KEYWORDS: Receivers, Optical amplifiers, Radio astronomy, Antennas, Astronomy, Observatories, Cryogenics, Simulation of CCA and DLA aggregates, Roads, Galactic astronomy
The Atacama large millimeter/submillimeter array (ALMA) band-1 receiver covers the frequency band between 35-50 GHz. An extension of up to 52 GHz is on a best-effort basis. Covering the longest wavelengths visible with ALMA, this receiver is enabling studies of dust grain evolution in proto-planetary systems probing dust grain sizes close to 1 cm, and with multiple red-shifted molecular lines it will open up a new window in the high-redshift universe. The band-1 project has recently achieved first light and with this passed a major project milestone. We present the challenges, from initial development to prototype, to establishing the infrastructure, integration, and evaluation of 73 production receiver units, and to the final tasks to complete the project. We conclude with the initial performance and characterization of the first band-1 receivers installed on ALMA.
The Atacama Large Millimeter/submillimeter Array (ALMA) Band 1 receiver covers the frequency range of 35-50 GHz. An extension of up to 52 GHz is on a best-effort basis. A total of 73 units have to be built in two phases: 8 preproduction and then 65 production units. This paper reports on the assembly, testing, and performance of the preproduction Band 1 receiver. The infrastructure, integration, and evaluation of the fully-assembled Band 1 receiver system will be covered. Finally, a discussion of the technical and managerial challenges encountered for this large number of receivers will be presented.
In this paper we discuss the latest developments of the STRIP instrument of the “Large Scale Polarization Explorer” (LSPE) experiment. LSPE is a novel project that combines ground-based (STRIP) and balloon-borne (SWIPE) polarization measurements of the microwave sky on large angular scales to attempt a detection of the “B-modes” of the Cosmic Microwave Background polarization. STRIP will observe approximately 25% of the Northern sky from the “Observatorio del Teide” in Tenerife, using an array of forty-nine coherent polarimeters at 43 GHz, coupled to a 1.5 m fully rotating crossed-Dragone telescope. A second frequency channel with six-elements at 95 GHz will be exploited as an atmospheric monitor. At present, most of the hardware of the STRIP instrument has been developed and tested at sub-system level. System-level characterization, starting in July 2018, will lead STRIP to be shipped and installed at the observation site within the end of the year. The on-site verification and calibration of the whole instrument will prepare STRIP for a 2-years campaign for the observation of the CMB polarization.
The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers the 35-50 GHz frequency band. Development of prototype receivers, including the key components and subsystems has been completed and two sets of prototype receivers were fully tested. We will provide an overview of the ALMA Band 1 science goals, and its requirements and design for use on the ALMA. The receiver development status will also be discussed and the infrastructure, integration, evaluation of fully-assembled band 1 receiver system will be covered. Finally, a discussion of the technical and management challenges encountered will be presented.
ALMA is the largest radio astronomical facility in the world providing high sensitivity between 35 and 950 GHz,
divided in 10 bands with fractional bandwidths between 19 and 36%. Having a lifespan of at least 30 years, ALMA
carries out a permanent upgrading plan which, for the receivers, is focused on achieving better sensitivity and larger
bandwidths. As result, an international consortium works on demonstrating a prototype receiver covering currents Bands
2 and 3 (67 to 116 GHz) which corresponds to a fractional bandwidth of 54%. Here we present the preliminary design,
implementation and characterization of suitable refractive optics. Results indicate an excellent performance in good
agreement with simulations.
The ALMA Band-1 receiver front-end prototype cold and warm cartridge assemblies, including the system and key
components for ALMA Band-1 receivers have been developed and two sets of prototype cartridge were fully tested. The
measured aperture efficiency for the cold receiver is above the 80% specification except for a few frequency points.
Based on the cryogenically cooled broadband low-noise amplifiers provided by NRAO, the receiver noise temperature
can be as low as 15 – 32K for pol-0 and 17 – 30K for pol-1. Other key testing items are also measured. The receiver
beam pattern is measured, the results is well fit to the simulation and design. The pointing error extracted from the
measured beam pattern indicates the error is 0.1 degree along azimuth and 0.15 degree along elevation, which is well fit
to the specification (smaller than 0.4 degree). The equivalent hot load temperature for 5% gain compression is 492 -
4583K, which well fit to the specification of 5% with 373K input thermal load. The image band suppression is higher
than 30 dB typically and the worst case is higher than 20 dB for 34GHz RF signal and 38GHz LO signal, which is all
higher than 7 dB required specification. The cross talk between orthogonal polarization is smaller than -85 dB based on
present prototype LO. The amplitude stability is below 2.0 x 10-7 , which is fit to the specification of 4.0 x 10-7 for
timescales in the range of 0.05 s ≤ T ≤ 100 s. The signal path phase stability measured is smaller than 5 fs, which is
smaller than 22 fs for Long term (delay drift) 20 s ≤ T < 300 sec. The IF output phase variation is smaller than 3.5° rms
typically, and the specification is less than 4.5° rms. The measured IF output power level is -28 to -30.5 dBm with 300K
input load. The measured IF output power flatness is less than 5.6 dB for 2GHz window, and 1.3dB for 31MHz window.
The first batch of prototype cartridges will be installed on site for further commissioning on July of 2017.
This work presents a complete study of the optical system for ALMA band 1, which covers the frequency range from 35 to 50 GHz, with the goal of extending the coverage up to 52GHz. Several options have been explored to comply with the stringent technical specifications, restrictions, and cost constraints. The best solution consists of a corrugated zoned lens, two infrared filters and a spline profiled corrugated horn. The calculated aperture efficiency is better than 75%, while the average noise contribution is lower than 10.3 K. The first prototypes of the system have been constructed and first evaluation results available.
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