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Radiochemistry and Nuclear Chemistry self-test # 8

Comprises Chapter 8

This is a self grading test of your knowledge. It consists of 20 randomly chosen questions with single or multiple answers. The questions with single answers have round buttons and the questions with perhaps more than one correct answer have square buttons. Answer the questions by clicking on the corresponding button in the list of alternative answers. On questions with a single answer (round buttons to click on), it is only possible to mark one of the alternative answers as correct.
Grading of the completed test is automatic when you click on the button marked "GRADE MY ANSWERS" at the end of the test.
Correct answers can be read by clicking on the button having the same number as the question. You find these buttons at the end of the test. You can also refresh your memory first by jumping directly to the answer buttons and click on them to get answers and read relevant parts of the book before doing this test.
On the questions with one or more possible answers (squares to click on) only the first click on each button is recorded as an answer. Hence you must click on the reset button below the question before you can change the original answer(s). Failure to do this will probably make the answers on this question regarded as wrong in the grading process.
Please observe that your teacher may require a deeper understanding of the treated subject than reflected by this test. In case you have any valuable comments or questions regarding this self-test, explain them in an e-mail to: jol@nc.chalmers.se 


Question # 1 (One answer) In order to distinguish between b-particles of low and high energy in a Cerenkov detector one can choose a suitable value of

    A) the absorption coefficient
    B) the beta energy
    C) the bremsstrahlung intensity
    D) the index of refraction
    E) the speed in vacuum

Question # 2 (One or more answers) An a-spectrum should be measured for nuclides present in a solution. Which of the following methods are suitable for preparation of a sample to be used to measure the spectrum?

    A) A filter paper is dipped into the solution and then dried
    B) The solution is mixed with sulfuric acid and poured into a measuring vial
    C) The elements of interest in the solution are plated out electrolytically on a Pt disk
    D) A windowless proportional counter is filled with the solution
    E) A small volume of the solution is evaporated on a stainless steel disk

In case of an error in the answers above, please click on this button before making any corrections 

Question # 3 (One answer) Which of the following detector types has the highest gain?

    A) Proportional counters
    B) GM-tubes
    C) Ion chambers
    D) Cutie-pies
    E) Solid-state detectors

Question # 4 (One answer) When counting the activity of a b-emitter one might obtain a too high count rate due to

    A) photo effects
    B) back scattering
    C) strong absorption in the detector
    D) an asymmetric distribution of counts
    E) a limited range of the radiation

Question # 5 (One answer) The term precision is used to describe

    A) how well a measured value is determined
    B) the error in a measurement
    C) how many times a measurement was made
    D) the difference between two measurements
    E) how often the same measured value was obtained

Question # 6 (One or more answers) The total efficiency of a detector with a window

    A) depends on the square of the distance between detector and sample
    B) increases when the window is made thicker
    C) can often be increased by prolonging the measurement
    D) is largest for short range radiation
    E) is largest when the window is covered with a thin lead foil

In case of an error in the answers above, please click on this button before making any corrections 

Question # 7 (One answer) The term dead-time means

    A) the time during which the detector is totally useless during a measurement
    B) the time delay needed after one ionization in order for the next ionization to give a full pulse height
    C) the time interval after one ionization during which a new ionization will give no output signal
    D) the smallest time interval that can be measured by a detector
    E) the time when a GM-tube stops working

Question # 8 (One or more answers in tabular form) A g-spectrum from 22Na looks as follows. Mark the squares in the Table below which corresponds to the correct names of the peaks designated by blue letters

 

 

Peak marking

A

B

C

D

E

F
Compton edge
Photo peak
Annihilation peak
Characteristic x-rays
Sum peak


Question # 9 (One or more answers) Before recording new tracks in a photographic emulsion it is usually convenient to erase all old tracks. One can then use

    A) Chromic acid
    B) Oxichinoline
    C) Hydrogen peroxide
    D) Sodium sulfite
    E) Ferro ammonium sulfate

In case of an error in the answers above, please click on this button before making any corrections 

Question # 10 (One or more answers) A gas-filled counter tube can be of one or more of the following types. Which?

    A) Proportional detectors
    B) Ion chambers
    C) Betatrons
    D) Fog chambers
    E) GM-tubes

In case of an error in the answers above, please click on this button before making any corrections 

Question # 11 (One or more answers) The uncertainty in a measurement of radioactivity

    A) is always the same fraction of the pulse height
    B) increases with the number of recorded pulses
    C) decreases with increasing duration of the measurement
    D) decreases always with decreasing count rate
    E) increases when the background is increased

In case of an error in the answers above, please click on this button before making any corrections 

Question # 12 (One or more answers) One or more of the following phenomena reduces the light output in liquid scintillation measurements. Which?

    A) Lack of quenching
    B) Chemical quenching
    C) Color quenching
    D) Light flashes
    E) Cerenkov radiation

In case of an error in the answers above, please click on this button before making any corrections 

Question # 13 (One answer) Which of the following is most suited for a-spectrometry?

    A) A surface barrier detector
    B) A BF3-tube
    C) A ZnS-scintillation detector
    D) A GM-tube
    E) A Cerenkov detector

Question # 14 (One or more answers) In order to measure number, direction, and length of a-tracks in a developed photographic film one normally uses

    A) a dark-room
    B) a microscope
    C) a stroboscope
    D) a ruler
    E) a compass

In case of an error in the answers above, please click on this button before making any corrections 

Question # 15 (One answer) The probability to obtain the "correct" measured value in case of very few counted pulses follows a

    A) hypergeometric distribution
    B) binomial distribution
    C) Gaussian distribution
    D) t-distribution
    E) Poisson distribution

Question # 16 (One answer) The dead-time of a detector

    A) is largest for g-radiation
    B) increases with the count rate
    C) increases with the number of measured pulses
    D) is always the same
    E) increases with counting time

Question # 17 (One answer) Many liquids are not transparent to UV-light. This can be circumvented in liquid scintillation counting by a suitable addition of

    A) Copper iodide
    B) POPOP
    C) TBP
    D) Acetyl acetone
    E) Iron chloride

Question # 18 (One or more answers) Measuring instruments for use in nuclear science are often produced as standardized modules and then usually belong to one of the following families

    A) ALI
    B) BIM
    C) CAMAC
    D) CRATE
    E) NIM

In case of an error in the answers above, please click on this button before making any corrections 

Question # 19 (One answer) A g-line corresponding to 1332 keV in energy is observed in a g-spectrum. What is the energy of the corresponding Compton edge?

    A) ~ 310 keV
    B) ~ 511 keV
    C) ~ 821 keV
    D) ~ 1118 keV
    E) ~ 2664 keV

Question # 20 (One or more answers) A NaI(Tl)-scintillation detector contains at least one or more of the following parts. Which?

    A) Scintillator
    B) Light guide
    C) Photo multiplier
    D) Discriminator
    E) Post-amplifier

In case of an error in the answers above, please click on this button before making any corrections 

Correct answers to each question can be obtained by clicking on the corresponding button below

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(Updated 2001-08-21)