Rad Data Handbook 20.. - Voss Associates
Rad Data Handbook 20.. - Voss Associates
Rad Data Handbook 20.. - Voss Associates
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32<br />
7. The bremsstrahlung from a 1 Ci P aqueous solution in a<br />
glass bottle is ~ 3 mrad/h (30 ìGy/h) at 1 m.<br />
8. Half-value thickness vs beta energy<br />
Isotope â max energy (KeV) Half-Value Thickness<br />
99<br />
Tc 292<br />
2<br />
7.5 mg / cm<br />
36<br />
Cl 714<br />
2<br />
15 mg / cm<br />
90<br />
Sr/Y 546 / 2270<br />
2<br />
150 mg / cm<br />
238<br />
U<br />
Betas from short lived progeny<br />
191 / 2290 130 mg / cm 2<br />
9. Estimating beta energy using a paper shield<br />
a) The density thickness of typical notepaper of 20 pound<br />
2<br />
weight is 7.5 mg/cm .<br />
b) Take a reading with your beta detector of the surface<br />
contamination you wish to estimate the energy of.<br />
c) A single sheet of notepaper will stop all but the most<br />
energetic of alpha particles, will have virtually no effect<br />
on gamma radiation, and will only stop very low energy<br />
14<br />
beta particles such as C .<br />
d) A single sheet of notepaper will reduce the count rate<br />
99<br />
from Tc by ½.<br />
e) Continue adding more sheet of notepaper until the net<br />
count rate is less than ½ the unshielded count rate.<br />
f) Multiply the number of sheet of notepaper necessary to<br />
2<br />
reduce the count rate to ½ by 7.5 mg/cm . That density<br />
thickness is your half-value layer and you can compare<br />
the required density thickness with the table in step 8 or<br />
some other reference.<br />
32<br />
7. The bremsstrahlung from a 1 Ci P aqueous solution in a<br />
glass bottle is ~ 3 mrad/h (30 ìGy/h) at 1 m.<br />
8. Half-value thickness vs beta energy<br />
Isotope â max energy (KeV) Half-Value Thickness<br />
99<br />
Tc 292<br />
2<br />
7.5 mg / cm<br />
36<br />
Cl 714<br />
2<br />
15 mg / cm<br />
90<br />
Sr/Y 546 / 2270<br />
2<br />
150 mg / cm<br />
238<br />
U<br />
Betas from short lived progeny<br />
191 / 2290 130 mg / cm 2<br />
9. Estimating beta energy using a paper shield<br />
a) The density thickness of typical notepaper of 20 pound<br />
2<br />
weight is 7.5 mg/cm .<br />
b) Take a reading with your beta detector of the surface<br />
contamination you wish to estimate the energy of.<br />
c) A single sheet of notepaper will stop all but the most<br />
energetic of alpha particles, will have virtually no effect<br />
on gamma radiation, and will only stop very low energy<br />
14<br />
beta particles such as C .<br />
d) A single sheet of notepaper will reduce the count rate<br />
99<br />
from Tc by ½.<br />
e) Continue adding more sheet of notepaper until the net<br />
count rate is less than ½ the unshielded count rate.<br />
f) Multiply the number of sheet of notepaper necessary to<br />
2<br />
reduce the count rate to ½ by 7.5 mg/cm . That density<br />
thickness is your half-value layer and you can compare<br />
the required density thickness with the table in step 8 or<br />
some other reference.<br />
127<br />
127<br />
32<br />
7. The bremsstrahlung from a 1 Ci P aqueous solution in a<br />
glass bottle is ~ 3 mrad/h (30 ìGy/h) at 1 m.<br />
8. Half-value thickness vs beta energy<br />
Isotope â max energy (KeV) Half-Value Thickness<br />
99<br />
Tc 292<br />
2<br />
7.5 mg / cm<br />
36<br />
Cl 714<br />
2<br />
15 mg / cm<br />
90<br />
Sr/Y 546 / 2270<br />
2<br />
150 mg / cm<br />
238<br />
U<br />
Betas from short lived progeny<br />
191 / 2290 130 mg / cm 2<br />
9. Estimating beta energy using a paper shield<br />
a) The density thickness of typical notepaper of 20 pound<br />
2<br />
weight is 7.5 mg/cm .<br />
b) Take a reading with your beta detector of the surface<br />
contamination you wish to estimate the energy of.<br />
c) A single sheet of notepaper will stop all but the most<br />
energetic of alpha particles, will have virtually no effect<br />
on gamma radiation, and will only stop very low energy<br />
14<br />
beta particles such as C .<br />
d) A single sheet of notepaper will reduce the count rate<br />
99<br />
from Tc by ½.<br />
e) Continue adding more sheet of notepaper until the net<br />
count rate is less than ½ the unshielded count rate.<br />
f) Multiply the number of sheet of notepaper necessary to<br />
2<br />
reduce the count rate to ½ by 7.5 mg/cm . That density<br />
thickness is your half-value layer and you can compare<br />
the required density thickness with the table in step 8 or<br />
some other reference.<br />
32<br />
7. The bremsstrahlung from a 1 Ci P aqueous solution in a<br />
glass bottle is ~ 3 mrad/h (30 ìGy/h) at 1 m.<br />
8. Half-value thickness vs beta energy<br />
Isotope â max energy (KeV) Half-Value Thickness<br />
99<br />
Tc 292<br />
2<br />
7.5 mg / cm<br />
36<br />
Cl 714<br />
2<br />
15 mg / cm<br />
90<br />
Sr/Y 546 / 2270<br />
2<br />
150 mg / cm<br />
238<br />
U<br />
Betas from short lived progeny<br />
191 / 2290 130 mg / cm 2<br />
9. Estimating beta energy using a paper shield<br />
a) The density thickness of typical notepaper of 20 pound<br />
2<br />
weight is 7.5 mg/cm .<br />
b) Take a reading with your beta detector of the surface<br />
contamination you wish to estimate the energy of.<br />
c) A single sheet of notepaper will stop all but the most<br />
energetic of alpha particles, will have virtually no effect<br />
on gamma radiation, and will only stop very low energy<br />
14<br />
beta particles such as C .<br />
d) A single sheet of notepaper will reduce the count rate<br />
99<br />
from Tc by ½.<br />
e) Continue adding more sheet of notepaper until the net<br />
count rate is less than ½ the unshielded count rate.<br />
f) Multiply the number of sheet of notepaper necessary to<br />
2<br />
reduce the count rate to ½ by 7.5 mg/cm . That density<br />
thickness is your half-value layer and you can compare<br />
the required density thickness with the table in step 8 or<br />
some other reference.<br />
127<br />
127