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ISOMERIC BEAMS

ISOMERIC BEAMS. Phil Walker – University of Surrey. Shell-model isomers in the 208 Pb region Stopped isomeric beams: τ < 1 ms Stopped isomeric beams: τ > 1 ms Fast isomeric beams: purification Fast isomeric beams: reactions. 212 Po = 208 Pb + α. 2911 keV, (18+) τ = 65 s , α decay.

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ISOMERIC BEAMS

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  1. ISOMERIC BEAMS Phil Walker – University of Surrey • Shell-model isomers in the 208Pb region • Stopped isomeric beams: τ < 1 ms • Stopped isomeric beams: τ > 1 ms • Fast isomeric beams: purification • Fast isomeric beams: reactions

  2. 212Po = 208Pb +α 2911 keV, (18+) τ = 65 s, α decay wait for one second: isomer purity = 100 % ground state, 0+, 430 ns, α decay

  3. Walker and Dracoulis, Nature 399 (1999) 35 E > 1MeV, τ > 1 ms isomers

  4. high-spin isomer chart a Phil Walker special

  5. long-lived, high-spin isomers Walker and Dracoulis, Hyp. Int. 135 (2001) 83

  6. hafnium (Z=72) isomers 178Hf 188Hf expt. calc. Walker and Dracoulis, Hyp. Int. 135 (2001) 83

  7. Super-FRS yields 215Ra

  8. τ = 800 ns, 43/2-, 3.8 MeV 407 keV γ-ray 215Ra from 206Pb(13C,4n) Stuchbery et al. Nucl. Phys. A641 (1998) 401

  9. 215Ra γ-ray spectrum Z. Podolyak, private communication from 238U fragmentation

  10. 29/2+, T1/2 = 740ns 217Ac level scheme 217Ac from (HI,xn) reactions Decman et al., Nucl Phys. A436 (1985) 311

  11. 217Ac γ-ray spectrum Z. Podolyak, private communication from 238U fragmentation

  12. 208Pb region 217Ac, 29/2+, 1μs 215Ra, 43/2-, 800ns 212Po, 18+, 65s many μs isomers expected

  13. Summary 217Ac: 1μs isomer purified by flight time through FRS (factor of 15 in 300 ns) good for RISING fast beam opportunity for (i) γ-gated Coulex (ii) knockout reactions …… and knockout to other isomers: RISING stopped beam 212Po: 65s isomer 100 % purified by flight time in ESR N~126, Z<82: many new μs isomers expected good for RISING stopped beam test N=126 shell-gap stability approach r-process path ….

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