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1 2 1.1............................ 2 2 3 3 8 3.1............................ 8 3.2............................ 8 3.3.............................. 11 3.4........................ 12 3.5......................... 13 3.5.1 delay,gain................... 13 3.5.2 HV gain........................ 13 3.5.3 ADC calibration................... 14 3.5.4 TDC calibration................... 16 4 18 4.1........................ 18 4.2 TQ............................ 22 4.2.1 TQ.................... 22 4.2.2 TQ.................... 25 4.2.3 TQ fitting................... 26 4.3 NaI2..................... 29 4.4 pick-off.......................... 29 4.4.1 pick-off.............. 30 4.4.2 pick-off fitting................. 35 4.5 pick-off....... 38 4.5.1 B pick-off................. 39 4.5.2 C................... 39 1

4.5.3 D β +................. 42 5 44 5.1.............................. 44 5.1.1.............. 44 5.2 TDCcalibration TQ......... 44 5.3 pick-off................ 44 6 48 6.1................ 48 6.2....................... 50 6.2.1 Threshold... 50 6.2.2........................ 51 6.2.3 BG....................... 51 6.2.4 pick-off............. 52 2

1 1.1 QED 3

2 (Ps) Ps QED L = 1 4 F µνf µν ψ(γ µ [ µ + iea µ ] + m)ψ (2.1) Ps ( ) QED Ps l=0,s=0 l=0,s=1 1 S 0 3 S 1 l s (p-ps) (o-ps) Ps QED fermionn n c Ψ = d 3 p 1 d 3 p 2 χ(p 1, σ 1 ; p 2, σ 2 )a (p 1, σ 1 )a c (p 2, σ 2 )Ψ vacuum (2.2) σ 1 σ 2 χ(p 1, σ 1 ; p 2, σ 2 ) = ±χ(p 2, σ 2 ; p 1, σ 1 ) CΨ = Ψ Ca (p, σ)c 1 = ξa c (p, σ),ca c (p, σ)c 1 = 4

ξ c a (p, σ), ξξ c = 1 C ξ charge conjugation parity p-ps χ o- Ps p-ps o-ps C / charge conjugation parity -1 Ca (k 1, σ 1, photon)a (k 2, σ 2, photon)...a (k n, σ n, photon)ψ vacuum = ( 1) n a (k 1, σ 1, photon)a (k 2, σ 2, photon)...a (k n, σ n, photon)ψ vacuum (2.3) Ca (k, σ, photon)c 1 = a (k, σ, photon) n C ( 1) n QED C p-ps o-ps o-ps p-ps 2,4,6,... o-ps 3,5,7,... differential transition rate dγ(α β) α β β + dβ initial particles 2 differential transition rate dγ(α β) = (2π) 4 V 1 M βα 2 δ 4 (p β p α )dβ (2.4) M βα α β S S βα = 2πiM βα δ 4 (p α p β )dβ (2.5) V transition rate differential transition rate 5

α n dσ(α β) dσ(α β) = V u α dγ(α β) (2.6) (2π) 4 u α M βα 2 δ 4 (p β p α )dβ (2.7) (p1 p 2 ) u α 2 m 2 1 m2 2 E 1 E 2 dσ(α β) flux transition rate flux H H 0 V S 1 S = dt 1 dt 2 dt N T (V (t 1 )V (t 2 ) V (t N )) (2.8) N! N=0 S p-ps o-ps transition rate Feynmen diagram Feynmen o-ps one-loop Feynmen diagrams S transition rate Feynmen 6

2.1: feynmen diagram p-ps decay rate transition rate Γ(p P s 2γ) = mα5 2 = 8.0325 10 9 sec 1 (2.9) [5] α m o P s 3γ z -1,0,1 1 3 τ 1 τ 2 τ 3 σ = 1 3 dσ(pσe, p σe + k 1 τ 1, k 2 τ 2, k 3 τ 3 ) τ 1 τ 2 τ 3 σ (2π) 4 [ (p 1 p 2 ) 2 m 4 E 1 E 2 ] 1 1 3! M pσe,p σe + k 1 τ 1,k 2 τ 2 k 3 τ 3 2 k 1 k 2 k 3 d k 2 d k 3 dω 3 dψ 23 (2.10) p 1, E 1 p 2, E 2 dω 3 k 3 ψ 23 k 2 7

