Presentation Transcript
Nuclear Radiation Detectors :Nuclear Radiation Detectors
No natural sense for the detection of nuclear radiation. :No natural sense for the detection of nuclear radiation. Nuclear Radiation can’t be:
Seen
Heard
Felt
Detection of ionizing radiation :Detection of ionizing radiation Radiation that has sufficient energy (> 33 - 35 eV) to produce ionization events
The operation of the most commonly used radiation detection devices :The operation of the most commonly used radiation detection devices the collection of ion pairs (gaseous detectors)
the counting of scintillation events (scintillation counters)
Scintillation Counter :Scintillation Counter
Slide 6:Incident ion pair Detector Gas Radiation - + Gaseous detectors collect ion pairs produced by the incident radiation in the detector gas
Scintillation detectors :Scintillation detectors Scintillation detectors utilize fluors
fluoresce-produce flashes of light when struck by incident radiation.
Slide 8:Regardless of the type of detector used make sure that the appropriate detector is used for the appropriate application
Slide 9:When performing quantitative and qualitative procedures, one must always take into account the detector’s efficiency for detecting a specific type of radiation.
Detector Efficiency :Detector Efficiency % efficiency = detected counts
actual disintegrations
% efficiency = cpm x 100%
dpm
dpm -disintegrations per minute
cpm - counts per minute
Sample Problem :Sample Problem A certain detector provides a count of 48,000 cpm when a 0.1?Ci Cs137 source is used as a sample. What is this instrument’s efficiency for the photons of Cs137?
Recall 1 Ci = 3.7 x 1010 dps
= 2.22 x 1012 dpm
0.1?Ci = 2.22 x 105 dpm
Sample Problem con’t :Sample Problem con’t % efficiency = cpm x 100%
dpm
% efficiency = 4.8 x 104 cpm x 100%
2.22 x 105 dpm
% efficiency = 0.216 or 21.6%
Instrument efficiency :Instrument efficiency Efficiency will vary with:
type of radiation
energy of the incident radiation
type of detector used