25 3 4

25 3 4

1 µ e + ν e +ν µ µ + e + +ν e + ν µ e e + TAC START STOP START veto START (2.04 ± 0.18)µs 1/2 STOP (2.09 ± 0.11)µs 1/8 G F /( c) 3 (1.21±0.09) 5 /GeV 2 (1.19±0.05) 5 /GeV 2 Weinberg θ W sin θ W (0.46 ± 0.02) (0.46 ± 0.01) 1

1 4 2 5 2.1................................. 5 2.2.............................. 6 2.2.1 G F............................. 8 2.3....................... 9 2.3.1....................... 9 2.3.2........................... 2.3.3................................. 12 2.4.................................... 15 3 17 3.1........................ 17 3.1.1............................... 17 3.2................................. 18 3.3................. 19 3.3.1 Discriminator............................... 19 3.3.2 Coincidence................................ 20 3.3.3 FAN-IN / OUT.............................. 20 3.3.4 Gate & Delay Generator......................... 20 3.3.5 TAC.................................... 20 3.3.6 ADC.................................... 20 3.3.7 MCA................................... 21 3.3.8 Scaler................................... 21 4 22 4.1 Discriminator........................ 22 4.2.......... 22 4.3 TAC+ADC........................... 23 5 26 5.1 2......... 27 5.1.1 Discriminator............ 27 2

5.1.2...................... 30 5.1.3 1 µs delay......... 36 5.2 2.................................. 38 5.3 TAC...... 40 6 43 6.1................................... 43 6.2........................ 43 6.2.1.............................. 43 6.2.2........................... 47 6.2.3.................................. 52 6.3 veto................. 54 6.3.1.............................. 54 6.3.2.................................. 56 6.4............... 58 6.4.1.............................. 58 6.4.2.................................. 60 7 63 7.1...................... 63 7.2........................ 64 8 65 8.1............................... 65 8.2.................................. 66 3

1 1 τ µ m µ G F G F 1. 1 2. 3. 1 (= ) τ µ 1 2 3 4 TAC+ADC 5 6 3 7 G F, g, Weinberg θ W 8 4

2 2.1 4 ( ) ( ) W ± Z 0 β β β β β β n p + e + ν e (1) 1935 E. Fermi 4 4 1 4- β 1.25 V-A µ V-A 4 W Z 0 2 W ± Z 0 1983 5

1 4- β 2 β W 2.2 1/2 2 µ e + ν e + ν µ µ + e + + ν e + ν µ (2) W 6

W 3 t N decay (t) N 0 τ µ N decay (t) = N 0 N 0 e t/τ µ = N 0 (1 e t/τ µ ) (3) t dn decay dt = N 0 τ e t/τ µ (4) τ µ E e N(E e )de e N(E e )de e = G 2 F 12π 3 ( c) 6 (m µc 2 ) 2 E 2 e (3 4E e m µ c 2 )de e (5) E e (MeV) 52.83 MeV 0 < E e < 52.83 3 ( ) W ( ) W + 7

4 37 MeV N(E_e) (x^(-19)) 120 0 80 60 40 20 0 0 20 30 40 50 60 E_e (MeV) 4 37 MeV 2.2.1 G F V-A Γ Γ = τ µ = G 2 F 192π 3 ( c) 6 (m µc 2 ) 5 (1 + ϵ) (6) ϵ m µ τ µ G F G F Particle Data Group [3] m µ τ µ m µ = 5.65836668(38) MeV/c 2 (7) τ µ = 2.19703 ± 0.00004 µs (8) 8

M fi g 1 Q 2 c 2 + M 2 W c4 g g2 M 2 W c4 (Q2 0) (9) g M W W Q 2 4 G F g G F G F 2 = πα 2 g2 e 2 ( c) 3 M 2 W c4 () α = 7.297 3 G F M W = (80.385 ± 0.015) GeV/c 2 g e = 1.602 19 C g e = g sin θ W (11) g (Weinberg )θ W 2.3 2.3.1 dx Bethe-Bloch de dx = D Z 1 ( [ 2mc 2 β 2 γ 2 ] A z2 β 2 ln β 2 + δ ) (12) I 2 β = v/c γ = 1/ 1 β 2 Z A z e 4 ( ) n A Z D = 4πϵ 2 0 mc2 ρ Z 0.3071 MeVcm2 /g n = ρ N A A ρ N A I δ D 0.3071 MeVcm 2 /g Z/A = 0.54141 I = 64.7eV ρ = 1.032g/cm 3 δ 9

