Types of radioactive decay

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Information about Types of radioactive decay
Health & Medicine

Published on July 14, 2009

Author: david.s.graff

Source: slideshare.net

Description

From my class on nuclear physics for nuclear medicine technologists. This class covers alpha, beta, and gamma decay, plus conversion electrons, Auger electrons, and k-alpha and other X-rays

Radioactive Decay

b ig T oo ns o to pr a ny ns m tro Too n eu a ny m T oo

Dataset #2: Authors: J. K. TULI, G. REED, B. SINGH Citation: Nuclear Data Sheets 93, 1 (2001) Parent Parent Parent Parent GS-GS Q-value Daughter Decay Mode Nucleus E(level) J" T 1/2 (keV) Nucleus Decay Scheme 99 99 Tc 14 2 . 6 8 3 2 1 1 1/2- 6.015 h 9 I T : 9 9 . 9 9 63 6 % Tc 43 43 Electrons: Energy Intensity Dose (keV) (%) ( MeV/Bq-s ) CE M 1.6286 11 74.595 % 0.0012149 Auger L 2.17 10.32 % 6 2 . 2 4 0 E - 4 14 Auger K 15.5 2.05 % 4 3.17E-4 6 CE K 119.4670 12 8.84 % 0.01056 CE K 121.59 3 0.55 % 5 6.7E-4 6 CE L 137.4685 11 1.07 % 0.00147 CE L 139.59 3 0.172 % 16 2.40E-4 23 CE M 139.9670 14 0.194 % 2.72E-4 CE NP 140.4430 22 0.0374 % 5.25310E-5 CE M 142.09 3 0.034 % 3 4.8E-5 5 CE NP 142.56 3 0.0066 % 6 9.4E-6 9 Gamma and X-ray radiation: Energy Intensity Dose (keV) (%) ( MeV/Bq-s ) 2.1726 4 6.201E-9 % 1.347E-13 XR l 2.42 0.447 % 11 1.08E-5 3 X R k #2 18.251 2.14 % 6 3.91E-4 11 X R k #1 18.367 4.07 % 12 7.47E-4 21 X R k !3 20.599 0.330 % 10 6.79E-5 20 X R k !1 20.619 0.639 % 18 1.32E-4 4 X R k !2 21.005 0.145 % 4 3.04E-5 8 140.511 1 89.06 % 0.1251 142.63 3 0.0187 % 18 2.7E-5 3

A conversion electron is ejected by a gamma photon from the nucleus

A conversion electron is ejected by a gamma photon from the nucleus

A kα X-ray comes when an electron from the L shell falls to the K shell

A kα X-ray comes when an electron from the L shell falls to the K shell

An Auger electron is ejected by a kα X-ray

An Auger electron is ejected by a kα X-ray

Gamma decay comes when nucleus falls from high energy state to low energy state Gamma rays can be absorbed by electrons in the atom Conversion electron: Gamma ray ejects electron k-α, L-β X-ray radiation when electrons from high shells fall to low shells Auger electrons when k-α absorbed by outer electrons, ejecting them.

Gamma decay comes when nucleus falls from high energy state to low energy state Gamma rays can be absorbed by electrons in the atom Conversion electron: Gamma ray ejects electron k-α, L-β X-ray radiation when electrons from high shells fall to low shells Auger electrons when k-α absorbed by outer electrons, ejecting them.

Alpha decay energy

MP (MD MHe ) 11-34 c2 Note that the mass of the two electrons in the He atom compensates for the fact that the daughter atom has two fewer electrons than the parent atom. Applying this to the example given in Equation 11-33, the mass of the 232Th atom is 232.038124 u The mass of the daughter atom 228Ra is 228.031139 u, and adding it to the 4.002603 u mass of 4He, we get 232.033742 u for the total mass of the decay products Equation 11-34 then yields Q/c 2 0.004382 u, which, when multiplied by the con- version factor 931.5 MeV/c 2, gives Q 4.08 MeV. Thus, the rest energy of 232Th is greater than that of 228Ra 4He; therefore, 232Th is unstable toward spontaneous decay. The kinetic energy of the particle (for decays to the ground state of the daugh- ter nucleus) is slightly less than the decay energy Q because of the small recoil energy of the daughter nucleus. If the parent nucleus is at rest when it decays, the daughter 1600 !286 Number of particles 1200 !61 !0 800 !334 !330 400 ! !376 342 !247 !174 !80 !350 !30 !280 !235 !124 5.70 5.80 5.90 6.00 Energy, MeV

Alpha decay when nucleus is too large Alpha particles emitted at specific energies Not dangerous from outside: can’t penetrate skin Dangerous when ingested/inhaled Gamma decay comes when nucleus falls from high energy state to low energy state Gamma rays can be absorbed by electrons in the atom Conversion electron: Gamma ray ejects electron k-α, L-β X-ray radiation when electrons from high shells fall to low shells Auger electrons when k-α absorbed by outer electrons, ejecting them.

Alpha decay when nucleus is too large Alpha particles emitted at specific energies Not dangerous from outside: can’t penetrate skin Dangerous when ingested/inhaled Gamma decay comes when nucleus falls from high energy state to low energy state Gamma rays can be absorbed by electrons in the atom Conversion electron: Gamma ray ejects electron k-α, L-β X-ray radiation when electrons from high shells fall to low shells Auger electrons when k-α absorbed by outer electrons, ejecting them.

