arXiv subjects

Jonas Zmuidzinas

Publications and source records attributed to Jonas Zmuidzinas.

39 records · Page 3Linked to original sources

arXiv2006

A Position Sensitive X-ray Spectrophotometer using Microwave Kinetic Inductance Detectors

The surface impedance of a superconductor changes when energy is absorbed and Cooper pairs are broken to produce single electron (quasiparticle) excitations. This change may be sensitively measured using a thin-film resonant circuit called a microwave kinetic inductance detector (MKID). The practical application of MKIDs for photon detection requires a method of efficiently coupling the photon energy to the MKID. We present results on position sensitive X-ray detectors made by using two aluminum MKIDs on either side of a tantalum photon absorber strip. Diffusion constants, recombination times, and energy resolution are reported. MKIDs can easily be scaled into large arrays.

cond-mat.supr-con↗

arXiv2004

The Future of Far-Infrared / Submillimeter Astrophysics with Single-Dish Telescopes

Although far-IR -- mm-wave astronomy has now been developing for several decades, access to this portion of the spectrum remains difficult and limited. Relative to their optical-wavelength counterparts, the submillimeter observatories are both small in units of wavelength and hot in units of photon energy, which imposes limits on their angular resolution and sensitivity. Nevertheless, even the modest far-IR and submillimeter observations obtained in the last two decades have revolutionized our understanding the physics and chemistry of the ISM, the formation of stars, and the cosmic history of these processes. The demonstration by COBE that about half of the radiant energy released in the universe since decoupling comes to us in the submm/far--IR has further underscored the scientific necessity of observations in this wavelength regime. The next decade promises even greater discoveries, as new observatories and detectors are still pushing toward fundamental limits. The paper briefly outlines some of the exciting capabilities and scientific roles of new single-dish far--IR -- mm-wave telescopes and their instruments.

astro-ph↗

arXiv1997

Discovery of Interstellar Hydrogen Fluoride

We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2 - 1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis of our model for the excitation of HF in Sgr B2, the observed line equivalent width of 1.0 nm implies a hydrogen fluoride abundance of 3E-10 relative to H2. If the elemental abundance of fluorine in Sgr B2 is the same as that in the solar system, then HF accounts for ~ 2% of the total number of fluorine nuclei. We expect hydrogen fluoride to be the dominant reservoir of gas-phase fluorine in Sgr B2, because it is formed rapidly in exothermic reactions of atomic fluorine with either water or molecular hydrogen; thus the measured HF abundance suggests a substantial depletion of fluorine onto dust grains. Similar conclusions regarding depletion have previously been reached for the case of chlorine in dense interstellar clouds. We also find evidence at a lower level of statistical significance (~ 5 sigma) for an emission feature at the expected position of the 4(3,2)-4(2,3) 121.7219 micron line of water. The emission line equivalent width of 0.5 nm for the water feature is consistent with the water abundance of 5E-6 relative to H2 that has been inferred previously from observations of the hot core of Sgr B2.

astro-ph↗