Difference between revisions of "Problem set 5"
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#Neutrons are produced with high energy. How do you reduce their energy without losing them.<br> | #Neutrons are produced with high energy. How do you reduce their energy without losing them.<br> | ||
#What is a neutron moderator and what is a neutron absorbent. Give two examples of both. | #What is a neutron moderator and what is a neutron absorbent. Give two examples of both. | ||
− | #Neutrons is often detected by gas- detektors filled with | + | #Neutrons is often detected by gas- detektors filled with <sup>3</sup>He. Why <sup>3</sup>He and not <sup>4</sup>He. |
− | #Neutral radiation is detected by making charged particles. Which reaction happens when tubes filled | + | #Neutral radiation is detected by making charged particles. Which reaction happens when tubes filled <sup>3</sup>He is used as neutron detectors. |
#What is the Q-value of the reaction in e)? is the reaction endothermic or exothermic. | #What is the Q-value of the reaction in e)? is the reaction endothermic or exothermic. | ||
#Two charged particles are created in the reactions, which particles. | #Two charged particles are created in the reactions, which particles. | ||
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<br> | <br> | ||
− | ''2''''':''' One of the quite few nuclear reactions that happened during the birth of the universe (“big bang”) is this one: n+p → d+γ.<br> | + | ''2''''':''' One of the quite few nuclear reactions that happened during the birth of the universe (“big bang”) is this one: n + p → d + γ.<br> |
#Calculate the Q-value of the reaction. | #Calculate the Q-value of the reaction. | ||
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'''3:''' The most important proses for solar energy is, in total 4p → α + 2e<sup>+</sup>+ 2neutrino. Calculate the Q-values and determine the end products for these reactions: <br> | '''3:''' The most important proses for solar energy is, in total 4p → α + 2e<sup>+</sup>+ 2neutrino. Calculate the Q-values and determine the end products for these reactions: <br> | ||
− | # | + | #<sup>40</sup>Ca(alpha,gamma)? |
− | # | + | #<sup>52</sup>Cr(aplha,gamma)? |
− | # | + | #<sup>56</sup>Fe(alpha,gamma)? |
#58Ni(alpha,gamma)? | #58Ni(alpha,gamma)? | ||
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#The maximum kinetic energy of the positron/electron for 64Cu both disintegrations | #The maximum kinetic energy of the positron/electron for 64Cu both disintegrations | ||
#Nuclei that decays by both beta minus and beta plus are of a special type. Why is this? | #Nuclei that decays by both beta minus and beta plus are of a special type. Why is this? | ||
− | #Calculate the mass of 228 Ra from information from the nuclide chart. | + | #Calculate the mass of <sup>228</sup>Ra from information from the nuclide chart. |
<br> | <br> | ||
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#Write down the nuclear reactions which gives new fissile atoms in a uranium-breeder reactor and in a thorium-breeder reactor. | #Write down the nuclear reactions which gives new fissile atoms in a uranium-breeder reactor and in a thorium-breeder reactor. | ||
− | #Calculate the work (in watt) that is generated when one kg. Uranium-metall is radiated in a neutron fluks 10 | + | #Calculate the work (in watt) that is generated when one kg. Uranium-metall is radiated in a neutron fluks 10<sup>14</sup> neutrons/(cm<sup>2</sup>s). |
<br> | <br> | ||
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#Write down the nuclear reaction that happens. | #Write down the nuclear reaction that happens. | ||
#Calculate the Q-value of the reaction. | #Calculate the Q-value of the reaction. | ||
− | #A fluks of 10 | + | #A fluks of 10<sup>14</sup> neutrons/Cm<sup>2</sup>s striking a area of 100 cm<sup>2</sup> is completely stopped in a by a wall of borium. Calculate the work (in watt). |
<br> | <br> | ||
− | '''7:''' The radionuclide | + | '''7:''' The radionuclide <sup>89</sup>Zr has a half-life of 78 hours and is often generated in hospitals by a cyclotron. It is generated by the nuclear reaction <sup>89</sup>Y(p,n)<sup>89</sup>Zr. The cross section of this reaction is 0.8 b when a proton energy of 12Mev is used.<br> |
#Calculate the Q-value of this reaction. | #Calculate the Q-value of this reaction. | ||
− | #What must the production speed be to generate a sample of 1Gbq of | + | #What must the production speed be to generate a sample of 1Gbq of <sup>89</sup>Zr when the target is radiated for 6 hours. |
#The target material is cheap in this case and there is no need to regenerate it. Explain why.<br> | #The target material is cheap in this case and there is no need to regenerate it. Explain why.<br> |
Revision as of 11:15, 19 June 2012
Particles and Nuclear Reactions
1:
- What it is a thermal neutron?
- Neutrons are produced with high energy. How do you reduce their energy without losing them.
- What is a neutron moderator and what is a neutron absorbent. Give two examples of both.
- Neutrons is often detected by gas- detektors filled with 3He. Why 3He and not 4He.
- Neutral radiation is detected by making charged particles. Which reaction happens when tubes filled 3He is used as neutron detectors.
- What is the Q-value of the reaction in e)? is the reaction endothermic or exothermic.
- Two charged particles are created in the reactions, which particles.
- What energy does each of the to particles receive when a thermal neutron reacts.
2: One of the quite few nuclear reactions that happened during the birth of the universe (“big bang”) is this one: n + p → d + γ.
- Calculate the Q-value of the reaction.
- What is the energy of the gamma ray?
- What is the energy of the deuterium. Assume a thermal neutron.
3: The most important proses for solar energy is, in total 4p → α + 2e++ 2neutrino. Calculate the Q-values and determine the end products for these reactions:
- 40Ca(alpha,gamma)?
- 52Cr(aplha,gamma)?
- 56Fe(alpha,gamma)?
- 58Ni(alpha,gamma)?
4: Use nuclear wallet cards to calculate:
- The maximum kinetic energy of the positron/electron for 14C
- The maximum kinetic energy of the positron/electron for the neutron
- The maximum kinetic energy of the positron/electron for 18F
- The maximum kinetic energy of the positron/electron for 64Cu both disintegrations
- Nuclei that decays by both beta minus and beta plus are of a special type. Why is this?
- Calculate the mass of 228Ra from information from the nuclide chart.
5: In a breeder-reactor a new fissile atom is created from each atom that is fissioned. Breeder-reactors can be made from thorium and uranium as starting material.
- Write down the nuclear reactions which gives new fissile atoms in a uranium-breeder reactor and in a thorium-breeder reactor.
- Calculate the work (in watt) that is generated when one kg. Uranium-metall is radiated in a neutron fluks 1014 neutrons/(cm2s).
6: Borium is a good absorbent of thermal neutrons.
- Write down the nuclear reaction that happens.
- Calculate the Q-value of the reaction.
- A fluks of 1014 neutrons/Cm2s striking a area of 100 cm2 is completely stopped in a by a wall of borium. Calculate the work (in watt).
7: The radionuclide 89Zr has a half-life of 78 hours and is often generated in hospitals by a cyclotron. It is generated by the nuclear reaction 89Y(p,n)89Zr. The cross section of this reaction is 0.8 b when a proton energy of 12Mev is used.
- Calculate the Q-value of this reaction.
- What must the production speed be to generate a sample of 1Gbq of 89Zr when the target is radiated for 6 hours.
- The target material is cheap in this case and there is no need to regenerate it. Explain why.