42.13 A major source of background ra- diation is Radon-222. 222 Rn is an a emit- ter, it has a half-life of 3.8 days, a decay energy of 5.6 MeV, and is itself created as part of the decay chain between Uranium and Lead. Radon is an important natural source of radiation despite the fact that its decay mode is via an a particle which would not be able to penetrate any significant air-gap, let alone our skin. Radon is a gas and has a long enough half-life to perme- ate out of soil and rock and into the air. Thus when it is created by the naturally occurring Uranium in soil/rock near the surface it can be easily ingested via res- piration before it decays and the a decay can happen inside our tissues. While varying quite a lot from place-to- place a typical dose from the decay of Radon-222 is on the order of 1.0 mSv per year. If we assume a 65 kg mass and that the RBE of the a particles produced is 20 then: (a) What is the dose in Gy over one year? (b) What is the amount of energy ab- sorbed due to the decay 222 Rn over the course of one year (in J)? (c) How many individual decay events does this correspond to? (d) What is the activity of the 222Rn in a persons body (in Bq)? (e) How many 222Rn atoms are present in a person at any given point in time?
42.13 A major source of background ra- diation is Radon-222. 222 Rn is an a emit- ter, it has a half-life of 3.8 days, a decay energy of 5.6 MeV, and is itself created as part of the decay chain between Uranium and Lead. Radon is an important natural source of radiation despite the fact that its decay mode is via an a particle which would not be able to penetrate any significant air-gap, let alone our skin. Radon is a gas and has a long enough half-life to perme- ate out of soil and rock and into the air. Thus when it is created by the naturally occurring Uranium in soil/rock near the surface it can be easily ingested via res- piration before it decays and the a decay can happen inside our tissues. While varying quite a lot from place-to- place a typical dose from the decay of Radon-222 is on the order of 1.0 mSv per year. If we assume a 65 kg mass and that the RBE of the a particles produced is 20 then: (a) What is the dose in Gy over one year? (b) What is the amount of energy ab- sorbed due to the decay 222 Rn over the course of one year (in J)? (c) How many individual decay events does this correspond to? (d) What is the activity of the 222Rn in a persons body (in Bq)? (e) How many 222Rn atoms are present in a person at any given point in time?
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Please do the last three questions (C, D and E)
Transcribed Image Text:42.13 A major source of background ra-
diation is Radon-222. 222Rn is an a emit-
ter, it has a half-life of 3.8 days, a decay
energy of 5.6MeV, and is itself created as
part of the decay chain between Uranium
and Lead.
Radon is an important natural source of
radiation despite the fact that its decay
mode is via an a particle which would
not be able to penetrate any significant
air-gap, let alone our skin. Radon is a gas
and has a long enough half-life to perme-
ate out of soil and rock and into the air.
Thus when it is created by the naturally
occurring Uranium in soil/rock near the
surface it can be easily ingested via res-
piration before it decays and the a decay
can happen inside our tissues.
While varying quite a lot from place-to-
place a typical dose from the decay of
Radon-222 is on the order of 1.0 mSv per
year. If we assume a 65 kg mass and that
the RBE of the a particles produced is 20
then:
(a) What is the dose in Gy over one
year?
(b) What is the amount of energy ab-
sorbed due to the decay 222Rn over
the course of one year (in J)?
(c) How many individual decay events
does this correspond to?
(d) What is the activity of the 222Rn in a
persons body (in Bq)?
(e) How many
in a person at any given point in
time?
222 Rn atoms are present
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