ANDES, the high-resolution spectrograph for the ELT: RIZ and UBV spectrographs’ preliminary design of the detector unit

The first generation of ELT instruments includes an optical-infrared High Resolution Spectrograph, ANDES (ArmazoNes high Dispersion Echelle Spectrograph. It covers a wide spectral range that goes from U to IZ . A common model of detector is planned for the two visible spectrographs. A total of 5 detectors will cover the latter spectral range. A common detector unit design has been developed based on ELT's standard components and inspired by the previous successful detector units designed for HARPS and ESPRESSO. It consists of a 9k x 9k CCD detector, a differential vacuum cryostat that keeps the detector in its dedicated vacuum chamber and a cryocooler that cools down the detector to minimise the dark noise. The required temperature, mechanical and pressure stabilities drive the design of the detector unit