electron positron collision

[claudio....]

Is it possible to simulate an head on collision between 2 beams one made of positron and one made of electron at 510 MeV?

o beam simulate one event per time?

thanks in advance,

Claudio

[Tom Roberts]

Neither Geant4 nor G4beamline are set up to simulate beam-beam collisions.  They only simulate decay and interactions with matter, for single particles. G4beamline has features to aggregate many single particles into a beam.

Tom Roberts

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[Daniel Kaplan]

But you could possibly simulate a positron beam on a fixed hydrogen target at the equivalent fixed-target energy, with some kind of particlefilter to kill interactions with protons. You could then Lorentz-transform the resulting ntuple of outgoing particles to the CMS frame and read it back into G4beamline to track the secondaries. Would that be convenient enough to be worth the trouble?

Dan Kaplan

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From: Tom Roberts <tjrobe...@sbcglobal.net>
Sent: Monday, January 20, 2025 1:15:28 PM
To: claudio.... <claudio....@gmail.com>; G4Beamline <g4bea...@muonsinc.com>
Subject: Re: [G4beamline] electron positron collision

 

To view this discussion visit https://groups.google.com/a/muonsinc.com/d/msgid/g4beamline/51f1c404-e63a-4e07-9bdf-5fc76eabd27d%40sbcglobal.net.

[Daniel Kaplan]

Hi Claudio,

        As an experiment I tried the attached deck, disabling a bunch of processes but using no particlefilter. It runs quite quickly and the results seem not unreasonable. For a million positrons incident on the (artificially dense) H2 target (which took only 25 s on my Mac), only positrons and electrons are recorded in the ntuple. The electron momentum distribution is attached, as well as the momentum distribution of all detected particles (i.e., electrons plus positrons) and of all positrons.

        I would continue by writing a simple Python program that would read in the ntuple, Lorentz-transform it to the CMS frame, and write an output ntuple that could be read by the G4beamline beam command. This should all be quite straightforward. A second G4beamline job could then read in the Lorentz-transformed ntuple and track the secondary particles through your desired colliding-beam detector configuration.

        You can of course tinker with the parameters however you like, or abandon this approach as undesirably complicated.

        Dan

> On Jan 20, 2025, at 8:17 PM, Daniel Kaplan <kap...@iit.edu> wrote:
>
> But you could possibly simulate a positron beam on a fixed hydrogen target at the equivalent fixed-target energy, with some kind of particlefilter to kill interactions with protons. You could then Lorentz-transform the resulting ntuple of outgoing particles to the CMS frame and read it back into G4beamline to track the secondaries. Would that be convenient enough to be worth the trouble?
>
> Dan Kaplan
>
> Get Outlook for iOS