neutron radiation

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neu·tron ra·di·a·tion

an emission of neutrons from the nucleus of an atom by decay or fission.
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To achieve the targeted neutron spectrum tailoring inside a thermal MTR, two options exist, i.e., either to remove the thermal spectrum component or to increase the fast/thermal neutrons ratio, using the appropriate neutron screens.
The hardening of the thermal neutron spectrum can be achieved either by the utilization of thermal absorbers or by the introduction of fission sources (boosters), enhancing thus the fast component of the neutron spectrum (Chrysanthopoulou et al., 2014a).
Assuming two "marginal" thicknesses of the tested material (i.e., 0.1 cm vs 1.0 cm) (Figure 6(a)), the effect on the reference neutron spectrum (i.e., in the JHR reflector) was examined.
Screens based on the heavier isotopes, i.e., [sup.139]La and [sup.197]Au, provided a neutron spectrum tailoring towards the desired direction (Figure 9).
Therefore, in order to somehow fit the experimental data in the framework of the traditional theory of neutron moderation in the low-energy part of the neutron spectrum, the Fermi spectrum (~ 1/[E.sub.n]) is set to a certain boundary energy ([E.sub.boundary]) below which the spectrum of moderated neutrons is given by the Maxwell spectrum, the form of which is defined by the temperature of the neutron gas, which in turn is calculated by the empirical formula, linking it with the temperature of the fissile medium (see Introduction).
This is not caused by the softened neutron spectrum (it is actually hardened as shown in Figure 17) but by the abrupt presence of [sup.239]Pu, which has a positive contribution to the VRC [33].
The decrease of moderator/fuel ratio (hardening neutron spectrum) results in the decrease of void reactivity feedback in comparison to reference moderation conditions as the system undergoes even less moderated conditions (see Figure 3).
Positive SRCC for parameter number 1 shows that the use of 238-group library in place of 44-group library results in softer neutron spectrum since the absolute values of void reactivity feedback decrease.
For a pure thermal neutron spectrum and including the CM/LAB transformation of the scattered flux in the direction of the detector, the value of [c.sub.av] = 0.83 [+ or -] 0.01 [9].
1 and the nn cavity filled with a heavy gas such as argon, for which the transformation of the neutron spectrum after scattering can be neglected.
Questions arise about the shape of the scattered neutron spectrum in the YAGUAR experiment and concerning the size g of a possible contribution to the thermal energy region from "fast-slow", [g.sub.fs.sup.s], and "fast-fast", [g.sub.ff.sup.s], collisions producing "slow" neutrons.