1. Testing the HiRes Detector Simulation against UHECR Data
ICRC in Tsukuba
Testing the HiRes Detector Simulation against UHECR Data
Andreas Zech
( Rutgers University)
for the HiRes - Fly´s Eye Collaboration

2. HiRes Collaboration University of Tokyo University of Adelaide
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
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

3. 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

4. The HiRes FADC Detector (HiRes-2)
256 photomultiplier tubes per mirror.
Flash ADC electronics record at a frequency of 10 MHz.

5. 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.

7. M.C. Input Energy & Composition
The Fly’s Eye Stereo
spectrum is used as an
input for the M.C.
The composition is
chosen from our HiRes
Stereo and HiRes/MIA
measurement.

8. CORSIKA Shower Library (proton & iron)
Fit parameters scale with primary energy:
Gaisser-Hillas fit to the shower profile:

9. Adding Noise to the M.C. Ambient light level (low amplitude) can
be measured from the
width of the FADC
pedestals.
FADC counts in all trigger channels
black: data
red: M.C.
total noise tubes distribution
black: data
red: M.C.
Additional sky noise
(high amplitude)
is added to the M.C. to
get agreement with
data of a certain period.

10. 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: events
M.C. : ~ 4 x data statistics

11. Signal tubes / χ of linear time fit2

12. Light per Track Length / Čerenkov Fraction

13. Rp / Rp Resolution

14. Energy / Energy Resolution

15. HiRes-2 Exposure
Flux:

16. HiRes-2 Energy Spectrum
HiRes-2 data from 12/’99 until 09/’01

17. HiRes Mono Energy Spectra
HiRes-1 data from 06/’97 until 02/’03
HiRes-2 data from 12/’99 until 09/’01

18. Conclusions
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.