3 H(e, e K + )X K + Method and performance of K + meson identification in the 3 H(e, e K + )X experiment 30

Transcription

1 3 H(e, e K + )X K + Method and performance of K + meson identification in the 3 H(e, e K + )X experiment 30

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3 i (uud,udd) s - - s (JLab) 3 H(e, e K + )nnλ nnλ JLab Hall A 3 H(e, e K + )nnλ (e ) K + JLab Hall A (HRS) nnλ K + HRS K + π + K K + K + (KID) K + nnλ E 100 kev K +

4 ii i (K, π ) (π +, K + ) (e, e K + ) nnλ GSI nnλ Λ nnλ JLab 3 H(e, e K + )nnλ JLab Continuous Electron Beam Accelerator Facility(CEBAF) JLab Target holder design Cooling system (HRS) HRS HRS-R Particles Identification Detector L-HRS Detector Packages

5 iii Beam Time Schedule H(e, e K + )Λ/Σ nnλ (x, y) VDC Scintilattion Trigger Counter(STC) TOF coincidence time (S2) Cherenkov AC K K H(e, e K + )Λ/Σ Λ/Σ AC cut Λ, Σ 0 S/N Λ, Σ AC S/N FOM p(γ, K + )Λ/Σ

6 iv KEK(E369) 89 Y(π +, K + ) 89 Λ Y n-p Λ Λ-p (I = 1/2) ( 4 Λ H, 4 ΛHe) ΛN-ΣN CERN 12 C(K, π ) 12 Λ C Λ JLab 12 C(e, e K + ) 12 Λ B JLab Hall C CH (e, e K + ) JLab CLAS γ + p K + Λ DWIA 12 Λ B K+ θ K GSI Li GSI Invariant mas t + π nnλ, 3 ΛH Λ-n nnλ (Geant4) nnλ Λ-n

7 v H(e, e K + )nnλ JLab Gas Target Ladder system Solid Target Ladder system H holder Top view of cell Cooling system HRS HRS Magnet GUI HRS-R Detectors Package AC S VDC HRS L Detector Package coincidence Coincidence trigger Gate nnλ Seive Slit Seive Slit p e, p K p e = 2.1 GeV Λ/Σ p e = 2.2 GeV/c H(e, e K + )Λ/Σ VDC VDC VDC VDC HRS-R path length coincidence time Offset S S2 coincidence

8 vi 3.19 AC AC coincidence time AC1, AC AC1 π +, p AC AC2 π +, p AC coincidence time H(e, e K + )Λ/Σ AC coincidence time (Al) π AC Λ AC Σ AC1 Λ AC2 Λ AC1 S Λ /N AC2 S Λ /N FOM AC FOM AC FOM AC1, 2 cut AC1 Λ AC Λ

9 vii d+π, t+π ( 5 Λ He d+3 He+ π )[15] CEBAF Target spessification HRS spectification HRS Dipole Magnet specification HRS Quadro Magnet specification AC specification VDC resolution table Beam Time table n M S2 p, π Particle identification with AC (AC1 < 1.0 PEs & 3.5 < AC2 < 10 PEs) (K +, π +, p) Λ, Σ AC Λ, Σ 0 S/N FOM

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11 1 1 (JLab Hypernuclear Collaborater) Thomas Jefferson National Acceletor Facility(JLab) Λ nnλ (E ) (AC) (STC) K + (KID) [1] (S=1/2) ( ) (R, B, G) (R, R), (B, B), (G, G) J P = (1/2) + uds ( 1.1) 1.1 s (p, n) (Λ, Σ 0, ±, Ξ ± ) Λ (m Λ = MeV/c 2 ) Λ Λ-

12 : x (Q) y (S) (e, e p), (p, 2p) E t ħ (1.1) s E 10 MeV Λ Λ Λ γ 200 ps Λ MeV

13 : KEK(E369) 89 Y(π +, K + ) 89 Λ Y [2] Λ (p, n) Λ (π +, K + ) Λ ( 1.10) 89 Λ Y ( 1.2) Λ ( ) QCD Λ Λ-n, Λ-p Λ-p

14 : n-p [13] (M fi ) σ M fi 2 ρ(p) (1.2) ρ(p) ( 1.3) 1950 Λ-p ( 1.4) Λ-p Λ-p Λ- Λ Λ Λ- Λ- Λ (CSB) Λ Λ- Λ (CSB) 1 MeV/c 2 SU(2) (I = 1/2) 3 H, 3 He B H B He = 0.76 MeV[16] 3 H, 3 He ( B em ) ( B = B H B He ) B B em = MeV (1.3) [16] 3 H, 3 He Λ 4 Λ H, 4 Λ He (J = 0+ ) (J = 1 + )

15 : Λ Λ-p [12] Λ-p p-n Λ-p Λ-p ( 1.5) 4 Λ H, 4 ΛHe B J + H, BJ + He 1.5 ( B0+ ) B 0+ = 0.35 MeV (1.4) ( 1.3) Λ Λ ΛN-ΣN ( 1.6) Λ- Λ (τ 260 ps) (M Λ = 1116 MeV/c 2 ) Λ ( 1.7) (ρ /fm 3 )

16 : (I = 1/2) ( 4 Λ H, 4 ΛHe) [5] 3 H, 3 He B = MeV Λ J = 0 + B = 0.35 MeV [5] ν e, ν e Λ n Λ + ν e + ν e (1.5) Λ Λ Λ ( 1.7) Λ Λ-n ( ) [6] (µ < 2.0 µm) Λ 1960 π (A 16) [7] 1970

