Revision as of 11:54, 18 June 2012 by Hansvl@uio.no
- 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: