Maybe a bug for Electric field

[1561103570 (Long Wang)]

Versions

Please provide the used software versions.

FLUKA:3.4-5.2
Flair:4-5.1

Description

Dear FLUKA developers and experts,
I am attempting to simulate electrons and protons passing through an electric field of a defined intensity. The particle energy is expected to increase, but the energy gain calculated by FLUKA is inconsistent with theoretical results—it is only about 70% of the theoretically predicted value. This issue occurs consistently across different field strengths. Have I missed any conditions, or is there a bug in the code?

		Initial Electron Energy 1MeV	Electron Accelerated in Electric Field	Initial Proton Energy 10MeV	Proton Accelerated in Electric Field
E strength [kV/cm]	E [kV]	Eenrgy Increased Analytic [MeV]	Eenrgy Increased FLUKA [MeV]	Ratio	Eenrgy Increased Analytic [MeV]	Eenrgy Increased FLUKA [MeV]	Ratio
10	1000	1	0.6	0.6	1	0.6	0.6
20	2000	2	1.4	0.7	2	1.4	0.7
30	3000	3	2.1	0.7	3	2.1	0.7
40	4000	4	2.8	0.7	4	2.8	0.7
50	5000	5	3.5	0.7	5	3.5	0.7
80	8000	8	5.6	0.7	8	5.6	0.7

Input files

Electric.inp (2.0 KB)

For EZ=-10 kV/cm, Elength=100cm, through this field electron increased Energy should be 1MeV, and detector 2 should be 2MeV. While it’s ~1.6MeV.

[dcalzola (Daniele Calzolari)]

Hello,

Thanks for this question, this is indeed a valid point. It is indeed a bug, which we have fixed and which will be solved in the upcoming release.

Without going into technicalities, the tracking algorithm was sometimes going into a different branch of the code that incorrectly calculated the particle energy while traveling in the electric field. As a result, only a fraction of the energy the particle was supposed to gain was actually accounted for.

Worry not, we will fix this issue in the upcoming release. I attach here the plot you would obtain after the next update:

Nice catch! Have a nice day.
Cheers,
Daniele

[1561103570 (Long Wang)]

Thank you very much for your explanation, Daniele. We look forward to the release of updated versions.