Studies of -delayed two-proton emission : The cases of 31 Ar and 35 - PowerPoint PPT Presentation

Studies of β -delayed two-proton emission : The cases of 31 Ar and 35 Ca Aarhus-Bordeaux-Madrid-CERN-Göteborg-Jyväskylä-GANIL Collaboration

Two-proton emission Rep. Prog. Phys. 71 (2008) 46301 Not yet observed Observables : (Partial) lifetime, and energy and angular correlations

Two-proton emission 45 Fe → 43 Cr + 2p Bordeaux Warsaw

Two-proton emission 45 Fe → 43 Cr + 2p Bordeaux Warsaw

Two-proton emission 45 Fe → 43 Cr + 2p Bordeaux Warsaw

Beta-delayed two-proton emission 22 Al, 23 Si, 26 P, 27 S, 31 Ar, 35 Ca, 39 Ti, 43 Cr, 45 Fe and 50 Ni

Region of interest

31 Ar-decay

31 Ar-decay

31 Ar-decay Many states Many states

31 Ar - a new look Study 30 S levels Many states Many states Search for direct 2p-decay

31 Ar-decay : Search for direct 2p-decay • Clean place to search for direct 2p-decay • Estimated ~10 -2-3 suppressed compared to sequential decay

31 Ar-decay : 30 S-spectroscopy Astrophysical interest : 29 P(p, γ ) 30 S reaction

31 Ar-decay : 30 S-spectroscopy • β -decay data competitive! • low energy region unclear • Search for 4704keV level • Search for other new levels • measure Γ p / Γ γ for levels PRC 76 (2007) 045803, MSU 29 P(p, γ ) 30 S reaction

35 Ca-decay Äystö 1985 Trinder 1997 Motivation • β -delayed two-proton emission • Spectroscopic information from 34 Ar • Fermi and Gamow-Teller strength

Production 31 Ar 35 Ca • CaO target, cold-plasma • Ti foil target (new design) • Yield ~ 3 atoms/s. • Yield ~ 1 atoms/s (estimate)

Setup Efficiencies: Charged particles 1p : 60-75% (25%) 2p : 35% (5%) Gammas Orders of magnitude more than last Surrounded by 3 four-leaf Ge clover detectors

1997 experiment Simulated response of planned setup

Beam request β -decay of 35 Ca : β -decay of 31 Ar : 6 shifts : Target test 27 shifts : Measurement and calibration - factor 5-15 more 2p events than previous measurement for 1-3 31 Ar/s. Total beam request 33 shifts