Attendees: Guang Yang (GY), Ciro Riccio (CR), Shih-Kai Lin (SKL), David Last (DL), Andriaseta Sitraka (AS), Chang Kee Jung (CK), Wilf Shorrock (WS), Vittorio Paolone (VP), Eric Chong (EC), Christopher Mauger (CM), Dana Douqa (DD), Perri Zilberman (PZ), Abraham Meles Teklu (AT)
Update on the reconstruction - Eric Chong
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CK: Slide 7: How PE is generated in MC? GY: MeV to PE conversion from SFGD data for which is 70 PE/MeV per fiber (before attenuation and MPPC correction). CK: How did they get that? DD: The value are extracted from 5x5 cm early prototype. GY: We will look at CERN proton data to further tune this conversion.
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CM: Slide 8: simulation with full detector? DD: Yes, full detector.
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CK: Slide 12: MC and data are different so you should use a different PE cut on data.
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CM: Slide 14: You have a neutron interactions and you have a single protons tracks, correct? GY: This is correct. Caveat: The spectrum of the neutron is flat. GM: How many events? EC: 17k neutron events. CM: last bullet:
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CM: What is the chi2 you are using? GY: It is defined as the minimal distance between the line and the voxel. CR: This is not a chi2, but the minimum of the minimized function (FCN in Minuit language).
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CM: This chi2 seems a different definition of linearity.
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CK: Suggestion: Showing efficiency and purity is good, but you should look first at the chi2 distribution first and the linearity distribution.
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DL: Slide 18: That the energy drop at 725 MeV looks odd. Make sure that the energy computation is correct, in particular the time window.
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CK: Slide 18: Why some bins are empty? DL: Those bins are finer than the resolution. GY: This is well know.
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CK: Slide 20: How can linearity be 0.9922 for this track? Linearity is not working, then.
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We will finish this discussion next week.
Invisible scattering update: vertices spread - Guang Yang
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CK: Slide 7: why two blue points at 0? GY: The one at (0,0) is a reference.
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CK: Why there are three blue and no black? Slide 11: They overlap.
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CK: Beamline scientist should have information about the shape of the beam spot. GY: For 90 m location and the collimator we used they do not have this information.
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CR: Slide 6: Can you add the RMS for each plot? It will help in visualizing the spread.
