Edited Invalid date
31.2 Radiation Detection and Detectors
This image shows where the most active bone cells are in a patient's body, an indication of bone cancer.
A short-lived radioactive substance is given to the patient, and the radiation is measured with an external detector.
The range of radiation that can leave the body is too small for it to be seen outside the patient.
See how the element, charge, and mass change when you build an atom out of protons, neutrons, and electrons.
Ionizing radiation does not cause nerve impulses.
There are stories in newspapers about people who fall ill with radiation poisoning but never feel the radiation.
The detection of radiation by instruments is more important than a research tool.
There is a brief overview of radiation detection in this section.
The fogged photographic plate was the first to detect radiation.
Medical and dental x rays use photographic film as the most common detector of ionizing radiation.
The mechanism for exposure to film by ionizing radiation is the same as the mechanism for exposure by photons.
A quantum of energy interacts with the film.
If there is more than a few eV of energy needed to induce the chemical change, the quantum can come from a photon.
The process is not perfect, since not all incident radiation interacts and not all interactions produce the chemical change.
Absorbers and other devices must be used to obtain energy, charge, and particle-identification information because the amount of film darkening is related to exposure.
Film badges contain film similar to that used in dental x-ray film and are sandwiched between various absorbers to determine the penetrating ability of the radiation as well as the amount.
The clicking and buzzing sound we hear in dramatizations and documentaries, as well as in our own physics labs, is usually an audio output of events detected by a Geiger counter.
A conducting cylinder with a wire along its axis is filled with a gas so that a voltage applied between the cylinder and wire produces almost no current.
The free ion pairs produced by ionizing radiation are attracted to the wire and cylinder, forming a current that is detected as a count.
There is no information on energy, charge, or type of radiation if you count the word count.
They don't detect every particle since some radiation can pass through without producing enough ionization.
In order to reveal the existence and relative intensity of ionizing radiation, a prompt output can be produced from the Geiger counter.
The current is registered as a count.
Light is recorded when radiation interacts with materials.
The energy of the radiation is enough to excite atoms in a material that may fluoresce, such as the phosphor used by Rutherford's group.
Solid or liquid strontium can be very efficient.
Information about the energy, charge, and type of radiation can be provided by their light output.
The detection of a huge number of particles in short periods of time is achieved by the use of strontium light flashes.
There are a variety of research and diagnostic applications for strontiumr detectors.
The detection of radiation from distant galaxies, the analysis of radiation from a person indicating body burdens, and the detection of exotic particles are some of the things that can be done.
The name photomultiplier comes from the photoelectric effect, in which stages are multiplied into a cascade of electrons.
Light entering the photomultiplier strikes a metal plate, causing it to release an electron that is attracted by a positive potential difference to the next plate, and so on.
The final output current is proportional to the energy of the light entering the tube.
Information such as energy, charge, particle identification, direction of motion, and so on can be obtained with scintillators.
Review flashcards and saved quizzes
Getting your flashcards
Privacy & Terms