Characteristics of the multi-telescope coincidence trigger of the HEGRA IACT system

Bulian, N.; Daum, A.; Hermann, G.; Heß, M.; Hofmann, W.; Lampeitl, H.; Pühlhofer, G.; Köhler, Christian; Panter, M.; Stein, M.; Börst, G.; Rauterberg, Matthias; Samorski, M.; Sauerland, C.; Stamm, W.

doi:10.1016/s0927-6505(98)00003-6

Cited by 22 publications

(24 citation statements)

References 7 publications

(4 reference statements)

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“…However, that would imply a drastic increase in the accidental trigger rate of up to 100 Hz and an increase of up to a 30% in the dead time (against a rate of 15 Hz and 5% dead time for the nominal trigger threshold of 7 ph.e. (see [10])). Moreover, current data acquisition system does not support such rate.…”

Section: Trigger Modesmentioning

confidence: 94%

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Observations of the Crab Nebula with the HEGRA system of IACTs in convergent mode using a topological trigger

Lucarelli

Konopelko

Aharonian

et al. 2003

Astroparticle Physics

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Section: Trigger Modesmentioning

confidence: 94%

“…For most of its operational time the HEGRA IACT system was running using a standard two-level trigger [10]. For that, the system telescopes were triggered locally when the signals in at least two photomultipliers (PMTs) exceeded a given trigger threshold of 7-8 ph.e.…”

Section: Trigger Modesmentioning

confidence: 99%

Observations of the Crab Nebula with the HEGRA system of IACTs in convergent mode using a topological trigger

Lucarelli

Konopelko

Aharonian

et al. 2003

Astroparticle Physics

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“…Shower signals in at least two telescopes are required to trigger the system. Details about the telescopes, their trigger system and their performance can be found in [9][10][11]6].…”

Section: Factors Governing the Energy Resolution Of Cherenkov Telescopesmentioning

confidence: 99%

Improved energy resolution for VHE gamma ray astronomy with systems of Cherenkov telescopes

Hofmann

Lampeitl

Konopelko

et al. 2000

Astroparticle Physics

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We present analysis techniques to improve the energy resolution of stereoscopic systems of imaging atmospheric Cherenkov telescopes, using the HEGRA telescope system as an example. The techniques include (i) the determination of the height of the shower maximum, which is then taken into account in the energy determination, and (ii) the determination of the location of the shower core with the additional constraint that the direction of the gamma rays is known a priori. This constraint can be applied for gamma-ray point sources, and results in a significant improvement in the localization of the shower core, which translates into better energy resolution. Combining both techniques, the HEGRA telescopes reach an energy resolution between 9% and 12%, over the entire energy range from 1 TeV to almost 100 TeV. Options for further improvements of the energy resolution are discussed.

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“…The system event rate and the relative optical efficiency As already mentioned, the optical efficiency κ ′ opt itself was not measured directly. Instead, the cosmic-ray induced event rate is a good measure for the overall detector threshold and sensitivity; the system practically does not trigger on noise events or local muons [10]. The event rate R of the system is shown in Fig.…”

Section: Relative Sensitivity Monitoringmentioning

confidence: 99%

The technical performance of the HEGRA system of imaging air Cherenkov telescopes

Pühlhofer

Bolz

Götting

et al. 2003

Astroparticle Physics

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Between early 1997 and late 2002, the HEGRA collaboration operated a stereoscopic system of 4 (later 5) imaging atmospheric Cherenkov telescopes. In this paper we present the calibration schemes which were developed for the system, and report on the performance of the detector over the years. In general, the telescope system was very well understood, regarding both the absolute calibration and the slight changes in performance over the years. The system had an energy threshold of 500 GeV for observations at zenith and under optimum detector conditions. With the corresponding calibration schemes, a systematic accuracy of 15 percent on the absolute energy scale has been achieved. The continuous sensitivity monitoring provided a relative accuracy of a few percent, and showed that the threshold did not exceed 600 GeV throughout the entire operation time. The readout electronics and the imaging quality of the dishes were well monitored and stable. The absolute pointing had an accuracy of at least 25 ′′ ; this number was guaranteed throughout the whole lifetime of the experiment.

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Characteristics of the multi-telescope coincidence trigger of the HEGRA IACT system

Cited by 22 publications

References 7 publications

Observations of the Crab Nebula with the HEGRA system of IACTs in convergent mode using a topological trigger

Observations of the Crab Nebula with the HEGRA system of IACTs in convergent mode using a topological trigger

Improved energy resolution for VHE gamma ray astronomy with systems of Cherenkov telescopes

The technical performance of the HEGRA system of imaging air Cherenkov telescopes

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