Showing papers by "S. S. Meyer published in 2004"

The South Pole Telescope

Abstract: A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over approximately 4000 degrees for galaxy clusters using the Sunyaev-Zel'dovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.

The South Pole telescope

Abstract: A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs a n off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and wil l feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key pro ject will be to conduct a survey over ∼ 4000 degrees for galaxy clusters using the Sunyaev-Zel’dov ich Effect. This survey should find many thousands of clusters with a mass selection c riteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable signifi cant constraints to be placed on the equation of state of the dark e nergy.

First Year Wilkinson Microwave Anisotropy Probe Observations: Dark Energy Induced Correlation with Radio Sources

Abstract: The first-year Wilkinson Microwave Anisotropy Probe (WMAP) data, in combination with any one of a number of other cosmic probes, show that we live in a flat Λ-dominated cold dark matter (CDM) universe with Ωm ≈ 0.27 and ΩΛ ≈ 0.73. In this model the late-time action of the dark energy, through the integrated Sachs-Wolfe effect, should produce cosmic microwave background (CMB) anisotropies correlated with matter density fluctuations at z 2 (Crittenden & Turok 1996). The measurement of such a signal is an important independent check of the model. We cross-correlate the NRAO VLA Sky Survey (NVSS) radio source catalog (Condon et al. 1998) with the WMAP data in search of this signal, and see indications of the expected correlation. Assuming a flat ΛCDM cosmology, we find ΩΛ > 0 (95% CL, statistical errors only) with the peak of the likelihood at ΩΛ = 0.68, consistent with the preferred WMAP value. A closed model with Ωm = 1.28, h = 0.33, and no dark energy component (ΩΛ = 0), marginally consistent with the WMAP CMB TT angular power spectrum, would produce an anticorrelation between the matter distribution and the CMB. Our analysis of the cross-correlation of the WMAP data with the NVSS catalog rejects this cosmology at the 3 σ level.

Monolithic silicon bolometers

Abstract: A new type of bolometer detector for the millimeter and submillimeter spectral range is described. The bolometer is constructed of silicon using integrated circuit fabrication techniques. Ion implantation is used to give controlled resistance vs temperature properties as well as extremely low 1/f noise contacts. The devices have been tested between 4.2 and 0.3 K. The best electrical NEP measured is 4 × 10 - 1 6 W/Hz at 0.35 K between 1- and 10-Hz modulation frequency. This device had a detecting area of 0.25 cm2 and a time constant of 20 msec at a bath temperature of 0.35 K.

A bolometer array for the spectral energy distribution (SPEED) camera

Abstract: The Spectral Energy Distribution (SPEED) Camera is being developed to study the spectral energy distributions of high redshift galaxies. Its initial use will be on the Heinrich Hertz Telescope and eventually on the Large Millimeter Telescope. SPEED requires a small cryogenic detector array of 2×2 pixels with each pixel having four frequency bands in the 150– 375 GHz range. Here we describe the development of the detector array of these high-efficiency Frequency Selective Bolometers (FSB). The FSB design provides the multi-pixel, multi-spectral band capability required for SPEED in a compact stackable array. The SPEED bolometers will use proximity effect superconducting transition edge sensors as their temperature-sensing element, allowing for higher levels of electronic multiplexing in future applications.

Zoë Wicomb on David's story

Abstract: (2004). Zoe Wicomb on David's story. Current Writing: Text and Reception in Southern Africa: Vol. 16, No. 2, pp. 131-142.

Frequency Selective Bolometers - Progress and Projections

Abstract: We describe recent progress in the modeling and production of Frequency Selective Bolometers operating in the frequency range of 150-1500 GHz. The Frequency Selective Bolometer (FSB) functions by incorporating a bolometer element into a resonant structure to control the range of frequencies over which it absorbs. Both the bolometer absorber and the backshort are planar metal layers with periodic patterns that resonate at the desired frequency. The bolometer layer is resistive and absorbs the incident radiation at the desired frequency while the backshort is a low resistivity resonant pattern. The transmission, reflection, and absorption spectra of this two laer structure are predicted with a numerical model and controlled by the design of the characteristics of the patterns. The key advantage to the FSB bolometer lies in the fact that the radiation not absorbed on the bolometer is transmitted through the device and passed on to subsequent FSB elements that are tuned to other frequencies. Thus a stack of FSB elements enables a multi-spectral single pixel with a geometry that can be close packed into an array of pixels. We describe the electromagnetic modeling and measurements of FSBs spanning 150 to 1500 GHz. The discussion is focused on two issues: prediction and control of the FSB passband and the projected high frequency limit of FSBs currently being produced. Results from FSBs produced for the SPEctral Energy Distribution (SPEED) receiver (150-350 GHz) are shown along with corresponding results from prototype FSBs for the Explorer of Diffuse high-z Galactic Emission (EDGE) telescope (300-1500 GHz).

A bolometer array for the Spectral Energy Distribution (SPEED)Camera

Abstract: The SPEED camera is being developed to study the spectral energy distributions of high redshift galaxies, Sunyaev-Zel'dovich effect in X-ray clusters and other cold objects in the universe. Its initial runs will be done on the 10 m Heinrich Hertz Submillimeter Telescope (HHSMT), with later runs using the Large Millimeter Telescope (LMT). SPEED requires a 2x2 pixel cryogenic detector array of Frequency Selective Bolometers (FSB). Each of the pixels will have four frequency bands in the ~150-350 GHz range. Here we describe the development of the detector array of these high efficiency FSBs. The FSB design provides the multi-pixel multi-spectral band capability required for SPEED in a compact, light weight, stackable array. The SPEED FSB bolometers will use proximity effect superconducting transition edge sensors (TES) as their temperature-sensing element permitting significantly higher levels of electronic multiplexing in future applications where larger numbers of detectors may be required.