Band 9 receiver cartridges for ALMA

Six of the 73 Band 9 receiver cartridges delivered by NOVA (the Netherlands Research School for Astronomy) under contract to ESO, for the Atacama Large Millimeter/submillimeter Array project. The so-called "Band 9" receivers are the second-shortest wavelength ALMA detectors, measuring light with wavelengths as short as 420µm (0.42 millimetres). The design and manufacture of receivers that can operate at these short wavelengths is particularly challenging.