T de/dx 5 5 T 200 MeV de/dx 2 MeV/cm 5 T de/dx T 200 MeV de/dx 2 MeV/cm 2.3.2 Bethe-Bloch The National Institute of Standards and Technology (NIST) ESTAR [9] T de/dx 6 6 T 1 MeV de/dx 2 MeV/cm 7

6 T de/dx T 1 MeV de/dx 2 MeV/cm 7 ( ) ( ) 11

2.3.3 : R(T 0 ) = T0 0 ( de ) 1 dx (T ) dt (13) T 0 T E Mc 2 de dx (T ) = D Z A z2 β 2 = Bethe-Bloch ( ( T Mc + 1) 2 2 T Mc ( T 2 Mc 2 T = E Mc 2 (14) T Mc ( T 2 Mc + 2) 2 ( T (15) Mc + 1) 2 2 [ 2mc 2 + 2) ln I T Mc 2 ( T ] ) Mc 2 + 2) 1 + δ 2 β T (13) 8 9 Bethe-Bloch 6 de/dx MeV/cm T MeV (13) 8 cm 60 MeV 0 MeV 0 MeV (16) 12

8 Bethe-Bloch T MeV R cm 9 T MeV R cm de/dx MeV/cm T MeV (13) 13

( ) ( ) 14

2.4 ( ) 20 ev 11 π K π + µ + + ν µ (17) π µ + ν µ (18) K + µ + + ν µ (19) K µ + ν µ (20) 1 cm 2 1 τ µ 144 cm 2 2.4 Hz 15

11 16

3 3.1 3.1 2 1 ( ) 8 cm 18 cm 1 cm 8 cm 16 cm cm 3.1.1 ([6]) 2 2 ([7]) 2 3 % 17

2 NaI 2 12 [CH 3 C 6 H 4 CHCH 2 ] n 3.2 18

20 50 ns 2 R7724 H7195 60.0 mm 3 3 (R7724, H7195) R7724 H7195 ( ) 1750 V ( 2000 V) 2000 V ( 2700 V) 2.1 ns (typical) 2.7 ns (typical) 29 ns (typical) 40 ns (typical) 1.2 ns (typical) 1.1 ns (typical) R7724 0.5 µs 3 µs H7195 3.3 NIM 5 6 13 3.3.1 Discriminator Discriminator N-TM 405 8CH Discriminator (Non- Updating) ( ) Discriminator 19

updating discriminator non-updating discriminator 4 3.3.2 Coincidence Coincidence N-TM 3 3CH 4-Fold Coincidence 2 veto (anti-coincidence) veto 4 3.3.3 FAN-IN / OUT OR PHILLIPS SCIENTIFIC MODEL 740 QUAD LINEAR FAN-IN/FAN-OUT 3 veto 3.3.4 Gate & Delay Generator Gate & Delay Module N-TM 307 2CH Gate and Delay Generator Type2 START delay 3.3.5 TAC Time to Amplitude Converter (TAC) ORTEC Model 566 Time to Amplitude Converter START STOP 3.3.6 ADC Analog to Digital Converter (ADC) Laboratory Equipment ADC500 20

装置である 本研究では TAC から出力された 時間差を波高に変換したアナログパル スをデジタル値 (チャンネル数) に変換するために利用する 3.3.7 MCA Multi-Channel Analyzer (MCA) として Laboratory Equipment 社の MCA5 を 使用した これは 入力されたデジタル信号をチャンネル毎に積算する装置である 本研 究では デジタル値 (チャンネル数) の積算により ミューオン崩壊の寿命の時間スペク トルを得るために利用する 3.3.8 Scaler Scaler として N-OR 425 8CH 0MHz Visual Scaler を使用した これは 入力し た信号をカウントするモジュールである 本研究では 光電子増倍管からの信号をカウン トして測定時間で割ることにより 計数率の測定に利用する 図 13 本研究で用いるデータ収集系 左から HV 電源 Discriminator Coincidence FAN-IN/OUT Gate & Delay Generator TAC ADC MCA Scaler である 21