_ n p + e– + ν p n + e+ + ν p + e– n+ ν n ν p+ β-

Dataset #3: Author: E. BROWNE Citation: Nuclear Data Sheets 82, 379 (1997) Parent Parent Parent Parent GS-GS Q-value Daughter Decay Mode Nucleus E(level) J! T1/2 (keV) Nucleus Decay 90 90 Scheme 39 Y 0 2- 64.00 h 21 "- : 100 % 2280.1 16 40 Zr Beta-: Energy End-point energy Intensity Dose (keV) (keV) (%) ( MeV/Bq-s ) 25.0 7 93.8 16 1.4E-6 % 3 3.5E-10 8 185.6 10 519.4 16 0.0115 % 14 2.1E-5 3 933.7 12 2280.1 16 99.9885 % 14 0.9336 12 Mean beta- energy: 933.6 keV 12, total beta- intensity: 100.0000 % 20, mean beta- dose: 0.9336 MeV/Bq-s 12

Decay radiation

n udd νe e+ W+ u du p

Positron decay makes back-to-back photons – + TOTAL Energy: 2mc2 = 1022 keV Charge: 0 Momentum: 0

Positron decay makes back-to-back photons 1 keV = 51 11 hν +5 1k eV – g y: : 0 er ge h/λ = 51 En ar m: : hν = 511 h entu gy : 0 er ge λ= - + C m Mo n r E a : h/ Ch men tum Mo TOTAL Energy: 2mc2 = 1022 keV Charge: 0 Momentum: 0

Authors: TILLEY, WELLER, CHEVES, CHASTELER Citation: Nuclear Physics A595, 1 (1995) Parent Parent Parent Parent GS-GS Q-value Daughter T1/2 Decay Mode Nucleus E(level) J! (keV) Nucleus Decay 18 18 Scheme 9 F 0 1+ 109.77 m 5 " + : 100 % 1655.50 63 8 O Beta+: Energy End-point energy Intensity Dose (keV) (keV) (%) ( MeV/Bq-s ) 249.8 3 633.5 6 96.73 % 4 0.2416 3 Mean beta+ energy: 249.8 keV 3, total beta+ intensity: 96.73 % 4, mean beta+ dose: 0.2416 MeV/Bq-s 3 Electrons: Energy Intensity Dose (keV) (%) ( MeV/Bq-s ) Auger K 0.52 3.072 % 11 1.597E-5 6 Gamma and X-ray radiation: Energy Intensity Dose (keV) (%) ( MeV/Bq-s ) XR k#2 0.525 0.009 % 3 4.5E-8 18 XR k#1 0.525 0.017 % 7 9E-8 4 Annihil. 511.0 193.46 % 8

Positron decay requires enough initial energy to make a positron p + e– n + ν p n + e+ + ν mp+me+Q = mn+Eout mp+Q = mn+me+Eout n ν p+ β-

Parent Parent Parent Parent GS-GS Q-value Daughter T1/2 Decay Mode Nucleus E(level) J! (keV) Nucleus Decay 57 57 Scheme Co 0.0 7/2- 271.74 d 6 ": 100 % 836.0 4 Fe 27 26 Electrons: Energy Intensity Dose (keV) (%) ( MeV/Bq-s ) Auger L 0.67 251 % 4 0.001684 24 Auger K 5.62 105.1 % 17 0.00591 10 CE K 7.3009 11 71.1 % 24 0.00519 18 CE L 13.5668 7 7.4 % 3 1.00E-3 3 CE K 114.9487 9 1.83 % 10 0.00211 12 CE L 121.2146 4 0.192 % 17 2.32E-4 21 CE K 129.3616 9 1.30 % 14 0.00169 18 Gamma and X-ray radiation: Energy Intensity Dose (keV) (%) ( MeV/Bq-s ) XR l 0.7 1.52 % 15 1.06E-5 11 XR k#2 6.391 16.6 % 9 0.00106 5 XR k#1 6.404 32.9 % 15 0.00211 10 XR k$1 7.058 3.91 % 19 2.76E-4 13 XR k$3 7.058 2.00 % 10 1.41E-4 7 14.4129 6 9.16 % 15 0.001320 22 122.06065 12 85.60 % 17 0.10448 21 136.47356 29 10.68 % 8 0.01458 11 230.4 4 4E-4 % 4 9E-7 9 339.69 21 0.0037 % 3 1.26E-5 10 352.33 21 0.0030 % 3 1.06E-5 11

Alpha decay when nucleus is too large Alpha particles emitted at specific energies Not dangerous from outside: can’t penetrate skin Dangerous when ingested/inhaled Beta decay: neutron turned into proton or proton turned into neutron Neutrino takes some energy: beta particle has range of energies Positron decay makes annihilation photons Electron capture: nucleus grabs low-lying electron Gamma decay comes when nucleus falls from high energy state to low energy state Gamma rays can be absorbed by electrons in the atom Conversion electron: Gamma ray ejects electron k-α, L-β X-ray radiation when electrons from high shells fall to low shells Auger electrons when k-α absorbed by outer electrons, ejecting them.

Alpha decay when nucleus is too large Alpha particles emitted at specific energies Not dangerous from outside: can’t penetrate skin Dangerous when ingested/inhaled Beta decay: neutron turned into proton or proton turned into neutron Neutrino takes some energy: beta particle has range of energies Positron decay makes annihilation photons Electron capture: nucleus grabs low-lying electron Gamma decay comes when nucleus falls from high energy state to low energy state Gamma rays can be absorbed by electrons in the atom Conversion electron: Gamma ray ejects electron k-α, L-β X-ray radiation when electrons from high shells fall to low shells Auger electrons when k-α absorbed by outer electrons, ejecting them.

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