17 : ΛN-ΣN (CERN) (BNL) (K, π ) Λ 1980 BNL (KEK) (π +, K + ) (π +, K + ) 2003 (e, e K + ) Λ (E91-016) (JLab) (MAMI-C) ELPH (e, e K + ) 2010 (GSI) nnλ (K, π ), (π +, K + ), (e, e K + ) (K, π ) (K, π ) K n(k, π )Λ (K, π ) (K, π )

18 : [14] (ρ 0 = 0.16 /fm 3 ) Λ Λ (K, π ) (σ 100 µb/sr) (K ) Stopped (K, π ) Λ p Λ 280 MeV/c Λ Magic momentum (K ) In-flight(K, π ) magic momentum ( 1.10) Magic momentum Λ ( L = 0) Λ substitutional state ( 1.11)

19 : (π +, K + ) (π +, K + ) (K, π ) π + Λ (π +, K + ) (K, π ) (σ 10 µb/sr)( 1.9) π + K + (K, π ) Λ Λ ( 1.2) (e, e K + ) (K, π ), (π +, K + ) (K, π ), (π +, K + ) Λ ( E) MeV 2000 (e, e K + ) 1 MeV [9] Λ (π +, K + ), (K, π ) (e, e K + ) Λ p(e, e K + )Λ

20 : [3] (e, e K + ) (e, e K + ) Λ Λ (π +, K + ), (K, π ) kev Λ, Σ 0 kev Λ, Σ 0 ( 1.14)

21 : [4] θ = 0 deg θ = 0 deg θ = 0 deg (K, π ) p beam = 0.5 GeV/c Magic momentum (K, π ), (π +, K + ), (e, e K + ) Λ Λ ( ) ( 1.21) (π ) (K, π ), (π +, K + ), (e, e K + ) 1.3 Λ K +, Λ ( 1.15) e e + γ (1.6) γ + p Λ + K + (1.7)

22 : CERN 12 C(K, π ) 12 Λ C [8] 1.1: Reaction Cross section E MeV momentum transfer (FWHM) In flight (K, π ) 100 µb 1 L = 0 (Magic momentum) Stopped (K, π ) 10 µb 1 L 1 (π +, K + ) 100 nb 1 L 3 (e, e K + ) 1 nb 0.5 L 3 Heavy ion 5 q = (ω, q) 4 P e = (E e, p e ) P e = (E e, p e ) q = p e p e (1.8) ω = E e E e (1.9) ω (K + + Λ) ( 1.16) σ tot 1.1 < E γ < 1.6 GeV σ tot 2 µb

23 : Λ [3] (e, e K + ) Γ d 3 [ σ dσt de edω = Γ + ϵ dσ L + ϵ cos(2ϕ) dσ T T edω K dω K dω K dω K Γ = d2 σ = α E γ E e dωdω e 2π 2 Q 2 ϵ = 1/ [1 + 2 q 2 Q 2 + cos ϕ 2ϵ(1 + ϵ) dσ ] LT dω K (1.10) (1.11) (1 ϵ)e e ] (1.12) tan2 ( θ e 2 ) Ω e, K K + σ T, L, T T, LT (transverse) (logitudinal) (polarization) (interference) (θ γk ) S = 1 (spin-flip) K + θ K (θ K 0 ) (θ K ) ( 1.17)

24 : JLab 12 C(e, e K + ) 12 Λ C [9] Λ 12 Λ B Λ (J P ) 1.4 nnλ nnλ Λ (I = 1) Λ pnλ( 3 Λ H), ppλ(3 Λ He) ( 1.18) (I = 0) 3 Λ H (B Λ = 130 kev) [21] 3 Λ H (2 H) Λ (I = 0, 1) I = 1 (I = 1) (pp, np, nn) Λ 2013 GSI nnλ [15] nnλ

25 1.4 nnλ : JLab Hall C CH 2 [11] Λ CH 2 Quasi-free( ) Λ/Σ QF nnλ GSI nnλ GSI nnλ (GSI) d + π, t + π GSI Li (UNILAC) (SIS18) (E beam = 2A GeV (FRS) (π, t) ( 1.21) ( 1.22) t + π ( 1.21) 2n + Λ (τ = ) ps π, t (π, t) nnλ ( 1.2) 5 Λ He d +3 He + π

26 : (e, e K + ) Λ, K + 1.2: d + π, t + π ( 5 Λ He d + 3 He + π )[15] Decay channel Counts rate 3 Λ H p + d + π 8 4 Λ H d + d + π 1 4 Λ H t + p + π 6 6 Λ He 4 He + d + π 3 4 Λ He p + p + d + π 8 5 Λ He d +3 He + π 1 (t, π ) 4 Λ H t + p + π ± 1.1 ± 2.2 MeV/c 2 MeV/c 2 GSI nnλ nnλ

27 1.4 nnλ : JLab CLAS γ + p K + Λ [10] s GeV (0.85 < cos θ K < 0.95) (µb) CLAS 2004 SAPHIR LEPS [10] Λ nnλ GSI nnλ (A=3, 4) nnλ nnλ nnλ 3 Λ H(J = 1/2+ ) ( 3 VNΛ NΣ T 1.0, 3 VNΛ NΣ T 1.2) (i) 3 Λ H nnλ (ii) nnλ 3 Λ H nnλ

28 : DWIA 12 Λ B K+ θ K [3] K + γ + p Λ + K + θ K 0 nnλ nnλ E R Γ E E = E R i Γ 2 (E R, Γ R) (1.13) Λn 1.24 Λ-n Λn Y Λn Λp Y Λp s s = Y Λn /Y Λp s s = 1.0 s = Λn Re[E] < 0, Im[E] < 0 nnλ

29 1.4 nnλ : 1.19: GSI [15] 6 Li UNILAC (SIS18) 6 Li FRS Re[E] > 0, Im[E] < 0 nnλ 1.24 s = % (δs = 0.05) Re[E] > 0 Y Λp 10 % nnλ

30 : 6 Li E = 12 GeV 6 Li 12 C ( ) π ( ) π nnλ GSI nnλ JLab Hall A (HRS) nnλ nnλ GSI nnλ nnλ nnλ JLab nnλ nnλ ( B Λ 100 kev) ( σ 100) kev (ACCBG) nnλ nnλ nnλ

31 1.4 nnλ : GSI Invariant mass [15] (π, t) t + π ±1.1 ± 2.2 MeV 1.22: t + π [15] 190 ps π + t Λ-n nnλ Γ B Λ 1.24 Λ-n Λ-n (Λ, n) Λ-n Λ-p CSB Λ Λ p 2000 event 20 % nnλ B Λ 100 kev, σ 100 kev % Λ n K + (KID) (AC) (STC) KID

32 : nnλ, Λ H : ΛN ΣN 3 VΛN ΣN T (1.0, 1.2) nnλ, 3 Λ H(J = 1/2+ ) nnλ (AC1, AC2) π +, p AC KID Λ, Σ 0 Λ, Σ 0 S/N AC Figure of meri(fom) peak significance S Λ / N B.G. AC Λ, Σ 0 S/N AC KID K + Λ, Σ 0 Λ, Σ 0 JLab Hall B Λ [10] KID KID nnλ

33 1.4 nnλ : Λ-n nnλ [22] [GeV] [GeV] Λ p Λ n S s = 2.5% Re[E] > 0 s 5 % nnλ 1.25: (Geant4) nnλ [26] nnλ nnλ B 100 kev σ 100 kev

34 : Λ-n [22] nnλ B 100 kev σ 100 kev nnλ Λ-n 5 %

35 25 2 nnλ nnλ (JLab) nnλ nnλ JLab (HRS) JLab 3 H(e, e K + )nnλ Thomas Jefferson National Accelerator Facility(JLab) Hall C (YN ) 2.1: 3 H(e, e K + )nnλ 4.3 GeV 3 H(e, e K + )nnλ K + (e ) HRS (p e = 2.2 GeV/c, θ ee = 13.2 ) K + (p K = 1.8 GeV/c, θ ek = 13.2 )

36 26 2 nnλ [23] (E ) Hall A Hall A (HRS) e, K + A Z A Λ (Z 1) (M HYP ) (B HYP ) K + ( p e, M HYP = p K ) (E e + M Target E e E K ) 2 ( p e p e p K ) 2 (2.1) B HYP = (Z 1)m p + (A Z)m n + m Λ M HYP (2.2) (P T arget = 0) 4.3 GeV 3 H nnλ nnλ K + HRS nnλ ( 2.1) K + (p e, p K ) (θ ee, θ ek ) (p e = 2.2 GeV/c, p K = 1.8 GeV/c), (θ ee = 13.2, θ ek = 13.2 ) 2.2 JLab Continuous Electron Beam Accelerator Facility(CEBAF) JLab Continuous Electron Beam Accelerator Facility(CEBAF)( 2.2) CEBAF 108 MeV (north linac, south linac) 12 GeV(5.5 pass) (Hall A, B, C, D) JLab CEBAF ( ) ( 2.1) CEBAF (E e ) ( E e ) E/E GeV

37 2.2 JLab : JLab (CEBAF)[24] 1.1 GeV 12 GeV(5.5 ) Hall A, B, C, D 450 kev HRS K +, e CEBAF σ 100µm 2.1: CEBAF [24] Beam Parametrers Max Energy (Hall A, B, C) 11 GeV Max Energy (Hall D) 12 GeV Max Intensity (Hall A, C/B) 85 µa/5 µa Energy spread ( E/E) < (FWHM) Bunch interval 2 ns

38 第 2 章 nnλ 実験の概要 28 表 2.2: Target spessification State of Target Target Gas Solid 2.3 thickness [mg/cm2 ] 3 H H H He 53.4 C 883 Al BeO 142 標的システム 本実験では トリチウム (3 H) 低温ガス標的 (40 K) を含む複数のガス標的と個体標的が使わ れ 図 2.3 図 2.4 のような標的システム内に設置されている ガス標的システムは (図 2.3) のように計５つのセルが連なっており 上から 3 H, 2 H, 1 H, 3 He, empty がそれぞれ収納さ れており それぞれの標的に対してビーム軸方向に厚さ 25 cm 約 34 cc のガスが収納されて いる (図 2.5) また 4 つのセルのガス標的の下には個体標的プレートが設置されており 上 から炭素フィルム標的 炭素穴標的 ラスター補正用標的 アルミ標的 炭素標的 チタニウ ム標的そして BeO 標的が連なって配置されている (図 2.4) 個体標的はパラメータ調整や補 正データを目的として使用され 内容の詳細については第３章で詳しく述べることにする 図 2.3: Gas Target Ladder system 図 2.4: Solid Target Ladder system

39 : 3 H holder Target holder design 3 H 40 TBq 25 cm ( 2.6) 2.5 (Al alloy ASTM B209 AL 7075-T651) ( 2.3) K + (295K) 1.38 MPa (0.28 MPa at 40 K) Cooling system JLab 1 (15 K) End Station Refrigerator (ESR) 15 K ESR 15 K Fin tube heat exchanger(hx) ESR ( 2.7) 22.5µA

40 30 2 nnλ 2.3: Position on cell Empty 3 H 2 H 1 H 3 He Entrance Exit Mid left Mid right : Top view of cell 2.4 (HRS) (E ) JLab Hall A (HRS) ( 2.8) HRS HRS 2.7: Cooling system

