1. Manolis Benis Formation mechanisms of the 1s2s2p 4 P J metastable state in 12 MeV C 4+ (1s 2 1 S, 1s2s 3 S) collisions with H 2, He, Ne and Ar Department of Physics, University of Ioannina PIPAMON workshop, Debrecen, March 24-26, 2015

2. OUTLINE  Ion-atom collisions  Population of the 1s2l2l' states  Literature Overview  Pauli exchange interaction  Radiative cascade feeding  Miscellaneous on mixed state beams and metastable states Auger decay detection  Results from older measurements  New data from new measurements  Ongoing research at Democritus Infrastructure

3. PIPAMON workshop, Debrecen, March 24-26, 2015 Ion-atom Collisions continuum K L M K capture K-M excitation E a - Auger energy KLM Auger transition e-e interaction Atomic Energy levels K ionization Atomic Structure: q, Z p, Z t, E x, E a … Collision Dynamics: b, V p, v t … Cross section: Few HCI: Few -electrons - simpler environment for testing theories Projectile spectroscopy: Control # of electrons on ion by selecting its charge Special interest: Two-electron processes, e- correlations and deviations from the IPM M-K radiative transition ExEx VpVp ZpZp ZtZt b e-e- e-e- Ion-atom collision vtvt Projectile Ion Charge q+ Target Atom

4. T+NTE PIPAMON workshop, Debrecen, March 24-26, 2015 Populating the 1s2l2l' states NTE V V RTE TargetProjectile V T (or C)

5. PIPAMON workshop, Debrecen, March 24-26, 2015 Spin statistics for 2p capture to 1s2s 3 S + 2p 4 P : 2 P - : 2 P + Finalbreakdown Probability Spin recoupling

6. PIPAMON workshop, Debrecen, March 24-26, 2015 Literature Overview Spin statistics Strohschein et al PRA 2008 Zouros et al PRA 2008

7. PIPAMON workshop, Debrecen, March 24-26, 2015 Mixed state (1s 2 1 S, 1s2s 3 S ) beams Use both measurements to obtain the fractions Benis et al PRA 2004 Practically ground state (1s 2 ) spectrum. < 3% metastable Ion Beam obtained by gas stripping at lower energies Mixed state (1s 2, 1s2s 3 S) spectrum 25% metastable Ion Beam obtained by foil stripping “Subtract” spectra to obtain pure metastable beam 1s2s 3 S spectrum!

8. Mixed state (1s 2 1 S, 1s2s 3 S ) beams PIPAMON workshop, Debrecen, March 24-26, 2015 Strohschein et al PRA 2008

9. PIPAMON workshop, Debrecen, March 24-26, 2015 Pauli exchange interaction (?) A target electron with spin aligned to the spin of the 1s projectile: b) cannot be captured into the 1s (or 2s) due to Pauli exclusion. Tanis et al PRL2004 The Pauli Exchange Interaction is reminiscent of the Transfer-Excitation mechanism, but with two identical electrons doing the Transfer and the Excitation! - Rather puzzling and difficult to calculate (not possible to date!) - Rather puzzling and difficult to calculate (not possible to date!) New idea: So instead it interacts with the 1s (or 2s) via a Pauli Exchange Interaction with one e- transferred to the 2p forming additional 4P states a) can be captured into the 2p directly to form the 1s2s2p 4 P

10. PIPAMON workshop, Debrecen, March 24-26, 2015 Radiative Cascade feeding (?) Significant capture to higher n=3-7 indicated by CDW calculations nl Zouros et al PRA2008

11. PIPAMON workshop, Debrecen, March 24-26, 2015 Radiative Cascade feeding (?) TJM Zouros, B. Sulik, L. Gulyas, K.Tokesi, PRA 77, 050701R (2008)

12. PIPAMON workshop, Debrecen, March 24-26, 2015 Current Status Strohschein et al PRA 2008 (50%) Röhrbein et al PRA 2010 (70%)

13. PIPAMON workshop, Debrecen, March 24-26, 2015 Ion-atom Collisions

14. PIPAMON workshop, Debrecen, March 24-26, 2015 The effective solid correction factor Doukas et al RSI (accepted)

15. PIPAMON workshop, Debrecen, March 24-26, 2015 SIMION simulations Doukas et al RSI (accepted)

16. PIPAMON workshop, Debrecen, March 24-26, 2015 Revisit of older data Benis et al PRA 2004 4MeV B 3+ +H 2

17. PIPAMON workshop, Debrecen, March 24-26, 2015 Current and future prospects In progress: Installation of terminal gas stripper to produce ground state beams Installation of post strippers (foil and gas) to produce He-like ions at lower energies Investigation of the systematics of the 4 P/ 2 P ratio in an isoelectronic sequence study using He-like ions from Li +, B 3+, C 4+, N 5+, O 6+, F 7+ in the 0.1-2 MeV/u Investigation of the systematics of the 4 P/ 2 P ratio in an isoelectronic sequence study using He-like ions from Li +, B 3+, C 4+, N 5+, O 6+, F 7+ in the 0.1-2 MeV/u Use different targets such as H 2, He, Ne, Ar Use different targets such as H 2, He, Ne, Ar

18. PIPAMON workshop, Debrecen, March 24-26, 2015 Ongoing Research Strohschein 2008 APAPES Results look very similar – except for 2-3 times larger 4 P (higher efficiency of our spectrograph)

19. PIPAMON workshop, Debrecen, March 24-26, 2015 Ongoing Research New calculations are needed to evaluate capture and cascade contributions for all measured collision systems New targets Higher Energy – 18 MeV

20. PIPAMON workshop, Debrecen, March 24-26, 2015 The team 5MV Tandem NCSRT Demokritos Dr S. Harissopulos (Director) M. Andrianis Dr T. Lagogiannis Dr. M. Axiotis Dr. A. Dimitriou (Post doc) I. Madesis (PhD) A. Laoutaris (MSc) Prof. Theo Zouros Univ. of Crete S. Doukas (MSc) Univ. of Ioannina Prof. Bela Sulik ATOMKI Prof. Omer Sise Univ. of Isparta Prof. Manolis Benis Univ. of Ioannina

21. Thank you for your attendance PIPAMON workshop, Debrecen, March 24-26, 2015 Acknowledgement: This research has been co-financed by the European Union (European Social Fund ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) Research Funding Program: THALES. Investing in knowledge society through the European Social Fund, grant number MIS 377289.