# Difference between revisions of "Problem set 5"

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#What it is a thermal neutron? | #What it is a thermal neutron? | ||

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#What energy does each of the to particles receive when a thermal neutron reacts. | #What energy does each of the to particles receive when a thermal neutron reacts. | ||

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''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> | ||

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#What is the energy of the deuterium. Assume a thermal neutron. | #What is the energy of the deuterium. Assume a thermal neutron. | ||

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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> | ||

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#58Ni(alpha,gamma)? | #58Ni(alpha,gamma)? | ||

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'''4:''' Use nuclear wallet cards to calculate: <br> | '''4:''' Use nuclear wallet cards to calculate: <br> | ||

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#Calculate the mass of 228 Ra from information from the nuclide chart. | #Calculate the mass of 228 Ra from information from the nuclide chart. | ||

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'''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.<br> | '''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.<br> | ||

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#Calculate the work (in watt) that is generated when one kg. Uranium-metall is radiated in a neutron fluks 10^14 neutrons/(cm<sup>2</sup>s). | #Calculate the work (in watt) that is generated when one kg. Uranium-metall is radiated in a neutron fluks 10^14 neutrons/(cm<sup>2</sup>s). | ||

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'''6:''' Borium is a good absorbent of thermal neutrons.<br> | '''6:''' Borium is a good absorbent of thermal neutrons.<br> | ||

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#A fluks of 10^14 neutrons/Cm^2s striking a area of 100 cm^2 is completely stopped in a by a wall of borium. Calculate the work (in watt). | #A fluks of 10^14 neutrons/Cm^2s striking a area of 100 cm^2 is completely stopped in a by a wall of borium. Calculate the work (in watt). | ||

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'''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.<br> | '''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.<br> |

## Revision as of 11:50, 18 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 228 Ra 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 10^14 neutrons/(cm
^{2}s).

**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 10^14 neutrons/Cm^2s striking a area of 100 cm^2 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.