A level Physics 9702- Nuclear Physics
A radiation detector is placed close to a radioactive source. The detector does not surround
the source. Radiation is emitted in all directions and, as a result, the activity of the source
and the measured count rate are different. Suggest other reasons why the activity and the
measured count rate may be different. - correct answer-• Self-absorption in the source
• The daughter nuclide of the radioactive decay may itself be unstable and so may emit
radiation.
• Detector may not be sensitive to all the radiations.
• Window of the detector may absorb some radiation.
• It may be due to the presence of background radiation.
• Dead-time of counter.
• Absorption in air before reaching detector.
Change in half-life if temperature increases?? - correct answer-There is no change in
half-life since radioactive decay is a spontaneous process.
Change in count rate if temperature increases?? - correct answer-Count rate fluctuates/is
different since radioactive decay is a random process.
A radiation detector is placed close to a radioactive source. The detector does not surround
the source. Radiation is emitted in all directions and, as a result, the activity of the source
and the measured count rate are different. Suggest other reasons why the activity and the
measured count rate may be different. - correct answer-• Self-absorption in the source
• The daughter nuclide of the radioactive decay may itself be unstable and so may emit
radiation.
• Detector may not be sensitive to all the radiations.
• Window of the detector may absorb some radiation.
• It may be due to the presence of background radiation.
• Dead-time of counter.
• Absorption in air before reaching detector.
Change in half-life if temperature increases?? - correct answer-There is no change in
half-life since radioactive decay is a spontaneous process.
Change in count rate if temperature increases?? - correct answer-Count rate fluctuates/is
different since radioactive decay is a random process.
