1. First look at non-Gaussian tails with the new Reconstruction Stathes Paganis Univ. of Sheffield LAr-H8 Working Group, 18-Oct-05

2. 18-Oct-05Non-Gaussian tails2 Data and MC: as in Gargnano  Runs: Period 5 (20,50,100,180GeV) Proposed by Isabelle W. from August, no extra Al material.  Simulation: 10.5.0 PS E-field extends 13/11 longer in MC. Added 0.15X0 close and 0.15X0 far  Recon: 10.5.0 + Tags by Marco OFCs : TB04-9 Pedestals: HEAD, Ramps, ADC2uA: TB04-default uA2MeV: “new set” TB04-default  Final Analysis (Gargnano): 0.91*Estrips (Data: first rough cross-talk approximation) 0.84*11/13*Eps (MC: to account for E-field extend) 0.97*Erec (MC: just a normalization) New

3. 18-Oct-05Non-Gaussian tails3 100GeV runs beam profiles (reweighted) The dip doesnot appear in the MC Data MC Question 1: what is the origin of the dip?

4. 18-Oct-05Non-Gaussian tails4 Uncorrected energy distribution Question 2: what is the origin of the tail

5. 18-Oct-05Non-Gaussian tails5 100GeV: Energy vs eta and phi profiles At lower eta we still see the dropA dip is seen at 0.008 only for data Remember as in Gargnano: a cut in eta reduces the tail dramatically

6. 18-Oct-05Non-Gaussian tails6 Eta vs Phi profile Phi Dip here

7. 18-Oct-05Non-Gaussian tails7

8. 18-Oct-05Non-Gaussian tails8 100GeV: Sampling energies I reduced the MC by 16% (data shifted down in the new version) Low energy tail

9. 18-Oct-05Non-Gaussian tails9 Observations on the tail events (50,100GeV run) 1. Cell energies: Ecell22 significantly lower 2. Middle Energy: significantly lower 3. Strips Energy: in very good agreement (!) 4. PS energy: shifted higher 5. Back energy: significantly lower 6. Eta of cluster: slightly shifted towards lower eta 7. Phi of cluster: slightly shifted towards lower phi 8. Tile Energy: small deposition in the tile

10. 18-Oct-05Non-Gaussian tails10 Based on these observations:  Cannot be pions: (observations 4, 8)  Cannot be lower E electrons: (4, 8)  They look like early showers: (4, 5)  They are not in our simulation.  Reminder: in photon runs, electrons show no tails My (strong) conclusion: Most of the tail comes from early showers far upstream the calorimeter. This contribution is not simulated. Most of the tail comes from early showers far upstream the calorimeter. This contribution is not simulated. To check the theory we need an early shower tagger: (a scintillator with a few cm hole would do; muHalo)

11. 18-Oct-05Non-Gaussian tails11 Ecluster vs muHalo

12. 18-Oct-05Non-Gaussian tails12 Tail reduced, eta dependence smaller The muHalo hole is 3.4 cm, so we can only veto rather developed showers.

13. 18-Oct-05Non-Gaussian tails13 Middle Sampling: Before/after muHalo cut:

14. 18-Oct-05Non-Gaussian tails14Conclusions/Plans  Part of the energy tail seems to come from early showering far upstream.  The tail has eta dependence  Addition of material in the MC will destroy the existing good agreement (since Gargnano) Unless we add more material at lower eta!  Dip structure in phiRec remains a puzzle. It looks like there is more (non-simulated) material in front of the strips in this region  It is clear that at some point we will have to decide on certain (optimum) cleaning cuts.

15. 18-Oct-05Non-Gaussian tails15 Extra slides

16. 18-Oct-05Non-Gaussian tails16 muHalo and eta cuts

17. 18-Oct-05Non-Gaussian tails17 Ecell32 energy vs phi