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Hypernuclear experiments at K1.1 in future Tohoku University H. Tamura

Hypernuclear experiments at K1.1 in future Tohoku University H. Tamura. Contents. 1. Gamma-ray spectroscopy of L hypernuclei at K1.1 2. Light S hypernuclei by (K - , p ±,0 ) at K1.1 3. g decay of S hypernuclei at K1.1

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Hypernuclear experiments at K1.1 in future Tohoku University H. Tamura

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  1. Hypernuclear experimentsat K1.1 in future Tohoku University H. Tamura

  2. Contents 1. Gamma-ray spectroscopy of L hypernuclei at K1.1 2. Light S hypernuclei by (K-,p±,0) at K1.1 3. g decay of S hypernuclei at K1.1 Coulomb-assisted hybrid states -> HR pion line (Noumi-san)

  3. 1. Gamma-ray spectroscopy of L hypernuclei at K1.1

  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 Lower half Beam and Setup for g spectroscopy • 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. Reaction / p (GeV/c) ; Beamline ; Features (1) Complete study of light (A<30) hypernuclei (K-,p-) p= 1.1 and 0.8 ; K1.1 ; gg coin, angular corr. , B(E2),.. (2) Systematic study of medium and heavy hypernuclei (K-,p-) p=0.8-1.8 ; K1.1 and K1.8; p-wave LN interaction (3) Hyperfragments K--in-beam (stopped K-) p=0.8 ; K1.1 ; p/n-rich hypernuclei, (4) n-rich and mirror hypernuclei (K-,p0) p= 1.1 and 0.8 ; K1.1 ; charge sym.break., shrinkage of n-halo, (5) B(M1) using Doppler shift (K-,p-) p= 1.1 and (p+,K+) p= 1.05 ; K1.1 ; mL in nucleus (6) B(M1) using g-weak coincidence (K-,p-) p= 1.1 and 0.8 ; K1.1 ; r, T dependence ofmL in nucleus …,20LNe, 23LNa, 27LAl / 28LSi LOI for g spectroscopy (2003) Partly in E13 LN interaction (LN-SN, p-wave, ..) Shrinkage, collective motion, ... “Table of Hyper-Isotopes” 89LY, 139LLa, 208LPb 8LLi, 8LBe, 9LB,… 7LHe, 9LLi, 12LB... Shirotori’s talk Partly in E13 7LLi and heavier

  6. E03, E07 S=-2 Reaction / p (GeV/c) ; Beamline ; Features (7) X atom X rays (K-,K+) p=1.8 GeV/c; K1.8 ; XN interaction (8) LL-hypernuclei (K-,K+) p=1.8 GeV/c; K1.8 ; LL, XN-LL interactions

  7. eh 2mqc (5),(6) B(M1) measurements mL in nucleus -> medium effect of baryons Constituent quark • mq= • mq changes in nucleus? Partly in E13 • Doppler shift attenuation method [same as B(E2), established] for light hypernuclei; Weak K- or p+ beam usable • g-weak coincidence method [new, only possible at J-PARC] • for 12LC and heavy hypernuclei; Intense K- beam necessary

  8. B(M1) measurement by g-weak coincidence method 12LC case 900 hours, 9x106 K-/spill at K1.1 (50 GeV full beam) -> 5% stat. error of B(M1)

  9. Best K- beam momentum K1.1: More yield x4 Less Doppler shift Need to move SKS to K1.1 (and construct “SKS2” at K1.8) or construct another SKS at K1.1 K- + n -> L + p- • = 20 msr (SPESII) • = 100 msr (SKS) Both spin-flip and nonflip states should be produced. -> pK = 1.1 or 1.5 GeV/c N(1.1) = 2.0x106/spill at K1.1 N(1.5) = 0.5x106/spill at K1.8 (30 GeV 9mA) 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.

