Simon E. Labov

Boron and silicon: filters for the extreme ultraviolet

Thin films of boron and silicon have been developed using electron beam deposition. The transmissions of these filters were measured from soft x-ray wavelengths to the far ultraviolet and at optical wavelengths. The boron filter transmission peaks near 66 A and the silicon filter peaks near 136 A as expected on theoretical grounds, but the extreme ultraviolet bandpass is narrower than expected. The peak transmission of these filters does not change with time, but the width of the silicon filter bandpass is reduced slightly as the filter ages.

Gamma-ray spectrometers using superconducting transition edge sensors with external active feedback bias

We are developing X-ray and gamma-ray spectrometers with high absorption efficiency and high energy-resolution for X-ray and gamma-ray spectroscopy. They are microcalorimeters consisting of a bulk Sn absorber coupled to a Mo/Cu multilayer superconducting transition edge sensor (TES). We have operated these microcalorimeters with an external active feedback bias to linearize the detector response, improve the count rate performance, and extend the detection energy range. We measured an energy resolution of 120 eV FWHM for 60 keV incident gamma-rays with no degradation of resolution from active bias. We present X-ray and gamma-ray results and operation of this detector design in both bias modes.

A new idea for a solid-state microrefrigerator operating near 100 mK

We propose a new design for a solid-state microrefrigerator based on Normal-Insulator-Superconductor (NIS) tunnel junctions. These devices are a promising means of providing continuous refrigeration from 0.3 to 0.1 K without vibration or moving parts. Previously, the area and cooling power of NIS refrigerators have been limited by heating of the superconducting electrode. This problem can be overcome by using a superconducting single crystal as both the substrate and superconducting electrode of the NIS junction. In this paper, we briefly explain the benefits of our new design and describe experimental progress towards building such a device.

Spectrometer system for diffuse extreme ultraviolet radiation

A unique grazing incidence spectrometer system has been designed to study diffuse line emission between 80 and 650 A with 10-30 A resolution. The minimum detectable emission line strength during a 5-min observation ranges from 100-2000 ph cm(-2) sec(-1) str(-1). The instrument uses mechanically ruled reflection gratings placed in front of a linear array of mirrors. These mirrors focus the spectral image on microchannel plate detectors located behind thin filters. The field of view is 40 min of arc by 15 degrees , and there is no spatial imaging. This instrument has been fabricated, calibrated, and successfully flown on a sounding rocket to observe the astronomical background radiation.

Calibration of a 1 meter diameter normal incidence extreme ultraviolet telescope/spectrometer

We have built a 1 meter normal incidence telescope, with a normal incidence concave diffraction grating spectrometer at its focus. The instruments spectral coverage is 350 to 1150 Å with a spectral resolution of 5 Å and a peak effective area of 6 cm2 at 500 Å . The instrument was launched on an Aries sounding rocket on November 27, 1983 in an effort to determine the hydrogen and helium abundance in the local interstellar medium. Here we present a description of this instrument with the primary emphasis on the methods used to calibrate it.

Spectroscopy of the extreme ultraviolet background radiation

Abstract Observations in the far ultraviolet and soft x-ray bands suggest that the interstellar medium contains several components of high temperature gas and should be emitting in the extreme ultraviolet. Indeed diffuse radiation has been detected in the extreme ultraviolet with photometric instruments, but no spectral measurements exist below 520A. We have designed a unique grazing incidence spectrometer to study the diffuse emission between 80 and 650A with 10 to 20A resolution. The instrument was launched on a Black Brant sounding rocket from White Sands Missile Range on April 22, 1986. Our preliminary analysis shows the expected geocoronal and interplanetary HeI 584A emission, and possibly other features which may originate in the hot ionized interstellar gas. Flux limits to these possible emission lines are compatible with previous broad band measurements.