4 4.1 Discriminator Discriminator updating non-updating 1 1 Discriminator non-updating 4.2 2 (PMT1 PMT2 ) R acc (Hz) (21) R acc = R 1 R 2 (h 1 + h 2 2h 3 ) (21) R 1 [Hz] R 2 [Hz] PMT1 PMT2 h 1 (s) h 2 (s) PMT1 PMT2 Discriminator h 3 (s) (21) R 1 R 2 Coincidence module h 1 h 2 h 3 h 1 h 2 PMT1 h 1 ns PMT2 h 2 ns 14 2 Coincidence module h 2 Coincidence module h 2 h 3 Discriminator 3 ns Coincidence module h 3 3 ns 22

14 PMT2 h 1 ns h 2 6 ns 5 6 4.3 TAC+ADC START STOP TAC (Time to Amplitude Converter) ADC (Analog to Digital Converter) TAC ADC 15 2 TAC START Gate & Delay Generator delay TAC STOP TAC Gate & Delay Generator TAC 20 µs START STOP 4, 8, 12, 16 µs 3 16 4 Channel (ch) Time (µs) 23

15 TAC START Discriminator STOP Gate&Delay Generator Delay Counts per channel (x^5) 24 22 20 18 16 14 12 8 6 4 2 0 0 500 00 1500 2000 2500 3000 3500 4000 Channel (ch) 16 TAC 4, 8, 12, 16 µs 4, 8, 12, 16 µs 17 Time = (4.797 ± 0.008) 3 Channel + ( 0.15 ± 0.02) (22) 5 6 (22) TAC+ADC 24

4 TAC START STOP (µs) (ch) (µs) 4 8 12 16 (ch) 867 1698 2530 3369 Time (µ s) 20 18 16 14 12 8 6 4 2 0 0 500 00 1500 2000 2500 3000 3500 4000 Channel (ch) 17 TAC 20 µs Time = (4.797 ± 0.008) 3 Channel + ( 0.15 ± 0.02) 25

5 R acc = R 1 R 2 (h 1 + h 2 2h 3 ) 1. R 1, R 2 2. h 1, h 2 3. delay 4. 5. PMT1, 2 R 1, R 2, R coin Scaler 0 18 18 26

5.1 2 5.1.1 Discriminator R 1, R 2 2 (H7195) PMT1, PMT2 19 19 2 Discriminator3, Discriminator4, Coincidence Scaler1,2,3 5 19 Discriminator1,2 Discriminator3,4 Discri1,2 Discri3 Discri4 Coincidence (ns) 70 6 PMT1 Discriminator1 70 ns Discriminator3 4 ns Discriminator 2 1 Discriminator 2 Discriminator PMT2 Discriminator2 Discriminator4 4 6 ns 27

Coincidence module 2 Discriminator1 Discriminator3 50, 0, 150, 200, 250 mv 3 (800 ) 2 R 1 R 2 V th R 1, R 2 R coin (21) R acc 6 20 6 V th (mv) R 1 (Hz) R 2 (Hz) R coin ( 3 Hz) R acc ( 3 Hz) 50 4678.2 ± 0.2 961.2 ± 0.1 50.0 ± 0.8 44.966 ± 0.005 0 23.3 ± 0.1 703.57 ± 0.09 13 ± 4 7.200 ± 0.001 150 699.58 ± 0.09 559.26 ± 0.08 6.7 ± 0.3 3.91245 ± 0.0008 200 587.59 ± 0.08 470.42 ± 0.07 2.1 ± 0.2 2.7642 ± 0.0006 250 488.77 ± 0.08 400.64 ± 0.07 2.1 ± 0.2 1.9582 ± 0.0004 20 R coin R acc R 1, R 2 28

Counting Rate (Hz) -1-2 -3 0 50 0 150 200 250 300 -Vth (mv) 20 2 250 mv 50 mv ( ) ( ) 29

