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For 4 weekends from April to July 2012: Proton beam delivered from SPC1 through K line to SSC Accelerated to 60 MeV by SSC Steered through X, P1, P2 and S lines to K600 vault The iThemba LABS cyclotron
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Search for low spin states at high excitation energies in 20Ne
with the p,t reactioniThemba LABS & Stellenbosch University
Energy Postgraduate Conference 2013
Alpha clustering in n-alpha nuclei
• Threshold rule: n-alpha cluster state expected above n-alpha breakup
threshold in all n-alpha nuclei e.g. 8Be, 12C • Want to find 5 alpha cluster state in 20Ne
• To use 22Ne(p,t)20Ne reaction with K600 magnetic spectrometer
For 4 weekends from April to July 2012:• Proton beam delivered from SPC1 through K line to
SSC • Accelerated to 60 MeV by SSC • Steered through X, P1, P2 and S lines to K600 vault
The iThemba LABS cyclotron
Experimental tool: The K600 spectrometerK600 contains:1 Quadrupole, 2 dipoles, H- and K-coil (focussing magnets)Best (p,p') resolution: 25 keVBest (α,α') resolution: ~50 keV (for 200 MeV beams)
Experimental tool: The 22Ne gas targetCell enclosed between two 6 micron Aramid windows containing gas• Entrance area: 1⨯3 cm2
• Target 1 cm thick• Gas target was used before with K600 during experiment in 2009...
Preliminary data22Ne(p,t)20Ne at 0°Red – 33.5 MeV Green – 36 MeV Orange – 41 MeV Blue – 46 MeV Magenta – 52 MeVBlack – Aramid background
Excitation energy [MeV]
Counts/10 keV
Preliminary data
Excitation energy [MeV]
Counts/10 keV
Candidate isobaric analogue states
22Ne(p,t)20Ne at 0°Blue – 33.5 MeV Red – 36 MeV Black – Aramid background
5-alpha prediction - PRC 69 024309 (2004)
Preliminary data
Angular distribution of known states
Angular distribution of Isobaric Analogue candidates
Interpretation of the new states
Prediction from Werner Richter's IMME calculation for strong isobaric analogue candidates:
Calculations for T=2 states20.59 MeV 20Ne - 3.856 MeV 20O 21.168 MeV 20Ne – 4.435 MeV 20O21.796 MeV 20Ne – 5.063 MeV 20O
Known in 20O 3.570 MeV 4+ 20O4.072 MeV 2+ 20O4.456 MeV 0+ 20O 4.850 MeV 4+ 20O5.002 MeV 20O5.234 MeV 2+ 20O
Interpretation of the new statesPrediction by Alex Brown using NuShellX and Fresco:
Experimental cross sections from present measurement at θLAB=0∘:
