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The Debugging of Coincidence Measurement Device in the Nuclear Electronic Laboratory



08021235










60

Co -

60Co ^ - ; ;

ABSTRACT
Coincidence Counting Method is used to research the events relating to time or direction in the process of nuclear decay and nuclear reactions, and it has been widely applied in various fields of nuclear technology. Coincidence Counting Method of absolute measurement of radioactivity is one of measuring technology of the application. It is the main method which is used for the absolute measurement of radioactivity of cascade decay radionuclide and is considered accurate measurement of radioactive one way. This paper is to 60Co source activity measurement for example, expounds the basic principle of - coincidence method for the measurement of radioactivity. The experimental device and measurement results are given in this paper. And the activity of 60Co source with conversion as a reference for the results. The experiments results show the method in the paper is really practical. This study is of great significance to the future research on digital coincidence technology. Key Words: - coincidence method; Radioactivity; Coincidence measurement device









................................................................ 1 ............................................ 2
2.1 ............................................... 2 2.1.1 ................................................. 2 2.1.2 ......................................... 3 2.1.3 ............................................... 3 2.1.4 ................................................. 3 2.1.5 ................................................. 4 2.1.6 ..................................... 4 2.2 ....................................... 5 2.3 ......................................... 7

........................................... 10
3.1 .................................................... 10 3.1.1 .............................................. 10 3.1.2 .................................................. 10 3.1.3 .......................................... 10 3.1.4 .................................. 11 3.1.5 ........................................ 11 3.1.6 .................................................. 12 3.1.7 .............................................. 13 3.1.8 ................................................. 13 3.1.9 - ....................................... 13 3.2 .............................................. 14 3.2.1 - ....................... 14 3.2.2 .................... 15

- 60Co ............................ 17
- 60Co ................................. 17 4.1.1 60Co ............................................... 17 4.1.2 60Co ........................................ 17 4.1.3 ........................................ 17 4.2 ...................................................... 17 4.3 ................................................ 18 4.1

................................ 21
5.1 5.2 ...................................................... 21 ........................................ 21





5.3 5.4

........................................ 22 ........................................ 22

.................................................................. 24 ............................................................... 25 ............................................................. 26






ޡ G[1] ৵ 1930 [2]60Co

1






G

2.1
2.1.1 ʦǡ 1 ɦš

1

2





2.1.2 [3] 2.1.3 ᳦ ֧ 2.1.4 [4] § 2

3





2

n||>tw FWHM 2tw 2.1.5 t=0 1 2š 2.1.6 FWHM 100%
4





1%

2.2
4 ި¨ n 0 60Co n n n c p1 p2
[5] 60

Co

n = n 0 p1

(2.1) (2.2) (2.3)

n = n 0 p2
n c = n 0 p1 p2
1.2.1 1.2.2 1.2.3

n0 ?

n n nc

(2.4)

2.4 ۧ ֧ - ݝ ĝp 1 n
b

ncb

n 0 = n C n
? C ncb nc 0 = n c

b

2.5 2.6

5





? n c ? n b ncb n nc
2 n n b
60

Co n 60Co 60Co

n b 60Co n n b + n

n 0 ? n ? (n b ? n ) ? n ? n
(3) [6]

2.7



??

n c 2n1n2

2.8

ӧ nb

n? c ? n c ? nb ? 2?n1n2 ? nb

2.9

nb n? c

n1 ? n2

60

Co 137Cs

n2 n? c 137Cs n1 n? c n1 ? n2
[7] 2 nb n n n c
6





- 2.9

nc0 ? nc ? (2?n n ? ncb ? n )
-

2.10

ncb0 ? n ? ncb ? 2? (n b ? n )n
2.7 2.10 2.11

2.11

ncb 0 n ncb

nc0 ? nc ? 2? (n ? n )n ? ncb0


2.12

A0 ?

(n ? n n ? n b nc ? 2? (n ? n n ? ncb0

2.13

2.3
n x j , y j y=mx+b 311 x j , y j j jth

7





3

y=mx+b4

4 y=mx+b

y m
2 b ?m, b) ? m xj ? b ? y j ) ?m, b) j ?1

?

n

8





?? ? 2? (mx j ? b ? y j ) x j ? 0 ?m

2.14

?? ? 2? (mx j ? b ? y j ) ? 0 ?b
2.14 2.15 mb

2.15

[ b?

1 n 1 n 2 1 n 1 n y ][ x ] ? [ x ][ xj yj ] ? j n? ? j n? j n j ?1 n j ?1 j ?1 j ?1 1 n 1 n [ ? x2 ] ? [ x j ]2 ? j n j ?1 n j ?1
2.16

1 n 1 n 1 n [ ? x j y j ] ? [ ? x j ][ ? y j ] n j ?1 n n j ?1 m? 1 n 2 1 n [ ? x j ] ? [ ? x j ]2 n j ?1 n j ?1
x ?