5.1.2 h 1, h 2 19 h 1 Discriminator 1 Discriminator 2 mv Discriminator 4 6 ns h 1, 20, 30, 40, 50,60 ns h 1 =, 20, 30 ns 1800 h 2 = 40, 50, 60 ns 3600 PMT1 PMT2 R 1 1580 Hz, R 2 145 Hz (21) h 1 + h 2 2h 3 ns ( Width ) R 1, R 2, R coin (21) R acc 7 h 1 + h 2 2h 3 (ns) (Hz) R 1, R 2, R coin 21 R coin R acc 22 7 h 1 (21) h 1 + h 2 2h 3 ns (= Width) R 1, R 2, R coin (21) R acc Width (ns) R 1 (Hz) R 2 (Hz) R coin ( 3 Hz) R acc ( 3 Hz) 1551.5 ± 0.7 143.8 ± 0.2 1.9 ± 0.7 2.230 ± 0.003 20 1626.9 ± 0.7 146.3 ± 0.2 5.6 ± 1.2 4.760 ± 0.007 30 1567.0 ± 0.7 142.2 ± 0.2 5.6 ± 1.2 6.69 ± 0.01 40 1559.7 ± 0.9 141.1 ± 0.3 11 ± 2 8.81 ± 0.02 50 1580.3 ± 0.9 142.6 ± 0.3 11 ± 2 11.3 ± 0.2 60 1583.4 ± 0.9 143.8 ± 0.3 19 ± 7 13.7 ± 0.3 R 1 R 2 22 R coin R acc R acc h 1 (21) R acc R 1 R 2 = h 1 + h 2 2h 3 (23) (23) h 1 + h 2 2h 3 ns R coin /(R 1 R 2 ) ns 30

Counting Rate (Hz) 4 3 2 1-1 -2-3 -4 0 20 30 40 50 60 70 Width (ns) 21 h 1 PMT1 R 1 ( ) PMT2 R 2 ( ) R coin ( ) R 1 R 2 R 1 1550 Hz, R 2 450 Hz 23 (21) R acc h 1 31

Counting Rate (Hz) -1-2 -3-4 0 20 30 40 50 60 70 Width (ns) 22 h 1 (21) R acc ( ) PMT1 PMT2 R coin ( ) R coin 21 R coin R acc Racc/(R1*R2) (ns) 0 90 80 70 60 50 40 30 20 0 0 20 30 40 50 60 70 Width (ns) 23 2 h 2 6 ns h 1 ns 60 ns 2 ( ) R acc /(R 1 R 2 )( ) 32

h 2 Discriminator 1 Discriminator 2 mv Discriminator 3 ns h 2 6, 16, 26, 36, 46, 56 ns h 2 = 6, 16, 26 ns 1800 h 2 = 36, 46, 56 ns 3600 PMT1 PMT2 R 1 1550 Hz, R 2 145 Hz (21) h 1 + h 2 2h 3 [ns] R 1, R 2, R coin (21) R acc 8 h 1 h 1 + h 2 2h 3 (ns) (Hz) R 1, R 2, R coin 24 R coin R acc 25 8 h 2 (21) h 1 + h 2 2h 3 ns (= Width) R 1, R 2, R coin (21) R acc Width (ns) R 1 (Hz) R 2 (Hz) R coin ( 3 Hz) R acc ( 3 Hz) 1551.6 ± 0.7 143.8 ± 0.2 1.9 ± 0.7 2.230 ± 0.003 20 1548.2 ± 0.7 150.9 ± 0.2 4.4 ± 1.1 4.673 ± 0.007 30 1563.9 ± 0.7 147.3 ± 0.2 5.8 ± 1.3 6.91 ± 0.01 40 1468.9 ± 0.9 135.8 ± 0.3 9.4 ± 2.3 7.98 ± 0.02 50 1625.1 ± 1.0 150.7 ± 0.3 12 ± 3 12.2 ± 0.2 60 1625.1 ± 1.0 150.7 ± 0.3 16 ± 3 14.7 ± 0.3 h 2 R 1 R 2 25 (21) h 2 h 1 h 1 + h 2 2h 3 ns R coin /(R 1 R 2 ) ns PMT1 PMT2 R coin /(R 1 R 2 ) (23) 24 (21) R acc h 2 (21) R acc h 1 + h 2 2h 3 33

