Gamma-ray spectroscopyof light hypernuclei
の Simulation
Proposed DAY-1 experiment
(1) Spin-flip B(M1) measurement and g in a nucleus 7
Li : Least ambiguities exist and most reliable.
(2) Further N interaction study from p-shell hypernuclei 10
B and 11B:
(3) Radial dependence of N interaction from sd-shell hypernuclei 19
F : Easiest in sd-shell
(4) Charge symmetry breaking in N interaction and
spin-flip property in hypernuclear production
4He : Largest CSB is suggested but previous data is suspicious.
Easiest to observe a spin-flip state
Confirmation of N spin-dependence NN coupling
DAY1 program: Feasible even with low intensity beam (~2A)
(K-,- ) at pK = 1.5 GeV/c
Inconsistency exists.Experimental data not enough.Few-body approach as well as shell model is possible.
Best K- beam momentum
pK = 1.1 GeV/c : K1.1 + “SKS” (ideal) pK = 1.5 GeV/c : K1.8 + SKS (realistic)
Both spin-flip and nonflip states should be produced. -> pK = 1.1 or 1.5 GeV/c
K- + n -> + -
High K/ ratio to minimize radiation damage to Ge detectors -> Double-stage separation. K1.8BR is not good.
1.5 GeV/c
Beam and Setup
Beamline: K1.8 0.5x106 K-/spill at 1.5 GeV/c (9A) K/ >> 1
Spectrometer: SKS (modified) p ~ 4 MeV (FWHM) ~ 110 msr
Hyperball-J ~ 7% at 1 MeV
-
K1.8
K-
SDC3,4: Large-size (2.0mx0.8m), fine cell (1~2cm)
SMF: Muon filter to suppress K- ->-
SP0: Veto counters to reject K- -> -0To be constructed
Ge crystalPWO suppressor
Gecoolingsystem
K- beam
target
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
Hyperball-J
+ Waveform readout (under deveopment) => Rate limit ~2x107 particles /s (x5 of Hyperball) => Yield: x 15 for single x 45 for
Grant: ~ 3.3Myen, 2005-2009 “Gamma spectroscopy of
strange baryon multi-body systems”科研費特定領域 ( 田村 )
Lower half
Photo-peak efficiency
SimulationSimulation
J-PARC K1.8 Beam Line
BDC1,2 BDC3,4 SDC1,2 BDC3,4
BH1 BH2 SFV SMFTOF
BAC SAC
SP0
Ge+PWO
Beam line part SKS part
Hyperball-J
Set up -SKS Minus-
Acceptance of SKS Minus
Acceptance Check by Present SKS
Next Simulation
Beam direction Target Point
Momentum resolution
To make formatter ↓Analyzing by SKS analyzer・・・・
Trigger Rate and Background Study
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