1. COSMIC RAY PHYSICS WITH AMS Joseph Burger MIT On behalf of the AMS-02 collaboration EPS2003 Aachen Particle Astrophysics July 17, 2003 Joseph.Burger@cern.ch

2. Cosmic Rays: p, D, He, C,…,e +,e -,γ Direct Search for Cosmic Antimatter Other Searches: Strangelets,… Dark matter search in morning session talk by Mariusz Sapinski

3. Cosmic Ray Flux AMS-02 is a large acceptance magnetic spectrometer which will extend high statistics measurements of cosmic ray properties to high rigidities.

4. AMS-02 3 years on ISS starting 2005-2006

5. Precursor Flight on STS91, June 2-12, 1998 10 days technical checkout also brought physics results and six publications: "Search for Antihelium in Cosmic Rays", M. Aguilar et al., Phys. Lett. B461 ( 2 Sep 1999) 387-396 "Protons in Near Earth Orbit", M. Aguilar et al., Phys. Lett. B472 (26 Jan 2000) 215-226 "Leptons in Near Earth Orbit", M. Aguilar et al., Phys. Lett. B484 (27 Jun 2000) 10-22 "Cosmic Protons", M. Aguilar et al., Phys. Lett. B490 (28 Sep 2000) 27-35 "Helium in Near Earth Orbit", M. Aguilar et al., Phys. Lett. B494 (30 Nov 2000) 193-202 "The Alpha Magnetic Spectrometer (AMS) on the International Space Station, Part I, Results from the test flight on the Space Shuttle", M. Aguilar et al., Physics Reports, vol. 366/6 (Aug.2002), pp.331-404. on e ±, p, antiprotons, D, He, antihelium,…

7. AMS-02 TRD (Transition Radiation Detector) Separates e ± from p, p̅ < 10 -2 -10 -3 from 10-300 GeV ToF (Upper Time of Flight) Velocity measurement, dE/dX, fast trigger Star Tracker (pointing to <1’) Superconducting Magnet 0.8T field for momentum, sign of charge Silicon Tracker 8 x-y planes with 10/30μm resolution, dE/dX Anticoincidence Counter Vetoes particles from outside trigger aperture ToF (Lower Time of Flight) Velocity measurement, dE/dX, fast trigger RICH (Ring Imaging Čerenkov Counter) Precision β measurement - separates isotopes ECAL (Electromagnetic Calorimeter) Separates e ± from p, p̅ < 10 -3 -10 -4

8. Transition Radiation Detector (TRD)  Highly relativistic charged particle generates photons at the boundary between media (ε r1 ≠ ε r2 )  Emission probability small (10 -2 )  20 layers  Photons detected in ~5300 straw tubes  Good photon identification: gas with high atomic number Z Xe:CO 2 80:20 TRD Beam Test

9. Time of Flight Counters Upper and lower each two layers of crossed scintillators Time-of flight to ~140psec for β and direction dE/dx measures Z (ΔE/E ~10% for MIPs)

10. Superconducting Magnet 2500 liters superfluid He planned to last 3 years without refill Field ~1T  measurement of rigidity to a few TV

11. Silicon Tracker Eight layers of double sided Si detectors ~10μm in bending direction, ~30μm orthogonal Measures rigidity up to a few TV Measures dE/dx for determining Z

12. Ring Imaging Cherenkov Counter (RICH) Accurate Velocity Measurements via Opening Angle of Čerenkov Cone   /  ~ 0.1%  Isotopic Separation. |Q| measurements Additional Particle Identification capability

13. Electromagnetic Calorimeter 16 X 0 of lead/scintillating fiber sandwiches Crossed layers for 3D sampling by 384 4-pixel PMTs ΔE/E ~ (12±0.4)%/√ E̅+(2.8±0.1)% (E in GeV) Distinguishes between hadrons and e,γ by shower shape Protons suppressed by 10 -3 -10 -4 from 10 to 300 GeV Together with TRD ~10 -6 Photon detector with angular resolution ~1°

14. Nuclei in Space The distribution of nuclei in cosmic rays is similar to the distribution in the solar system with some exceptions. Li (except 7 Li), Be and B were not produced in the primordial nucleosynthesis, nor made in stars, but by spallation reactions involving p and α colliding with C,N,O in supernovas. Measure cosmic ray confinement time in galaxy and mean density of interstellar matter.

15. AMS-02 Expected Performance 1 year 10 Be/ 9 Be ratio measurement Among all β-radioactive secondary nuclei in cosmic rays, 10 Be is the lightest isotope having a half-life comparable with the confinement time of cosmic rays in the galaxy (~2x10 6 yr). AMS-02 will be able to separate 10 Be from stable 9 Be in the range 0.15<E<10 GeV/n. AMS- 02 will collect 10 5 10 Be in 3 years.

16. AMS-02 Expected Performance 6 months B/C ratio measurement In 3 years AMS-02 will collect 10 5 C and 10 4 B with energies above 100 GeV/n, measuring the ratio of boron to its primary carbon up to 1 TeV/n

17. AMS-02 Expected Performance 1 day 3 He/ 4 He ratio measurement AMS-02 can distinguish 3 He from 4 He in the range 0.1<E<10 GeV/n

18. Search for Antimatter AMS-01 10 day precursor flight

20. Search for Antimatter AMS-02 sensitivity in 3 years

22. Dark Matter Search: AMS-02 e + Flux Structure in spectrum from SUSY neutralinos χ 0 Examples for m χ 336 GeV and 130.3 GeV

23. AMS-02 Antiproton Flux AMS-02 will measure the antiproton spectrum with a few percent energy resolution up to hundreds of GeV

24. Other Exotic Matter: Strangelets Heavy Particle with Low Charge Stable mixtures of u,d,s quarks with many different quarks in lowest energy state Signature is anomalous Z/A (Z~0.3A 2/3 )(nuclei Z/A=0.33-0.67)  AMS sensitive to ~10<A<3000

25. AMS-02 Sensitivity to Strangelets Shaded region from rough estimate of strangelet creation and absorption in galaxy (Chikanian et al.)

26. Search for doubly charged anomalously heavy nuclei with AMS-01 More than 4x10 6 He events collected during 10 day STS91 flight Searched for anomalously heavy nuclei (Z/A ~ β·γ·m proton /Rigidity) Tight quality cuts on measured rigidity and velocity One candidate event found, corresponding to flux 5x10 -5 (m 2 ·sr·sec) -1 Estimate background from ordinary nuclei < 10 -3 events

27. Summary / Conclusions COSMIC RAY PROPAGATION light isotope abundances ANTIMATTER SEARCH limit on antihelium/helium 10 -9 STRANGE MATTER SEARCH anomalous Z/A DARK MATTER SOMETHING NEW?