Counting Rate (Hz) 4 3 2 1-1 -2-3 -4 0 20 30 40 50 60 70 Width (ns) 24 h 2 PMT1 R 1 ( ) PMT2 R 2 ( ) R coin ( ) R 1 R 2 R 1 1550 Hz, R 2 450 Hz Counting Rate (Hz) -1-2 -3-4 0 20 30 40 50 60 70 Width (ns) 25 h 2 (21) R acc ( ) PMT1 PMT2 R coin ( ) R coin 24 R coin R acc 34

Racc/(R1*R2) (ns) 0 90 80 70 60 50 40 30 20 0 0 20 30 40 50 60 70 Width (ns) 26 2 h1 ns h2 6 ns 56 ns 2 ( ) R acc /R 1 R 2 ( ) 35

5.1.3 1 µs delay 1 µs delay h 1 = 40 ns h 2 = 6 ns 27 PMT 2 1µs delay PMT 1 1800 PMT1 PMT2 R 1, R 2 R coin (21) R acc 9 R acc R coin 28 28 delay delay (21) 27 2 Delay Box delay Discri2 Discri4 Delay Box PMT2 1µs delay Discriminator3, Discriminator4, Coincidence Scaler1, 2, 3 9 h 1 = 40 ns h 2 = 6 ns R 1, R 2, R coin (21) R acc R 1 (Hz) R 2 (Hz) R coin ( 3 Hz) R acc ( 3 Hz) 1586.1 ± 0.9 143.3 ± 0.3 9.4 ± 2.3 9.09 ± 0.02 36

Counting Rate (Hz) -1-2 -3-4 0 20 30 40 50 60 70 Width (ns) 28 h 1 = 40 ns, h 2 = 6ns PMT1 1µs delay ( ) ( ) h 1 37

5.2 2 2 1 2 29 2 ns 1 µs delay delay 6 ns delay delay h 1 = ns, h 2 = 6 ns V th 25, 50, 75, 0, 125 mv 6 (21600 ) PMT1 PMT2 R 1, R 2 R coin R acc R coin R acc 30 30 (21) 29 2 ns 1 µs delay 38

V th 25mV R 1, R 2, R coin (21) R acc V th (mv) R 1 (Hz) R 2 (Hz) R coin ( 3 Hz) R acc ( 3 Hz) -25 859.5 ± 0.3 905.3 ± 0.3 7.781 ± 0.003 9.2 ± 0.9-50 422.0 ± 0.2 524.4 ± 0.2 2.213 ± 0.001 1.8 ± 0.4-75 259.0 ± 0.2 355.9 ± 0.2 0.9216 ± 0.0007 0.93 ± 0.30-0 160.0 ± 0.1 238.9 ± 0.1 0.3822 ± 0.0003 0.37 ± 0.13-125 125.1 ± 0.1 207.0 ± 0.1 0.2589 ± 0.0002 0.23 ± 0. Counting Rate (Hz) -1-2 -3-4 -5 0 20 40 60 80 0 120 140 -Vth (mv) 30 2 ns 1 µs delay ( ) ( ) 39

5.3 TAC 31 TAC START PMT1 PMT2 STOP PMT3 PMT1 PMT2 12 cm 2 PMT3 PMT1 PMT2 START STOP TAC ADC START STOP TAC µs START STOP µs START µs STOP PMT1 PMT2 R 1 (Hz), R 2 (Hz) R acc (Hz) (21) µs ( 6 s) R acc R 1 R 2 ( 6 ) (24) R acc TAC 18 (65000 ) 31 65000 START STOP R 1, R 2 (24) R acc 11 31 0.01 µs µs n 0 n 0 = 2.18 ± 0.42 ( /0.4808 µs) R BG R BG = (6.43 ± 1.34) 4 (Hz) R BG (24) R acc (24) TAC ADC 40