(p k 3 azimuthal angle 1 p 2 ) 2 m 4 E 1 E 2 M βα S βα = δ(β α) 2πiM βα δ 4 (p α p β ) scattering amplitude o-ps Feynmen diagram decay rate k 1, k 2, k 3 σ(o P s 3γ) σ(o P s 3γ) = 1 (p 3 27 π 6 1 p 2 ) 2 m 4 [ E 1 E 2 τ 1 τ 2 τ 3 σ ] 1 E1 +E 2 E1 +E 2 d k 2 d k 3 0 E 1 +E 2 k 2 1 3! M pσe,p σe + k 1 τ 1,k 2 τ 2 k 3 τ 3 2 k 1 k 2 k 3 (2.11) decay rate Γ(o P s 3γ) = 2 1 1 9π mα6 dx 1 dx 2 [( 1 x 1 ) 2 + ( 1 x 2 ) 2 + ( 1 x 3 ) 2 ] x3 =2 x 0 1 x 1 x 2 x 3 x 3 x 1 x 1 x 1 x 2 2 = 2 9π (π2 9)mα 6 = 7.2112 10 6 sec 1 (2.12) [5] o-ps one-loop diagram transition rate 7.03893(7) 10 6 sec 1 [5] transition rate Γ transition rate Ps lifetime = transitionrate 1 p-ps o-ps p-ps 124.5 10 12 sec o-ps 138.7 10 9 sec one-loop 142.1 10 9 sec 8

3 3.1 22 Na β + e + e Ps β + γ NaI Ps o-ps 3.2 22 Na β + ADC 60 Co ADC 137 Cs ADC NaI NaI1,2,3 HV1,2,3 ADC1,2,4 TDC1,2,4 HV4 ADC5 TDC5 NaI SiO 2 β + 9

3.1 3.2 3.3 3.1 3.1: 10

図 3.2: 配置図図 3.3: 配置図 11

3.3 3.4 HV1 NaI1 div1 diccri1 FAN Coin TDC HV2 NaI2 div2 discri2 delay1 1 2 4 5 HV3 NaI3 div3 discri3 HV4 P.S. div4 discri4 Gate1 Gate2 ADC delay2 1 2 4 5 3.4: HV Negative High Voltage Div divider P.S. Plastic Scintillator Discri discriminator Gate Gate Generator FAN Coin Coincidence Delay Delay1 Fixed Delay Delay2 ADC 12

Time P.S. threshold delay gate NaI threshold delay Coin. TDC1,2,4 decay time TDC5 3.5: TDC start stop TDC start NaI,P.S. coincidence TDC5 TDC1,2,4 TDC5 TDC1,2,4 delay 390-400 ns 3.4 13

100 hp a A B C D NaI 22 Na γ NaI P.S. 3.5 3.5.1 delay,gain gate1 FAN coincidence gate gate1 824 ns delay1 TDCstart stop NaI 105 ns P.S. 840 ns fixed delay gate2 ADC 1600 ns dalay2 ADCgate delay out 3.5.2 HV gain HV NaI1-3 HV1-3 22 Na β + ADC NaI 511 kev ADC HV 1300V 1200 V 1200 V ADC NaI3 3.1 14

3.1: HV gain HV V pedestal 511 kev NaI1 1080 298.1 1041 743.9 NaI2 1025 175.6 629 451.0 NaI3 1200 250.3 1026 775.7 HV NaI2 4 3.5.3 ADC calibration ADC NaI Co,Cs fitting 3.1 Energy[ kev ] = a ADC + b (3.1) 3.2: A ADC calibration pedestal 511 kev ADC1 300.064 1047.3 ADC2 169.203 616.44 ADC4 246.218 999.45 3.3: A a,b a ADC1 1.46230 300.064 ADC2 0.87521 169.203 ADC4 1.47403 246.218 b 15

3.4: B calibration pedestal 511 kev ADC1 305.985 1040.2 ADC2 167.818 1092.0 ADC4 246.481 977.43 3.5: B a,b a ADC1 1.436879 305.985 ADC2 1.808517 167.818 ADC4 1.430434 246.481 b 3.6: C calibration pedestal 5112 kev ADC1 305.852 1043.1 ADC2 169.437 601.64 ADC4 247.033 984.00 3.7: C a,b a ADC1 1.44274 305.852 ADC2 0.845793 169.437 ADC4 1.44221 247.033 b 16

