A new Monte Carlo algorithm that solves the transport equations for the neutron noise in the frequency domain has been developed. Neutron noise equations, which are obtained by assuming small perturbations of macroscopic cross-sections around a steady state in the neutron field and by subsequently taking the Fourier transform in the frequency domain, are usually solved by analytical techniques or by resorting to diffusion theory. A stochastic approach has been recently proposed in the literature by using particles with complex-valued weights and applying a weight cancellation technique which requires the positive and negative values of the real and imaginary parts of particule weights to be summed up over a sufficiently fine spatial mesh. The new stochastic method presented here does not need any weight cancellation technique and relies on a modified collision operator. In this paper, the two Monte Carlo methods are compared with the usual deterministic methods (diffusion and transport) in the case of a heterogenous one-dimensional rod geometry for several noise frequencies. Our stochastic method is shown to be faster (except at very high frequencies) and easier to implement.

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