8-12 July 2013
Africa/Johannesburg timezone
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Search for the 5 alpha cluster state in 20Ne

9 Jul 2013, 11:10
20m
Oral Presentation Track B - Nuclear, Particle and Radiation Physics NPRP

Speaker

Mr Jacobus Swartz (Stellenbosch University)

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

No

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

Yes

Abstract content <br> &nbsp; (Max 300 words)

The primary aim of this experimental investigation was to search for the elusive 0+ 5 alpha cluster state in 20Ne, which is expected in the energy region above the 5 alpha threshold in 20Ne (Ex = 19.17 MeV) [1].
It would be an analogue to the Hoyle state in 12C [2,3], which plays a crucial role in stellar nucleosynthesis and has a well established 3 alpha cluster structure [4].

The secondary aim was to search for new low spin states at high excitation energy in 20Ne.

During four weekends between April and July of 2012, the 22Ne(p,t)20Ne reaction was investigated with the iThemba LABS K600 magnetic spectrometer. A proton beam with an energy of Elab = 60 MeV from the Separated Sector Cyclotron (SSC) facility impinged on a 22Ne gas target at lab angles of θlab = (0˚, 7˚, 16˚, 27˚).

At least three new states in 20Ne have been observed. Two of these appear to be isobaric analogues of known states in 20O. There is also a tentative candidate for the 5 alpha cluster state at around Ex = 22.49 MeV in 20Ne.

[1] K. Ikeda, N. Takigawa and H. Horiuchi, Suppl. Prog. Theo. Phys., Extra Number p 464 (1968).

[2] F. Hoyle, The Astrophysical Journal, Supplement Series, Vol. 1 p. 12 (1954).

[3] C.W. Cook, W.A. Fowler, C.C. Lauritsen and T. Lauritsen, Phys. Rev. 107, 508 (1957).

[4] A. Tohsaki, H. Horiuchi, P. Schuck and G. Rӧpke, Phys. Rev. Lett. 87, 192501 (2001).

Main supervisor (name and email)<br>and his / her institution

Prof. Paul Papka
papka@sun.ac.za
Stellenbosch University

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD)?

PhD

Primary authors

Mr Jacobus Swartz (Stellenbosch University) Prof. Paul Papka (Stellenbosch University) Dr Retief Neveling (iThemba LABS) Dr Ricky Smit (iThemba LABS)

Co-authors

Dr Deon Steyn (iThemba LABS) Mr Fhumulani Nemulodi (iThemba LABS) Prof. Martin Freer (University of Birmingham) Prof. Nico Orce (University of the Western Cape) Dr Siegfried Fortsch (iThemba LABS) Dr Tzany Kokalova (University of Birmingham) Dr Zinhle Buthelezi (iThemba LABS)

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