41 2.4 (HRS) : HRS [27] JLab Hall A (HRS) CEBAF Hall A HRS HRS QQDQ HRS(HRS-R) p K = 1.8 GeV/c K + HRS(HRS-L) p e = 2.2 GeV/c HRS 2.4 HRS 2.4: HRS spectification HRS General Charactors Momentum Range GeV/c Congiuration QQDQ Beam Angle 45 Optical Length 23.4 m Momentum Acceptance ± 4.5 % Momentum Resolution(FWHM)

42 32 2 nnλ 2.9: [30] HRS QQDQ QQ (D ) D Q HRS HRS 2.9 (Q) (D) HRS-R, HRS-L HRS Q D (D ) (Q1, Q2) D 2000 A(2 T) 4.6 GeV/c (p) δp/p 4.5% ( 2.5) D GUI D ( 2.10) SN QQ

43 2.4 (HRS) : HRS Dipole Magnet specification spesification Dipole Maxium current 2000 A (10 V) Maxium magnetic field 2 T Effective length 6.6 m Bend radius 8.4 m Bending angle 45 Q1 Q2, Q3 ( 2.6) Q 2.10: HRS Magnet GUI HRS GUI HRS K + Q1, Q2, D, Q3 K + HRS

44 34 2 nnλ 2.6: HRS Quadro Magnet specification spesification Q1 Q2/Q3 Bore radius 150 mm 300 mm Magnetic length 948 mm 1800 mm Maximum Mag-fileld gradient 8.31 T/m 3.5 T/m Maxium current 3250 A 1850 A 2.11: HRS-R Detectors Package GUI ( 2.10) HRS-R Particles Identification Detector HRS HRS-R π +, p K + π +, p (AC) (STC) K + (VDC) HRS-R 2.11 HRS-R

45 2.4 (HRS) : AC AC1 24 PMT 2.7: AC specification AC1 AC2 Refractive index PMT Burle RCA 8854 Photonis XP 4572B Number of PMT Thickness 9 cm 5 cm HRS (ACD) K + (AC1, 2) AC K + π + ( 2.7) AC1, AC2 [n 1 = 1.015(Matsushita silica aerogel SP15), n 2 = (Matsushita silica aerogel SP50)) ( cm 3 ] AC1(9 cm),

46 36 2 nnλ 2.13: S2 AC2(5 cm) Millipore (GSWP00010) Millipore 400 nm 95 % (UV ) 315 nm 80 % Millipore 3M 3M the Enhanced Specular Reflector(ESR) PMT( ) AC Burle RCA 8854 PMT 26 AC2 Photonis XP 4572B 24 Burle Quantacon PMT UV (390 nm) 22.5 % AC2 XP 4572 PMT UV 24 % Scintillation Trigger Counter (STC) HRS-L (S0, S2) S0 S0 10 mm BICRON408 S0 (170 L 25 W cm 2 ) S0 PMT(XP4312B) PMT NIM

47 2.4 (HRS) 37 moduls S2 S2 16 STC ( 2.13) 43.2 L 14.0 W 5.08 T cm 3 (EJ-230) PMT(Photonis XP2282B) S0 S2 2 m S0, S2 v S0, S2 (x=2.0 m) S0, S2 (t 0, t 2 ) β β = = x 1 (2.3) t 2 t 0 c pc (2.4) m2 c 4 + p 2 c 2 m, p p = 1.8 GeV/c β β (VDC) VDC HRS 23 cm ( 2.14) (VDC) 45 2 ( 2.14) 20 µm 368 VDC (1472 ch) Fastbus(LeCroy 1877) TDC VDC Ar 30 l 7 l/h (MAD card) Fastbus TDC HRS VDC 2.8 θ, ϕ p z, D p x θ = Arctan(p x /p z ), ϕ = Arctan(p y /p z ) θ, ϕ

48 38 2 nnλ 2.14: VDC [30] HRS VDC VDC 2.8: VDC resolution table [25] Angle FWHM resolution (mrad) Reconstruction accuracy (mrad) θ(p x /p z ) 6.00 ± 0.60 ϕ (p y /p z ) 2.3 ± L-HRS Detector Packages HRS-L ( 2.15) p e = 2.2 GeV/c HRS-L π, µ e STC VDC µ µ HRS-L 2.15 VDC, STC(S0, S2) HRS-R (2.4.2 )

49 : HRS L Detector Package HRS (e, K + ) (LHRS, RHRS) T 1 = (S0 & S2) L (2.5) T 2 = ((S0 & S2)& GC) L (2.6) T 3 = ((S0 S2) & GC) L (2.7) T 4 = (S0& S2) R (2.8) (T 1, T 2, T 3 ) K + T 4 T 1 (S0, S2) TDC T 2, T 3 S0, S2 (GC) TDC K + (T 4 ) S0, S2 HRS-R, HRS-L (C 1 ) C 1 = (S0 & S2) L &(S0 & S2) R (2.9) (2.10) (C 1 ) LHRS RHRS 2.16 C 1 K + T ns

50 40 2 nnλ 2.16: coincidence 40 ns (T 1, T 2 ) ( 2.17) T 1, T 3, T 4, C Beam Time Schedule /31-11/26 27 [C] 2.9

51 : Coincidence trigger Gate 2.9: Beam Time table Target Kinematics (p e, p K ) GeV/c Beam Charge [C] Days 3 H (2.2, 1.8) 16.6 C 16 days 1 H (2.2, 1.8) 1.0 C 0.5 days 1 H (2.1, 1.8) 4.7 C 5 days 3 He (2.2, 1.8) 0.5 days Total 19 C 27 days

52 42 3 H(e, e K + )Λ/Σ 0 STC, AC, VDC H(e, e K + )Λ/Σ 0 K + nnλ 3.1 nnλ nnλ K + VDC reference plane reference plane 3.1: nnλ

