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High energy (fast) neutrons are often produced in large quantities in the vicinity of accelerator targets. Although the induced activity decreases by one half in the first 10 minutes after shut-down, long-lived activation products may persist. Common activation products near the target include: Mg-27, Na-24, Cu-62 and Al-28. Tritium, which is an internal hazard, can also be produced in a large quantities, especially in pump oil, e.g. ion pumps. N-16 can be produced in the air near the target and in the cooling water supply by the activation of 0-16. The following factors need to be considered: 1. Stability of the reaction product 2. Half-life of the activation product Factors Affecting Activation 3. Radiation emitted by the activation product 4. Cross section of the target nuclide 5. Abundance of the target nuclide 6. Neutron fluence rate (and mass of target element) The following section will consider each of these in turn using the element hydrogen as an example. Shielding neutrons involves three steps: 1. Slow the neutrons Neutron Shielding 35 2. Absorb the neutrons 3. Absorb the gamma rays A fissile nuclide can be induced to fission by thermal neutrons, e.g., U-233, U-235, Pu-239, Pu- 241. Most fissile nuclides are alpha emitters and all have odd atomic mass numbers. Fission 33 A fissionable nuclide requires fast neutrons to induce fission, e.g., U-238. Fission usually produces two fission products. The split is asymmetric.
Common activation products near the target include: Mg-27, Na-24, Cu-62 and ______
Al-28
Tritium, which is an internal hazard, can also be produced in large quantities, especially in ______, e.g. ion pumps
pump oil
N-16 can be produced in the air near the target and in the cooling water supply by the activation of ______
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Factors Affecting Activation: 1. Stability of the reaction product 2. Half-life of the activation product 3. Radiation emitted by the activation product 4. Cross section of the target nuclide 5. Abundance of the target nuclide 6. Neutron fluence rate (and mass of target element) The following section will consider each of these in turn using the element ______ as an example
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A fissile nuclide can be induced to fission by thermal neutrons, e.g., U-233, U-235, Pu-239, Pu- 241. Most fissile nuclides are ______ emitters and all have odd atomic mass numbers
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