3.8: D calibration pedestal 511 kev ADC1 299.561 1035.44 ADC2 166.653 1086.24 ADC4 245.264 977.208 3.9: D a,b a ADC1 1.440076 299.561 ADC2 1.799583 166.653 ADC4 1.432375 245.264 b 3.5.4 TDC calibration TDC fixed delay TDC 3.2 fitting T ime[ ns] = c T DC + d (3.2) 17

3.10: TDC cariblation ns 51.9 114.3 167.8 231.0 284.8 348.5 400.0 TDC1 257.7 515.8 730.3 980.0 1194 1447 1661 TDC2 261.0 516.8 729.6 977.2 1190 1440 1652 TDC4 262.9 520.4 734.4 983.4 1197 1449 1663 TDC5 259.7 518.0 732.5 982.3 1197 1449 1663 ns 465.0 517.0 580.8 633.3 700.3 753.0 819.5 TDC1 1907 2122 2372 2587 2846 3061 3317 TDC2 1897 2110 2358 2571 2827 3040 3295 TDC4 1909 2123 2373 2587 2845 3059 3315 TDC5 1910 2125 2375 2590 2849 3064 3320 3.11: TDC fitting c d TDC1 3.984 ± 0.0005067 58.86 ± 0.2459 TDC2 3.948 ± 0.0005188 65.76 ± 0.2575 TDC4 3.972 ± 0.0004954 65.97 ± 0.2408 TDC5 3.984 ± 0.0004679 62.88 ± 0.2209 18

4 4.1 4.1 NaI1 200 kev 511 kev 1274 kev 200 kev 511 kev 100 kev threshold 4.2 4.3 NaI2,NaI3 4.1: Energy vs ADCcount(NaI1) 19

4.2: Energy vs ADCcount(NaI2) 4.3: Energy vs ADCcount(NaI3) 20

4.4 NaI1 TDC T 1 T = const T 1 (4.1) const 0[ ns] 4.5 4.6 NaI2,NaI3 4.4: Time vs TDCcount(NaI1) fitting τ f(t) = p exp( t τ ) + r (4.2) 4.1 4.7 NaI1 21

4.5: Time vs TDCcount(NaI2) 4.6: Time vs TDCcount(NaI3) 22

4.1: [ ns] NaI1 82.0675 ± 2.66602 NaI2 132.530 ± 6.45133 NaI3 133.743 ± 5.32666 const (511 kev,20 ns) p-ps (1274 kev,20 ns) β + 511 kev p-ps pick-off p-ps (511 kev,70 ns ) pick-off (511 kev,40 ns) p-ps (511 kev 100 ns ) p-ps pick-off o-ps 4.10 threshold 4.8 4.9 NaI2,NaI3 4.2 TQ threshold threshold TDC TQ 4.2.1 TQ T 23

4.7: Time vs Energy(NaI1) 4.8: Time vs Energy(NaI2) 24

図 4.9: Time vs Energy(NaI3) 図 4.10: Time vs Energy(NaI1) の分布 25

V V=0 w1 w2 Time T h Threshold 4.11: ADC = 1 2 h(w 1 + w 2 ) (4.3) T : w 1 = δ : h (4.4) T = (w 1 + w 2 )w 1 δ 2ADC (4.5) T E ADC T = const (T 1 a E + b ) (4.6) a = (const T 1 ) + ( + c) (4.7) E + b T 1 TDC 4.2.2 TQ (1) 4.7 1274 kev 511 kev 1 0[ ns] 26

1274 kev 511 kev 0 ns (2) fitting a,b,c const T 1 = 0 T = a E + b + c (4.8) (1) ( 0[ ns]) 4.2.3 TQ fitting 1274 kev p-ps 511 kev NaI1 150[ kev ] 1200[ kev ] NaI2 275[ kev ] 1200[ kev ] NaI3 150[ kev ] 1200[ kev ] fitting fitting 4.15 fitting (a,b,c) 4.2 4.2: a b c NaI1 5172.32 ± 15.9457-69.1897 ± 3.61979 15.4189 ± 0.0275984 114.670 ± 6.08470 NaI2 7152.35 ± 29.5262-164.453 ± 0.532816 16.4340 ± 0.0533343 92.9171 ± 10.7862 NaI3 5630.24 ± 14.5309-51.4607 ± 0.391571 14.3964 ± 0.0203178 132.000 ± 6.81112 27

