[Clas12_verystrange] [EXTERNAL] Electron energy correction

[William Phelps]

Hello Geraint,

I have been thinking about this electron correction (briefly). It seems to me that it would make sense to have the correction as a ratio P_missing/P_reconstructed as a function of P_reconstructed. So all we would need to do is scale the electron momentum (and recalculate energy). You mentioned that you are going to take another look at your correction during the meeting, is this what you are thinking about doing?

I attached a 2d histogram that might make more sense than what I said in the paragraph above.

A secondary question to the group: If the reconstructed momentum is incorrect does this mean that the angle is also incorrect?

Thanks,
-Will

[cid:F253E635-7957-40F7-B576-8A35BD3956D6]

On Apr 3, 2020, at 9:58 AM, Geraint Clash <geraintclash at gmail.com<mailto:geraintclash at gmail.com>> wrote:

Hello all,

I carried out a study on the difference between the energy of the electron when you treat it as missing and the measured electron using skim3 data from this path: /volatile/clas12/users/clas12/rich/dst/recon/005038/. For this, the exclusive reaction ep->e’p pi+pi- was selected, with three-sigma cuts around missing mass squared of all products and the missing mass of the proton.
The plot of the difference in energy ("missing" electron - detected electron) against the electron measured energy is the attached file Del_E. Y-projections were fitted with Gaussians and the means were fitted with a fourth-order polynomial establishing the correction function (see attached).

The energy correction which should be added to the measured electron energy, E, is: -0.0004x^4+0.0071x^3-0.0432x^2+0.1356x-0.0257.

Thanks,
Geraint Clash.
<Del_E_mean_fit.png><Del_E.png>_______________________________________________
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