ALMA Matters

From/de Gerald Schieven
(Cassiopeia – Summer/été 2016)

ALMA Band 1 Goes into Production

Figure 1 - the prototype Band 1 (35-52 GHz (8.5-5.7 mm)) cartridge

Figure 1 – the prototype Band 1 (35-52 GHz (8.5-5.7 mm)) cartridge

Band 1 is the lowest frequency band for ALMA and covers the 35 to 52 GHz region of the millimetre-wave spectrum. Science drivers for this band include dust continuum studies of protoplanetary disks, red-shifted molecular lines from galaxies at high redshift, the Sunyaev-Zel’ovich effect, and much more (Di Francesco et al. 2013).

Band 1 development for ALMA is being led by ASIAA in Taiwan in collaboration with NAOJ, the University of Chile, NRAO, and NRC Herzberg. A successful Critical Design Review was held in Taipei in January 2016, and the ALMA Board has now approved the Band 1 project team to go into production of the 73 Band receiver cartridges needed to equip all ALMA antennas in Chile. The production schedule proposed by ASIAA would see all Band 1 cartridges delivered to the JAO by the end of 2019.

Figure 2 - the prototype orthomode transducer (OMT), designed and produced by NRC Herzberg

Figure 2 – the prototype orthomode transducer (OMT), designed and produced by NRC Herzberg

The NRC Herzberg technical contribution to Band 1 is the design, production, and testing of the orthomode transducers (OMTs), precision passive millimetre-wave devices which separate the incoming radiation into its two orthogonal linearly polarized components. This permits ALMA to make observations of the polarization of continuum and spectral line sources in Band 1. NRC Herzberg will be producing the production OMTs (one per receiver cartridge) in-house using the precision machining facilities provided by NRC’s Design and Fabrications Services workshop in Victoria, and will verify the performance of each unit through cryogenic testing in its millimetre-wave instrumentation laboratory.

Face-to-face Visits

If you wish to travel to Victoria for face-to-face assistance with ALMA data reduction and analysis, please contact Brenda Matthews.

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