) KE 43AMeV FC JLM 83AMeV KE FC JLM 43AMeV 1.1 from YKE density from BW density from FC(HF) density from PD density DOM HF density 1 30 JLM HF density E(AMeV) S ct b c (fm) 23

24 ρ(fm -1/3 ) Density dependence ρ(fm -1/3 ) e-06 rms(fm) Exp 2.56 ± 0.05 FC(HF) YK-E 9C PD density BW FC(HF) YK-E 9C PD density BW BW 2.35 PD 2.34 (2 YK-E 2.49 HF e e r(fm) r(fm) In σ R large distances are important while breakup is localized around the distance of closest approach à R s 24

25 Legenda and thanks to: FC Florin Carstoiu PD Pierre Descouvemont Y K-E Yoshiko Kanada Enyo BW Robert Wiringa 25

26 Conclusions Strong absorption model seems to work also for light BOUND very exotic nuclei (N/Z=1/3) but surface effects (halo structure) are very important. Experimental reaction cross sections are extremely useful to determine sizes and densities of nuclei but also dynamics Energy dependence on n,p-target optical potential seems OK but how to include n,p-projectile energy dependence? OR Folding is first order in the interaction Folding contains only gs density à NO excited state effects Can we use transition densities? Energy dependence? 26

27 Rewriting Nuclear Physics textbooks 30 years with Radioactive Ion Beam Physics Pisa (Italy), July 20 th 24 th, 2015 Photo copyright Robert Charity 2014 The scope of the activity is twofold. First we will celebrate 30 years since the first work on radioactive ion beams (RIBs) used to study structural properties of atomic nuclei. Since then Low Energy Nuclear Physics research fed by experiments at various facilities all over the world has experienced a great revival supported by widespread theoretical efforts which have changed deeply our understanding of nuclei and their interactions. The second scope of the event is to attract and educate the best possible students introducing them to the wonders of Physics with RIBs. We shall try to convey to such students a view of the rich variety of on-going activities in the field, both experimental and theoretical such that the progresses we have made in the last 30 years can be developed further in the future. The planned activities will be directed towards students who are in the process of deciding what graduate studies to specialize on. Program Isao Tanihata (Osaka and Beijing) Magda Kowalska (CERN, Geneva) Riccardo Raabe (Leuven) Giovanna Benzoni (Milano) Sonia Bacca (TRIUMF, Vancouver) Stefan Typel (GSI) Robert J. Charity (St Louis) Tomohiro Uesaka (RIKEN) Alexandre Obertelli (Saclay) Andrea Jungclaus (Madrid) Lucio Gialanella (Napoli) Ulli Koester (ILL-Grenoble) Bjorn Jonson (Göteborg) How it all started Global properties of atomic nuclei: masses, radii and modern methods to measure them Making radioactive ion beams, detecting reaction products Strong, weak and electromagnetic forces at work in atomic nuclei, decay properties Structure models: from shell model to ab initio methods Reaction theory Resonance phenomena: from compound nucleus decay to proton radioactivity Experimental methods and measured observables with polarized proton targets: understanding spin-orbit Probing nuclear structure with direct reactions: observables, methods and recent progress with rare isotopes Single particle versus collectivity, shapes of exotic nuclei Radioactive ion beams in experimental nuclear astrophysics Applications of physics of unstable nuclei to energy, medicine, material science What s next in Nuclear Physics with RIBs 24/7/2015: Visit to the INFN Legnaro National Laboratory where SPES, the Italian RIB's facility is under construction Local Organizing Committee Angela Bonaccorso, INFN, Pisa (co-chair) Giovanni Casini, INFN, Firenze (co-chair) Ignazio Bombaci, Department of Physics, University of Pisa Alejandro Kievsky, INFN, Pisa Laura Elisa Marcucci, Department of Physics, University of Pisa Valeria Rosso, Department of Physics, University of Pisa Michele Viviani, INFN, Pisa Lucia Lilli and Claudia Tofani, INFN, Pisa (Secretaries): ExoticNuclei2015@pi.infn.it 27 Poster designer: Ignazio Bombaci