Official Pierre Auger Observatory performances

Pierre Auger Observatory performances
from J. Cronin and B. Dawson

1  Auger properties

The Surface Detector (SD) has a total aperture of approximatively 7 350 km2.sr for zenith angles less than 60°.

Detection efficiency

energy

zenith  < 60° zenith  > 60°
1018 0 0
3×1018 0.3

0.5 (70°)
0.75 (75°)
0.8 (80°)


1019 0.98 1
3× 1019 1 1
1020 1 1




Precisions (space angle containing 68% of events)

zenith angle (deg) photon (deg) proton (deg)

LPM (unconverted photons)


201.1 0.6 4.0
40 0.6 0.5 2.5
60 0.4 0.3 1.0
80 0.3 0.2 1.0




Energy resolution

Energy (eV) resolution
< 1020 12%
> 1020 10%

2  Hybrid mode

Detection efficiency

Energy

efficiency

% of triggers that are stereo or better


1018 0.35 0
3× 1018 0.79 24
1019 0.98 68
3× 1019 0.99 88
1020 1 95

The second column of this array shows the percentage of triggering showers that actually trigger 2, 3 or 4 eyes.




precision on the direction

Energy (eV) direction error (deg) core error (m) Rp error (m)
 50 % 68 % 90 % 50 % 68 % 90 % 50 % 68 % 90 %
1018 0.50 0.73 1.55 35 61 155 20 35 97
1019 0.35 0.51 1.10 35 50 120 16 28 76
1020 0.35 0.51 0.90 30 49 100 13 25 64




precision on the energy and Xmax

Energy (eV) energy error (%) Xmax error (g.cm-2)
  50 % 68 % 90 % 50 % 68 % 90 %
1018 9.5 13 21 21 38 74
1019 4.5 6.5 13 14 25 62
1020 2.5 5.5 17 12 24 69




Rates (based on AGASA (PRL v81, 1163 (1998)),
for one year at one 3 000 km2 site and a zentih angle < 60°

Energy

Surface array (only)

Hybrid (SD + one or more FD)

6× 1017 0 ~ 45 000
1018 0 30 000
3× 1018 15 000 4 700
1019 5 150 515
2× 1019 1 590 159
5× 1019 490 49
1020 103 10
2× 1020 32 3
5× 1020 10 1

FD rates assume a coincidence of 2 tanks with 4 VEM and 10% duty cycle.
SD rates assume a coincidence of 5 tanks with 4 VEM each.

The FD rate becomes 10% of SD rate above 1019 eV because the surface detector is fully efficient at that energy. One can see the advantage of the hybrid for the lower energy. The addition of events with zenith angle greater than 60° will add about 50% to the rates quoted above.

File translated from TEX by TTH, version 2.51.
On 23 May 2001, 18:06.