Status of the Monoscopic Analysis Chains for H.E.S.S. II

TL;DR

This paper reports on the current status of monoscopic analysis methods for H.E.S.S. II, an advanced gamma-ray telescope array, using two independent analysis chains to improve low-energy gamma-ray detection and reconstruction.

Contribution

It introduces and compares two independent monoscopic analysis chains for H.E.S.S. II, enhancing low-energy gamma-ray analysis with different reconstruction techniques.

Findings

Two analysis chains are developed and tested.

Preliminary results on Crab Nebula data are presented.

Both methods show promising performance for monoscopic analysis.

Abstract

H.E.S.S. is a system of Imaging Atmospheric Cherenkov Telescopes (IACTs) measuring cosmic gamma-rays with very high energies in Namibia. Extending the array with a fifth telescope with a mirror area of 600 m$^2$ leads to a lower energy threshold as well as an increased sensitivity of the system. Moreover, it is now the first IACT array consisting of telescopes with different sizes. Low-energetic gamma-rays detected by the telescopes can either be analyzed monoscopically, allowing for a lower threshold, or stereoscopically, using hybrid events only which leads to a better reconstruction performance. We present the status of the monoscopic analysis of H.E.S.S. II events. In order to cross-check the results, we use two independent analysis chains, based on different reconstruction methods. The first method uses the second moments of the cleaned camera image (Hillas parameters) in order to deduce the properties of the primary particle. The background discrimination of this method can be optimized with multi-variate analysis techniques. The second method is based on the comparison of the camera image with the results of a semi-analytical model of the air shower using a Loglikelihood-Maximization. We present the status of these analysis efforts and their respective performances. One of the chains has been applied on real data of the Crab Nebula. All results shown here have to be considered preliminary.