Hi, I will like to broaden the distribution of this information and to point out that when you introduce cuts that remove 2/3 of all events even though they look marginal in the 2D plot we must understand the bias on the other distributions. One concern with the ZDC is that possible central events are thrown out? - Could you look at the distribution in Tile(mult) for the two classes of data. - The intensity in the band looks similar but could you quantify this ? The cut that we use to select 'good' events for spec analysis has also had a V(BB)-V(ZDC) cut of +-15 cm (2 sigma) and did cut out a large number of events. For Michael/Andreev what energy threshold was on the discr for module 2? Flemming ----- Original Message ----- From: "Bj|rn Hallvard Samset" <b.h.samset@fys.uio.no> To: "Flemming Videbaek" <videbaek@bnl.gov>; "Michael Murray Tel 409 845 1411,FAX 1899, Home 823 3386" <MURRAY@cycomp.tamu.edu>; <MAKEEV@comp.tamu.edu> Cc: "Trine Spedstad Tveter" <t.s.tveter@fys.uio.no> Sent: Monday, January 08, 2001 5:51 AM Subject: ZDC data reduction Good morning :-) I've had a brief look at the new zdc rdo module with the slewing corrections. What causes the loss in data is that earlier we only required that the tdc of the first module gave a value between 20 and 2040, while now the module demands an adc AND tdc value for modules 1 AND 2 between 0 and 2000. For the different cuts, in 50k events: Loose (old cut): 42086 Strong (new cut): 13679 But - the new cut drastically cleans up the data (as I suppose was the point in the first place). Have a look at the included ps-file to see the difference. The figure on the left shows how nice the corr. with BB has now become :-) I'll leave it to Michael and Andrei to say what the cuts should be in the code - we need to decide between cleanness of data and efficiency, I guess... ------------------------------------------------ Bjørn H. Samset Hovedfagsstudent, tungionefysikk Mob: 92 05 19 98 Lesesal: 22 85 77 62 Adr: Kri 2A709 Sognsveien 218 0864 Oslo
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