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The Yuan Tseh Lee Array (YTLA)

YTLA (formerly AMiBA) Website

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This custom plate assembly was design to generate and distribute 2 to 18 GHz wide-band noise or CW tone for in-situ calibration and test of the I/Q down converters and digital backend correlator system. The plate is mounted on the platform and is controlled remotely via Ethernet.

Noise/Tone Calibration Plate, YTLA Project

This photo represents the first production in-phase/quadrature down converter designed for the YTLA project as an upgrade to the AMiBA analog correlator system. The design was based on the results of a prototype development conducted the previous year.

In-Phase/Quadrature Down Converter Production Bracket, YTLA Project

This is a photo of the YTLA clock distribution drawer packaged in a standard rack mount 2U height EMI chassis.

Clock Distribution Chassis, YTLA Project

Early prototype of in-phase/quadrature down converter for YTLA upgrade. The goal was to down convert and digitize any 2 GHz portion of the 2-18 GHz IF spectra from the receiver output using our new in-house board development of a 5 Gsps ADC board (courtesy of H.M. Jiang).

In-Phase/Quadrature Down Converter Prototype Plate, YTLA Project

Photo of wide-band radio frequency translator plate. This prototype provides signal conditioning and frequency translation of a pair of intermediate frequency channels to baseband for digitization.

Early Prototype Down Converter Plate, YTLA Project

Photos of analog correlator module. Left - top view of module with custom low noise DC amplifier board. Right - bottom view of custom 4-lag wide-band analog correlator module consisting of two 4-way Wilkinson power dividers and four double balanced mixers.

Wideband Analog Correlator Module, AMiBA Project

The Y.T. Lee Array (YTLA, formerly AMiBA) was dedicated on Mauna Loa in Hawaii during October 2006. It is the first and only instrument dedicated to the study of cosmology in Asia. This frontier instrument for cosmology is led, designed, constructed, and operated by the ASIAA, with major collaborations with the Physics Department and Electrical Engineering Department of the National Taiwan University. Located at a 3400m elevation, the YTLA (formerly AMiBA) has a very sensitive view of the structures of the cosmic microwave background (CMB) radiation that accompanied the initial expansion of the Universe. The CMB structures tightly constrain the constituents of the Universe, such as the contributions of ordinary matter, dark matter, and the hypothetical form of energy, known as dark energy thought to be responsible for the acceleration of the Universe. The YTLA (formerly AMiBA) will also detect and map distant clusters of galaxies via their inverse Compton scattering of the CMB photons. The signatures of the galaxy clusters, which are revealed as a slight cooling of the radiation at a wavelength of 3mm, is independent of distance to the galaxies, making them a very powerful probe for detecting the structures of the distant Universe which would otherwise be invisible. YTLA (formerly AMiBA) operations began in 2007. Initial detections of 8 distant clusters of galaxies have been made via their cooling of the CMB. In 2009, we completed the expansion of YTLA (formerly AMiBA) to increase the number of elements from 7 to 13 and the size of reflectors from 0.6m to 1.2m. This improved our speed by a factor of about 60.