1. Ricardo GoncaloReview Meeting 4th December 20011 Neutral Current: Ongoing Systematic Studies and loose ends SFEW Review Meeting 4 th December 2001 Chris Cormack Alexander Kappes Henning Schnurbusch Matthias Moritz Ricardo Gonçalo Photoproduction normalisation: Henning First inner ring and hadronization + Checks of new MEPS sample: Ricardo

2. Ricardo GoncaloReview Meeting 4th December 20012 Energy spectrum from Lumi-e detector for loose DIS cuts and E lumi-  < 2GeV E-p Z distribution with loose DIS cuts: MC generated with Et>30GeV Selection cuts: DST bit 12 Q 2 DA > 120 GeV 2 E lumi-  < 2 GeV (avoid bremstrahlung) 5 GeV < E lumi-e < 15 GeV (acceptance) E T > 30 GeV |Z-vertex| < 50 cm E electron CAL > 10 GeV Photoproduction normalisation

3. Ricardo GoncaloReview Meeting 4th December 20013 Photoproduction normalisation Herwig Et>10GeV (direct PhP only) & Pythia 96/97 (some visible DIS contribution) Herwig Et>30GeV + DJANGOH & Herwig Et>10GeV (direct PhP only) + DJANGOH

4. Ricardo GoncaloReview Meeting 4th December 20014 Hadronization and FCAL Inner Ring Remove IR energy from DA calculations for  had > 0.314rad ? Vary energy scale in IR ? Take cells for low  had or do W cut à la 96/97 ? Vary remnant parameters in Monte Carlo ? To do: Use all MC for better stats Redo properly with CureMyCalDoc From September Review Meeting: Ariadne reproduces the data except in FCAL 1st IR This affects low y / high x / low  had Need a good systematic error estimation in IR: - remove IR energy from DA calculations for  had > 0.314rad ? (??????) - vary energy scale in IR ? - take cells for low  had or do W cut à la 96/97 ? (problem with large syst. error) - Vary remnant parameters in MC? (no noticeable effect on en.flow) To do: Use all MC for better stats Redo properly with CureMyCalDoc Now: Ariadne  |Ariadne - MEPS| will be used as systematic error for several effects FCAL Inner Ring: several studies done

5. Ricardo GoncaloReview Meeting 4th December 20015 Hadronization and FCAL Inner Ring Sources of systematic error (hard to disentagle): FPC-FCAL leakage & backscattering Hadronisation (parton showers) Imprecise dead material map Angular non-uniformities of detector response Modelling of remnant For most of the phase space: Ariadne  |Ariadne - MEPS| Systematic for low y region: Is the  had measurement at high y affect by the very forward region ? Island -> Cells splitting ? W JB > 20 GeV cut ? Ariadne  |Ariadne - MEPS| - is this sufficient? Combined systematic error determination:

6. Ricardo GoncaloReview Meeting 4th December 20016 (Preliminary from Matthias & Henning) Eff = 50% but Syst Err = 140% (island splitting) Error > 50% Hadronisation at low y : Island -> cell splitting Do sum over cells for islands in FCAL with radius < 30 cm: For the reduced cross section, systematic errors around 2% except at low y DA One good bin shows very large effect

7. Ricardo GoncaloReview Meeting 4th December 20017 Checks of new MEPS sample Current MEPS sample was generated with Soft colour Interactions card ON New sample being generated for e-p: number of vertex refitted tracks now agrees with data Old and new sample seem to agree well in the hadronic energy flow: BUT Old MEPS (e+p) islands New MEPS (e-p) islands Old MEPS (e+p) cells New MEPS (e-p) cells

8. Ricardo GoncaloReview Meeting 4th December 20018 Checks of new MEPS sample - R.G.