31 2 TAC START STOP µs 11 65000 START STOP R 1, R 2 (24) R acc (Hz) R 1 0.715 ± 0.003 R 2 85.66 ± 0.04 (6.12 ± 0.03) 4 R acc 41

Counts per channel 9 8 7 6 5 4 3 2 1 0 0 2 4 6 8 Time (µ s) 32 TAC START STOP 18 (65000 ) 42

6 3 6.1 START µs STOP TAC (4) n 0 dn decay dt = N 0 τ e t/τ µ + n 0 (25) τ µ 3 0 Scaler Discriminator 50 mv H7195 R7724 33 4 6.2 6.2.1 34 35 36 37 12 TAC START #1 #2 #3 STOP #2 43

33 4 #1 #2 #3 #1 #2 2 12 4 34 (ns) #1.0 #2 6.0 #3 70.0 #1 #2 #3.0 44

34 TAC Start #1 #2 #3 Stop #2 35 45

図 36 片側読み出しのブロック型プラスチック シンチレータを用いた従来のミュー オン寿命測定の実験装置 図 37 片側読み出し回路による寿命測定に使用するブロック型プラスチック シンチ レータとライトガイドの寸法 プラスチック シンチレータからの信号を 片側に接着 したライトガイドを通して光電子増倍管に伝える 46

6.2.2 (25) 34 84 (30 ) 34 TAC START STOP R ST ART, R ST OP (24) R acc 13 13 TAC START STOP R 1, R 2 (24) R acc (Hz) R ST ART 0.80 ± 0.09 R ST OP 309.5 ± 1.8 R acc (5.0 ± 0.6) 3 Counts per channel 500 450 400 350 300 250 200 150 0 50 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) 38 84 (30 ) 1.0 µs 20 µs (25) t n 0 2 47

n 0 39 t 0.5 (µs) (25) t 0.5 (µs) t = 1.0 (µs) Counts per channel 4 3 2 0 2 4 6 8 12 14 16 18 20 Time (µ s) 39 84 1.0 µs 20 µs 48

τ µ, n 0 6 µs 20 µs (25) τ µ n 0 40 41 n 0 R BG (Hz) 42 tau (µ s) 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 0 2 4 6 8 12 14 16 18 20 22 Max value of fitting range (µ s) 40 τ µ 1.0 µs 12 µs 2 µs µs 49

n_0 (/0.4797*µ s) 40 30 20 0 - -20-30 -40 0 2 4 6 8 12 14 16 18 20 22 Max value of fitting range (µ s) 41 n 0 1.0 µs 13 µs 35.5 /0.48 µs 12 µs R_BG (x^(-3) Hz) 6 4 2 0-2 -4-6 0 2 4 6 8 12 14 16 18 20 22 Max value of fitting range (µ s) 42 n 0 R BG (Hz) 1.0 µs 13 µs R BG 50

40 τ µ 12 µs 2 µs µs 41 n 0 13 µs 35.5 /0.48µs 12 µs 12 µs 42 (4.9 ± 0.2) 3 Hz 12 µs (5.0 ± 0.6) 3 Hz 20 µs 1.0 µs 20 µs τ µ = (2.04±0.) µs (4.9±0.2) 3 Hz 51

6.2.3 43 1.0 µs 20 µs τ µ = 2.13 ± 0.21 µs 1 n 0 = (6.08 ± 0.61) /(0.48 µs) R BG R BG = (3.9 ± 0.4) 3 Hz START STOP R ST ART R ST OP R acc 14 τ µ τ µ = 2.20µs[3] R BG R acc 1.0 20µs ( ) (295 ± 25) R µ (4.5 ± 0.4) 3 Hz R BG R µ : R BG 5 : 4 14 START STOP R ST ART R ST OP R acc (Hz) R ST ART 0.78 ± 0.09 R ST OP 290.1 ± 1.7 R acc (4.5 ± 0.6) 3 52

Counts per channel 0 90 80 70 60 50 40 30 20 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) 43 20 µs 1.0 20 µs τ µ = 2.13 ± 0.21 µs n BG = 12.7 ± 1.3 /µs 53

