Measurement the Higgs mass via the channel: e + e - → Z H → e + e - + X & Analog vs. Digital Energy Reconstruction in the Si-W ECal Youssef KHOULAKI ILCP Meeting, CERN – Genève, 25/10/2010

ILC & ILD 25-Sep-102Y.khoulaki

25-Sep-10Y.khoulaki3 Detection of the Higgs boson from its production mechanism (Simulations) The H observation does not dependent on its decay mode Response provided whatever the scenario The H recoil mass is given by:

Parameters in simulations 25-Sep-10Y.khoulaki4 ILD_00 detector: M H = 120 GeV  s = 250 GeV e + polarization = 30% e - polarization = 80% L= 250 fb -1 Background: - SM events with 2 and 4 fermions including e+e- Identification of the Z boson: - Selection of the e+e- pair which gives the best mass for the Z boson : MZ reconstructed = MZ ± 10 GeV - Central leptons : |cos(  i)| < Opposite charges

25-Sep-10Y.khoulaki5 Event selection ( Cuts on kinematic variables) If you cannot see the values of the cuts, go on to the Backup slides

25-Sep-10Y.khoulaki6 Reconstruction of the Higgs recoil mass Signal measurement: Function Gaussian Peak Exponential Tail: Background measurement: Fitted by a polynomial sum Polarization mode (+,-)

25-Sep-10Y.khoulaki7 Reconstruction recoil mass Polarisation (30%, 80%) (+,-)(-,+) Signal seulSignal + BDFSignal seulSignal + BDF ± ± ± ± ± ± ± ± Presentation and proceedings at: International Linear Collider Workshop 2010 (LCWS10 & ILC10), Beijing : China, « Measurement of the Higgs mass via the channel » Y. Khoulaki, D. Benchekroun, L. Morin, J.Y. Hostachy

Analog and Digital Energy reconstruction Data : Energy reconstruction : N i : Number of hits in the compartment i (i=1,2,3) 8Y.khoulaki25-Sep-10

With experimental data Ehit > 0.5 MIPs (standard reconstructed data) Y.khoulaki25-Sep-109 Ehit > 0.5 MIPs  Linear behavior at low energy  Digital method better for E<2 GeV : Landau fluctuations CALICE Analysis Phone Meeting, November 10th 2008 « Comparison of analog and digital energy measurements using DESY-2006 data » D. Benchekroun, Y. khoulaki

New REC. DATA (without threshold ) Initializing the threshold : CALICE RAW2CALOHIT package //... _signalThreshold = 0.; // … New DESY Rec. Data: Our the results can be found at the addresses: 1 GeV : /grid/calice/users/khoulaki/tb-desy/My_REC_without_threshold/ Run230098_rec_kh.000.slcio 2 GeV : /grid/calice/users/khoulaki/tb-desy/My_REC_without_threshold/ Run230099_rec_kh.000.slcio 3 GeV : /grid/calice/users/khoulaki/tb-desy/My_REC_without_threshold/ Run230100_rec_kh.000.slcio 4 GeV : /grid/calice/users/khoulaki/tb-desy/My_REC_without_threshold/ Run230101_rec_kh.000.slcio 5 GeV : /grid/calice/users/khoulaki/tb-desy/My_REC_without_threshold/ Run230104_rec_kh.000.slcio 6 GeV : /grid/calice/users/khoulaki/tb-desy/My_REC_without_threshold/ Run230248_rec_kh.000.slcio  The thresholds are defined by hand during the analysis Y.khoulaki25-Sep-1010

Linearity and Resolution for different thresholds 0 MIPs ≤ E hit ≤O.2 MIPs 0.4 to 1 MIPs 0.3 MIPs Y.khoulaki25-Sep Same behavior for all energies - Better resolution around 0.2 – 0.3 MIPs E hit > 0.3 MIPs : E < 5 GeV E hit > 0.4 MIPs : E < 3 GeV

Y.khoulaki Methoda(%)C(%) Analog Analog + Digital (0.4 MIPs) Sep E < E cross : resolution taken from digital - E > E cross : resolution taken from analog

Y.khoulaki Data – MC Comparison (Number of hit Cells vs. Energy ) 25-Sep Digitization of MC done using a simple processor (from D. Ward) - No noise added to the non-hitted cells Red : MC Blue : DATA

Y.khoulaki Energy resolution vs. Thresholds (Comparison between the DESY data (in Red) and the MC predictions (in blue)) 25-Sep-1014

Conclusion for the Analog/Digital Part Digital method can give better resolution using lower thresholds ( MIPs) Results to be confirmed by MC simulations ( for the E hit > 0.4 MIPs) Next steps : digitization MC (with K. Krastev, LPSC) Simulations for 5x5 mm 2 detection pads Y.khoulaki25-Sep-1015 CALICE Collaboration meeting at Casablanca, September 22-24, 2010 «Analog vs. Digital Energy Measurement in the ECAL » Y. Khoulaki Y. Khoulaki, D. Benchekroun sId=0&materialId=slides&confId=4776

BACKUP SLIDES Y.khoulaki25-Sep-1016

Event selection (cuts on kinematic variables) 25-Sep-10Y.khoulaki17

Y.khoulaki25-Sep-1018 Total Number of hits for different Energy ( MC Prediction) Slide 6

Total Number of hits for different thresholds ( MC Prediction) Y.khoulaki25-Sep-1019

Resolution for different thresholds ( DESY DATA) Y.khoulaki25-Sep-1020

Y.khoulaki25-Sep-1021 Resolution for different thresholds ( MC Prediction)