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Gamma-ray spectroscopy of light hypernuclei の Simulation

Gamma-ray spectroscopy of light hypernuclei の Simulation. Proposed DAY-1 experiment. (K - , p - g ) at p K = 1.5 GeV/c. DAY1 program: Feasible even with low intensity beam (~2 m A). (1) Spin-flip B(M1) measurement and g L in a nucleus

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Gamma-ray spectroscopy of light hypernuclei の Simulation

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  1. Gamma-ray spectroscopyof light hypernucleiの Simulation

  2. Proposed DAY-1 experiment (K-,p- g) at pK = 1.5 GeV/c DAY1 program: Feasible even with low intensity beam (~2mA) (1) Spin-flip B(M1) measurement and gL in a nucleus 7LLi : Least ambiguities exist and most reliable. (2) Further LN interaction study from p-shell hypernuclei 10LB and 11LB: (3) Radial dependence of LN interaction from sd-shell hypernuclei 19LF : Easiest in sd-shell (4) Charge symmetry breaking in LN interaction and spin-flip property in hypernuclear production 4LHe : Largest CSB is suggested but previous data is suspicious. Easiest to observe a spin-flip state Confirmation of LN spin-dependence LN-SN coupling Inconsistency exists. Experimental data not enough. Few-body approach as well as shell model is possible.

  3. Best K- beam momentum K- + n -> L + p- Both spin-flip and nonflip states should be produced. -> pK = 1.1 or 1.5 GeV/c pK = 1.1 GeV/c : K1.1 + “SKS” (ideal) pK = 1.5 GeV/c : K1.8 + SKS (realistic) High K/p ratio to minimize radiation damage to Ge detectors -> Double-stage separation. K1.8BR is not good.

  4. SMF: Muon filter to suppress K- ->m-n SDC3,4: Large-size (2.0mx0.8m), fine cell (1~2cm) To be constructed SP0: Veto counters to reject K- -> p-p0 Beam and Setup • Spectrometer: SKS (modified) Dp ~ 4 MeV (FWHM) W ~ 110 msr p- • Hyperball-J e ~ 7% at 1 MeV K- 1.5 GeV/c • Beamline: K1.8 0.5x106 K-/spill at 1.5 GeV/c (9mA) K/p >> 1 K1.8

  5. Lower half Hyperball-J • Single (r.e.~70%) x 30-40 peak efficiency ~ 7% at 1MeV ( x3 of Hyperball) • Mechanical cooling (under development) -- Lower temp. for less radiation damage -- save space for flexible arrangement • PWO background suppression counters replaced from BGO for higher rate Grant: ~ 3.3Myen, 2005-2009 “Gamma spectroscopy of strange baryon multi-body systems” 科研費特定領域(田村) Photo-peak efficiency + Waveform readout (under deveopment) => Rate limit ~2x107 particles /s (x5 of Hyperball) => Yield: x 15 for single g x 45 for gg

  6. Simulation

  7. J-PARC K1.8 Beam Line BDC1,2 BDC3,4 SDC1,2 BDC3,4 BH1 BH2 SFV TOF SMF BAC SAC SP0 SKS part Beam line part Ge+PWO Hyperball-J

  8. Set up -SKS Minus-

  9. Acceptance of SKS Minus

  10. Acceptance Check by Present SKS

  11. Next Simulation • Trigger Rate and Background Study • Beam direction • Target Point • Momentum resolution • To make formatter 　　　　　　↓ • Analyzing by SKS analyzer ・・・・

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