H.M. Del Castillo

The BOOMERANG North America Instrument: A Balloon-borne Bolometric Radiometer Optimized for Measurements of Cosmic Background Radiation Anisotropies from 0.°3 to 4°

We describe the BOOMERANG North America instrument, a balloon-borne bolometric radiometer designed to map the cosmic microwave background (CMB) radiation with 0.3degrees resolution over a significant portion of the sky. This receiver employs new technologies in bolometers, readout electronics, millimeter-wave optics and filters, cryogenics, scan, and attitude reconstruction. All these subsystems are described in detail in this paper. The system has been fully calibrated in flight using a variety of techniques, which are described and compared. Using this system, we have obtained a measurement of the first peak in the CMB angular power spectrum in a single, few hour long balloon flight. The instrument described here was a prototype of the BOOMERANG Long Duration Balloon experiment.

Photoresponse model for Si/sub 1/spl minus/x/Ge/sub x//Si heterojunction internal photoemission infrared detector

A photoresponse model has been developed for the Si/sub 1/spl minus/x/Ge/sub x//Si heterojunction internal photoemission (HIP) infrared detector at wavelengths corresponding to photon energies less than the Fermi energy. A Si/sub 0.7/Ge/sub 0.3//Si HIP detector with a cutoff wavelength of 23 /spl mu/m and an emission coefficient of 0.4 eV/sup /spl minus/1/ has been demonstrated. The model agrees with the measured detector response at /spl lambda/>8 /spl mu/m. The potential barrier determined by the model is in close agreement (difference /spl sim/4 meV) with the potential barrier determined by the Richardson plot, compared to the discrepancies of 20-50 meV usually observed for PtSi Schottky detectors.<<ETX>>

Doping-spike PtSi Schottky infrared detectors with extended cutoff wavelengths

A technique incorporating a p/sup +/ doping spike at the silicide/Si interface to reduce the effective Schottky barrier of the silicide infrared detectors and thus extend the cutoff wavelength has been developed. In contrast to previous approaches which relied on the tunneling effect, this approach utilizes a thinner doping spike ( >

Long‐wavelength stacked SiGe/Si heterojunction internal photoemission infrared detectors using multiple SiGe/Si layers

Utilizing low temperature silicon molecular beam epitaxy growth, long‐wavelength stacked SiGe/Si heterojunction internal photoemission (HIP) infrared detectors with multiple SiGe/Si layers have been fabricated and demonstrated. Using an elemental boron source, high doping concentration (≊4×1020 cm−3) has been achieved and high crystalline quality multiple Si0.7Ge0.3/Si layers have been obtained. The detector structure consists of several periods of degenerately boron doped (≊4×1020 cm−3) thin (≤50 A) Si0.7Ge0.3 layers and undoped thick (≊300 A) Si layers. The multiple p+‐Si 0.7Ge0.3/undoped‐Si layers show strong infrared absorption in the long‐wavelength regime mainly through free‐carrier absorption. The stacked Si0.7Ge0.3/Si HIP detectors with p=4×1020 cm−3 exhibit strong photoresponse at wavelengths ranging 2–20 μm with quantum efficiencies of about 4% and 1.5% at 10 and 15 μm wavelengths, respectively. The detectors show near ideal thermionic‐emission limited dark current characteristics.

7-μm-cutoff PtSi infrared detector for high sensitivity MWIR applications

PtSi Schottky infrared detectors with extended cutoff wavelengths of 5.7, 6.6, and 7.3 /spl mu/m have been demonstrated by incorporating a thin p+ layer at the PtSi-Si interface for high sensitivity medium wavelength infrared imaging applications. The response uniformity of the 7-/spl mu/m cutoff detector was studied.<<ETX>>

MAXIMA: An Experiment to measure temperature anisotropy in the cosmic microwave background

We describe the MAXIMA experiment, a balloon-borne measurement designed to map temperature anisotropy in the Cosmic Microwave Background (CMB) from l=80 to l=800. The experiment consists of a 1.3 m diameter off-axis Gregorian telescope and a receiver with a 16 element array of bolometers cooled to 100 mK. The frequency bands are centered at 150, 240, and 410 GHz. The 10′ FWHM beam sizes are well matched to the scale of acoustic peaks expected in the angular power spectrum of the CMB. The first flight of the experiment in its full configuration was launched in August 1998. A 122 deg2 map of the sky was made near the Draco constellation during the 7 hour flight in a region of extremely low galactic dust contamination. This map covers 0.3% of the sky and has 3200 independent beamsize pixels. We describe the MAXIMA instrument and its performance during the recent flight.

Digital Doppler measurement with spacecraft

Digital and analog phase-locked loop (PLL) receivers were operated in parallel, each tracking the residual carrier from a spacecraft. The PLL tracked the downlink carrier and measured its instantaneous phase. This information, combined with a knowledge of the uplink carrier and the transponder ratio, permitted the computation of a Doppler observable. In this way, two separate Doppler measurements were obtained for one observation window. The two receivers agreed on the magnitude of the Doppler effect to within 1 mHz. There was less jitter on the data from the digital receiver. This was due to its smaller noise bandwidth. The demonstration and its results are described. >