4.12: TQ (NaI1) 4.13: TQ (NaI2) 28

4.14: TQ (Na13) 4.15: TQ fitting fitting (NaI1) 29

4.3 NaI2 NaI2 NaI2 511 kev 4.13 300 kev ADC NaI2 NaI2 4.3: ADC2 calibration-1 energy kev ADC 22 Na 511 1053 1274 2075 137 Cs 662 1272 60 Co 1173 1953 1333 2166 4.4: ADC2 calibration-2 energy kev ADC 22 Na 511 1038 1274 2209 137 Cs 662 1264 60 Co 1173 1931 1333 2157 NaI3 4.2 NaI1 γ background NaI3 NaI1 4.4 pick-off o-ps p-ps p-ps o-ps o-ps p-ps o-ps,p-ps 30

4.5: ADC2 calibration-3 energy kev ADC 22 Na 511 1004 1274 2123 137 Cs 662 1252 60 Co 1173 2018 1333 2251 p-ps p-ps o-ps p-ps pick-off pick-off 4.4.1 pick-off 100 E 400 400 E 520 fitting n(t) = exp( t τ ) + c (4.9) τ 100 E 440 440 E 600 τ all τ pick 4.11 4.6: TQ τ all τ pick NaI1 n all (t)dt : 0 E 440[ kev ] t t + dt event n pick (t)dt : 440 E 600[ kev ] t t + dt event 31

n all,n pick n all = exp( t τ all ) + c (4.10) n pick = exp( t τ pick ) + c (4.11) N total (t) : t P s N pick (t) : t pick off P s N 3γ (t) : t o Ps 3γ P s N 0 : 0 P s Γ total (t)dt : t t + dt P s Γ pick (t)dt : t t + dt P s pick off Γ 3γ (t)dt : t t + dt P s o P s 3γ pick-off Γ 3γ (t) Γ 3γ (t) Γ total (t) = Γ pick (t) + Γ 3γ (4.12) pick-off Γ pick (t) Γ 3γ Γ total τ all Γ pick(t) Γ 3γ N 3γ = N pick = N total = t 0 t 0 t 0 (N 0 N total (t))γ 3γ (t)dt (4.13) (N 0 N total (t))γ pick (t)dt (4.14) (N 0 N total (t))γ total (t)dt (4.15) P compton : NaI compton P kouden : NaI 32

pick-off 2γ n all (t)dt = N 3γ t 3P compton + N pick 2P compton (4.16) t n pick (t)dt = N pick 2P kouden (4.17) t n all (t)dt = 3P compton (N 0 N total (t))γ 3γ (t) + 2P compton (N 0 N total (t))γ pick (t) n pick (t)dt = 2P kouden (N 0 N total (t))γ pick (t) 100 E 400 n all (t)dt 3P compton (N 0 N total (t))γ 3γ (t) (4.18) n all n pick N total Γ pick P compton P kouden Γ pick n pick (t) n all (t) = 2P kouden Γ pick (t) 2P compton Γ pick + 3P compton Γ 3γ (4.19) 2Γ pick(t) 3Γ 3γ (4.20) = p exp( t q ) + r (4.21) P kouden P compton Γ pick n all (t) = n 0 exp[ 1 t (1 + Γ pick )] + B (4.22) τ 3γ 0 Γ 3γ 100 kev threshold 33

count Enegy[keV] 4.16: threshold threshold 4.16 threshold count Γ pick(t) Γ 3γ threshold n all n pick background threshold background n T HR dt : threshold (4.23) n all (t)dt (n all (t) + n T HR )dt (4.24) n pick (t)dt (n pick (t) + n T HR )dt (4.25) ε = n T HR /(n T HR + n 3γ ) (4.26) 34

50[ ns] 4.7 background p-ps, o-ps BG background 4.18 background A H 4.17 4.7 base Γ pick (t) pick-off o-ps 4.19 511KeV base o-ps scale o-ps pick-off ( pick off ) = ( ) ( scale ) (base ) N 3γ : 3γ (4.27) N pick : pick off (4.28) N T HR : T HR (4.29) ɛ : N T HR /(N T HR + N 3γ ) (4.30) background pick-off 4.21 4.21 N pick (t) N 3γ (t) + N T HR 2Γ pick(t) 3Γ 3γ (4.31) = p exp( t q ) + r (4.32) 35

