1. Study for rejection of muons from p/K decays Sergio Grancagnolo Stefania Spagnolo Andrea Ventura

2. Outline Definition of sample under study and goal p T spectra for selected particles Establish amount of events to generate Reproduction of p T spectra Rejection of p not in the spectrometer Identification of selection criteria DoneIn progressTo do

3. Sample under study minimum bias (MB) and dijets (J1-J8) data samples pythia csc11 v11000401 - v11004201 - v11004202 Dataset pT ranges (*) (GeV) expected cross-section (mb) Events analyzed MB92242287 J117 – 351.4242287 J235 – 709.3 E-02257508 J370 – 1405.9 E-0330299 J4140 – 2803.1 E-0410100 J5280 – 5601.2 E-055050 J6560 – 11203.6 E-0750000 J71120 – 22805.7 E-095050 J8>22802.4 E-1110100 (*) https://uimon.cern.ch/twiki/bin/view/Atlas/JetMissingET

4. Selection Cuts at athena level – select p, K, K L – p T > 500 MeV – |eta| < 2.7 Cuts at root level – p T > 2500 MeV – Distance to the interaction point = 0. Events with selected particles are weighted and merged for each MB and J1-J8 data sample Entries are rescaled to the minimum bias luminosity, corresponding to ~2.5×10 -3 nb -1

5. p T vs eta spectra for p Gaussian smearing is used for MB (J1-J2) events with pT > 8.8 (20) GeV

6. Reproduction of spectra pT vs eta spectra used for generation –Sliced in 31 pT bins (more dense where more events) –At higher pT values expo function is used to model pT –Pol2 function is used to model eta in each pT bin –Special treatment for last slice

7. Muon generation To estimate an efficiency of the order of 10 -4 with a relative error of 10% are required 10 6 muons in a certain pT bin range –Considering 10 pT bins of 500 MeV between 2.5 and 7.5 GeV –Factor 3 including endcaps –Expected 1 over 100 pions that decay before the calorimeter Required ~3×10 9 single pion events

8. Generation and simulation Event generation machinery ready to use for production –Generation of 10 5 events require 10 3 CPU sec and a disk space of 15 Mbytes –Expected to run less than 200 jobs into 1nd queue to produce all required statistic For simulation plans to use a G4 UserAction to save only events with a pion decaying before the muon spectrometer –This reduce by a factor 10 2 the amount of used disk space for simulation –Time not reduced