  10. Light S hypernuclei by (K-,p±,0) at K1.1

  11. D SL SN T (MeV) ND -0.048 -0.131 -0.264 0.018 NF 0.072 -0.175 -0.266 0.033 NSC89 1.052 -0.173 -0.292 0.036 NSC97f 0.754 -0.140 -0.257 0.054 ( “Quark” 0.0 -0.4 ) Exp. 0.4 -0.01 -0.4 0.03 G-matrix calc. by Yamamoto Strength equivalent to quark-model LS force by Fujiwara et al. Quark DOF really necessary in BB interaction? • LN spin-orbit force(L-spin-dependent LS force ~ 0) -- 9LBe, 13LC g-spectroscopy data • SN (T=3/2,S=1) strong repulsion (quark Pauli) -- 28Si(p-,K+) suggests strongly repulsive S-nuclear pot. • Strong attraction in H dibaryon channel ~ Attraction in LL/ XN / SS (T=0,S=0) state -- No H, weak attraction in LL

  12. S hypernuclei and SN interaction • 4SHe bound state -> T=1/2 attractive 4He(K-,p+) -> T=3/2 repulsive • Lane term (sSsN)(tStN) consistent with Nijmegen interactions • No bound-state peaks in 6SLi, 7SLi, 9SBe, 12SC • S atomic data – attraction at outer nuclear region (not direct information) • 28Si,..(p-,K+) spectrum -> spin-averaged pot. strongly repulsive (~ +30 MeV) =>Lane term (sSsN)(tStN) (by p/r.. exchange) consistent, but strength of each spin-isospin channel and SN->LN not determined yet. T=3/2,S=3/2 channel strongly repulsive? (by quark Pauli) => More data for light (spin-isospin unsaturated) hypernuclei

  13. G-matrix results for various interactions Rijken et al., PRC59 (1999) 21 Rijken, Yamamoto PRC73 (2006) 044008 ESC04d 6.5 -21.0 -3.4 -20.2 24.0 -20.9 -26.0 fss2(quark) 6.7 -23.9 -5.2 -9.2 41.2 -1.4 7.5 Fujiwara et al., Prog.Part.Nucl.Phys. 58 (2007) 439 kf=1.35 fm-1 quark Pauli effect Lane term (sSsN)(tStN) by p/r exchange

  14. T=1/2, 3/2 S=0 4SHe by (K-,p) Substitutional (DL=0) state: n(s1/2)-1L(s1/21) T=1/2, 3/2 S=0 T=3/2 only S=0 Nagae et al., PRL 80 (1995) 1605 Large spin-isospin dependence(Lane term) Consistent with SN interaction in Nijmegen D model (I,S) = (3/2,0), (1/2,1) attractive, (3/2,1), (1/2,0) repulsive No peaks in other S hypernuclei Width (SN->LN) > 10 MeV in general-- spectroscopy difficult T=3/2 only S=0 Hayano et al., PLB B231 (1989) 355

  15. Bart et al. PRL 83 (1999) 5238 Other S hypernuclei? 4SHe No S bound states in A>4 6SLi Iwasaki Ph.D thesis (1987) 12SBe 9SBe Yamada, Ikeda 7SLi has a bound state for ND but no bound state for NF.

  16. Repulsive potential? US ~ +30 MeV Data: Noumi et al., PRL 87 (2002) 072301 Calc: Kohno et al., PRC 74 (2006) 064613

  17. Previous 3He(K-,p-) data at BNL E774

  18. Proposed 3He experiment • 3He (K-,p±,0L) at threshold, pK~0.5~0.6 GeV/c (q < 50 MeV/c) • 3SHe, 3SH, 3Sn : different combination of (TNS,SNS ) = (3/2,1), (3/2,0), (1/2,1), (3/2,0) from 4SHe, 4Sn • 3-body systems can be accurately calculated -> direct comparison with various interactions (how sensitive? – theoretical calculations essential) • Apparatus: Low momentum beam line (K1.1BR) + beam spectrometer + SPESII and p0 spectrometer + L tagger (CDS) Excited states (p states) of 4SHe by 4He (K-,p-L) and 12SC by 12C(K-,p-L) , pK~1.1 GeV/c at q~10o (q~250 MeV/c) Koike-Harada (NPA611(1996)461) “Unstable bound states” ES (G) SAP-1(ND) SAP-F(NF) 3SHe (T=1,S=1/2) --- +1.77 (7.58) MeV 3S0H (T~1,S=1/2) +0.01 (1.95) +0.63 (8.2) MeV 3Sn (T=1,S=1/2) --- +0.55 (9.05) MeV Spectral shapes should be calculated.

