Design studies for a multi-TeV gamma-ray telescope array : PeX (PeV eXplorer)

TL;DR

This thesis proposes a design for a multi-TeV gamma-ray telescope array called PeX, utilizing large core distance events and a novel time-based image cleaning method to enhance detection capabilities in high background conditions.

Contribution

The work introduces a new array design inspired by existing systems and demonstrates a time-based image cleaning technique that significantly improves performance under high night sky background levels.

Findings

Time cleaning improves angular resolution by 1.5x at Galactic center background levels.

Sparse array design effectively detects multi-TeV gamma-ray sources.

Large core distance events enhance array performance for multi-TeV observations.

Abstract

(Abridged) This thesis presents work towards the design of a new array of Image Atmospheric Cherenkov Telescopes (IACTs) to detect multi-TeV gamma-ray sources. The array consists of 5 telescopes in a square layout with one central telescope, known as the Pevatron eXplorer or PeX. PeX is a PeV (10^{15} eV) cosmic ray explorer that aims to study and discover gamma-ray sources in the 1 to 500 TeV range. The initial PeX design has been influenced by the HEGRA CT-System and H.E.S.S. configurations. One important feature of multi-TeV air showers is their ability to trigger telescopes at large core distance (>400m). PeX will utilise large core distance events to improve the performance and illustrate the viability of a sparse array for multi-TeV gamma-ray astronomy. One important aspect of the thesis (Chapter 6) was the investigation of a new time-based image cleaning method. The arrival time between photons in two adjacent pixels in the camera is used to apply an extra cut which helps mitigate night sky background. To illustrate the robustness of the time cleaning cut, various level of night sky background have been considered. These levels include: off-Galactic plane, on-Galactic plane and towards the Galactic centre. The most important result is that PeX performance with a time cleaning cut improves results when a high level of night sky background is present. For a Galactic centre level of night sky background there is a factor of 1.5 improvement in angular resolution, effective area and quality factor when a time cleaning cut is applied compared to using no time cleaning cut.