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Ionizing Radiation

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Title: Slide 1 Last modified by: Dr. Ahamad Created Date: 2/16/2006 7:33:57 AM Document presentation format: On-screen Show Other titles: Arial Tahoma Times New Roman ... – PowerPoint PPT presentation

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Title: Ionizing Radiation


1
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2
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3
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4
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Ionizing Radiation
Radioactive Atom
Alpha Particle Neutron Particle Beta Particle
Gamma Ray (X Ray)
????????? ??
?????? ???? ???? ?????? ? ? ???? ????
5
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6
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8
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    ?1Mev ???? ???? ?????

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?????? ? ?????? ????? ? ????? .35 volt ?????
N 1 x106/352.85x104 QN x e 1
x106/352.85x104X1.6x10-19C 4.56x10-15 C
9
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10
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11
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Ne Helium Halogen Dry air
12
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13
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14
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15
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16
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17
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???????
Is ???? ?????? ???? ?? ?? ??????? ????????
18
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0.68V
19
????? ???? ??????
RI V RC dV/dt V RI(1e-t/RC) RCt VRI(1-1/e)
0.68 RI0.68 Vo
Vo 0.68V
time
20
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?? ?????? ??? ????? ????? ?????????? ??????? ???
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?????? ?????? n 5B10 3Li7 a
21
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G t2- t1
G
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t1 t t2
22
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???? ?????? ????? RC -??????? ???
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23
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24
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25
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26
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?? ???? ????????? r ?????? ??????? ??? ????
???? ????? e
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??? ??? ????????? ??????? b
??? ??????V
????
a0.01 cm, b1 cm, V 100 volt, r0.01 cm
e 6000 volt/cm
??????? ???? ?????? ??????? ????? ?????? ?? ???
??????
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27
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28
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29
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    ?????? ???? .

30
????? ??????
Q eMnph eMCTFSE ???? ????????? e ?????
??????? ?? ??????? M ??? ???????????
??????? ?? ??????? nph ?????? ????? ??????
??????? ?? ????? ?????? C ??????? ??? ????
????? ???? ?????? ?????? ???????( ????
????????? T ??????? ???? ???? ???? ??? ?????????
???????? ) ?????? ???? ??????? ?????? F ??????
??????? ?????? (??? ????????? S ??????? ????
???? ???? ??? ????????? ???????? ) ???? ??????
?????? E.
31
????? ??????
V 100 10
Mk eI, IV
104 105 106 107 M
32
????? ??????
  • - ????? ???????? ??????? ??? ??????? ?????
  • d3 ? ????? d2 - ?????? d1
  • ????? ??????? ????? ???? M
  • n ????? M d1 d2 d3 ... dn
  • M dn d1d2d3..dn
  • ???? ??? ????????? 10 ????? ???????
    ??????? 106
  • 3. 95 ????? ???????? ???????

33
????? ??????
34
? ?????? ??????? ????????
NaI(Th) ??????? ???? ????? ????? ( ?????
?????- ??? ??? ????) ????? ??? ??? ???????
???? ???? ???? ???? ????? ?????? b ??????
????? ???? ?????? ????? ????? ???? ????? ???????
- ?? ???? NaI(Th) ???? ???? ???? ???? ??????
????? ????? ??????????? ????? ?? ????????
???????? ??????? ?? ????? ?????????? ?? ??????
???????? . Li (B) ?? ???? LiI (Th ) ?? ????
????????? ?????? ?? ???? ????????? ??????
??????? ???????? ?? ????? ????? ??? ????
????? ?? ?????????? ????? ??????? ???????? .
35
?????? ????????
????
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B Ga ?????? ???????
P As ?????? ???????
???? ?????????? ??? ?????? ????? ?????? ?????
36
?????? ????????
???? ?????? ??????? Si Ge
?????? ???????? 1.12 eV 0.72 eV
?? ???? ????? ?????? ????? ???
???????????? ????????? ??????????? 110131
10 11
????? ?????
?????? ??????? ?????? ??? ????? 3.5 ????????
???? ???? ??????? ????? ??? ?? ????? ????
?????? ????? ?? ??????? ?????? ???? ???????
????? ??? ??? ?????? ??? ??? ???????
-??????? 1- 6 10
37
?????? ????????
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38
????? ?????????
d dn dp
vme 107 cm/s, d o.1 cm Time d/v 3x10-9 10-7s
?????? ????? ?? ???????? ???????? ??????? ???
????- ??????????
39
????? ???????????-??????
??? ????? ??????? 1-3 ?? ????? ??? ????? ???????
???? ???? ?????? ??? ???? ??? ????? ??????? ?????
?? ???? ????
????? ????? ????? ????? 10 ???? ?????? 2 ?? ??
?????????? ???????
????? ?????? ??????- ?? ???? ???????
???? ????? ?????
40
????? ????? ??????
41
????? ????? ????? ??????
  • ?????? Z ???? ?????? (eV)
    ??????/??? ????? /(eV)
  • Si 14 1.12
    3.61
  • Ge 32 0.74
    2.98

1- ???? ??????? ????? 2- ????? ???? ??? ????
????? ??????? ???????? 3- ??? ??? ??????
???????? 4- ??????? ????? ??? ????? ???????
?????? ??? ??????? ?????? 5- ??????? ??? ???????
???????? ?? ???????? ???????? ??????? ?? ?????
??????? ?? ??? ????? ??????? 6- ??? ????? ??????
??????? 7- ??? ????????
?????? ?????????? 8 - ??????
?????? ?????? ??????
42
???? ???? ???????? ????????
  • ?????? Z ???? ?????? (eV)
    ??????/??? ????? /(eV)
  • Si 14 1.12
    3.61
  • Ge 32 0.74
    2.98
  • CdTe 48 -52 1.47
    4.43
  • Hgl 280 -53 2.13
    6.5
  • GaAs 31-33 1.43 5.2

43
???? ??????? ?????? ??????? ??????
  • (keV FWHM) vs. ??? ??????/ ??????? ??????
  • ?????? (keV) 5.9 1.22
    1.332
  • Proportional Counter 1.2 ----
    ----
  • X-ray NaI(Tl) 3.0 12.0
    ----
  • 3 x 3 NaI(Tl) ---- 12.0
    60
  • Si(Li) 0.16
    ---- ----
  • Planar Ge 0.18 0.5
    ----
  • Coaxial Ge ---- 0.8
    1.8

44
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????? ???????
45
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46
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48
Fundamental law of radioactive decay
AActivity?N
A (t) ½ Ao, at tT1/2
Here T1/2 is the half-life, the time it takes for
half the nuclei to decay - i.e. for A to decrease
to A/2.
? - Units time-1 (s-1, d-1, m-1, y-1)
Here ? is called the average lifetime.
49
Half-Life
50
Radioactive Decay
14C 14N
51
Carbon and Uranium dating
52
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