4D & 6D emittance by errors study

[Didier]

Dera Bruce,

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After looking for an explanation, I found in the Error_data.txt file that in some cases, the emittance error is negative, which I understand as the value is lower than the nominal. Is it correct?

Correct

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If that is the case, it could be that one random error selects emittance values lower than the nominal, thus, when I compared the emittance are lower than the nominal without beam losses.

I don't quite understand your comment. Unless you specifically requested it, the initial beam emittances of the simulations are strictly identical to the nominal beam.

Regards,

Didier

[Bruce Yee]

Dear Didier,

Thank you for your answers.

Please allow me to explain myself better.

About my previous comment
"If that is the case, it could be that one random error selects emittance values lower than the nominal, thus, when I compared the emittance are lower than the nominal without beam losses."

I mean that, when simulating the emittance error for statistical input beam errors, there are cases where the randomly assigned emittance error is negative, thus simulating a case with an emittance lower than the nominal one.
This special case can result in a final emittance lower than the nominal value. This explains why I obtained cases with lower emittance and no beam loss.

I hope my comment is clearer now.

Thanks for your help and time,

Bruce

[Didier]

Dear Bruce,

Ok, I didn't realise that you also put errors on the input emittances. So yes, the error may be negative and therefore cause what you observed because the reference emittance always remains that of the nominal beam.

Regards,

Didier

[Bruce Yee]

Dear Didier,

Thank you very much for your confirmation.

Best regards,

Bruce