53 3.1 nnλ : n M n m x tar x tar y tar y tar z tar p = M x RP x RP y RP y RP (x, y, z) (x, y ) (3.1) x = p x /p z (3.2) y = p y /p z (3.3) p reference plane x tar x tar y tar y tar z tar p x RP x RP y RP = M y RP x RP x RP (3.4) ( 3.1) ( (p) (x, y, z) (x, y )) -reference plane (β)

54 44 3 H(e, e K + )Λ/Σ 0 3.2: VDC Reference Plane (x RP, x RP, y RP, y RP ) M (x T, x T, y T, y T, p T ) (x T, y T ) (x T, y T, z, p) (x, y) JLab (σ e < 100 µm) (x, y) ( 2 ) (Carbon hole) ( 3.3) (x, y) ( ) JLab (CH 2 )(z<1 cm) z 1 cm

55 3.1 nnλ : x y (z) z 25 cm (z) (Malti Carbon film) z 10 ( 3.4) (z) ( )

56 46 第 3 章 H(e, e K + )Λ/Σ0 のデータ解析 図 3.4: 炭素フィルム標的 厚さ 2 mm の炭素フィルムが 10 枚設置されている 炭素フィルム は 2 cm の間隔で設置されており 右から２番目と３番目にはスペースがある 非対称の設置 を行うことによりビーム上流と下流の方向を確認できる 角度補正 逆輸送行列の要素群として粒子の位置情報の他に粒子の角度情報が含まれている ハイパー核 のエネルギー分布を求めるための質量欠損法 (式 2.1) は引数として 散乱電子と K + 中間子の 運動量ベクトル ( p = (px, py, pz )) の合計６つのパラメータ群が必要である HRS の粒子検 出器群で観測できるパラメータ量は位置 角度 時間情報であり それらの情報から式 (3.2) で定義した粒子の運動量ベクトル情報に変換する ( p = pz(x, y, 1)) 標的での角度 (x, y ) は穴が空いた Seive Slit を用いることでシーブスリットの穴を通過した粒子を区別することが できる シーブスリットの穴の位置情報と逆輸送行列で再構成した標的での角度情報を比較 し 逆輸送行列のパラメータ調整を行うことで角度の決定精度を高めることができる

57 3.1 nnλ : z (m) (2 cm) z (e, K + ) 2.1 (p) H(e, e K + )Λ/Σ 0 Λ, Σ 0 Λ, Σ 0 (p) Λ, Σ 0 Λ, Σ 0 HRS 4.5 %(= p/p) nnλ (p e, p K ) = (2.2, 1.8) GeV/c Σ 0 ( 3.10)

58 48 3 H(e, e K + )Λ/Σ 0 3.6: Seive Slit Seive Slit HRS Seive Slit HRS Sieve Slit Seive Slit (H(e, e K + )Λ/Σ 0 ) (p e, p K ) = (2.1, 1.8) GeV/c(Kine1: 3.9) nnλ (p e, p K ) = (2.2, 1.8) GeV/c(Kine2: 3.10) Λ, Σ 0 Kine1, Kine2 Λ Kine1 Λ, Σ 0 Kine2 Λ nnλ ( 3 He, H) 3 H He (ν e ) 3 H 3 He + e + ν e (3.5) 2017 JLab H 3 He 3 He 3 Λ H 1 H 1 H 1 H 3 H ( 3 He, H)

59 : Seive Slit [30] Sieve Slit 49 4 mm 2 mm 12.5 mm, 25 mm Sieve Slit 14 cm, 20 cm VDC VDC VDC Bethe-Bloch de ρdx = C Z z 2 [ ( 2mc 2 γ 2 β 2 ) A β 2 ln β 2 δ ] (3.6) I 2 C = e 4 n 4πϵ 2 0 mc 2ρ (3.7) I δ VDC ( a, l) (b) (E),

60 50 3 H(e, e K + )Λ/Σ 0 3.8: p e, p K E=4.3 GeV, θ ee = 13.2, θ γk = 0 Λ, Σ 0, nnλ HRS p = 0.045p p e = 2.2 GeV/c( ) Σ 0 Λ, Σ 0 (p e = 2.1GeV/c)( ) ( ) p e = 2.1 GeV/c Λ Λ (V) E = Q 2πϵrl V = Q 2πϵl ln b a (3.8) (3.9) (3.8, 3.9) E = V r ln b a (3.10) VDC w t 0

61 : p e = 2.1 GeV Λ/Σ GeV/c 2 Λ 1.2 GeV/c 2 Σ 0 Λ, Σ 0 t 1 x x = t1 t 0 wdt (3.11) JLab VDC 3.11 [25] VDC TDC t = b > 2 cm 3.13 VDC VDC 2 VDC(VDC1, VDC2) 2 VDC1(u1, v1) VDC2(u2, v2) VDC 1) S2 & S0

62 52 3 H(e, e K + )Λ/Σ : p e = 2.2 GeV/c Σ Σ 0 Λ 3.9 Λ nnλ 2) Pion Event (AC1 > 1000 ch & AC2 > 6000 ch) VDC (1), (2) VDC % Scintilattion Trigger Counter(STC) HRS 2 (S0, S2) (S0, S2) β HRS-R β β PMT PMT y hit PMT y 2 PMT (TOF) TOF = ts2 R + ts2 L 2 ts0 R + ts0 L 2 (3.12) t R, t L 2 PMT S2, S0 PMT 3.12 β

63 : VDC [25] 3.12: VDC x, y [25] 3.11 y (b < 0.1) σ β = β t T OF σ T OF (3.13) t T OF S0, S2 β 3.13 β KID TOF TOF HRS-R K + KID (S2) TOF t tar S2 t S2 l path β TOF t TOF = l path βc (3.14) β ( 3.24) RHRS (π +, K +, p) TOF HRS S2

