1. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson The next 10 years in Particle Astrophysics Workshop summary Some personal observations Tribute to Alan

2. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Solar flare shock acceleration Coronal mass ejection 09 Mar 2000 09 Mar 2000

3. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson SOHO/ LASCO CME of 06-Nov 1997

4. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Lessons from the heliosphere ACE energetic particle fluences: Smooth spectrum –composed of several distinct components: Most shock accelerated Many events with different shapes contribute at low energy (< 1 MeV) Few events produce ~10 MeV –Knee ~ Emax of a few events –Ankle at transition from heliospheric to galactic cosmic rays R.A. Mewaldt et al., A.I.P. Conf. Proc. 598 (2001) 165

5. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Heliospheric cosmic rays ACE--Integrated fluences: –Many events contribute to low-energy heliospheric cosmic rays; –fewer as energy increases. –Highest energy (75 MeV/nuc) is dominated by low-energy galactic cosmic rays, and this component is again smooth Beginning of a pattern? R.A. Mewaldt et al., A.I.P. Conf. Proc. 598 (2001) 165

6. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Knee Ankle Highest energy cosmic rays E max ~  shock Ze x B x R shock for SNR –  E max ~ Z x 100 TeV –Many potential sources Knee region: –Differential spectral index changes at ~ 3 x 10 15 eV,    –Some SNR can accelerate protons to ~10 15 eV (Berezhko & Völk) –10 16 to 10 18 eV: a few special sources? Reacceleration? Ankle at ~ 3 x 10 18 eV: –Flatter spectrum –Suggestion of change in composition –New population of particles, possibly extragalactic? Look for composition signatures of “knee” and “ankle” Extragalactic? galactic

7. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson 30 Rigidity-dependence Acceleration, propagation – depend on B: r gyro = R/B –Rigidity, R = E/Ze –E c (Z) ~ Z R c r SNR ~ parsec –  E max ~ Z * 10 15 eV – 1 < Z < 30 (p to Fe) Slope change should occur within factor of 30 in energy Characteristic pattern of increasing A with energy

8. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Direct measurements to 100 TeV: No major composition change RUNJOB: thanks to T. Shibata ATIC (preliminary): thanks to E-S Seo & J. Wefel

9. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Recent Kascade data show increasing fraction of heavy nuclei 10 15 -3x10 16 eV Note anomalous He / proton ratio in recent Kascade analyses K-H Kampert et al., astro-ph/0204205 ICRC 2001 (Hamburg) M. Roth et al., Proc ICRC 2003 (Tsukuba) vol 1, p 139

10. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Völk & Zirakashvili, 28 th ICRC p. 2031 Galactic models of knee & beyond: conspiracy or accident? Axford: –continuity of spectrum over factor 300 of energy implies relation between acceleration mechanisms – reacceleration by multiple SNR V ö lk: – reacceleration by shocks in galactic wind (analogous to CIRs in heliosphere) Erlykin & Wolfendale: –Local source at knee on top of smooth galactic spectrum – (bending of “ background ” could reflect change in diffusion @ ~1 pc) What happens for E > 3x10 16 eV? Erlykin & Wolfendale, J Phys G27 (2001) 1005

11. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Chem. Composition A MANDA 1 km 2 km SPASE-AMANDA Astropart. Phys. (2004) AMANDA (number of muons ) Spase (number of electrons) Iron Proton log(E/PeV) SPASE (Bartol-Leeds)

12. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Rates of contained, coincident events in IceCube Area--solid-angle ~ 1/3 km 2 sr (including angular dependence of EAS trigger) 3000 x aperture of SPASE-AMANDA

13. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson IceTop station Two Ice Tanks 3 m 2 x 0.9 m deep (scaled down from Haverah, Auger) Integrated with IceCube: same hardware, software Coincidence between tanks = potential air shower Signal in single tank = potential muon Significant area for horizontal muons Low Gain/High Gain operation to achieve dynamic range Two DOMs/tank gives redundancy against failure of any single DOM because only 1 low-gain detector is needed per station

14. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Large showers with E ~ 100-1000 PeV will clarify transition from galactic to extra-galactic cosmic rays. Showers triggering 4 stations give ~300 TeV threshold for EAS array Small showers (2-10 TeV) associated with the dominant  background in the deep detector are detected as 2-tank coincidences at a station. Detection efficiency ~ 5% provides large sample to study this background

15. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Test station deployed at South Pole November, 2003

16. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Filling 03/04 test tanks Tank10 (1 m deep) – Filled Nov 22, 2003 20 minutes to fill < 10 RPSC man hours for transport and filling Tank09 ( 0.9 m ) –Filled Nov 26, 2003 Freeze time 60+ days – 40 days planned –Plan revised to finish freeze after closing tank

17. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Tanks closed Jan 23-26 a) Dec 6 during freeze (cover used as extra sun shade) b) Jan 23 after closing, tent used as outer cover over black vinyl sheeting Tank10 during freeze and after closing

18. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Feb 10/11, 2004 Tank 9 with  telescope Tank 10 Remote operation since February pre-pre-production DAQ and main board monitoring temperatures during austral winter limited muon data

19. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Primary composition with IceCube N  from deep IceCube; N e from IceTop High altitude allows good energy resolution Good mass separation from N  /N e 1/3 km 2 sr (2000 x SPASE-AMANDA) Covers sub-PeV to EeV energies Simulations of R. Engel

20. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Transition from Galactic to Extra- galactic origin? Where is the transition? (Hillas’ talk) Composition signature: –From mostly heavy primaries at end of galactic origin to large fraction of protons Continuous coverage over a large energy range would be helpful (G Thomson’s talk)

21. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson = 0, E > 3 10 16 eV Protons = 4 ±2, E ~ 10 15 eV Elongation rate, X max & composition (Linsley & Watson 1981) X max = ln(E 0 /A) + B Analysis of fluctuations in rise-time, 1973: “…departure of individual showers from the mean behaviour … most readily understood if some of the primary particles of energy E ~ 10 18 eV are light, probably protons…” ---A.A. Watson & J.G. Wilson, 1974

22. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Change of composition at the ankle? Original Fly’s Eye (1993): transition coincides with ankle G. Archbold, P. Sokolsky, et al., Proc. 28 th ICRC, Tsukuba, 2003 HiRes new composition result: transition occurs before ankle

23. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Exposure of giant arrays (as of ICRC-2003, thanks to M.Teshima) 10 18 -10 19 eV threshold regime

24. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson More questions about UHECR What are the sources: – GRB? (Waxman), AGN? (Berezinsky), Top-down? (Sigl) Does spectrum continue past GZK limit? What is the distribution of sources? – Medina- Tanco, Olinto, Sommers –Clustering? – How many sources? –Point sources? –Galactic halo distribution? –Importance of magnetic fields? Need all-sky coverage for full picture

25. Energy content of extra-galactic component depends on location of transition Normalize @ 10 19 eV:  CR = 2 x 10 -19 erg/cm 3 Power ~  CR / 10 10 yrs ~ 10 45 erg/Mpc 3 /yr Uncertainties: Normalization point: 10 18 to 10 19.5 used Factor 10 / decade Spectral slope  =2.3 for rel. shock = 2.0 non-rel. E min ~ m p (  shock ) 2

26. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson GRB model Assume E -2 spectrum at source, normalize @ 10 19.5 10 45 erg/Mpc 3 /yr ~ 10 53 erg/GRB Evolution like star- formation rate GZK losses included Galactic  extragalactic transition ~ 10 19 eV Bahcall & Waxman, hep-ph/0206217 Waxman, astro-ph/0210638

27. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Berezinsky et al. AGN Assuming a cosmological distribution of sources with: –dN/dE ~ E -2, E < 10 18 eV –dN/dE ~ E , 10 18 < E < 10 21 –  = 2.7 (no evolution) –  = 2.5 (with evolution) Need L 0 ~ 3 ×10 46 erg/Mpc 3 yr They interpret dip at 10 19 as –p +  2.7   p + e + + e - Berezinsky, Gazizov, Grigorieva astro-ph/0210095

28. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Plot from HiRes, astro-ph/0208301 Does spectrum exceed GZK? AGASA now finished –No sign of cutoff –Clusters  10 -5 sources/Mpc 3 HiRes –Consistent with GZK cutoff –No clustering observed Auger South –Should answer the question within a year or so

29. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson UHECR Spectrum Haverah Park Edge et al., 1973 1 event per km 2 per century with E > 10 20 eV

30. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Connection to  -rays and Talks of Völk, Hinton, Weekes, Mirzoyan Is there more than electron acceleration in GRB and AGN ? Zas: p/ as a probe of top-down vs acceleration models of UHECR –Also probes evolution of sources

31. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson New experiments Telescope array Auger North EUSO Neutrino telescopes –AMANDA, Baikal continue in short term –ANTARES (& Nestor) in 2005, 2006? –IceCube –Km 3 in Mediterranean –Radio detection for UHE

32. Matter Distribution 7 Mpc < D < 21 Mpc Cronin astro-ph/0402487 [Kravtsov]

33. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Closing remarks Thanks to –Johannes, Jeremy and colleagues –to Carol Ward and Maria –to Mansukh Patel Thanks to Auger Collaboration for a great experiment Best wishes to Alan for future science

34. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Power needed for extragalactic cosmic rays assuming transition at 10 19 eV Energy density in UHECR,  CR ~ 2 x 10  erg/cm 3 –Such an estimate requires extrapolation of UHECR to low energy –  CR = (4  /c)  E  (E) dE = (4  /c){E 2  (E)}  E=10 19 eV x ln{E max /E min } –This gives  CR ~ 2 x 10  erg/cm 3 for differential index  = 2,  (E) ~ E -2 Power required ~  CR /10 10 yr ~ 10 45 erg/Mpc 3 /yr –Estimates depend on cosmology and extragalactic magnetic fields: –3 x 10 -3 galaxies/Mpc 3 5 x 10 39 erg/s/Galaxy –3 x 10 -6 clusters/Mpc 3 4 x 10 42 erg/s/Galaxy Cluster –10 -7 AGN/Mpc 3 10 44 erg/s/AGN –~1000 GRB/yr 3 x 10 52 erg/GRB Assume E -2 spectrum. Then signal ~ 10 to 100/km 2 yr –~20% have E  >50 TeV (greater than atmospheric background)

35. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Remote operation of DOMs Pre-production main boards; pre- production DAQ –Use SPASE GPS clock for time stamp –Slow readout (large dead-time) No local coincidence Study main board temperatures during austral winter

36. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Remote operation of DOMs

37. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Energy-dependence of secondary/primary cosmic-ray nuclei B/C ~ E -0.6 Observed spectrum: –  (E) = dN/dE ~ K E -2.7 Interpretation: –Propagation depends on E –  (E) ~ E -0.6 –  (E) ~ Q(E) x  (E) x (c/4  ) Implication: –Source spectrum Q(E) ~ E -2.1

38. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Problems of simplest SNR shock model Expected shape of spectrum : –Differential index  ~ 2.1 for diffusive shock acceleration  observed ~ 2.7  source ~2.1;  ~ 0.6   esc (E) ~ E -0.6 c  esc  T disk ~100 TeV  Isotropy problem E max ~  shock Ze x B x R shock –  E max ~ Z x 100 TeV with exponential cutoff of each component –But spectrum continues to higher energy:  E max problem Expect p + gas   (TeV) for certain SNR –Need nearby target as shown in picture from Nature ( April 02) –Interpretation uncertain; see Enomoto et al., Aharonian (Nature); Reimer et al., astro-ph/0205256 –  Problem of elusive  0  -rays

39. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson Speculation on the knee K-H Kampert et al., astro-ph/0204205 3 components   Total protons helium CNO Mg… Fe

40. Tom Gaisser, Leeds, July 23, 2004 in honor of Alan Watson UHECR spectrum Haverah Park, Edge et al., 1973