sPHENIX bulk physics topical group

[Ejiro Umaka <ejironaomiumaka AT gmail.com>]

Hi Chris,

I don’t disagree. This is why I wanted to discuss this with a bigger audience. We won’t use the raw psi_2 in any case, but it will be good to know why they changed. I can look at the no pile up option (and now that I think of it, I probably did and got the same results). 

If we rule out pile up, what else changed in the simulation? In the past we just ran sHIJING with flow after burner.

Regards,

Ejiro 

On Thu, Apr 27, 2023 at 11:27 pinkenburg <pinkenburg AT bnl.gov> wrote:

Hi Ejiro,

I sincerely doubt that this is pileup. The epd integrates over a single
bunch crossing and for a single bunch crossing the pileup is somewhere
in the sub percent range. Basically the events you get from the sims for
the epd are single events without pileup. Also you can remove pileup
events from your analysis if you want to make sure

Chris



On 4/27/2023 11:14 AM, Ejiro Umaka wrote:
> Hi all,
>
> I've been working on the event plane determination for the EPD (and
> other subsystems). Initially (~ 2 years ago) when we first looked at
> the EPD raw psi_2, we got a flat distribution, but the most recent
> simulation results were not. The only thing I can think of as to what
> changed between then and now is pile-up in the current simulations.
> I proceeded to look at the phi -weighted psi_2 distributions and they
> are flat (attached)!
>
> I'd like to discuss this further at the EPD/bulk meeting next week.
>
> Best regards,
> Ejiro

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Christopher H. Pinkenburg       ;    pinkenburg AT bnl.gov
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