1. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Template Analysis of DRS Data  Motivations  Preliminary results F. Bedeschi, R. Carosi, M. Incagli, F. Scuri, INFN-Pisa DREAM Collaboration Meeting Rome, March 16, 2009 OUTLINE

2. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Motivations  Several problem found in standard electron analysis:  Baseline fluctuations  Signal at large t does not return to 0 (long tails in Cherenkov)  Non linearity and temperature drifts  Try using average signal as template for response  Mostly attempt to correct for baseline and signal shape problems  However …. non linearity and T drifts probably unaffected

3. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa The method  Analysis steps (1):  Preparation: Equalize towers with 50 GeV e  (runs 313-334 tower position scans) Use standard signal integral technique Select electrons: Sum Cherenkov + Scintillator signal cut   Tower isolation cut   Store average signal Different shape for each tower and type (S/Q)   Store as TSpline5 Normalize to peak Shift time scale: 0 = peak position Check: is it right shape for all events? Fit event displays with A f(t-t 0 ) + c    t0 constrained within 1.5 nsec Use A as measure of Scintillator/Cherenkov energy in tower Re-equalize/ normalize towers with 50 GeV electrons

4. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa The method  Analysis steps (2)  Basic standard analysis: For each event: fit each tower signal with form A f(t-t 0 ) + c 2*19 fits/event  use dedicated routine to speed up procedure Select electrons/pions as appropriate with usual cuts (sum, iso)sumiso Energy (S/Q) = sum A from all (S/Q) towers  Electron analysis plan: Compare resolution and linearity vs. E to what obtained by F. Scuri (see previous talk) and previous DREAM results  Pion analysis plan: Compare resolution and linearity to Scuri’s and previous DREAM results Apply dual readout correction

5. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Electron results (Linearity 1)  Gaussian fit of peaks  Looks good enough  Linearity definitions  Fit measured energy E* vs E beam E* = a*E beam  Fractional linearity: fL = (E*-a*E beam )/(a*E beam ) 20 GeV

6. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Electron results (Linearity 2)  Fractional linearity  S: max 8% @ 20 GeV – Q: max 4% @ 20 GeV  Better than Fabrizio’s analysis/consistent with DREAM paperspapers  Other findings  aS=0.94 / aQ=1.02:  S response changed ~ 6% after calibration Run 333

7. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Electron results (Resolution)  Definition:  Frac. Res. = sigma/mean  Sigma, mean from gaussian fit to energy peak  Results:  S: 28.2%/√E  6.1% Scuri: 33.0%/√E  6.1% DREAM: 23.8%/√E  6.7%  Q: 47.3%/√E  2.2% Scuri: 49.0%/√E  2.2% DREAM 40.0%/√E  2.2%

8. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Pion results  Uncorrected results  Gaussian fits OK  Mean lower that Ebeam  Correlation in S vs. Q E beam = 50 GeV S Q

9. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa DREAM  Basic math  Assumes calibration with electrons (ie. f=1)  Solving for E (Q/S method):  related to correlation between s and q:  Expected resolution: Scintillator: r s = (h/e) s = 0.77 Cherenkov: r q = (h/e) q = 0.2 You don’t always improve!! ~ 0.28

10. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Pion results  Data correction  Extract from fit of S vs Q correlation plot  Define corrected energy as E = (s- q)/(1- )  Results:  @ 50 GeV calibration restored  ~ 0.6 much bigger than expected E beam = 50 GeV S Q S Q

11. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Pion results  Linearity  Uncorrected data consistent with DREAM  Correction works well for 50 and 100 GeV, but ─15% @ 20 GeV +10% @ 200 GeV DREAM

12. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Pion results  Resolution  Q: 97.1%/√E + 8.2% 116%/√E + 6.4% Leak corrected  S: 53.2%/√E + 6.5% 61%/√E + 4.0% Leak corrected  E corr = 55.9%/√E + 10.1% 68.7%/√E + 5.2% Leak corrected  Comments  Results worse than DREAM  No improvement with Q/S correction DREAM 2005 No leakage corr......... NO correction ------ Leakage corrected

13. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa A note on resolution  Look at resolution vs Q-S correlation at constant  Q /Q and  S /S

14. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Conclusions  Electron analysis  Template technique improves both linearity and resolution with respect to the standard analysis by F. Scuri  Results still do not reach the level of accuracy shown in previous DREAM papers  Pion analysis  Linearity problems at 20 and 200 GeV Possibly problems with data quality  Resolution results puzzling as dual readout correction does not appear to improve the energy resolution Correlation parameter is inconsistent with DREAM value  More work needed to understand the source of all these problems

15. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Type Selection (S vs. Q)  Cut on Q+S:  Clean selection of electron, pions and muons  Q, S refer to single tower signals Electrons Hadrons Mu S+Q Q S back

16. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Type selection (isolation)  Fraction of Energy in hit tower:  Require > 90% for electrons ( 20% for pions)  Plot shown is after Q+S cut back ee ee  

17. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Typical reference signal shapes  Typical templates of signal time evolution  Hor. Scale 1 = 0.5 nsec  Zero of timeline shifted to position of peak Ch. #1 back

18. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa Event displays  Fits to event displays back

19. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa DREAM electrons  NIM A 536 (2005)  Electron linearity back

20. DREAM Coll. Meeting, Rome 2009F. Bedeschi, INFN-Pisa DREAM pions  NIM A 537 (2005) 537–561 back