  19. Experiment • Beam spectrometer ( DpFWHM <1.5 MeV/c at 600 MeV/c ) in place of K1.1BR B3 • 3He target • L tagger => CDS • p± spectrometer (DpFWHM <1.5 MeV/c at 500 MeV/c) => SPESII • p0 spectrometer (DpFWHM ~ 3 MeV/c at 500 MeV/c) Yield (K-, p±): NK-・ds/dW・DW・Ntarget・e(Ltag) ・e ＝ 5x105 /spill・50x10-30cm2/sr・0.02sr・0.09g/cm3/ 3・10cm・ 6x1023 ・0.3・0.5 => 1400 counts/100hours ->Lower beam momentum? Yield (K-, p±0): => ~100 counts/100hours

  20. tagging is essential Data: Nagae et al., PRL 80 (1995) 1605 calc: Harada, PRL 81(1998) 5287

  21. 3. g decay of S hypernuclei at K1.1

  22. S = 1 S = 0 u u d d + g L S S = 1/2 s S = 1/2 s Spin-flip of u/d quarks – large medium effect ? G∝ B(M1) ∝｜〈 ｜m｜ 〉｜2 is sensitive to w.f. S = 0 S = 0 u d u d + g L L s s S = 1/2 S = 1/2 Spin-flip of s quark – small medium effect ? Spin-flip M1 transitions

  23. How large is the effect? • Shift of constituent quark mass in a nucleus Dmu,d ~ -20%, Dms /ms~ -4% -> Dm (S)~ 20%, Dm (L)~ 4% DB(M1) for S~ +40%, DB(M1) for L~ +8% • Quark Cluster Model Takeuchi et al., N.P. A481(1988) 639 dm/m : 4LHe(1+) -1% ~ -2%, larger by S mixing 4S+Li(1+) -40% ~ -100% b = 0.6 fm -> 0.8 fm, m becomes twice large.

  24. Measurement ofG(S0->Lg) in a nucleus S in nucleus = S hypernuclear bound states -> 4SHe Free S0 -> Lg 100%,Eg = 74 MeV Gfree S->Lg = 1 / 7.4x10-20 sec-1 ~ 9x10-3 MeV GSN->LN ~ 10 MeV for 4SHe => BR(S0->Lg in nucleus) ~GS->Lg/ GSN->LN ~ 0.001 (K-,p-) reaction at 600 MeV/c using K1.1BR ds/dW (4SHe)~ 100 mb/sr (Nagae et al.) Yield: NK-・ds/dW・DW・BR・Ntarget・BR(L->np0)・e 　　　　＝ 5x105 /spill・100x10-30・0.02・0.001・0.12g/cm3/ 4・20cm・6x1023 ・0.3・0.5 => 56 counts/1000hour Background: QF S0 escape, S0 -> Lg (-BS>0 only) p0 -> g g from L -> n p0 (Eg ~ 50~100 MeV) => Tag 3 energetic (> 50 MeV) g rays => cover the target region with a calorimeter Theoretical calculation necessary – how large change is expected?

  25. T=1/2, 3/2 S=0 4SHe by (K-,p) Substitutional (DL=0) state: n(s1/2)-1L(s1/21) T=1/2, 3/2 S=0 T=3/2 only S=0 Nagae et al., PRL 80 (1995) 1605 Large spin-isospin dependence(Lane term) Consistent with SN interaction in Nijmegen D model (I,S) = (3/2,0), (1/2,1) attractive, (3/2,1), (1/2,0) repulsive No peaks in other S hypernuclei Width (SN->LN) > 10 MeV in general-- spectroscopy difficult T=3/2 only S=0 Hayano et al., PLB B231 (1989) 355

  26. Harada, PRL 81(1998) 5287

  27. S0 escape 0+ Expected 3g-tagged spectrum (イメージ） • S0 → L g • → np0 • → gg Assuming that 3HeL, pdL, ppnL never emit 3 energetic g’s

  28. Summary • g-ray spectroscopy of L hypernuclei at K1.1 • Various experiments using SKS + Hyperball-J • S hypernuclei at K1.1BR • 3He(K-,p) for SN spin-isospin dependence • g decay of S hypernuclear bound states • New apparatus to be build 2nd SKS (or “SKS2” at K1.8) Beam spectrometer for K1.1BR p0 spectrometer Calorimeter (crystal barrel)

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