Difference between revisions of "Solutions 5"
From mn/safe/nukwik
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| − | #Thermal neutrons have a kinetic energy of about 0.025eV | + | #Thermal neutrons have a kinetic energy of about 0.025eV |
| − | #Fast neutrons are “braked” with elastic collisions with particles with the same size as the neutrons. A moderator also needs to have a low cross-section for absorbing neutrons. | + | #Fast neutrons are “braked” with elastic collisions with particles with the same size as the neutrons. A moderator also needs to have a low cross-section for absorbing neutrons. |
| − | #A moderator is a material that brakes the neutrons, for instance H<sub>2</sub>O, D<sub>2</sub>O, C, Be. A neutron absorbent catches the neutrons and reacts with the neutron. Good absorbants are borium and gadolinium. | + | #A moderator is a material that brakes the neutrons, for instance H<sub>2</sub>O, D<sub>2</sub>O, C, Be. A neutron absorbent catches the neutrons and reacts with the neutron. Good absorbants are borium and gadolinium. |
| − | #From the nuclide carte we can see that <sup>3</sup>He has a high cross-section for the n,p-reaction. | + | #From the nuclide carte we can see that <sup>3</sup>He has a high cross-section for the n,p-reaction. |
| − | #The reaction <sup>3</sup>He+n arrow <sup>3</sup>H<sup>+</sup>+<sup>1</sup>H(+<sup>2</sup>e<sup>-</sup>). The charged particles from the reaction creates more ionisations when they travel towards the anode and the cathode, this gives a electric signal. | + | #The reaction <sup>3</sup>He+n arrow <sup>3</sup>H<sup>+</sup>+<sup>1</sup>H(+<sup>2</sup>e<sup>-</sup>). The charged particles from the reaction creates more ionisations when they travel towards the anode and the cathode, this gives a electric signal. |
| − | #The Q-value from the reaction is 764 keV, the reaction is exothermic. | + | #The Q-value from the reaction is 764 keV, the reaction is exothermic. |
| − | #<sup>3</sup>H<sup>+</sup> and <sup>1</sup>H<sup>+</sup> is created. | + | #<sup>3</sup>H<sup>+</sup> and <sup>1</sup>H<sup>+</sup> is created. |
#The two products in the reaction recives opposing recoils 180 degrees. Conversion of momentum m<sub>1</sub>v<sub>1</sub>=m<sub>2</sub>v<sub>2</sub> gives: <br> | #The two products in the reaction recives opposing recoils 180 degrees. Conversion of momentum m<sub>1</sub>v<sub>1</sub>=m<sub>2</sub>v<sub>2</sub> gives: <br> | ||
| − | <math>m_{1}^{2}v_{1}^{2}=m_{2}^{2}v_{2}^{2}\ | + | <math>m_{1}^{2}v_{1}^{2}=m_{2}^{2}v_{2}^{2}\rightarrow m_{1}E_{1}=m_{2}E_{2}\rightarrow E_{1}=\frac{m_{2}}{m{1}}E_{2}=\frac{1}{3}E_{2}</math> |
| + | |||
| + | <math>E_{1}+E{2}=Q=764 keV\rightarrow E_{1} = 190 Kev, E_{2}=570 keV</math> | ||
Revision as of 12:54, 18 June 2012
1:
- Thermal neutrons have a kinetic energy of about 0.025eV
- Fast neutrons are “braked” with elastic collisions with particles with the same size as the neutrons. A moderator also needs to have a low cross-section for absorbing neutrons.
- A moderator is a material that brakes the neutrons, for instance H2O, D2O, C, Be. A neutron absorbent catches the neutrons and reacts with the neutron. Good absorbants are borium and gadolinium.
- From the nuclide carte we can see that 3He has a high cross-section for the n,p-reaction.
- The reaction 3He+n arrow 3H++1H(+2e-). The charged particles from the reaction creates more ionisations when they travel towards the anode and the cathode, this gives a electric signal.
- The Q-value from the reaction is 764 keV, the reaction is exothermic.
- 3H+ and 1H+ is created.
- The two products in the reaction recives opposing recoils 180 degrees. Conversion of momentum m1v1=m2v2 gives:
