The Large-Size Telescope (LST) project team consists of more than 100 scientists from eight countries: Brazil, France, Germany, India, Italy, Japan, Spain and Sweden. Because gamma rays with low energies produce a small amount of Cherenkov light, telescopes with large mirrors are required to capture the images. Four LSTs will be arranged at the centre of both the northern and the southern hemisphere arrays to cover the unique low energy sensitivity of CTA between 20 and 200 GeV. The LSTs will also have a very good sensitivity up to energies of several TeV, which is, however, covered by Medium-Size Telescopes (MSTs) more efficiently.
The LST is an alt-azimuth telescope. It has a 23 m diameter parabolic reflective surface, which is supported by a tubular structure made of reinforced carbon fibre and steel tubes. A reflective surface of 400 m2 collects and focuses the Cherenkov light into the camera, where photomultiplier tubes convert the light in electrical signals that can be processed by dedicated electronics. Although the LST will stand 45 m tall and weigh around 100 tonnes, it will be extremely nimble, with the goal to be able to re-position within 20 seconds.
An illustrative schematic of the telescope with the main assemblies: