Neutrons Flashcards
Primary contributor of absorbed energy from thermal neutrons in the body to tissue samples with dimensions less than 1cm
Recoil protons from the N-14 (n, proton) C-14 reaction. 0.626 MeV.
Main mechanism of energy transfer in tissue for fast neutron up to 20 MeV
Elastic scattering
Binding energy of a neutron in any element
8 MeV
Dose to tissues from 6 MeV neutrons is delivered primarily by
Recoil Protons
In an elastic scattering interaction between an neutron and an atomic nucleus:
A proton or a neutron will be emitted form the nucleus
Generally, to protect personnel against neutrons, what type of material is used?
Low Z ( Z < 20)
Activation analysis occurs when
Radiation is emitted after absorption of a neutron
Average quality factor for estimating the dose equivalent in a radiation field consisting of an unknown spectrum of fast neutrons
10
Albedo dosimetry works by
Fast neutrons being moderated in the body and reflected into the dosimter
Albedo dosimetry will function properly if
A cadmium filter is used between the dosimeter and the external neutron field, and neutrons are reflected form the body into the dosimeter. Cadmium has a high capture cross section and is used to shield against thermal neutrons.
When performing in-vivo measurements of personnel after a criticality accident to assess neutron dose, what is the nuclide of concern?
Na-24. For in-vivo measurements of criticality accident proportions, the Na-23(n,gamma)Na-24 reaction from large blood pools in the body (armpit, abdomen) is most useful.
What is the Cadmium absorption edge?
The energy level at which the neutron capture cross-section of cadmium shows a steep decrease. ~0.2 MeV for cadmium
Neutron Activation Equation
1 barn is equal to
10E-24 cm2
