-This is a reference for indicating tendencies of questions and kinds/degrees of knowledges to be tested
in the examination.
-There are cases in which the form of real questions in the examination is different from this.
1. Answer the following questions about the generation of X-ray from an X-ray tube.
（1）In the X-ray tube, tube voltage E is applied between the targe and the filament.
a) Two types of X-ray are emitted from the tube. Answer the names of types, and explain about
wavelengths of them respectively.
b) Show the minimum wavelength of X-ray λmin. Here, the Plank’s constant is h, the speed oflight is c, and, the elementary electric charge is e.
（2）Consider about an atom of which binding energy of K electron shell and L electron shell is
EK and EL respectively. The nucleus absorbs an electron, and a vacancy arises in K-shell.
a) When X-ray is emitted from the atom, show the X-ray energy.
b) When electron is emitted from the atom, provide the name of electron and show the emission
energy.

2. Answer the following questions when a photon of energy Eγ [keV] enters a detector made ofa substance that is composed of a single element (atomic number: Z). Here, the binding energyof K electron shell and L electron shell is EK [keV] and EL [keV] respectively.
(1) Find the condition in which the photoelectric effect occurs.
(2) Find the condition in which the pair production occurs.
(3) The interaction probability of the photoelectric effect is equal to that of the Compton
scattering in measurement of the photon applying the detector. Answer the probability ratio of
the photoelectric effect to the Compton scattering when other detector made of a different kindof substance (atomic number: 2Z) is applied.
(4) The mass attenuation coefficient is 7 cm2/g when Z=82 and Eγ=90keV. Answer the photon
interaction cross section per atom when photoelectric effect with K-shell electron only
contributes to attenuation of the photon in the detector.

3. Answer the following questions about the interaction between radiation and material.
(1)When heavy charged particles A(mass: m A, Atomic Number: Z A) and B(mass: m B, Atomic
Number: Z B) enter a material at the same velocity, the range of particle A and B are R A and R B
respectively. Show the relation between m A and m B(2) Let Sα and Sp be the stopping powers of10 MeVα particle and 1 MeV proton in a material,respectively.
Find S α / S p.
(3) Cherenkov light was generated when charged particles were incident on a substance with arefractive index of n. Explain the generation mechanism and of Cherenkov light and show thevelocity conditions of charged particles in the material. Here, the speed of light is c.

3. Answer the following questions about the accelerator.
(1) When categorizing accelerators in terms of the electric field of acceleration, acceleratorgroups such as Cockcroft-Walton accelerators and Van de Graaff accelerators are classified into
different types from linear accelerators and cyclotrons. Explain the difference between these twotypes.
(2) Proton and alpha particle are accelerated by the potential difference of V [MV]. After theacceleration, the velocity of the proton and the alpha particle are V p and V a, respectively.
Show the relation between V p and V a.

5. A gas-filled detector is installed in a radiation field where monochromatic alpha rays aregenerated. The detector is operating in pulse mode The detector is connected to a chargesensitive preamplifier, and the current signal from the detector is converted into a voltage signal(hereinafter referred to as a pulse). Voltage E [V] was applied to the detector and the generated
pulse is observed with an oscilloscope. When the operating voltage E is changed in the range ofE 1 ≤ E ≤ E 2, The frequency of occurrence and the peak voltage of pulses are always constant atany voltage. Answer the following questions.

(1) When the operating voltage was gradually lowered from E 1, the observed pulse changed.
Describe the details of the changes that may occur and the reasons for them.
(2) When the operating voltage was set to E >> E 2, the frequency of pulse generation increased
significantly. Explain this possible reason.

6. Answer the following questions about the radiation measurement.
(1) Gamma rays from a gamma ray source which emits 3 MeV gamma rays are measured by aNaI(Tl) scintillation detector with an energy resolution of 15 % for 3 MeV gamma rays.
a) Show the full with at half maximum value (MeV) for the full energy peak.
b) List all the energies of the peaks that may occur the energy spectrum in addition tothe full energy peaks.
(2) The measurement is performed for 10 seconds, a count of 1000 counts was obtained. Afterremoving the source, the measurement is performed again for 100 seconds. A count of 100 counts
was obtained.
a) Obtain the net count rate for the source.
b) show the statistical error of the net count rate.

7. Answer the following questions about the molecular-level effects on radiation biology.
(1) Write the reason why DNA damage caused by indirect action is dominant for irradiation oflow LET radiation.
(2) Irradiate a solution with radiation and measure the inactive molecules. Complete therelationship between solute concentrations and inert molecules for irradiations of low and highLET radiation in the graph, respectively.

8. Answer the following questions about the cell-level effects on radiation biology.
(1) Survival rate S of single target single hit model is given by S = exp (-D / D0) when the dose isdefined as D.

(A) Derive the survival rate S of the multi target single hit model from the survival rate S of thesingle target single hit model.
(B) In a multi target single hit model, answer the slope of the curve with the survival rate S on
the longitudinal axis and the dose D on the horizontal axis, when the dose D is sufficiently higher
than D0.

9. Answer the following questions about the effects of organs/ tissues and individual levels onradiation biology.
(1) Acute radiation disease is a series of symptoms that occur when a fairly wide area of thewhole body or body is exposed to radiation of 1 Gy or more in a short time.
(a) Explain what dose LD50 (60) is.
(b) In cancer radiotherapy, patients receive fractionated irradiation of 1 Gy or more of radiation.
Answer the advantages of fractionated irradiation with regard to the oxygen effect.
10. Answer the following questions about radiation exposure in body.
(1) Radioactivity of a radionuclide taken into the body decreased by exactly 1/16 in a year. Thephysical half-life of this radionuclide is two years.
(a) Answer a biological half-life [day].
(b) As a result of appropriate treatment immediately after taking radionuclides in the body topromote excretion, radioactivity of radionuclides decreased by 1/32 in a year. Answer how many
percent the absorbed dose will be reduced by this procedure.