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ICRC 2003 in Tsukuba. Testing the HiRes Detector Simulation against UHECR Data. Andreas Zech ( Rutgers University) for the HiRes - Fly´s Eye Collaboration. J.A. Bellido, R.W. Clay, B.R. Dawson, K.M. Simpson University of Adelaide

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Testing the hires detector simulation against uhecr data

ICRC 2003 in Tsukuba

Testing the HiRes Detector Simulation against UHECR Data

Andreas Zech

( Rutgers University)

for the HiRes - Fly´s Eye Collaboration

Hires collaboration

J.A. Bellido, R.W. Clay, B.R. Dawson,

K.M. Simpson

University of Adelaide

J. Boyer, S. Benzvi, B. Connolly, C. Finley, B. Knapp, E.J. Mannel, A. O’Neil, M. Seman, S. Westerhoff

Columbia University

J. Belz, M. Munro, M. Schindel

Montana State University

G. Martin, J.A.J. Matthews, M. Roberts

University of New Mexico

D. Bergman, L. Perera,

S. Schnetzer, G.B. Thomson, A. Zech

Rutgers University

N. Manago, M. Sasaki

University of Tokyo

T. Abu-Zayyad, J. Albretson, G. Archbold,

J. Balling, K. Belov, Z. Cao, M. Dalton,

A. Everett, J. Girard, R. Gray, W. Hanlon, P. Hüntemeyer, C.C.H. Jui, D. Kieda, K. Kim, E.C. Loh, K. Martens, J.N. Matthews, A. McAllister, J. Meyer, S.A. Moore, P. Morrison, J.R. Mumford, K. Reil,R. Riehle, P. Shen, J. Smith, P. Sokolsky, R.W. Springer, J. Steck, B.T. Stokes, S.B. Thomas, T.D. Vanderveen, L. Wiencke

University of Utah

J. Amann, C. Hoffman, M. Holzscheiter, L. Marek, C. Painter, J. Sarracino, G. Sinnis, N. Thompson, D. Tupa

Los Alamos National Laboratory

HiRes Collaboration

The hires fadc detector hires 2
The HiRes FADC Detector (HiRes-2)

  • The newer one of the 2 HiRes air fluorescence detectors

  • 2 rings with 21 mirrors each

  • Located on Camel’s Back Ridge in Dugway (Utah)

  • Started taking data in fall 1999

The hires fadc detector hires 21
The HiRes FADC Detector (HiRes-2)

  • 256 photomultiplier tubes per mirror.

  • Flash ADC electronics record at a frequency of 10 MHz.

The role of monte carlo simulations in the hires experiment

We need M.C. to calculate the acceptance of our

detectors for the flux measurement:

M.C. is also a powerful tool for resolution studies

and for tests of our reconstruction programs.

This requires a simulation program that

describes the shower development and

detector response as realistically as possible.

We want our code to simulate events under the exact data-taking conditions.

The Role of Monte Carlo Simulations in the HiRes Experiment

M c input energy composition

The composition is

chosen from our HiRes

Stereo and HiRes/MIA


The Fly’s Eye Stereo

spectrum is used as an

input for the M.C.

M.C. Input Energy & Composition

Corsika shower library proton iron

Gaisser-Hillas fit to the shower profile:

Fit parameters scale with primary energy:

CORSIKA Shower Library (proton & iron)

Adding noise to the m c

Ambient light level

(low amplitude) can

be measured from the

width of the FADC


Additional sky noise

(high amplitude)

is added to the M.C. to

get agreement with

data of a certain period.

Adding Noise to the M.C.

FADC counts in all trigger channels

black: data

red: M.C.

total noise tubes distribution

black: data

red: M.C.

A few data monte carlo comparisons
A few Data / Monte Carlo Comparisons

or:Testing how well we understand our experiment ...

  • HiRes-2 data shown from 12/99 until 09/01.

  • ~ 556 Hours of good weather data.

  • average atmosphere used for consistency with HiRes-1.

  • Statistics:

    • rec. geometry: 6309 events

    • after all cuts: 2274 events

  • M.C. : ~ 4 x data statistics

Signal tubes of linear time fit
Signal tubes / χ of linear time fit


Hires 2 energy spectrum
HiRes-2 Energy Spectrum

  • HiRes-2 datafrom 12/’99 until 09/’01

Hires mono energy spectra
HiRes Mono Energy Spectra

  • HiRes-1 datafrom 06/’97 until 02/’03

  • HiRes-2 data from 12/’99 until 09/’01


  • Our data analysis relies on a realistic M.C. simulation for the aperture calculation and for resolution studies.

  • We have generated air showers and detector response for the HiRes FADC detector under the exact data-taking conditions.

  • We have tested our simulation successfully against data taken by HiRes-2.

  • Our M.C. simulation provides a realistic and detailed model of our experiment.

Hires and fly s eye stereo
HiRes and Fly’s Eye Stereo

  • HiRes-1

  • HiRes-2

  • Fly’s Eye Stereo

Hires and fly s eye stereo1
HiRes and Fly’s Eye Stereo

  • HiRes-1

  • HiRes-2

  • Fly’s Eye Stereo

    Energy rescaled by - 6 %

Hires and hires mia
HiRes and HiRes / MIA

  • HiRes-1

  • HiRes-2

  • HiRes Prototype & MIA muon array ( hybrid )

Hires and agasa
HiRes and AGASA

  • HiRes-1

  • HiRes-2


Track length

Number of signal tubes

Zenith angle

Track angle

Psi angle

Error in Psi angle


Good weather conditions

Time tangent fit Chi Squared

Profile fit Chi Squared

Čerenkov light fraction

‘Bracketing’ cut


Erenkov light simulation

The Longitudinal Profile

calculated in the M.C.

is in good agreement

with results from CORSIKA.

Lateral Profile:

- we fit CORSIKA density profiles to the sum of 3 exponentials.

- fits are parametrized with zenith angle and distance between detector and Xmax.

Čerenkov Light Simulation

black: CORSIKA long. Čerenkov profile vs.

atmospheric depth

red: our M.C. simulation

red: CORSIKA lateral Čerenkov density vs.

radial distance in meter

black: our fit using the sum of 3 exp.

Pseudodistance angle of shower axis in shower detector plane
Pseudodistance / Angle of shower axis in shower-detector plane