Problem Set 4.3: Technological Applications of Radiation Instructions: Use your textbook p.149 – 151 and other resources (internet, books, etc.) to fill in the following chart.

Category	Application	Radioactive Isotope (If used)	Description (How does it work? How is it used?)
Home	Smoke Detectors		is produced and recovered from nuclear reactors. Alpha particles emitted by the decay of ionize the air (split air molecules into electrons and positive ions) and generate a small current of electricity that is measured by a current-sensitive circuit. When smoke enters the detector, ions become attached to the smoke particles and cause a decrease in detector current. When this happens an alarm sounds.
	Microwave Ovens	N/A	Used to heat food. An electronic device called a magnetron is used to produce microwaves. The microwaves pass through the into the enclosed metal of cavity. They are reflected around the oven walls and absorbed by the food.
	TV	N/A	Used to form images on a screen. TVs form an image by shooting streams of electrons towards the screen. Magnets are used to bend the stream. The beam is scanned back and forth; the electrons cause the screen to light up producing an image.
Medical	Nuclear Medicine: Radioisotopes for diagnosis and treatment	(discovered 1938) (1937) (1938) (1941)	Used by people who are in hospitals, one-third are treated with nuclear medicine. Effectively used in short-lived positron emitters such as , , , in PET. Diagnosis is effected by detecting annihilation gamma rays – two gamma rays of identical energy emitted when a positron and an electron annihilate each other. By attaching a positron emitter to a protein and allowing the body to metabolize it, we can study functional aspects of organs. PET imaging becomes even more valuable when we can observe the functional image compared to the anatomical image. MRI can provide detailed images of the anatomy. These help researchers better understand what is healthy tissue vs. disease tissue.
	Nuclear Medicine: Cancer Therapy		emits gamma rays that are used to destroy cancer cells. Massive particles such as protons or alpha particles will deposit energy before they stop. If energy is well chosen, most energy will be dumped into tumor, using 3D water degrader columns, tumors can be mapped out and irradiated.

	X-rays	None	Used by doctors and dentists to show broken bones, state of internal organs, or decay in teeth. X-rays are absorbed by the dense material, such as bones and teeth. X-rays pass through the flesh of the patient to an X-ray film.
Industry	Industrial Applications: Structural Flaw Detection	None	Used to detect flaws in quality of metal in cars, jet engines, thickness of tin and aluminum etc. X-rays are used to determine the thickness of materials. It is based un the X-rays and gamma rays ability to pass through the metal and other materials. X-rays are used to show the discontinuities and inclusions within the material. This detects any flaws within the material.
	Removal of Land Mines	Nitrogen	Used to neutralize mines without loss of life. Nitrogen has a nucleus with an ellipsoidal shape. This non-sphericity produces a unique set of very narrowly spaced energy levels. An explosive compound can be therefore identified by the subtle effect of its constituent N atoms. This could also differentiate explosives from scrap metals in the ground.
	Nuclear Weapons		Used as a weapon. Used either fission or fission. Weapons need constant maintenance. Radiation damage affects the materials and triggers devices that must act together for weapons to work. Tritium, used in weapons, naturally decays. Storage and disposal are a difficulty but a manageable problem.
Scientific	Radioactive Dating		Used to determine the age of a material. Very accurate measurement of the amount of remaining, either by observing the beta decay of or by accelerator mass spectroscopy allows one to date the death of once living things. A potassium-argon method of dating measures the amount of arising from decay is compared to the remaining. From the ratio, time since formation of the rock can be calculated. Using decays of U or thorium an find age of very ancient rock.
	Neutron Activation Analysis		Used to measure the concentration of the stable element in a sample. Typically done with a nuclear reactor. The nucleus absorbs one neutron and becomes a radioactive nucleus. By detecting the decay of these nuclei, one can measure the concentration of the stable element of interest in the sample.

	Space Application: Radiation-Induced Effects	None	Used to measure total dose effects, displacement damage, or single event effects. The inner belt (begins at 1000 km above the earth’s surface) contains primarily protons. The offset between Earth’s geographical and magnetic poles causes an asymmetry in the radiation belt allowing inner belt to reach min. altitude of 250 km. Low orbiting satellites spend as much as 30% of their time here. During solar flare, the number of protons suddenly increases by more than a million.
Recreational	Tanning Machines	None	Used recreationally for aesthetics. The tanning beds use less harmful UV rays than the sun called UV-A rays. They use filters to filter light. The light I snow less harmful containing only UV-A rays and not UV-B rays (harmful).
Other Applications (Bonus)	Nuclear Medicine Radioactive tracers Food irradiation	Thallium-201 Technicium-99m Fluorine-18 Phosphorus-32 Cobalt-60	Used to diagnose heart disease. Patients are monitored before and after stress. Used to develop images of internal body organs. Used with PET camera to create images Used to help understand the chemical and biological processes in plants. Inject phosphorus-32 into the plant and then Geiger counter is used to detect movement of the phosphorus-32 through the plant. Used to treat food in order to make it safer to eat and have a longer shelf life. Food irradiated by exposing it to the gamma rays. The energy from the gamma rays passing through the food is enough to destroy the disease. It is enough to kill the bacteria but not enough to change the quality, texture or taste of the food.