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ハドロン原子のカスケード過程

2006 年 3 月 1 日　「 QCD とハドロン物理の新展開」研究会 , KEK. ハドロン原子のカスケード過程. 理研　岩崎先端中間子研究室　　 小池　貴久. Today’s topics ★ X-ray spectrum of X - - 12 C atoms for J-PARC ★ K - mass mesurement using K - - 14 N atom x-rays at DA F NE. ◆ Exotic Atom / Hadronic Atom / Mesic Atom.

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ハドロン原子のカスケード過程

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  1. 2006年3月1日　「QCDとハドロン物理の新展開」研究会, KEK ハドロン原子のカスケード過程 理研　岩崎先端中間子研究室　　 小池　貴久

  2. Today’s topics ★ X-ray spectrum of X --12C atoms for J-PARC ★K- mass mesurement using K--14N atom x-rays at DAFNE ◆Exotic Atom / Hadronic Atom / Mesic Atom X- = m -, p -, K-, p, S-, X-, W-, … ・ Hypernucleus formation --- stoppedK-, X- reactions ・ Some exotic structures --- long-lived p-4He --- deeply bound nuclear state ・ X-ray spectroscory --- deducing X--nucleus strong interaction, X- mass, nuclear radius, … etc. ・ Collison problem of unusual atoms/molecules

  3. Part. I Cascade Calculation ofK--14N Atom --- for the precise K- mass mesurement planned at DAFNE.

  4. Cited from Particle Data Group Review; S. Eidelman et. al, Phys. Lett. B592, 1 (2004) ←C ←Pb, W ←K (potassium) ←Pb ←Au, Ba Most two recent data differ 60 KeV, although their uncertainties are about 10 KeV ! New mass mesurement using kaonic nitrogen atom x-rays is planned at DAFNE.

  5. ~ 0.1 eV diff. in 6-5 x-ray energy ~10 keV diff. in kaon mass Electron screening effect becomes crucial for determing kaon mass within 10 keV errors!

  6. ◆ Problem on the precise mass determination ・ The electron screening effect of the x-ray energy can not be acculately evaluated without the knowledge of; How many electron remain at the moment of x-ray emmision? The DAFNE measurement uses the gaseouse nitrogen target at the density r = 3.4 rNTP. Complete ionization ??? --- not sure… ・ The atomic cascade calculation including electron refilling prosess enables us to determin the electron configration.

  7. ~48 for X --12C X --12C

  8. Pick-up from outside K- Na(t) G 1s-Augf1s(t) + G 2s-Augf2s(t) + G 2p-Augf2p(t) radiative Na’(t) ◆Our electron refilling model e e f2p(t) e e f2s(t) KLL-Auger f1s(t)

  9. ◆ Auger transition b d a c ・Multipole expansion

  10. ・LS coupling scheme ・using analytic hydrogen-like atom wave functions with the effective charge Z*. ・ Z*is estimatedusing semi-emprical rule.

  11. ◆ Kaon-electronAuger transition rate formulas ・ Auger transition rate for ejecting one1s-electron ・ Auger transition rate for ejecting one2s-electron ・ Auger transition rate for ejecting one2p-electron

  12. kaon population n l

  13. One electron remains with the prob. of ~4% at n = 6.

  14. K-shell filled cases

  15. K-shell half-filled cases

  16. K-shell empty cases

  17. Part.II Cascade Calculation ofX--12C Atom --- for the S=-2 strangeness nuclear physics sector at J-PARC.

  18. ◆ Twin L-hypernucleus fomation events in KEK-PS E176 ・Yokohama event ・Korea event interpreted as the nuclear absorption from X--12C atom 2p-state, assuming Woods-Saxon typeof X- - nucleus potential with V0 ~ -16 MeV.

  19. “attractive shift” “repulsive shift” V0 = -16 MeV case V0 = -24 MeV case ・ X--nucleus strong interaction → Woods-saxon potential V0 : parameter, W0 = -1 MeV, Rreal = 1.1×A1/3 fm, Rimag = 0.9×A1/3 fm, a = 0.65 fm

  20. (V0 = -16 MeV case)

  21. ◆ Calculated decay profile of 12C-X- atom

  22. Same as 16 MeV case Same as 16 MeV case ◆ Calculated x-ray yields for 12C-X- atom

  23. ・Natural line width is taken into account. ・No detector resolution. ・No buckground. Preliminary calculation Detectable ???

  24. ◆ Summary ・ The atomic cascade code of exotic atoms with many electrons has been developed . Topic 1: K- mass mesurement using K--14N atom 6 → 5 x-ray at DAFNE ・ The electron configration at the moment of the x-ray emmision is important to achive the desired accuracy (~10 keV). ・ Only 1 electron remains in 1s-orbit with the probabilie of 4% under the DAFNE condition (gas, r = 3.4 rNTP). ・The complicated electron configrations at high density target. Topic 2: X-ray spectroscopy of X--12C atom at J-PARC. ・ 2p-state; V0= -16 MeV → attractive shift, -24 MeV → repulsive shift. ・ 3d→2p x-ray yields = 1~2 % per stopped X-. ・ The expected x-ray spectrum can be calculated. ・ Is there any other suitable atoms? --- more studies are now in progress.

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