6.3 veto 6.3.1 44 45 46 veto 1 3 START veto veto R µ (Hz) 3 TAC START 0.8 Hz START veto 4 2 TAC START 0.4 Hz 1/2 15 44 (ns) #1.0 #2 6.0 #3, 4, 5 70.0 #1 #2 (#3 #4 #5).0 54

44 34 veto 3 3 OR coincidence module veto TAC Start #1 #2 (#3 #4 #5) Stop #2 45 44 PMT 55

46 veto 3 6.3.2 47 1.0 µs 20 µs τ µ = 2.04±0.18 µs 1 n 0 = (2.65±0.40) /(0.48µs) R BG R BG = (1.7 ± 0.3) 3 Hz START STOP R ST ART R ST OP R acc 16 R ST ART 0.4 Hz τ µ τ µ = 2.20 µs[3] R BG R acc 1.0 20µs ( ) (280 ± 16) R µ (4.3 ± 0.2) 3 Hz R BG R µ : R BG 5 : 2 1/2 56

16 3 veto START STOP R ST ART R ST OP R acc (Hz) R ST ART 0.41 ± 0.06 R ST OP 253.1 ± 1.6 R acc (2.0 ± 0.4) 3 Counts per channel 0 90 80 70 60 50 40 30 20 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) 47 veto 3 20 µs 1.0 20 µs τ µ = 2.04 ± 0.18 µs n BG = 5.5 ± 0.8 /µs 57

6.4 6.4.1 48 49 50 51 17 TAC START #1 #2 #3 STOP #2 #2 STOP #2 STOP TAC STOP STOP Hz TAC STOP Hz 17 48 2 B 1,B 2 (ns) #1.0 B 1.0 B 2 6.0 #2.0 #3 70.0 #1 #2 #3 14.0 58

48 #2 TAC Start #1 #2 #3 Stop #2 49 2 50 59

図 51 両側読み出し回路によるミューオン寿命測定の実験装置 6.4.2 実験結果 TAC の設定を 20µs にして約 18 時間 (65000 秒) ミューオンの寿命測定を行った結果 図 52 のような時間スペクトルが得られた フィットの範囲は 1.0 µs 20 µs である フィットにより得られたミューオンの寿命は τµ = 1.60 ± 0.15 µs 1 ビンのバックグラウ ンドは n0 = (1. ± 0.28) /(0.48µs) となった 得られたバックグラウンドを計数率 RBG に変換すると RBG = (7.0 ± 1.8) 4 Hz である この実験における START 信号と STOP 信号の計数率 RST ART, RST OP と 予想されるバックグラウンドの計数率 Racc は表 18 のようになった 表 18 両側読み出し回路によるミューオン寿命測定の START 信号と STOP 信号の 計数率 RST ART RST OP と予測されるバックグラウンドの計数率 Racc 信号 計数率 (Hz) RST ART RST OP Racc 0.98 ± 0. 32.35 ± 0.57 (6.8 ± 0.7) 4 得られたミューオンの寿命 τµ は 文献値 τµ = 2.20µs[3] よりも小さな値となってい るが 得られたバックグラウンドの計数率 RBG は 予測されるバックグラウンドの計数 60

Counts per channel 0 90 80 70 60 50 40 30 20 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) 52 20 µs 18 1.0 20 µs τ µ = 1.60 ± 0.15 µs n BG = 2.28 ± 0.58 /µs R acc 1.0 20 µs (181 ± 22) R µ (2.8 ± 0.2) 3 Hz (4.3±0.2) 3 Hz 2/3 18 84 (30 ) 53 53 1.0 µs 20 µs τ µ = 2.09 ± 0.11 µs 1 n 0 = (3.54 ± 0.49) /(0.48 µs) R BG R BG = (4.9 ± 0.7) 4 Hz START STOP R ST ART R ST OP R acc 19 τ µ τ µ = 2.20 µs[3] R BG 61