Γ pick (t)/γ 3γ pick-off 4.22 4.7: [ ns] A 100 150 B 150 200 C 200 250 D 250 300 E 300 350 F 350 400 G 400 450 H 450 500 base 500 750 BG 700 750 4.4.2 pick-off fitting pick-off 4.8 sebsection 4.8 Γ pick /Γ 3γ C D 6 D 5.1 fitting p = 3.56073 10 2 ± 1.00005 q = 1.39779 10 2 ± 1.41421 r = 3.55832 10 2 ± 1.00002 36

4.17: number of events 700<t<750 140 h_bg_nai1 Entries 3528 Mean 418.1 RMS 266.2 120 100 80 60 40 20 0 0 200 400 600 800 1000 1200 1400 4.18: BG 37

number of events 500<t<750 80 h_i_nai1 Entries 877 Mean 539.2 RMS 375.2 60 40 20 0-20 -40 0 200 400 600 800 1000 1200 1400 4.19: base 4.8: pick-off N T HR N pick N 3γ ɛ Γ pick /Γ 3γ A 3892 994.146 5015.85 0.436918 0.167405 B 2674 644.89 2930.11 0.477150 0.172612 C 2156 442.69 2155.31 0.500116 0.154022 D 1260 392.86 1300.14 0.492188 0.230179 E 854 259.202 792.798 0.518834 0.236096 F 826 228.332 653.668 0.558233 0.231469 G 420 128.195 383.805 0.522515 0.239228 H 294 84.396 286.654 0.506326 0.218020 38

gamma_pick/gamma_3gamma vs time 0.28 χ 2 / ndf 0.09467 / 2 p0 356.1 ± 1 p1 1.398e+07 ± 1.414 p2-355.8 ± 1 0.26 0.24 0.22 0.2 0.18 0.16 250 300 350 400 450 500 4.20: pick-off τ 3γ = 114.670 ± 6.00 4.5 pick-off pick-off o-ps 4.9 2 A,B,C,D 4.10 τ 3γ A section pick-off 39

4.9: A B pick-off A C β + A D A B C D 4.10: 4.5.1 B pick-off pick-off Ps pick-off 4.21 TQ time vs energy 4.22 fitting τ normal = 100.652 ± 6.30 4.5.2 C τ not heated = 119.609±7.87 40

Time vs. Energy in NaI1 500 400 h0_te Entries 541586 Mean x 384.4 Mean y 19.76 RMS x 195 RMS y 71.33 3 10 300 200 2 10 100 0 10-100 0 200 400 600 800 1000 1200 1400 1 4.21: B-Time vs Energy Decay Time of ortho positrons 300 h0_t_ortho Entries 295318 Mean 317.1 RMS 211.4 250 200 150 100 50 100 200 300 400 500 600 700 4.22: B lifetime-fitting 41

Time vs. Energy in NaI1 500 400 h0_te Entries 445562 Mean x 386.7 Mean y 20.44 RMS x 193.1 RMS y 72.63 3 10 300 200 2 10 100 10 0-100 0 200 400 600 800 1000 1200 1400 1 4.23: C-Time vs Energy Decay Time of ortho positrons 100 90 h0_t_ortho Entries 239010 Mean 369.1 RMS 197.8 80 70 60 50 40 30 20 10 100 200 300 400 500 600 700 4.24: C lifetime-fitting 42

4.5.3 D β + β + Ps τ no taget = 121.323 ± 13.764 Time vs. Energy in NaI1 500 400 300 h0_te Entries 254730 Mean x 380.9 Mean y 20.06 RMS x 196.8 RMS y 72.53 2 10 200 10 100 0-100 0 200 400 600 800 1000 1200 1400 1 4.25: D-Time vs Energy 4.11: TQ A 114.67 ± 6.08 B 119.60 ± 7.87 C 100.65 ± 6.30 D 121.32 ± 13.76 43

Decay Time of ortho positrons h2_t_ortho Entries 133923 Mean 379.5 RMS 196.6 50 40 30 20 10 100 200 300 400 500 600 700 4.26: D lifetime-fitting 44

5 5.1 TD- Ccalibration TQ pick-off pick-off pick-off NaI2 NaI3 NaI1 5.1.1 q = (x 1, x 2,..., x n ) x 1, x 2,..., x n σ x1, σ x2,..., σ xn q σ q σ q = ( q x 1 σ x1 ) 2 + ( q x 2 σ x2 ) 2 + + ( q x n σ xn ) 2 (5.1) 5.2 TDCcalibration TQ (3.5.4),(4.12) ROOT fitting 5.3 pick-off 4.4.2 Γ pick / Γ 3γ 45

