rcnp01may-2

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しょうすけよしなが
5 years ago
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1 E22 RCP Ring-Cyclotron

2 K beam K-atom HF X K, +,K + e,e K + -spectroscopy OK U U I= First-order -exchange - coupling I= U LS U LS Meson-exchange model /5/ I= Symmetric LS Anti-symmetric LS ( σ Λ σ ) ( σ σ ) V = V + l SLS SLS Λ V = V l ALS ALS Λ Λ U LS Λ = VSLS + VALS 2

3 isospin Mesonic decay + isospin/2 or 3/2 + p MeV/c /2 rule I=/2 I=3/2 K decay Λ p + π 2 dominant n + π 2 on-mesonic decay + + p MeV/c K K 3

4 on-mesonic decay Decay branch Λ + p p + n a pn Λ + n n + n a = 2a nn pn " I = 2 rule" isospin= known CG isospin= Decay branch n p isospin Decay asymmetry decay asymmetry amplitude parity isospin a b α p Re[ 3a e* + b( c 2 d) * 3 f ( 2 c + d) *] c d Decay asymmetry p P V P C e f I P

5 Decay branchn p He bubble chamber counter experiment p He nm H nm He R R J = J = = Spin Γ Γ ( Λ ) ( Λ ) He 2R + 3R + R nm n p p H 3R + R + 2R nm n n p R = 2R I=/2 rule n p c + d + e + f a b Γp = > 37 3 Γ Λ. n ( He) R n R n a b c d e f I J L f 2 R p R p 5

6 Isospin Γ ( Λ H) Γ ( Λ He) 3( R R ) ( R R ) nm nm n n n p ( 2 ( f c d e )) ( 2 2 a b ) = I J L f a R > R, c + d + e + f > a + b J = J = R R c + d + e f J =, I= J =, I=, f > c, d, e > a, b b c d e 2 f He bubble chamber f >> a, b, c, d, e 6

7 Decay asymmetry p amplitude Counter experiment p - He bubble chamber p -.5 KEK-PS E6, E278 E6 2 Λ C, Λ B p = -.3. E278 5 Λ He p =.2.2 Branch asymmetry Asymmetry n n p systematic error KEK-PS E62 2 E n KEK-PS E62 5 Λ He 7

8 I Meson exchange model a I=/2 rule, K,, K*, exchange b 2 2 c + d > f > a, b, e c d ( ) ( Γn / Γp, Γnm Λ H / Γnm Λ He) e α p f Quark exchange model I=/2 I=3/2 I=/2 f dominant K exchange I=3/2 a, b dominant exchange Amplitude I=/2 rule BL-AGS E93 J L f 2 meson ( Λ ) >. ( = 2) >. 7 ( = 3 2) Γp Γn H I or I K quark I=3/2 I=3/2 I=/2 8

9 I=/2 rule R.A. Schumacher, P A57 (992) 3c R R n p γ γ γ = Γnm γ γ γ ( Λ He) Γnm( Λ H) 5 γ = Γn Γp Λ He, γ 5 = Γn Γp = + 5 ( ) ( Λ He) 9

10 pn p Λ σ pn p Λ Γ p ( Λ p pn ) r r n( p, Λ ) p P p, α = p. 62 Λ π r Ap: n( p, Λ ) p helicity polarized beam, asymmetry ( Λ) A : n p, r p unpol. p beam, pol. in beam direction Λ A Λ α p T Ap Ap L r r Λ, Λ: n( p, Λ) p T or L pol. beam, polarization transfer abetani et al. amplitude PRC6 (999) 7

11 p s/p s-shell / p-shell physical background p + n p + Λ T = 368 MeV threshold p + n p + Σ T = 5 MeV + threshold p + n n + K + Λ T = 6. GeV threshold Tp = 6 MeV RCP Ring-Cyclotron Cross section Challenge cross section σ pn p Λ cm = b instrumental background σ strong = 3 σ pn pλ

12 pnp Parreno et al., nucl-th/982 correlation 2

13 RCP Ring-Cyclotron Yield = σ ε cross section target beam event pn pλ tgt beam σ pn p Λ 39 cm 2 Γnm = vσ pn pλ ρn uλ dr efficiency 39 2 σ pn p Λ. 5 cm by Haidenbauer et al =. 5. cm by Parreno et al cm by Inoue et al. event 2 event / day tgt = 2 neutron / cm 2 cm Cu beam = 2 proton / s 6nA( 6MeV proton) ε =. 25 MC: pn pλ Λ p + π 2 3 collimator 5 CDC+hodoscopep+π 2 invariant mass = m Λ SSDp+π vertex R&D E22 3

Mｏｔｔ散乱によるParity対称性の破れを検証

Mｏｔｔ散乱によるParity対称性の破れを検証 Mott Parity P2 Mott target Mott Parity Parity Γ = 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 t P P ),,, ( 3 2 1 0 1 γ γ γ γ γ γ ν ν µ µ = = Γ 1 : : : Γ P P P P x x P ν ν µ µ vector axial vector ν ν µ µ γ γ Γ ν γ