The Status of MUSIC: The Multiwavelength Sub/millimeter Inductance Camera

The Multiwavelength Sub/millimeter Inductance Camera (MUSIC) is a four-band photometric imaging camera operating from the Caltech Submillimeter Observatory (CSO). MUSIC is designed to utilize 2304 microwave kinetic inductance detectors (MKIDs), with 576 MKIDs for each observing band centered on 150, 230, 290, and 350 GHz. MUSIC’s field of view (FOV) is 14′ square, and the point-spread functions (PSFs) in the four observing bands have 45′′, 31′′, 25′′, and 22′′ full-widths at half maximum (FWHM). The camera was installed in April 2012 with 25% of its nominal detector count in each band, and has subsequently completed three short sets of engineering observations and one longer duration set of early science observations. Recent results from on-sky characterization of the instrument during these observing runs are presented, including achieved map- based sensitivities from deep integrations, along with results from lab-based measurements made during the same period. In addition, recent upgrades to MUSIC, which are expected to significantly improve the sensitivity of the camera, are described

The cryomechanical design of MUSIC: a novel imaging instrument for millimeter-wave astrophysics at the Caltech Submillimeter Observatory

MUSIC (Multicolor Submillimeter kinetic Inductance Camera) is a new facility instrument for the Caltech Submillimeter Observatory (Mauna Kea, Hawaii) developed as a collaborative effect of Caltech, JPL, the University of Colorado at Boulder and UC Santa Barbara, and is due for initial commissioning in early 2011. MUSIC utilizes a new class of superconducting photon detectors known as microwave kinetic inductance detectors (MKIDs), an emergent technology that offers considerable advantages over current types of detectors for submillimeter and millimeter direct detection. MUSIC will operate a focal plane of 576 spatial pixels, where each pixel is a slot line antenna coupled to multiple detectors through on-chip, lumped-element filters, allowing simultaneously imaging in four bands at 0.86, 1.02, 1.33 and 2.00 mm. The MUSIC instrument is designed for closed-cycle operation, combining a pulse tube cooler with a two-stage Helium-3 adsorption refrigerator, providing a focal plane temperature of 0.25 K with intermediate temperature stages at approximately 50, 4 and 0.4 K for buffering heat loads and heat sinking of optical filters. Detector readout is achieved using semi-rigid coaxial cables from room temperature to the focal plane, with cryogenic HEMT amplifiers operating at 4 K. Several hundred detectors may be multiplexed in frequency space through one signal line and amplifier. This paper discusses the design of the instrument cryogenic hardware, including a number of features unique to the implementation of superconducting detectors. Predicted performance data for the instrument system will also be presented and discussed

A microwave kinetic inductance camera for sub/millimeter astrophysics

The MKID Camera is a millimeter/submillimeter instrument being built for astronomical observations from the Caltech Submillimeter Observatory. It utilizes microwave kinetic inductance detectors, which are rapidly achieving near-BLIP sensitivity for ground-based observations, and a software-defined radio readout technique for elegant multiplexing of a large number of detectors. The Camera will have 592 pixels distributed over 16 tiles in the focal plane, with four colors per pixel matched to the 750 μm, 850 μm, and 1.0 - 1.5 mm (split in two) atmospheric transmission windows. As a precursor to building the full-up camera and to enable ongoing detector testing, we have built a DemoCam comprised of a 16-pixel MKID array with which we have made preliminary astronomical observations. These observations demonstrate the viability of MKIDs for submillimeter astronomy, provide insight into systematic design issues that must be considered for MKID-based instruments, and they are the first astronomical observations with antenna-coupled superconducting detectors. In this paper, we describe the basic systems and specifications of the MKID Camera, we describe our DemoCam observations, and we comment on the status of submillimeter MKID sensitivities

Optics for MUSIC: a new (sub)millimeter camera for the Caltech Submillimeter Observatory

