Performance of SIS mixers for upgrade of CHAMP+ 7-pixel arrays

Abstract

We present here the performance of SIS mixers for upgrade of CHAMP+ array instrument on APEX telescope. In total it includes 14 mixers: 7 for the low band (600-720 GHz) and 7 for the high band (790-950 GHz). The mixers are a replacement for the existing set, which was commissioned on APEX in 2006. The low band mixers are based on Nb/AlN/Nb single tunneling SIS junction and high band ones -on Nb/AlN/NbN SIS twin junctions. The corrected DSB noise temperature of the low band mixers is roughly between 60 K and 120 K for the entire frequency range, and the corrected DSB noise temperature of the high band mixers varies from about 200 K at low frequencies to 400 K at the high end