Right.
then.. I would need your input..
> Dear Paola,
> thanks for your answer. I agree that, if a mu- decays, then it produces
> both a nu_mu and a nu_e_bar, while if it is captured by a nuclei, only a
> nu_mu is produced. However, in case of a capture:
>
> mu- p -> n nu_mu
>
> The energy of the emitted nu_mu is ~ 100 MeV, with an enlargement due to
> the Fermi motion of the proton inside the nucleus. This is visible in the
> spectrum that I obtained.
>
> Instead, in case of a decay, mu- -> e- nu_mu nu_e_bar, the two neutrinos
> have energy less than ~ mu/2 ~ 50 MeV . Therefore, I was expecting to have
> the same number of nu_mu and nu_e_bar in this region of the spectrum.
>
> Thanks,
> Bests,
> Andrea
>
>> On Dec 10, 2020, at 13:18, Paola Sala <paola.sala_at_mi.infn.it> wrote:
>>
>> Dera Andrea,
>> sorry for the late answer, maybe you found already -)
>> My impression is that you start with a largely different number of
>> positive and negative pions decaying at rest, that are then originating
>> low energy mu+ and mu- . This can bee seen by the monochrmatic peak at
>> 30 MeV in the nu-mu and nu-mu-bar, the numu (pion+ -> mu+ numu) being
>> almost two orders of magnitude more than the num-bar (pion->mu-
>> numubar).
>> This large difference reflects in the lfact that you get a lot of
>> numubar
>> and nue fom the positive muon decay.
>>
>> The few negative muons, all of them produce a nu_mu, either from decay
>> or
>> when captured, two orders of magnitude less than numubar and nue from
>> muon+.
>> Then, only the non-captured fraction produces a nuebar. From the plot,
>> the
>> capture probability seems to be around 50%
>>
>> Check it...
>> ah yes, the negative pions are preferentially interacting or being
>> captured by nuclei when at rest
>>
>> Paola
>>> 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.
>>>
>>> Thanks,
>>> Bests,
>>> Andrea
>>>
>>>
>>
>>
>> Paola Sala
>> INFN Milano
>> tel. Milano +39-0250317374
>> tel. CERN +41-227679148
>
>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Thu Dec 10 2020 - 17:55:30 CET