Re: [fluka-discuss]: Energy loss of relativistic nuclei in a crystal

From: maestro <>
Date: Mon, 24 Jun 2019 22:22:16 +0300

Hello Paola,
I set the BEAM card at -30000, i.e. 30 TeV/nucleon, if I correctly understood the card instructions.
Oxygen kinetic energy is extracted from a E^-1 distribution up to 200 TeV of particle energy, then it should be fine.
I noticed the same behaviour also using carbon nuclei; the dE/dx “anomalous" rise starts around 10-15 TeV of particle energy.
I send you annexed my input and geometry cards for physics and the source.f file I have modified for spectrum generation.
Thank you for your help

> On 24 Jun 2019, at 11:47, Paola Sala < <>> wrote:
> Hello
> From a fist check, with oxygen ions at fixed energies, I cannot reproduce
> your results. The dE/dx stays fairly constant, as expected.
> One doubt: did you set the energy in the BEAM card to a sufficiently high
> value to cover all the source ions? If not, de/dx tabulations will not be
> correctly initialized. If yes.. could you please send me your input, or at
> least the card you use for physics and transport settings?
> Thanks
> Paola
>> Hello fluka developers,
>> I am doing simulations of the energy deposit of oxygen nuclei at high
>> energy in a bar of PWO crystal (density 8.28 g/cm^3, 2 cm thick).
>> Oxygen nuclei have generated according to KE^-1 spectrum, where KE is the
>> kinetic energy per particle spanning from 178 GeV to 316 TeV.
>> I made plots (see attached figure to this email) of the energy loss
>> (dE/dx) distributions (computed from the energy deposited in the bar, and
>> dividing by
>> the square of the particle charge) for different energy intervals of KE.
>> In these plots, nuclei undergoing hadronic inelastic interaction
>> (somewhere in the crystal) are not included.
>> As you can see, dE/dx has a nearly constant value (around 2 MeV cm^2/g,
>> as expected) up to KE ~ 10 TeV, then it increases dramatically for higher
>> KE.
>> I wonder which might be the physical reason for this increase of dE/dx.
>> I would have expected an almost constant value for relativistic charged
>> particles (in the Fermi plateau).
>> Are there any radiative effects turned-on for ultra-relativistic charged
>> particles?
>> Thanks for your help.
>> Paolo Maestro
> Paola Sala
> INFN Milano
> tel. Milano +39-0250317374
> tel. CERN +41-227679148

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Received on Mon Jun 24 2019 - 23:08:01 CEST

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