1. 高強度高分解能２次ビームラインを用いたハイパー核研究
味村周平（阪大ＲＣＮＰ）
E10/E22 experiments
The next experiments by High intensity High resolution beam line

2. Study on Neutron-Rich Hypernuclei J-PARC/E10
Aim to produce neutron-rich and exotic hypernuclei by the double charge-exchange (DCX) reaction
NCX: (K-,p-), (p+,K+) reaction
L-hypernuclei
SCX: (K-,p0), (p-,K0) reaction
DCX: (K-,p+), (p-,K+) reaction
NCX
ordinary nuclei
SCX
this study
DCX
N>>Z, exotic
L-N interaction
in n-rich env.
glue-like
role of
L-hyperon
6LH 5H n p n p n n
unbound
nucleus L
bound hypernucleus n n n n

3. Production by DCX reaction
KEK-E521 experiment established
　　　　reaction
Clean reaction
g.s.
K6 beam
SKS spectrometer
good energy resolution
DBL = 2.5MeV (FWHM)
BL=0
ds/dW~10nb/sr (1/1000 of NCX)
~45 events in bound region
Increase yield 10 at J-PARC

4. beams, experimental equipments, beamtime request and prospects for E10
Pion beam
High-Quality and High-Intensity negative pion beam
Need STABLE slow beam extraction
1.5107 pion/spill (3 sec
Experimental setup
K1.8 beam line and SKS spectrometer
Good resolution and large acceptance
Beamtime
Yield estimation
Tiny (p-,K+) cross section (~10nb/sr)
Not thick targets (3.5g/cm2) for resolution
Need 3 weeks of beamtime per target
Expect 300 n-rich hypernuclei in bound region
Precise information on B.E. of n-rich hypernuclei
resolution ~ 2.5MeV(FWHM)
expected spectrum
6Li(p-,K+)6LH and 9Be(p-,K+)9LHe
6LH
bound

5. J-PARC E22
Measurement of nonmesonic weak decay branch of 4LHe, G(Ln->nn) and G(Lp->np)
Subjects: Properties of LN weak interaction
spin/isospin structure
parity information
DI=1/2 rule in B-B int. (need meas. of both 4LH & 4LHe) }
Determination of partial decay amplitudes
n n p Λ
p p n Λ
p p n n Λ 0+ 0+ 0+ 0+
Ln→nn: 1S0, 3S1 1S0 1S0, 3S1
Lp→np: 1S0 1S0, 3S1 1S0, 3S1

6. Decay arm system n n p p CDC: veto p- from mesonic decay n/g TOF
Large acceptance and high efficiency for NN
Good PID capability (n/p/p/g) n n p p
CDC: veto p- from mesonic decay
n/g TOF
p/p E/DE/range
n/p charge-veto

7. beams, experimental equipments, beamtime request and prospects for E22
Pion beam
High-Quality and High-Intensity negative pion beam
Need STABLE slow beam extraction
1.5107 pion/spill (3 sec
Experimental setup
K1.8 beam line and SKS spectrometer
Good resolution and large acceptance
Beamtime
Yield estimation
cross section (~10mb/sr)
Targets thickness (2g/cm2)
Need 4 weeks of beamtime per target
Expect 50,000 n-rich hypernuclei in bound region
1,300 Lpnp (BR~10%) and 75 Lnnn (if BR=1%)
resolution ~ 2MeV(FWHM)

8. The next step: High Intensity High Resolution beam line
intensity: 109 p/spill
x 100 of K1.8
Dp/p ~ 10-4

9. With HIHR beamline Neutron-rich hypernuclei
6LH and 9LHe→systematic study of n-rich hypernuclei
Short beamtime with high intensity (x100)
3 weeks → 1 day for the same statistics of E10
Precise information on the levels of n-rich hypernuclei
Nonmesonic weak decay
Pp =1.8 GeV/c
Ks spectrometer: reduce the
acceptance by ~1/1000 (need optimize)
Elementary cross section x0.2
BR(Ks→pp)=0.35
20msr each p+ p- Ks

10. backups

11. Beam Momentum bgct = 9.7 cm @ PK=1.53 GeV/c 1/5
At standard momentum for (p,K) reaction, 1050 MeV/c, bgct for kaon is 3.9cm.
bgct = 9.7 PK=1.53 GeV/c