N : 0 E 600 N 1 : 0 E 440 N b : base N b1 : N b 0 E 440 N 3γ : 3γ N pick : pick-off N pick : pick-off N 3γ : 3γ N T HR : THR ɛ 3γ : N T HR /(N T HR + N 3γ ) w,x,y u = Γ pick = 3N pick = 3 Γ 3γ 2N3γ 2 (1 ɛ 3γ) N pick = 3wx N 3γ 2y (5.2) w = 1 ɛ 3γ (5.3) x = N pick (5.4) y = N 3γ (5.5) N, N 1, N b, N b1 x = N N 1 N b1 N b (5.6) y = N 1N b N b1 (5.7) ɛ 3γ = N T HR N T HR + y (5.8) Q σ Q 5.1 σ x = ± N 1N ( b N ) b1 2 σ ( σ ) Nb1 2 ( σ ) Nb 2 ( σ ) N1 2 N + + + (5.9) N b1 N 1 N b N b1 N b N 1 σ y = ± N 1N ( b σ ) N1 2 ( σ ) Nb 2 ( σ ) Nb1 2 + + (5.10) N b1 N 1 N b N b1 ( σ ) x 2 σ u = ± ( σ ) y 2 + (5.11) x y A A N, N 1, N b, N b1 46

5.1: N N 1 N T HR 100 T 150 6010 4182 3892 150 T 200 3575 2443 2674 200 T 250 2598 1797 2156 250 T 300 1693 1084 1260 300 T 350 1052 661 854 350 T 400 882 545 826 400 T 450 512 320 420 450 T 500 371 239 294 5.2: σn σ N1 σ Γpick /Γ 3γ 100 T 150 75.5241 64.6683 3.278 10 2 150 T 200 59.7913 49.4267 3.211 10 2 200 T 250 50.9706 42.3910 3.180 10 2 250 T 300 41.1461 32.9242 3.610 10 2 300 T 350 32.4345 25.7099 3.862 10 2 350 T 400 29.6985 23.3452 3.763 10 2 400 T 450 22.6274 17.8885 4.787 10 2 450 T 500 19.261 15.4596 5.429 10 2 5.3: base N b σn b N b1 σ Nb1 788 28.071 657 25.6320 47

gamma_pick/gamma_3gamma vs time 0.28 χ 2 / ndf 0.09467 / 2 p0 356.1 ± 1 p1 1.398e+07 ± 1.414 p2-355.8 ± 1 0.26 0.24 0.22 0.2 0.18 0.16 250 300 350 400 450 500 5.1: pick-off (5.11) (5.1) (5.12) fitting p q Γ pick /Γ 3γ = p exp( t q ) + r (5.12) p = 3.56073 10 2 ± 1.00005 (5.13) q = 1.39797 10 2 ± 1.41421 (5.14) r = 3.55832 10 2 ± 1.00002 (5.15) Γ pick / Γ 3γ N(t) = N 0 exp( 1 τ 3γ (t pq exp( t/q))) + B (5.16) τ 3γ = 114.67 ± 6.00[ ns] (5.17) 48

6 6.1 TQ pick-off 10 (1) (2) (3) 6.1 NaI 49

6.1: ( min 1 ) error (1) 194.9 14.0 (2) 198.3 14.1 (3) 213.1 14.6 TQ pick-off spin TQ 3.1 7 cm pick-off pick-off 4.8 Γ pick /Γ 3γ NaI 50

pick-off 6.2 6.2.1 Threshold pick-off Threshold Thr. 4.8 50 pick-off Thr. discri Thr. Thr. Hi-Vol gain photomul 1300V divider amp photomul divider Thr. amp Thr. BG BG Thr. Thr. Na Thr. Thr. 51

6.2.2 NaI3 4.9 NaI BG NaI 6.2.3 BG NaI BG fitting pick-off BG BG BG 3 γ NaI coinsidence BG BG BG NaI 52

BG 6.2.4 pick-off pick-off A 53

[1],,, [2],.F., [3] Michael A. Stroscio Positronium: A review of the theory o-ps p- Ps decay rate Feynmen diagrams [4] S.Weinberg Quantun theory of fields 1 [5] Gregory S.Adkins Radiative Corrections to Positronium Decay 55