Is it possible to define pulses with the desired time duration?

Dear Fluka experts,

My source is an XFEL (X-ray Free Electron Laser) which is a type of laser source.
Is it possible to define pulses with the desired time duration?
Is the default Fluka source considered a continuous source?

Best regards,

Dear @marziyeh.tavakkoly,

By default, in Fluka, particles are assumed to start all at t=0.
It is possible to define an irradiation profile when performing an activation study.
It is possible to access to access the information about the “timing” of the particles.
It is also possible to set the initial time of the particle in a dedicated source routine, but I would say that this is a pretty advanced feature and useful in a very limited number of cases.
What would be your use case?

Dear Amario,

Each pulse starts at t=0 and the pulse duration is 10 fs, the next pulse comes after 220 ns. I want to simulate for one single pulse and/or 100 pulses.

How can I define the radiation profile and pulse duration?

Dear @marziyeh.tavakkoly,

It depends on your use case? What is it? What do you want to investigate with the simulations?

Dear @amario,

I have a silicon mirror. The source is an X-ray free electron laser (XFEL) with an energy of 1-12 keV.
I want to simulate the absorbed dose and also the absorbed energy fraction for silicon.

It is known from experiments performed using femtosecond pulses that during this time the electron system can transport the energy far beyond the absorption layer.
In grazing incidence, the penetration of the x-rays into the material is quite small so that the transport of photo-electrons may lower the dose by spreading it to deeper layers of the material.

Ref: DOI: 10.3788/COL202321.023401

Absorbed Dose.flair (2.4 KB)
Absorbed Dose.inp (1.7 KB)

Dear Marziyeh,
I had a look at the reference. The Monte-Carlo calculation by GEANT 4 does not take account of the time structure of the beam, but the calculation of the enthalpy transport, equations 4 and 5.
In eq. 5, the source term S(z,t) is the product of a time-and intensity-dependent term and AEF(z), the Monte-Carlo result which depends only on the depth z (and the incident angle, photon energy etc).
Relating to your previous question, in S(z,t) appears I_0, the laser fluence in J/cm2, here is your normalisation ! AEF(z), the ratio of absorbed energy at depth z to total absorbed energy, can be calculated from the MC result “per primary”

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Dear @totto ,
This was very helpful, I really appreciate it.