64 54 3 H(e, e K + )Λ/Σ : VDC (26 m) T tof π = 87.0 ns T tof K = 90.0 ns T tof p = 97.8 ns (3.15) (3.15) TOF K + K + π + TOF 3 ns K + π + (K + : π + = 1 : 1000) TOF coincidence time K + (S0, S2) t coin HRS(L-R) S2 t L (S2), t R (S2) (t L (tar), t R (tar)) t coin t coin = (t R (S2) t R (tar)) (t L (S2) t L (tar)) (3.16) (t L (tar), t R (tar)) coincidence time S2 S2 coincidence time

65 : VDC2 VDC π + S0, S2, AC1, AC2 VDC 0 < t < 4 ns VDC1 99.4% S (S2) Path Length Correction t tar S2 t S2 t tar = t S2 l path /cβ (3.17) 3.17 ( 3.15) coincidence time coincidence time R-HRS K + L-HRS e β K, β e β K, e = p (3.18) p2 + (m K, e c) 2 t corr = l path /cβ K, e (3.19) (3.16) (3.19) t coin t coin = (t R (S2) l path /(cβ K )) (t L (S2) l path /(cβ e )) (3.20)

66 56 第 3 章 H(e, e K + )Λ/Σ0 のデータ解析 図 3.15: 補正前後の HRS-R path length と coincidence time の相関図 軸は粒子の通った距 離 (path length) 縦軸は coincidence time を表している 補正前の相関図では coincidence time が path plength 依存性を持っていることがわかる 補正後の coincidence time は path length 依存性が小さいことがわかる と表すことができ K +, e 粒子における coincidence time の軌跡依存性の補正を行った (図 3.15) S2 offset parameter tuning HRS では 16 セグメントの S2 シンチレータカウンターを用いて粒子の観測を行う しかし ハードウェアによる時間情報の読み込みの差がセグメント毎に生じてしまうため補正を適用 させる必要がある S2 の F1TDC のオフセットを合わせる前の coincidence-time での陽子 π + 中間子の分解能はそれぞれ σπ = 1.10 ns, σp = 1.25 ns であり S2 の要求精度に十分満た していないため HRS 両アームの S2 の offset parameters の調整を行う必要がある (図 3.17) coincidence time のセグメント依存性を図に示す π + 中間子の選択を行うためにカット条 件として AC カットを用いた (AC1 > 150 & AC2 > 2000) ある S2 セグメントを通過した イベントでの coincidence time をガウス関数でフィットした中心値を取得 比較を行った S2 offset を合わせる前ではセグメント毎にばらつきが確認できたため HRS 両アームの S2 の offset を合わせた図 3.16 S2 offset パラメータ調整前では coincidence time のセグメ ント毎の振れ幅がそれぞれのアームに対して 2 ns あるのに対し パラメータ調整後では coincidence time のセグメント依存性を 50 ps 以下に抑えることができた 以上の補正をを 加えた coincidence time を図 3.17 に示す

67 : Offset S2 HRS-L HRS-R S2 π + 50 ps Cherenkov (n) (c/n) PMT cos θ c = 1 nβ (3.21) 3.2: S2 p, π + Coin-time resolution σ coin [ns] π + p No correction S2 offset and path length correction

68 58 3 H(e, e K + )Λ/Σ : S2 coincidence time S2 path length correction offset coincidence time path length S2 offset coincidence time π +, p (Z) (n) (λ) (α) d 2 ( N dλdx = 2πZ2 α λ ) β 2 n 2 (3.22) (n(λ)) ACD (λ 1 < λ < λ 2 ) ( dn 1 dx = 2πϵαZ2 sin 2 θ 1 ) λ 1 λ 2 (3.23) ϵ AC1, AC2 (3.23) 3.18 KID 2 p K = 1.8 GeV/c (β) β π = β K = β p = (3.24)

69 : Particle identification with AC index π + K + p n=1.015 (AC1) detection no detection no detection n=1.055 (AC2) detection detection no detection trigger condition AC1 & AC2 AC1 &AC2 AC1 &AC2 βn > 1(n: ) (n=1.015, 1.055) (π +, K +, p) AC2, AC AC1, HRS-R ACD gain FADC ADC ADC AC 1photon-electron(1PE) ADC (NPE) NPE = ADC ADC ped ADC 1PE ADC ped (3.25) 3.18: AC1 AC2

70 60 3 H(e, e K + )Λ/Σ : AC1 2.0 PEs ADC 1PE, ADC ped 1PE ADC Fit NPE AC ADC NPE AC AC1, 2 PMT (3.19, 3.20) AC1, AC AC AC1, AC2 (N AC1, N AC2 ) = (6, 30) AC1 30 % AC2 75 % AC1 π + 2 PEs K +, π AC K + S2 Coincidence-time β π +, p ( 3.17) AC π K + K + π +, p K + coincidence-tme AC1, 2 ( 3.21) 3.21 (t ct = 2 ns) (ACCBG) ACCBG π +, p AC1, AC2 coincidence time π +, p K +

71 3.3 AC K : AC2 20 PEs (t ct 0 ns)accbg AC1, AC2 π +, p ( 3.22, 3.23) AC1, AC2 threshold(th1, th2 min, th max ) AC1 < th1 (3.26) th2 min < AC2 < th2 max (3.27) π +, p ( 3.28) 3.23 th2 max = 60 PEs th2 min 0 60 y = p ( 0 (x p1 ) 2 exp 2π 2p 2 2 ) + ACC. (ACC : const) (3.28) (3.29) y ACCBG ACCBG coincidence time ACCBG ( 20 < t ct < 15 ns) 3.22, 3.23 π +, p AC1, AC2 coincidence time K +, π +, p AC1 NPE < 1.0 (3.30) 3.5 < AC2 NPE < 8 (3.31)

