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Flashcards in Calculations Deck (13):
1

Given a uniform disk source of radiation, at what minimum distance from the disk source would the point source formula have only about 1% difference from the disk source formula?

3 diameters

2

The average distance a photon will travel will be the _____ of the linear

reciprocal. e.g. photon linear attenuation coefficient of 0.0023cm

3

Semi-infinite cloud of gamma-emitting noble gas estimation of absorbed dose rate (D):

D=.25(Energy)(concentration in uci/cc) D is in Rad/sec

4

Formula to estimate exposure rates

6CEN=X. 6(Activity in Curies)(Energy in MeV)(Photon Fraction per disintigration). Gives R/hr at 1 ft.

5

1 HVL

= ln(2)/attenuation coefficient (u)

6

Buildup Factor

B=All primary photons and secondary photons/primary photons. e.g. at a point outside a thick photon radiation shield the exposure due to primary photons is 0.25 of the exposure from secondary photons. What is the buildup factor at that point? B=1.25/.25=5

7

1/10th life ratio

3.32 - Multiply by half life to get 1/10th life

8

Equation for specific activity

Decay constant * Number of atoms in a gram (activity/gram)

9

The DAC is calculated based on the average airborne concentration that a person would receive in what period of time?

2000 hours/year. DAC = (ALI/(1.2 m^3/hr)*2000 hr)

1.2 m^3/hr = reference man breathing rate

10

What is the mathematical relationship of the wavelength of a photon to its frequency?

Inverse. c=frequency*wavelength

11

1 Relaxation length

the thickness of shield that will attenuate a narrow beam to 1/e of its original intensity.

12

Secular Equilibrium before 7 half lives

A daughter = A parent (1-e^(-lambda(t))

13

Branching decay half life

T1/2 = ln2/(lambda1+lambda2)