1. Laboratory Astrophysics in Taiwan-studying properties of cosmic ray showers using NSRRC 1.5 GeV electron beam G.-L. Lin National Chiao-Tung U. Taiwan KAW4 2006

2. Outline General Features of Laboratory Astrophysics Fluorescence Measurements Using SLAC 28.5 GeV e - beam Cherenkov Measurements Using NSRRC 1.5 GeV e - beam Concluding remarks

3. 1. Calibration of observations - Precision measurements to calibrate observation processes - Development of novel approaches to astro-experimentation - Though non-exotic, value to astrophysics most certain 2. Investigation of dynamics - Astro-conditions hard to recreate in the lab - Many MHD or plasma processes scalable by extrapolation 3. Probing fundamental physics - Underlying physical principles in nature still to be discovered - Extreme limits render signatures faint – a challenging task - Though challenging, potential returns in science most significant General Features of LabAstro -Using Lasers and Particle Beams as Tools - P. Chen, Workshop on laboratory astrophysics using high intensity particle and photon beams.

4. Fluorescence from Air in Showers (FLASH) J. Belz 1, D. Bergman 5, Z. Cao 2, F.Y. Chang 4, P. Chen 3*, C.C. Chen 4, C.W. Chen 4, C. Field 3, P. Huentemeyer 2, W-Y. P. Hwang 4, R. Iverson 3, C.C.H. Jui 2, G.-L. Lin 4, E.C. Loh 2, K. Martens 2, J.N. Matthews 2, J.S.T. Ng 3, A. Odian 3, K. Reil 3, J.D. Smith 2, P. Sokolsky 2*, R.W. Springer 2, S.B. Thomas 2, G.B. Thomson 5, D. Walz 3, A. Zech 5 1 University of Montana, Missoula, Montana 2 University of Utah, Salt Lake City, Utah 3 Stanford Linear Accelerator Center, Stanford University, CA 4 Center for Cosmology and Particle Astrophysics (CosPA), Taiwan 5 Rutgers University, Piscataway, New Jersey * Collaboration Spokespersons

5. The Motivation For FLASH The ultra-high energy cosmic ray (UHECR) spectra measured by HiRes (fluorescence) and AGASA (scintillation counter ground array) differ significantly in slope for E~10 20 eV. This discrepancy can be possibly accounted for by a systematic difference in the energy scale (~25%)

6. The Detection of UHECR Air Fluorescence Detector: HiRes AGASA Detector Hybrid: Auger

7. The Energy Reconstruction of UHECR in the Fluorescence Technique Fitted from the atmospheric scintillation process—model independent ! D. J. Bird et al., APJ 424, 491-502,(1994)  How well do we know the fluorescence efficiency?  Can the fluorescence yield accurately reconstruct the longitudinal profile N e (X)? Integrating the energy deposition along the path and correcting for missing energy

8. SLAC E-165 Experiment Fluorescence in Air from Showers (FLASH) 28.5 GeV e - beam

9. Beam spot monitor Main fluorescence chamber Grating spectrograph Beam dump Toroid The thin target Experiment Layout PMT Filter wheel LEDs Fluorescence vessel bafflers

10. The Existing Air Fluorescence Yield Measurements—without Showers Kakimoto et al., NIM A372 (1996) Nagano et al., Astroparticle Physics 20, 293-309 (2003) Belz et al., to appear in Astroparticle Physics; astro- ph/0506741 Huentemeyer et al., presented at ICRC 05

11. Thick Target apparatus Available shower depth: 2,4,6,8,10,14 radiation lengths Ion chamber

12. Universal electron energy distribution in different shower ages F. Nerling et al., astro-ph/0506729 The shower age S=3X/(X+2X max ) determines the electron-positron spectrum. Mean electron (positron) energies near the shower maximum are very similar for primary 30 GeV electrons and primary 10 19 eV protons —superposition at works! SLAC is a right place as 3  10 10 eV  5  10 8 /bunch~10 19 eV. Back to 15

13. The Fluorescence Technique Validated Comparison of fluorescence yields and ionization longitudinal profiles. The sum of points in each profile is independently normalized to unity. The ion chamber data points correspond to slightly larger radiation lengths. Both fluorescence and ionization longitudinal profiles agree well with simulations(Geant3 and EGS4). astro-ph/0510375, to appear in Astroparticle Physics

14. Studying Cherenkov light from air showers with NSRRC 1.5 GeV e - beam T.C. Liu a, F.Y. Chang a, C.C. Chen b,C.W. Chen b, Y. T. Yang d, K.T Hsu. d,M.A. Huang c, P.W.Y. Hwang b, G.L. Lin a (a) Institute of Physics, National Chiao-Tung University, 1001 Ta Hsueh Rd., Hsin- chu, 300, TAIWAN, ROC. (b) Institute of Astrophysics, National Taiwan University, 1, Sec. 4, Roosevelt Rd. Taipei, 106, TAIWAN, ROC. (c) Department of Physics, National United University, 1, Lien-da, Kung-ching Li, Miao-Li, 36003, TAIWAN, ROC (d) National Synchrotron Radiation Research Center

15. Motivation Cherenkov light is an important background in the fluorescence measurement. A correct estimation of this contribution is needed. F. Nerling et al. for Auger Collaboration, ICRC 05 Previous estimation of Cherenkov contribution were based upon simulations. It is desirable to have a direct measurement. Page 12 Page 30

16. NSRRC (National Synchrotron Radiation Research Center) 1993 Apr. First beam stored in the storage ring Oct. Taiwan Light Source Dedication Ceremony 2000 Feb. 1.5 GeV full energy injection

17. The 1.5 GeV electron beam National Synchrotron Radiation Research Center Each bunch carries 10 9 electrons Total energy ~ 1 EeV The electrons are injected from booster ring with 10 Hz frequency

18. Exp

19. Experimental Platform 1.5 GeV electron beam Removable radiator system Light path Thin Foil Lateral Profile Each block contains 1/3 R.L. 10cm 2.9cm 10cm 1 r.l.=8.9 cm

20. The CCD quantum efficiency is not uniform Fluorescence contributions arise between 300 nm and 400 nm.

21. CCD Background—beam off

22. We have also subtracted the background with beam on and the chamber in vacuum.

23. 2.3 r.l. Shower maximum

24. 5 r.l. Shower maximum

25. Preliminary Shower maximum occurs at 2.3 r.l. Counts at 0 r.l. subtracted

26. One incident electron Shower maximum GEANT4 simulations e-e+γe-e+γ

27. One incident electron 15 blocks

28. Shower maximum occurs near 2.3 r.l. Shower longitudinal profiles @4.5  10 6 simulations

29. Separately normalized to respective total counts/event # Preliminary A consistency check

30. The Cherenkov photon yield verse particle energy The simulated longitudinal profile has to be folded with Cherenkov photon yield. Back to 15

31. Geant 4 simulation with Cherenkov photons

32.  The fluorescence contribution has to be subtracted from the data—using simulations tested by FLASH thick target experiment.  Angular distributions of Cherenkov photons will be studied as well.

33. Concluding Remarks A brief history of laboratory astrophysics program in Taiwan was reviewed. We have shown the results of FLASH thin and thick target runs. The rationale of FLASH thick target run is applied to measure the Cherenkov light from particle showers using NSRRC 1.5 GeV electron beams. Work in progress!

34. Result: Fluorescence Spectrum 22nd Texas Symposium on Relativistic Astrophysics

35. Statistics low at low and high radiation lengths --to be improved Preliminary