1. Physics whit ACORDE (ALICE Cosmic ray detector) Arturo Fernández for ACORDE-ALICE group

2. Outline Cosmic ray physics with ALICE detectors Cosmic ray physics with ALICE detectors

3. ALICE: the dedicated HI experiment Solenoid magnet 0.5 T Central tracking system: ITS TPC TRD TOF MUON Spectrometer: absorbers tracking stations trigger chambers dipole Specialized detectors: HMPID PHOS Forward detectors: PMD FMD, T0, V0, ZDC Cosmic rays trigger

4. Contribution of ALICE to Cosmic ray physics Tune and tests of hadronic interaction models (pp, PbPb interactions) Tune and tests of hadronic interaction models (pp, PbPb interactions) A better comprehension of hadronic interactions at very high energy Fundamental for the description of CR interactions atmosphere. ACORDE + TPC + TRD + TOF ACORDE + TPC + TRD + TOF Sofisticated tracking system, precise measurement of particle momentum and muon energy up to 1-2 TeV (B = 0.5T) Sofisticated tracking system, precise measurement of particle momentum and muon energy up to 1-2 TeV (B = 0.5T) Capability to track high density of muons Capability to track high density of muons

5. Simulation programs to explain the data CORSIKA code  Hadronic interaction models : QGSJET, VENUS, DPMJET, NEXUS, SIBYLL … The models are tuned using data from accelerators p-p p-pbar A-A collisions. Usually at Tevatron energies ~ 10 15 eV or s 1/2 = 630 or 900 GeV LHC energy s 1/2 = 14 TeV  proton with E = 10 17 eV with fixed target Much above the energy of the knee of cosmic rays (E=3 10 15 eV) The most relevant measurements for ALICE are : the pseudo-rapidity distributions of identified hadrons the hadron transverse momentum distributions Considerable interesting should be the study of N-N interactions

6. Multiplicity distribution of charged particles with different hadronic interaction models Heck, Nucl. Phys B, 2003

7. Physics topics of interest Multi-muon events  most promising Multi-muon events  most promising CosmoAleph measurements CosmoAleph measurements Inclusive muons (single muon) Inclusive muons (single muon) L3+C measurements L3+C measurements Cosmic ray point sources, Antiproton flux limit Cosmic ray point sources, Antiproton flux limit Large area coincident experiment Large area coincident experiment

8. CHALLENGE: L3+C measurements “Measurement of the shadowing of high energy cosmic rays by the Moon: A search for TeV-energy antiprotons”, Astroparticle Phys. 23(2005)p411. “Measurement of the shadowing of high energy cosmic rays by the Moon: A search for TeV-energy antiprotons”, Astroparticle Phys. 23(2005)p411. “Observation of a Flare Signal from a fixed position in the hemisphere through muons with L3+C”, ICRC 2005. “Observation of a Flare Signal from a fixed position in the hemisphere through muons with L3+C”, ICRC 2005. “A search for low velocity exotic particles with the L3+C spectrometer”, ICRC 2005. “A search for low velocity exotic particles with the L3+C spectrometer”, ICRC 2005. “Search for Kolar-like Measurement of the atmospheric muon spectrum from 20 to 3000GeV”, Phys. Lett. B (2004)p15. events from L3+C data”, ICRC 2005. “Search for Kolar-like Measurement of the atmospheric muon spectrum from 20 to 3000GeV”, Phys. Lett. B (2004)p15. events from L3+C data”, ICRC 2005. “The L3+C detector, a unic tool-set to study cosmic rays”, NIMA 488(2002)p209. “The L3+C detector, a unic tool-set to study cosmic rays”, NIMA 488(2002)p209.

9. The trigger conditions Running during standard Alice data taking imposes stringent conditions for cosmic trigger : low trigger rate (few Hz) live time constrictions (statistical problems) Inclusive muons trigger  450 Hz (too high) We can take only vertical muons  60-70 Hz (high) Statistical problems to measure : Single muon momentum distribution and charge ratio Point source in a standard way Antiproton flux limit Multi-muon events  few Hz

10. Multi-muon events COAMOALEPH : Astroparticle Physics 19 (2003) 513-523 580000 events during 1997-99 runs t = 174 days of data taking t = 20 days effective run time Multim. events E  th = 70 GeV Standard LEP trigger : cosmic muons deposit energy in the e.m. and hadronic calorimeter Selection : events without reconstructed vertex at least one track p>5 GeV/c

11. Fe 10 12 <E<10 17 eV p 10 12 <E<10 17 eV Alice (Torino, Puebla) Aleph

12. Muon energy measurements Some contribution to disentangle among primaries could come from the measurement of the energy of each muon. This is a really new measurement never done in cosmic ray underground apparata Average energy of muons in the core for different number muons in the core of the shower. Proton and Fe primary E = 10 15 eV

13. Physics Performance Report Vol. II Cosmic ray physics 6.11