Physics whit ACORDE (ALICE Cosmic ray detector)

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

2. Outline • Cosmic ray physics with ALICE detectors

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

4. Contribution of ALICE to Cosmic ray physics • 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 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

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 ~ 1015 eV or s1/2 = 630 or 900 GeV LHC energy s1/2 = 14 TeV  proton with E = 1017 eV with fixed target Much above the energy of the knee of cosmic rays (E=3 1015 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 CosmoAleph measurements • Inclusive muons (single muon) L3+C measurements • Cosmic ray point sources, Antiproton flux limit 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. • “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. • “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.

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 Multim. events Emth= 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 580000 events during 1997-99 runs t = 174 days of data taking t = 20 days effective run time

11. Alice (Torino, Puebla) Fe 1012<E<1017 eV p 1012<E<1017 eV 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 andFeprimary E = 1015 eV

13. Physics Performance Report Vol. IICosmic ray physics 6.11