Counts per channel 300 250 200 150 0 50 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) 53 20 µs 84 1.0 20 µs τ µ = 2.09 ± 0.11 µs n BG = 7.34 ± 1.02 /µs 19 START STOP R ST ART R ST OP R acc (Hz) R ST ART 0.88 ± 0.05 R ST OP 32.27 ± 0.23 R acc (5.4 ± 0.6) 4 R acc 1.0 20µs (732 ± 19) R µ (2.44 ± 0.06) 3 Hz R BG R µ : R BG 5 : 1 62

7 7.1 ( 1) veto 3 ( 2) ( 3) 54 τ µ R BG R µ R µ R BG 20 Counts per channel 0 90 80 70 60 Counts per channel 0 90 80 70 60 Counts per channel 300 250 200 50 40 30 50 40 30 150 0 20 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) ( A ) 20 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) ( B ) 50 0 0 2 4 6 8 12 14 16 18 20 Time (µ s) ( C ) 54 (A) 1 18 (B) 2 18 (C) 3 84 20 1, 2, 3 τ µ R BG R µ R µ R BG 1.0 20µs (s) τ µ (µs) R BG ( 3 Hz) R µ ( 3 Hz) R µ : R BG 1 65000 2.13 ± 0.21 3.9 ± 0.4 4.5 ± 0.4 5 : 4 2 65000 2.04 ± 0.18 1.7 ± 0.3 4.3 ± 0.2 5 : 2 3 300000 2.09 ± 0.11 0.49 ± 0.07 2.44 ± 0.06 5 : 1 τ µ 2 1 veto 3 63

1/2 τ µ 3 1 1/8 1/2 3 τ µ 3 2 7.2 1, 2, 3 G F /( c) 3, g, Weinberg θ W 21 21 1, 2, 3 τ µ G F /( c) 3, g, Weinberg sin θ W τ µ (µs) G F /( c) 3 ( 5 /GeV 2 ) g ( 19 C) sin θ W 1 2.13 ± 0.21 1.18 ± 0. 3.48 ± 0.15 0.46 ± 0.02 2 2.04 ± 0.18 1.21 ± 0.09 3.52 ± 0.13 0.46 ± 0.02 3 2.09 ± 0.11 1.19 ± 0.05 3.49 ± 0.08 0.46 ± 0.01 τ µ 2.19703 ± 0.00004 µs[3] G F /( c) 3 = (1.16375±0.00002) 5 /GeV 2, g = (3.4505±0.0006) 19 C, sin θ W = 0.464285± 0.00009 21 64

8 8.1 1 ( 1) veto 3 ( 2) ( 3) 3 τ µ G F g Weinberg θ W 1 18 τ µ (2.13 ± 0.21)µs R BG (3.9 ± 0.4) 3 Hz 1 20µs 5 : 4 R µ (4.5±0.4) 3 Hz sin θ W (1.18 ± 0.) 5 /GeV 2, (3.48 ± 0.15) 19 C, (0.46 ± 0.02) 2 TAC START 2 2 veto 3 18 τ µ (2.04 ± 0.21)µs R BG (1.7 ± 0.3) 3 Hz 1 τ µ 1/2 1 20µs 5 : 2 R µ (4.3±0.2) 3 Hz sin θ W 65

(1.21 ± 0.09) 5 /GeV 2, (3.52 ± 0.13) 19 C, (0.46 ± 0.02) 3 TAC STOP 84 τ µ (2.09 ± 0.11)µs R BG (4.9 ± 0.7) 4 Hz 1 1/8 1 20µs 5 : 1 R µ (2.44 ± 0.06) 3 Hz 1 R µ 1/2 R µ sin θ W (1.19 ± 0.05) 5 /GeV 2, (3.49 ± 0.08) 19 C, (0.46 ± 0.01) 8.2 START veto 2 veto 2 veto START R µ 3 STOP 2 6 (R BG /R µ ) 3 66

6 Discriminator 50 mv STOP 67

Root 68

[1] 2009 [2] B. 2012 [3] J. Beringer et al. (Particle Data Group), PR D86, 0001 (2012) [4] Kanetada Nagamine, Introductory Muon Science, 2011, Cambridge University Press [5] [6] [7] I [8] 20 [9] NIST (National Institute of Standards and Technology) the ESTAR program, http://physics.nist.gov/physrefdata/star/text/estar.html 69