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Study of the b -decay of 20 Mg. Hans Fynbo on behalf of M.J.G. Borge , J. Cederkäll , L.M. Fraile , T. Giles, K.L Jensen, J.S. Johansen, B. Jonson, G. T. Koldste , E. Nacher , T. Nilsson, A. Perea , K. Riisager , T. Storra , O. Tengblad. rp -process. ( p, g ). ( a , g ).
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Study of the b-decay of 20Mg Hans Fynbo onbehalf of • M.J.G. Borge, J. Cederkäll, L.M. Fraile, T. Giles, K.L Jensen, J.S. Johansen, B. Jonson, G. T. Koldste, • E. Nacher, T. Nilsson, A. Perea, K. Riisager, T. Storra, O. Tengblad
rp-process (p,g) (a,g) b Ann.Rev.Nucl.Part.Sci. 2010. 60:381-404 (p,a) hCNO cycle
Direct19Ne(p,g)20Na measurement at Louvain-la-Neuve (1995-2004) • Upper limit wg<15meV • Complete spectroscopy at Argonne with GammaSphere (2004) • No solution as to 1+ or 3+ • Measurements of b-decay of 20Mg (1981-1995) • Population of 2643keV not observed • Limit too weak to exclude 1+ Nucl.Phys. A616 (1997) 107c.
bp ba
20Mg b-decay • Only 1+ states populated in allowed GT decays • Search for b-delayed proton line at 450keV, or b-delayed g-emission • Approach challenging due to b-delayed a-emission from daughter decay of 20Na
Berkeley 1981 • RIKEN, MSU 1992 • GANIL 1995 Previous measurements RIKEN 1992 GANIL1995
Berkeley1981 MSU 1992 a DE-E telescope GANIL1995 RIKEN 1992 a-subtracted a
20O Overview of previous work 3.65(6) 3.740(6)
New measurement at ISOLDE • Measure b-delayed proton and gspectrum with high statistics and under much improved conditions • Measure bp, bg and gp coincidences to correctly assign p-peaks. • Physics : • Mirror symmetry • GT-distribution • assignment of 2645keV level
TWO measurements: Gas-Si telescope Large efficiency setup
ISOLDE production of 20Mg? Production of Mg from SiC with RILIS (ions/mC): 2×104
Summary and beam request • We ask for 18 shifts of radioactive beams • 6 shifts for Gas-Si telescope (3shifts tuning) • 12 shifts for High Efficiency setup (3 shifts tuning) • If scheduled at LA1 and LA2 back-to-back save 3 shifts