We will present the design and implementation, along with calculations and some measurements of the performance, of the room-temperature and cryogenic optics for MUSIC, a new (sub)millimeter camera we are developing for the Caltech Submm Observatory (CSO). The design consists of two focusing elements in addition to the CSO primary and secondary mirrors: a warm off-axis elliptical mirror and a cryogenic (4K) lens. These optics will provide a 14 arcmin field of view that is diffraction limited in all four of the MUSIC observing bands (2.00, 1.33, 1.02, and 0.86 mm). A cold (4K) Lyot stop will be used to define the primary mirror illumination, which will be maximized while keeping spillover at the sub 1% level. The MUSIC focal plane will be populated with broadband phased antenna arrays that efficiently couple to factor of (see manuscript) 3 in bandwidth, and each pixel on the focal plane will be read out via a set of four lumped element filters that define the MUSIC observing bands (i.e., each pixel on the focal plane simultaneously observes in all four bands). Finally, a series of dielectric and metal-mesh low pass filters have been implemented to reduce the optical power load on the MUSIC cryogenic stages to a quasi-negligible level while maintaining good transmission in-band

MUSIC for sub/millimeter astrophysics

MUSIC (the Multiwavelength Submillimeter kinetic Inductance Camera) is an instrument being developed for the Caltech Submillimeter Observatory by Caltech, JPL, the University of Colorado, and UCSB. MUSIC uses microwave kinetic inductance detectors (MKIDs) - superconducting micro-resonators - as photon detectors. The readout is almost entirely at room temperature and is highly multiplexed. MUSIC will have 576 spatial pixels in four bands at 850, 1100, 1300 and 2000 microns. MUSIC is scheduled for deployment at the CSO in the winter of 2010/2011. We present an overview of the camera design and readout and describe the current status of the instrument and some results from the highly successful May/June 2010 observing run at the CSO with the prototype camera, which verified the performance of the complete system (optics, antennas/filters, resonators, and readout) and produced the first simultaneous 3-color observations with any MKID camera

MKID multicolor array status and results from DemoCam

We present the results of the latest multicolor Microwave Kinetic Inductance Detector (MKID) focal plane arrays in the submillimeter. The new detectors on the arrays are superconducting resonators which combine a coplanar waveguide section with an interdigitated capacitor, or IDC. To avoid out-of-band pickup by the capacitor, a stepped-impedance filter is used to prevent radiation from reaching the absorptive aluminum section of the resonator. These arrays are tested in the preliminary demonstration instrument, DemoCam, a precursor to the Multicolor Submillimeter Inductance Camera, MUSIC. We present laboratory results of the responsivity to light both in the laboratory and at the Caltech Submillimeter Observatory. We assess the performance of the detectors in filtering out-of-band radiation, and find the level of excess load and its effect on detector performance. We also look at the array design characteristics, and the implications for the optimization of sensitivities expected by MUSIC

Status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera

We present the status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera, a new instrument for the Caltech Submillimeter Observatory. MUSIC is designed to have a 14', diffraction-limited field-of-view instrumented with 2304 detectors in 576 spatial pixels and four spectral bands at 0.87, 1.04, 1.33, and 1.98 mm. MUSIC will be used to study dusty star-forming galaxies, galaxy clusters via the Sunyaev-Zeldovich effect, and star formation in our own and nearby galaxies. MUSIC uses broadband superconducting phased-array slot-dipole antennas to form beams, lumpedelement on-chip bandpass filters to define spectral bands, and microwave kinetic inductance detectors to sense incoming light. The focal plane is fabricated in 8 tiles consisting of 72 spatial pixels each. It is coupled to the telescope via an ambient-temperature ellipsoidal mirror and a cold reimaging lens. A cold Lyot stop sits at the image of the primary mirror formed by the ellipsoidal mirror. Dielectric and metal-mesh filters are used to block thermal infrared and out-ofband radiation. The instrument uses a pulse tube cooler and ^(3)He/^(3)He/^(4)He closed-cycle cooler to cool the focal plane to below 250 mK. A multilayer shield attenuates Earth's magnetic field. Each focal plane tile is read out by a single pair of coaxes and a HEMT amplifier. The readout system consists of 16 copies of custom-designed ADC/DAC and IF boards coupled to the CASPER ROACH platform. We focus on recent updates on the instrument design and results from the commissioning of the full camera in 2012