[fluka-discuss]: Question about neutrino production in FLUKA

From: Andrea Celentano <andrea.celentano_at_ge.infn.it>
Date: Thu, 26 Nov 2020 17:34:16 +0100

Dear all,
I am using FLUKA to sample the neutrino production by a 11 GeV electron beam impinging on a thick target.

I have a custom mgdraw.f code that samples (via entry BXDRAW) each neutrino passing through a plane, perpendicular to the beam axis, downstream the target.

The following plot shows the neutrino current, in neutrinos / GeV / impigning_electron, where each color refers to a different neutrino species.

In the low energy part of the spectrum (E < ~ 50 MeV), the continuous part of the distribution is due to the decay at rest of muons:

mu- -> e- nu_mu nu_e_bar
mu+ -> e+ nu_mu_bar nu_e

I observe that nu_e and nu_mu_bar are produced with higher intensity than nu_mu and nu_e_bar, due to the fact that mu- can be captured by nuclei and give rise to mu- X(Z,A) -> nu_mu X(Z-1,A) (with the large peak in the nu_mu distribution at ~ 100 MeV).

However, while the contribution of nu_e and nu_mu_bar is the same at low energy, this is not true for nu_mu and nu_e_bar.
I do not understand why, since any time a mu- decays at rest, it will produce a nu_mu and a nu_e_bar. Here it seems there is a factor x2 difference.

Note that I am considering phase-space decays, hence the energy spectra for decay-at-rest are all the same.


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Received on Thu Nov 26 2020 - 19:16:27 CET

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