72 62 第 3 章 H(e, e K + )Λ/Σ0 のデータ解析 適切な AC カット条件を coincidence time に課すことによって K + イベント数を見積もっ た しかし AC カット条件を課すことによって π +, p と同時に K + 中間子イベントも削り取 られていることから K + イベント数は AC カット条件により変動する そこで coincidence time の K + 領域における S/N 比及び K + イベントを十分確保できるような 適切な AC カッ ト条件を求める必要がある K + イベント及び coincidence time の K + 領域における S/N 比 の AC カット依存性の評価について第４章にて詳細に述べる 図 3.21: coincidence time と AC1, AC2 光電子数の相関図 上図は AC1 の光電子数と coincidence time の相関図 下図は AC2 と coincidence time の相関図を表している 2 ns 毎 にアクシデンタルバックグランドがあり coincidence time(tct =3 ns) 付近に π + イベント tct =-7 ns 付近に p イベントが確認できる

73 3.3 AC K : AC1 π +, p AC1 3.4: (AC1 < 1.0 PEs & 3.5 < AC2 < 10 PEs) (K +, π +, p) particles Events mean [ns] σ [ns] K π p

74 64 3 H(e, e K + )Λ/Σ : AC2 π +, p AC2

75 3.3 AC K : AC coincidence time p, K +, π +

76 66 4 K + E (H(e, e K + )Λ/Σ 0 ) K + KID K + nnλ θ K 0 Λ H(e, e K + )Λ/Σ 0 θ K 0 Λ Λ, Σ 0 K + K + Λ, Σ 0 Λ, Σ 0 ) 4.1 H(e, e K + )Λ/Σ 0 K + coincidence time π +, p AC 4.1:

77 4.1 H(e, e K + )Λ/Σ : H(e, e K + )Λ/Σ 0 coincidence time K + ( 1 < t ct < 1) ns (ACC) coincidence time π +, K +, p ( 40 < t ct < 20, 20 < t ct < 40) ns AC Λ, Σ 0 coincidence time K + AC coincidence time K + coincidence time AC Λ/Σ 0 Λ, Σ 0 K + K Λ/Σ AC H(e, e K + ) (ACCBG) Λ, Σ 0 ACCBG coincidence time ACC 4.3 ACCBG Λ/Σ 0 π +

78 68 4 K + 4.3: AC coincidence time AC coincidence time CEBAF 2 ns (ACC) K + π + ACC 4.4 (m) (±0.125 m) Λ, Σ 0 π + (f Al, f π ) (f BG ) f Al f π = p 0 exp ( (x p 1) 2 ) 2p 2 + p 4 exp ( (x p 5) 2 ) 3 2p 2 6 = p 0 exp ( (x p 1) 2 ) 2p 2 3 (4.1) (4.2) f BG = p BG 0 f Al + p BG 1 f π (4.3) p 0, p 1, p 2, p 3, p 4, p 5 ( 4.5)f Al π + ( 4.6)f π + p BG 0, p BG 1 (4.3) 4.7

79 4.2 AC cut Λ, Σ 0 S/N : [m] [GeV/c] (z = 0.125, 0.125) m (Al) 0.1 < z < 0.1 m 4.2 AC cut Λ, Σ 0 S/N K + AC AC K + AC K + (e, e K + ) K +, e π +, p K + 3 Λ/Σ 0 Λ/Σ 0 coincidence time K + AC K + Λ/Σ 0 Λ/Σ 0 ( 3.1) , 700

80 70 4 K + 4.5: (Al) ( 0.1 < z & 0.1 < z) m( 4.4) 4.6: π + coincidence time π + 2 < t ct < 4 ns ( 4.3) K + K + AC K + π + S/N ratio AC 2 π + ( ) K + coincidence time S/N coincidence time K + S/N

81 4.2 AC cut Λ, Σ 0 S/N : π + (f Al f π ) f BG f BG f Al, f π ( 4.3) AC K + π Λ, Σ 0 K + AC AC K + π +, p coincidence time K + AC coincidence time K + AC1, AC2 K + Λ, Σ 0 K + H(e, e K + )Λ/Σ 0 K + Λ, Σ 0 Λ, Σ 0 Λ, Σ 0 AC Λ, Σ 0 Λ, Σ 0 Λ, Σ 0 Λ, Σ 0

82 72 4 K + 4.8: Λ 4.1: Λ, Σ 0 Particles Events mean(µ) MeV/c 2 σ MeV/c 2 S/N Λ 796± ± ± Σ 0 127± ± ± f Λ, Σ = p 0 exp ( (x p 1) 2 ) + p 3 x + p 4 (4.4) 2p 2 3 ( 4.4) Λ, Σ 0 Λ, Σ Λ, Σ 0 K + (p e = 2.1 GeV/c) K + (N K 920) Λ, Σ 0 (±3σ) S/N S Λ /N = 1.02, S Σ0 /N = 0.13 S Λ, Σ 0 N

83 4.2 AC cut Λ, Σ 0 S/N : Σ AC AC Λ NΛ cut Λ NΛ tot Λ R Λ R AC Λ = NΛ cut /NΛ tot (4.5) AC1, AC2 (4.5) Λ ( 4.10, 4.11) Λ AC1, AC2 Λ Λ S/N AC coincidence time π +, p 3.24 K + coincidence time K + S/N AC S(Signal) K + N(Background) ACC π + AC threshold S/N

