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Hi Norman, We took a look at this and I think this is due to lack of depth/position correction (since the one in the reconstruction code is for data with b-field). There is an analytic correction that requires only geometry (track and crystal angles) and shower depth as inputs. And we have a measure of the shower depth for these same crystals measured from a previous experiment (albeit with photons, average energy around 1.5 GeV). If we estimate the average geometry from the 2-d plot you showed and remember that target is 4m upstream from ecal, this gives average expected y-errors of -2.5 mm for top and +2.5 mm for bottom, and -3 mm for x. This happens to be a good match with the residuals you measure. Need to parameterize the crystal angles as function of x/y and then send a correction for you to try. There also is a small x-rotation for top half of ecal from the survey which is not in lcsim. That could explain the difference in dx for top/bottom. -Nathan & Holly On Jul 29, 2015, at 14:40, Graf, Norman A. <[log in to unmask]> wrote: > Hello Stepan, > Yes, the residuals are cluster - track. > Norman > > -----Original Message----- > From: Stepan Stepanyan [mailto:[log in to unmask]] > Sent: Wednesday, July 29, 2015 11:38 AM > To: Graf, Norman A.; hps-software; [log in to unmask] > Subject: Re: SVT ECal relative alignment > > Norman, > > On X-axis, is it really cluster_position-track_postion? > > Stepan > > On 7/29/15 1:13 PM, Graf, Norman A. wrote: >> Hello All, >> I've taken the straight tracks from the field-off run 5784 and >> projected them to the Ecal. The residuals are plotted in the >> attachment using the z position of the cluster (which was essentially >> constant at 1393.7). Although the accuracy is quite good (~2.5 to ~3 >> mm) there are clear systematic shifts in both x and y for both top and >> bottom. Do these patterns make sense to anyone? I've also attached the >> cluster x-y positions, showing the fiducial cuts imposed on the clusters. >> >> I should note that these events were reconstructed using a >> non-production steering file. The calorimeter positions were taken >> from the uncorrected cluster collections pointed to by the >> ReconstructedParticle objects. The reconstruction did use the >> >> HPS-EngRun2015-Nominal-v2 >> >> detector which has the SVT survey incorporated. Have the ECal survey >> numbers been incorporated into this detector? If not, are these shifts >> commensurate with any of the measured offsets? >> Thanks, >> Norman >> >> ###################################################################### >> ## >> Use REPLY-ALL to reply to list >> >> To unsubscribe from the HPS-SOFTWARE list, click the following link: >> https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1 > > > _______________________________________________ > Hps-analysis mailing list > [log in to unmask] > https://mailman.jlab.org/mailman/listinfo/hps-analysis ######################################################################## Use REPLY-ALL to reply to list To unsubscribe from the HPS-SOFTWARE list, click the following link: https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1