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

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

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.

Fluorescence from Air in Showers(FLASH)

J. Belz1, D. Bergman5, Z. Cao2, F.Y. Chang4, P. Chen3*, C.C. Chen4, C.W. Chen4, C. Field3, P. Huentemeyer2, W-Y. P. Hwang4, R. Iverson3, C.C.H. Jui2,

G.-L. Lin4, E.C. Loh2, K. Martens2, J.N. Matthews2, J.S.T. Ng3, A. Odian3, K. Reil3, J.D. Smith2, P. Sokolsky2*, R.W. Springer2,

S.B. Thomas2, G.B. Thomson5, D. Walz3, A. Zech5

1University of Montana, Missoula, Montana2University of Utah, Salt Lake City, Utah

3Stanford Linear Accelerator Center, Stanford University, CA4Center for Cosmology and Particle Astrophysics (CosPA), Taiwan

5Rutgers University, Piscataway, New Jersey

* Collaboration Spokespersons

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~1020 eV.

• This discrepancy can be possibly accounted for by a systematic difference in the energy scale (~25%)

The Detection of UHECR

Air Fluorescence Detector: HiRes

AGASA Detector

Hybrid: Auger

The Energy Reconstruction of UHECR

in the Fluorescence Technique

L. R. :

0

00

dX

dE

X

E

eXdXXNX

EE

ionc

ec

em

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 Ne(X)?

Integrating the energy deposition alongthe path and correcting for missing energy

SLAC E-165 ExperimentFluorescence in Air from Showers (FLASH)

28.5 GeV e- beam

Beam spot monitor

Main fluorescence chamber

Grating spectrograph

Beam dump

Toroid

The thin target Experiment Layout

PMT

Filter wheel

LEDs

Fluorescence vessel

bafflers

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

Thick Target apparatus

Available shower depth: 2,4,6,8,10,14 radiation lengths

Ionchamber

Universal electron energy distribution in different shower ages

F. Nerling et al., astro-ph/0506729

•The shower age S=3X/(X+2Xmax) determines the electron-positron spectrum. •Mean electron (positron) energies near the shower maximum are very similar for primary 30 GeV electrons and primary 1019 eV protons —superposition at works! SLAC is a right place as 31010 eV5 108/bunch~1019 eV.

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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

Studying Cherenkov light from air showers with NSRRC 1.5 GeV e- beam

T.C. Liua, F.Y. Changa, C.C. Chenb,C.W. Chenb, Y. T. Yangd, K.T Hsu.d,M.A. Huangc, P.W.Y. Hwangb, G.L. Lina

(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

Motivation• Cherenkov light is an important background in the fluorescence me

asurement. 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.

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NSRRC (National Synchrotron Radiation Research Center)

1993 Apr. First beam stored in the storage ring Oct. Taiwan Light Source Dedication Ceremony2000 Feb. 1.5 GeV full energy injection

The 1.5 GeV electron beamNational Synchrotron Radiation Research Center

Each bunch carries 109 electrons

Total energy ~ 1 EeVThe electrons are injected from booster ring with 10 Hz frequency

Exp

Experimental Platform

1.5 GeV electron beam

Removable radiator system

Light path

Thin Foil

Lateral Profile

Each block contains 1/3 R.L.

10cm2.9cm

10cm

1 r.l.=8.9 cm

The CCD quantum efficiency is not uniform

Fluorescence contributions arise between 300 nm and 400 nm.

CCD Background—beam off

We have also subtracted the backgroundwith beam on and the chamber in vacuum.

2.3 r.l. Shower maximum

5 r.l. Shower maximum

Preliminary

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

One incident electron Shower maximum

GEANT4 simulations

e-

e+

γ

One incident electron

15 blocks

Shower maximum occurs near 2.3 r.l.

Shower longitudinal profiles @4.5106 simulations

Separately normalized to respective total counts/event #

Preliminary

A consistency check

The Cherenkov photon yield verse particle energy

The simulated longitudinal profile has to be folded with Cherenkov photon yield.

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Geant 4 simulation with Cherenkov photons

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.

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!

Result: Fluorescence Spectrum

22nd Texas Symposium on Relativistic Astrophysics

Statistics low at low and high radiation lengths--to be improved

Preliminary