2.17

1 n 1 n 1 n 1 n 2 2 x y ? y x y ? x y ? x ?? ? j ? j ? j j ? x j n j ?1 n j ?1 n j ?1 n j ?1



y? ? x 2 ? ? x ? x y b? ? x 2 ? ?[ x ]2

2.18

m?

xy ? x ? y ? x 2 ? ?[ x ]2

2.19

9






3.1
3.1.1 ~ ûpp ɼ 30K 50K 12V Q9J4 3.1.2

։^ É^ 3.1.3 C É^ 5 E K1 K2
10





C K1 K2 C R æ E CR R 100 E C ^ K1K2

5

3.1.4 E1 E2 E2-E1= E RS 3 2 a RS Ħ ʉ^ a RS 8 3.1.5 ša 1
11





1 + + + ++ + +

3.1.6 BH1218 NIM FH-1001AFH-1002A K 00.51 23456us RV KB A1 A1 KB A1 A2 K3 A4 ˦ K4 A5 T2T3T4 50 A6 A5 ߧ ݌ k

12





3.1.7 FH1093B ˡ 3.1.8 BH1283N 1.5V 0.3kV~1.5kV p RW 150V3% R13 R14 +- 20 ˦˨ 3.1.9 - - 60Co a

13





FJ-367 BH1218 FH1007A

FH-374 BH1218

BH1221

FH1093B

FH1007A

6 -

FJ-367 FJ-374 NaITl

3.2
3.2.1 - - 6 [8] FJ-374 FJ367 BH1218 BH1239A BH1283N 1.5kV BH1211 () FH1013B FH1093B DS5102CA 60Co 137Cs

14





7

NaI(T1) 60Co 3.2.2 td td [9] 8 2

8
15





9





֡















š

9

16



- Co

60

- 60Co
4.1 - 60Co
4.1.1
60

Co

60Co 60Ni 60Ni 10-20s 710 s
-13

4.1.2 60Co 60Co
[10]

60

Co



A0 ?

(n ? n n ? n b nc ? 2? (n ? n n ? ncb0

n n n c

n ncb 0 n b
? 4.1.3 137Cs 137Cs 137Ba 2.6min s [11]

4.2
1 6 [12] 1 60Co
17



- Co

60

0.5V 20 MAX - 4V 3 0.20.5us(4) 0.20.5V 5V 1 2.
137

Cs [13] n

3. 60Co 1 n n 2 60Co n ncb 0 nc 4. 60Co n b 5.f 2.13 60Co

4.3
60Co 2002 12 11 8.84104Bq60Co 5.27 A ? A0 e
[14]

??t

? A0 e

?0.693

t T



25919Bq 1 2
2
137

Cs



s 30 30 30

1cps 2954 17239 31

2cps 3068 16893 32

3cps 3035 17111 31



? nb n c

? 2?n1n2 ? nb n? c n1 n2
=0.6364 us
60

2.19 2[15] Co
60

Co

60Co 3

18


60

- Co Co

60

3

N N Nc N Ncb0

s 10 10 200 10 20

1 4623 9435 3092 1060 93

2 4357 9459 3107 1010 83

3 4556 9322 3179 1036 90

4 4480 9441 3136 1013 87

5 4576 9432 3094 1001 91

3
n ? N 4518 .4 ? ? 451.84 t 10 N 9417 .2 ? ? 941.72 t 10
N c 3121 .6 ? ? 15.608 t 200



n ?
nc ?





n ?
ncb0 ?

N 1024 ? ? 1 0 .2 4 t 10



N cb0 88.8 ? ? 4.44 t 20

3 60Co 4
4

N b N b Ncb

s 100 10 1000

1 262 1171 70

2 238 1228

3 259 1112

4 242 1211

5 232 1175

4
n b ? N b 1179 .4 ? ? 117.94 t 10

1.2.13 60Co

19



- Co

60

A0 ?

(n ? n n ? n b ? 26785 ( Bq) nc ? 2? (n ? n n ? ncb0



26785 ? 25919 ?100 % ? 3.3% 25919

20






5.1
1 7 1V 45V 2šަ td [16]

5.2
500Hz 10s 1V 4.66V š 1.970 us =1.970 us ަ td 8
600 500



400 300 200 100 0 -3 -2 -1 0 td 1 2 3 1

8

8 3.94 us 2 8

21





5.3
2000Hz 10s 1V 4.80Vš 1.980 us =1.980 us ަ td 9
n 2500 2000 1500 1000 500 0 -3 -2 -1 0 td 1 2 3 1

9

9 3.96 us 2 9

5.4
15000Hz 10s 1V 4.96Vš 2.12 us ަ td 10

22





16000 14000 12000 10000 8000 6000 4000 2000 0 -3 -2 -1 0 td 1 2 3 1

n

10

10 4.24 us 2 10 3 2 š ɧ [17]

23






-
60

Co - 60Co

- 60Co 1. - 2. - 3. 4. -
60 60

Co

Co 3.3%

24









fk ݦ˧ݧ

25






[1]kĥ1964 [2].[J].2010.305 694-697 [3] . . 2001. [4].Matlab [M].2008.2 [5].[D].2008 [6] . ().2006 [7] . . 1989. [8].[J].2004.383 200-203 [9] P.J. Csmpion. lnt. J. Appl. Radiat. Isot. 4 (1959) 232. [10]ĥ1986 [11] ֧EJ]200225()139 145 [12]ĥ1997 [13] D. Smith. Metrologia 11 ( 1975) 73 [14] k[M]1ɭ19792128 [15][M]3ɭ1997190-195 [16]. [M].1988.12 [17]. [M].1984.11

26





A

-
27


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