84 74 4 K : AC1 Λ AC1 threshold(th1) NPE < th1 Λ 4.11: AC2 Λ AC2 threshold(th2) th2 < NPE Λ (ACCBG) coincidence time ACC K + ACC ACC (2 ns) 4.3 ACCBG K + ACCBG AC1, AC2 AC1, AC2 threshold th1, th2 AC1 < th1 (4.6) th2 < AC2 (4.7) K + coincidence time(ct) 1 < ct < 1 ns AC1, 2 (4.6, 4.7) S/N ( 4.12, 4.13) PEs< th1 S/N 1.0 th1 < 15 PEs threshold S/N 4.13 S/N AC2 threshold(th2)

85 4.2 AC cut Λ, Σ 0 S/N : AC1 S Λ /N AC1 threshold(th1) NPE<th1 S Λ /N (S Λ ) Λ N Λ (±3σ Λ ) 4.13: AC2 S Λ /N AC2 threshold(th2) th2<npe S Λ /N (S Λ ) Λ N Λ (±3σ Λ ) FOM AC Λ, Σ 0 S/N Λ S/N AC FOM Λ (S) S/N (S/N) FOM = S/N S (4.8) (4.8) peak significance AC1, AC2 (4.6, 4.7) FOM (4.14, 4.15) 4.14 AC2 threshold ( ) FOM AC1 cut 4.15 FOM

86 76 4 K : FOM AC1 AC1 threshold FOM AC2 threshold 1.0, 2.0, 5.0 PEs FOM 4.15: FOM AC2 AC2 threshold FOM AC1 threshold 0.1, 1.0, 3.0 PEs FOM 4.2: AC Λ, Σ 0 S/N FOM Particles Events S/N Survival ratio FOM Λ 440 ± Σ ± total (Λ + Σ 0 ) AC2 cut FOM AC1, AC2 FOM AC1, AC2 ( 4.16) FOM 4.16 (4.6, 4.7) AC1, AC2 threshold FOM AC AC1 < PEs (4.9) 2.0 PEs < AC2 (4.10)

87 4.3 p(γ, K + )Λ/Σ : FOM AC1, 2 cut AC1, AC2 threshold FOM AC1, AC2 threshold (4.14, 4.15) FOM AC1 AC1, threshold(th1) (AC1<th1) AC2 threshold(th2) th2<ac2 4.3 p(γ, K + )Λ/Σ 0 Λ, Σ 0 p(γ, K + )Λ/Σ 0 p(γ, K + )Λ/Σ 0 dσ dω = 1 1 N T N γ 1 1 ε SR ε K Ω N T N γ (4.11) Ω HRS N Λ, Σ 0 Λ, Σ 0 f decay K + ε K virtual photon flux(γ) (E e E e ) HRS (Ω e ) N γ = ΓdΩ e de e (4.12)

88 78 4 K + (Q) N γ = Q ΓdΩ e de e (4.13) e Γ HRS Ω (4.13) N γ N γ = Q e Γ (4.14) 4.7 C H (2.38 C) (1.11) virtual photon flux(γ) Γ = α E γ E e 2π 2 Q 2 = /(MeV sr e) (4.15) (1 ϵ)e e (4.15) (2.38 C) HRS ( Ω = 6 msr, E e = 180 MeV ) (4.14) ( 4.16) N γ = (4.16) N T N T N T = g/cm /mol 2 g/mol 2 = /cm 2 (4.17) K + ε K K + (τ K ) s K + HRS HRS l = 23 m[27] K + (ε K ) ε K = e l/cβγt K = (4.18) K + HRS VDC, STC(S0, S2), AC(AC1, AC2) (ε V DC, ε ST C, ε AC ) AC1, AC2 K % S0, S2 100 % VDC AC VDC HRS ε tot ε tot = (ε V DC ε ST C ε AC ) R (ε V DC ε ST C ) (4.19) = ((0.995) ) R ((0.995) 4 1.0) L (4.20)

89 4.3 p(γ, K + )Λ/Σ 0 79 VDC 99.5 % AC (4.11) Λ, Σ 0 dσ Λ dω dσ Σ 0 dω = 400 ± 20 nb/sr (4.21) = 120 ± 20 nb/sr (4.22) Λ, Σ (4.15) vartual photon flux 4.19 virtual photon flux HRS HRS p/p = 4.5 % virtual photon flux (4.15) HRS virtual photon flux Γ max = /(MeV sr e) (θ ee = 11.2, E e = 2.2 GeV) (4.23) Γ min = /(MeV sr e) (θ ee = 15.2, E e = 2.0 GeV) (4.24) Λ dσ Λ dω = 400 ± nb/sr (4.25) JLab CLAS (γ, K + ) Λ [10] (θ γk 0 ) dσ C.M. /d cos θ γk 2.2 µb CLAS CLAS C.M. Ω/ cos θ = 2π CLAS 360 nb/sr Λ KID

90 80 4 K KID Λ CLAS (4.25) virtual photon flux θ ee E e Monte Calro Simulator(Gean4) Λ, Σ 0 nnλ KID H(e, e K + )Λ/Σ 0 m 100 kev

91 : AC Λ 4.18: AC2 Σ 0

92 82 4 K : 2.2, 2.1, 2.0 GeV HRS p/p = 4.5 % HRS (p e = 2.1 GeV/c) (θ ee = 13.2 ) virtual photon flux /(MeV sr e)

93 GSI HypHI nnλ nnλ (JLab) m 100 kev nnλ (HRS) K + K + HRS π +, p K K + KID HRS time of flight coincidence time π +, p π +, p (AC) threshold AC Λ, Σ 0 Λ, Σ 0 Λ, Σ 0 peak significance FOM AC cut tuning AC1, AC2 (4.9, 4.10) Λ peak significance 54 Λ 60 % KID Λ dσ Λ /dω = 400 ± nb/sr Λ JLab CLAS Λ dσ Λ /dω = 360 nb/sr KID KID nnλ nnλ

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96 86 JLab JLab JLab HLab meeting JLab JLab GP-PU JLab Tang JLab Tang Bishnu