1.A neutron generator uses ansource, such as radium, to bombard beryllium, inducing the reaction⁴He +⁹Be¹²C +n. Such neutron sources are called RaBe sources, or PuBe sources if they use plutonium to get the's.Calculate the energy output of the reaction in MeV. (Assume

1 u = 931.5 MeV/c².)

MeV

2.

(a)

Two annihilationrays in a PET scan originate at the same point and travel to detectors on either side of the patient. If the point of origin is8.03cmcloser to one of the detectors, what is the difference in arrival times(in s)of the photons? (This could be used to give position information, but the time difference is small enough to make it difficult.)

s

(b)

How accurately (in s) would you need to be able to measure arrival time differences to get a position resolution of2.40mm?

s

3.

The activities of¹³¹I and¹²³I used in thyroid scans are given inthis tableto be 50 and70Ci,respectively. Find the masses (in g) of¹³¹Iand¹²³Iin such scans, given their respective half-lives are8.04 dand13.2 h.The masses are so small that the radioiodine is usually mixed with stable iodine as a carrier to ensure normal chemistry and distribution in the body. (Assume the atomic masses of¹³¹Iand¹²³Iare 130.91 and122.91 g/molrespectively.)

m₁₃₁= gm₁₂₃= g

4.

What is the dose in mSv for the following?

(a)

a0.2Gy x-ray

mSv

(b)

3.3mGy of neutron exposure to the eye

mSv

(c)

2.0mGy ofexposure

mSv

5.

How many Gy of exposure is needed to give a cancerous tumor a dose of35Sv if it is exposed toactivity?

Gy

6.

What is the dose in Sv in a cancer treatment that exposes the patient to330Gy ofrays?

Sv

7.

A beam of175MeV nitrogen nuclei is used for cancer therapy. If this beam is directed onto a0.185kg tumor and gives it a2.00 Svdose, how many nitrogen nuclei were stopped? (Use an RBE of 20 for heavy ions.)

nuclei

8.

(a)

If the average molecular mass of compounds in food is46.0g, how many molecules are there in 1.00 kg of food?

molecules

(b)

How many ion pairs are created in 1.00 kg of food, if it is exposed to 1,000 Sv and it takes29.5eVto create an ion pair? (Assume RBE to be 1.)

ion pairs

(c)

Find the ratio of ion pairs to molecules.

ion pairs

molecules

=

(d)

If these ion pairs recombine into a uniform distribution of 2,000 new compounds, how many parts per billion is each?

parts per billion

9.

Calculate the energy (in MeV) output in each of the fusion reactions in the proton-proton cycle, and verify the values given below. (Assume the mass of an electron is0.00054858 uand1 u = 931.5 MeV/c².Enter your answers to at least 2 decimal places.)

¹H +¹H²H +e⁺+_eE_reactants= MeVE_products= MeVE=0.42 MeV

¹H +²H³He +E_reactants= MeVE_products= MeVE=5.49 MeV

³He +³He⁴He +¹H +¹HE_reactants= MeVE_products= MeVE=12.86 MeV

10.

The energy produced by the fusion of a 1.00 kg mixture of deuterium and tritium is3.3710¹⁴J. Approximately how many kilograms would be required to supply the annual energy use of2.4010¹⁸JinEgypt?

kg

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11.

Tritiumis naturally rare, but can be produced by the reaction

n +²H³H +.

How much energy in MeV is released in this neutron capture? (Assume1 u = 931.5 MeV/c².)

MeV

12.

Consider the following.

n+²³⁵U⁹²Sr+¹⁴⁰Xe+4n

(a)

Calculate the energy (in MeV) released in the neutron-induced fission reaction above, givenm(⁹²Sr) =91.911029uandm(¹⁴⁰Xe) =139.921636u.(Assume1 u = 931.5 MeV/c².)

MeV

(b)

Confirm that the total number of nucleons and total charge are conserved in this reaction. (The electron family number is abreviated "efn".)

A_i=A_f= efn_i= efn_f=

13.

Confirm that each of the reactions listed for plutonium breeding below conserves the total number of nucleons, the total charge (in terms ofq_e), and electron family number.

238U +n		239U +
239U		239Np ++e
239Np		239Pu ++e

²³⁸U +n ²³⁹U +

A_i=A_f=Q_i=Q_f= q_eefn_i= efn_f=

²³⁹U ²³⁹Np ++_e

A_i=A_f=Q_i=Q_f= q_eefn_i= efn_f=

²³⁹Np ²³⁹Pu ++_e

A_i=A_f=Q_i=Q_f= q_eefn_i= efn_f=

14.

Find the mass (in g) converted into energy by a13.5kT bomb.

g

15.

Fusion bombs use neutrons from their fission trigger to create tritium fuel in the reactionn+⁶Li³H +⁴He. What is the energy released by this reaction in MeV? (Assume

1 u = 931.5 MeV/c².)

MeV