# Difference between revisions of "Problem set 5"

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− | = Particles and Nuclear Reactions<br> = | + | = Particles and Nuclear Reactions<br> = |

− | + | ====== Return to [[Problem Solving Sets]] ====== | |

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− | '''1 | + | '''1:'''<br> |

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

+ | #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. | ||

+ | #Neutrons is often detected by gas- detektors filled with <sup>3</sup>He. Why is <sup>3</sup>He used and not <sup>4</sup>He? | ||

+ | #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 5)? 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? | ||

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− | ' | + | '''''2'':''' One of the quite few nuclear reactions that happened during the birth of the universe (“big bang”) is: n + p → d + γ.<br> |

− | #Calculate the Q-value of the reaction. | + | #Calculate the Q-value of the reaction. |

− | #What is the energy of the gamma ray? | + | #What is the energy of the gamma ray? |

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

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− | + | '''3:''' The most important process for fusion in the sun is, in total 4p → α + 2e<sup>+</sup>+ 2 <span class="texhtml">μ</span>. Calculate the Q-values and determine the end products for these reactions: <br> | |

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− | + | #<sup>40</sup>Ca(alpha,gamma) | |

+ | #<sup>52</sup>Cr(aplha,gamma) | ||

+ | #<sup>56</sup>Fe(alpha,gamma) | ||

+ | #<sup>58</sup>Ni(alpha,gamma) | ||

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− | '''5:''' In a breeder-reactor a new fissile atom is created from each atom that | + | '''4:''' Use Nuclear Wallet Cards to do the following calculations: <br> |

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+ | #The maximum kinetic energy of the positron/electron for <sup>14</sup>C. | ||

+ | #The maximum kinetic energy of the positron/electron for the neutron. | ||

+ | #The maximum kinetic energy of the positron/electron for <sup>18</sup>F. | ||

+ | #The maximum kinetic energy of the positron/electron for <sup>64</sup>Cu ( both disintegrations). | ||

+ | #Nuclei that decays by both beta minus and beta plus are of a special type. Why is this? | ||

+ | #Calculate the mass of <sup>228</sup>Ra from information from the Chart of the Nuclides. | ||

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+ | <br> | ||

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+ | '''5:''' In a breeder-reactor a new fissile atom is created from each atom that fissions. Breeder-reactors can be made from thorium and uranium as starting material.<br> | ||

#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 | + | #Calculate the work (in watt) that is generated when one kg of uranium metal is irradiated in a neutron flux of 10<sup>14</sup> neutrons/(cm<sup>2</sup>s). |

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+ | '''6:''' Borium absorbs thermal neutrons well.<br> | ||

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+ | #Write down the nuclear reaction that happens. | ||

+ | #Calculate the Q-value for the reaction. | ||

+ | #A flux of 10<sup>14</sup> neutrons/(cm<sup>2</sup>s) striking an area of 100 cm<sup>2</sup> is completely stopped by a wall of borium. Calculate the work (in watt). | ||

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− | + | '''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 for this reaction is 0.8 b with 12MeV protons.<br> | |

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− | + | #Calculate the Q-value for this reaction. | |

+ | #Find a production speed that is able to generate a sample of 1 Gbq of <sup>89</sup>Zr with 6 hours of irradiation time. | ||

+ | #In this case the target material is cheap and there is no need to regenerate it. Why is it so? <br> | ||

− | + | [[Category:Unsolved Problems]]<br> [[Category:Bachelor]] | |

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## Latest revision as of 09:02, 9 July 2012

# Particles and Nuclear Reactions

###### Return to Problem Solving Sets

**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
^{3}He. Why is^{3}He used and not^{4}He? - Neutral radiation is detected by making charged particles. Which reaction happens when tubes filled
^{3}He is used as neutron detectors? - What is the Q-value of the reaction in 5)? 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: 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 process for fusion in the sun is, in total 4p → α + 2e^{+}+ 2 μ. Calculate the Q-values and determine the end products for these reactions:

^{40}Ca(alpha,gamma)^{52}Cr(aplha,gamma)^{56}Fe(alpha,gamma)^{58}Ni(alpha,gamma)

**4:** Use Nuclear Wallet Cards to do the following calculations:

- The maximum kinetic energy of the positron/electron for
^{14}C. - The maximum kinetic energy of the positron/electron for the neutron.
- The maximum kinetic energy of the positron/electron for
^{18}F. - The maximum kinetic energy of the positron/electron for
^{64}Cu ( 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 Chart of the Nuclides.

**5:** In a breeder-reactor a new fissile atom is created from each atom that fissions. 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 of uranium metal is irradiated in a neutron flux of 10
^{14}neutrons/(cm^{2}s).

**6:** Borium absorbs thermal neutrons well.

- Write down the nuclear reaction that happens.
- Calculate the Q-value for the reaction.
- A flux of 10
^{14}neutrons/(cm^{2}s) striking an area of 100 cm^{2}is completely stopped by a wall of borium. Calculate the work (in watt).

**7:** The radionuclide ^{89}Zr has a half-life of 78 hours and is often generated in hospitals by a cyclotron. It is generated by the nuclear reaction ^{89}Y(p,n)^{89}Zr. The cross section for this reaction is 0.8 b with 12MeV protons.

- Calculate the Q-value for this reaction.
- Find a production speed that is able to generate a sample of 1 Gbq of
^{89}Zr with 6 hours of irradiation time. - In this case the target material is cheap and there is no need to regenerate it. Why is it so?