Records |
Author |
Semenov, A.; Richter, H.; Hübers, H.-W.; Smirnov, K.; Voronov, B.; Gol'tsman, G. |
Title |
Development of terahertz superconducting hot-electron bolometer mixers |
Type |
Conference Article |
Year |
2003 |
Publication |
Proc. 6th European Conf. Appl. Supercond. |
Abbreviated Journal |
Proc. 6th European Conf. Appl. Supercond. |
Volume |
181 |
Issue |
|
Pages |
2960-2965 |
Keywords |
NbN HEB mixers |
Abstract |
We present recent results of the development of phonon cooled hot-electron bolometric (HEB) mixers for airborne and balloon borne terahertz heterodyne receivers. Three iomportant issues have been addresses: the quality of NbN films the HEB mixers were made from, the spectral properties of the HEB mixers and the local oscillator power required for optical operation. Studies with an atomic force microscope indicate, that the performance of the HEB mixer might have been effected by the microstructure of the NbN film. Antenna gain and noise temperature were investigated at terahertz frequencies for a HEB embedded in either log-spiral or twin-slot feed antenna. Comparison suggests that at frequencies above 3 THz the spiral feed provides better overall performance. At 1.6 THz, a power of 2.5 µW was required from the local oscillator for optimal operation of the HEB mixer. |
Address |
Sorrento, Italy |
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
0750309814, 978-0750309813 |
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
|
Serial |
1505 |
Permanent link to this record |
|
|
|
Author |
Aberle, N.; Witte, U. |
Title |
Deep-sea macrofauna exposed to a simulated sedimentation event in the abyssal NE Atlantic: in situ pulse-chase experiments using 13C-labelled phytodetritus |
Type |
Journal Article |
Year |
2003 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
Mar Ecol Prog Ser |
Volume |
251 |
Issue |
|
Pages |
37-47 |
Keywords |
Deep-sea; Pulse-chase experiment; δ13C; Benthic carbon remineralisation; Macrofauna; Atlantic Ocean, Porcupine Abyssal Plain |
Abstract |
Tracer experiments with 13C-labelled diatoms Thalassiosira rotula (Bacillariophycea, 98% 13C-labelled) were conducted at the Porcupine Abyssal Plain (PAP) in the NE Atlantic (BENGAL Station; 48<b0>50'N, 16<b0>30'W, 4850 m depth) during May/June 2000. In situ enrichment experiments were carried out using deep-sea benthic chamber landers: within the chambers a spring bloom was simulated and the fate of this food-pulse within the abyssal macrobenthic community was followed. In focus was the role of different macrofauna taxa and their vertical distribution within the sediment column in consuming and reworking the freshly deposited material. T. rotula is one of the most abundant pelagic diatoms in the NE Atlantic and therefore 0.2 g of freeze dried T. rotula, equivalent to 1 g algal C m-2 yr-1, was injected into each incubation chamber. Three different incubation times of 2.5, 8 and 23 d were chosen in order to follow the uptake of 13C-labelled phytodetritus by macrofauna. After only 2.5 d, 77% of all macrofauna organisms showed tracer uptake. After 23 d the highest degree of enrichment was measured and 95% of the individuals had taken up 13C from the introduced algal material. In addition to that a downward transport of organic matter was observed, even though the mixing was not very intense. The initial processing of carbon was dominated by polychaetes that made up a percentage of 52% of total macrofauna. In general macrofauna organisms that lived close to the sediment surface had higher access to the simulated food-pulse, confirming the hypothesis that individuals close to the sediment surface have the strongest impact on the decomposition of phytodetritus. In our study we observed only modest vertical entrainment of 13C tracers into the sediment. With regard to contradictory results from former 13C-enrichment experiments in bathyal regions, compared to results from our study site in the abyssal plain, we thus propose pronounced differences in feeding strategies between macrofauna communities from continental margins and abyssal plains. |
Address |
Aberle, Witte: Max Planck Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany; Aberle: Present address: Max Planck Institute for Limnology, August-Thienemann-Str. 2, 24306 Pl<f6>n, Germany; Email: aberle@mpil-ploen.mpg.de |
Corporate Author |
|
Thesis |
|
Publisher |
Inter-Research |
Place of Publication |
Oldendorf/Luhe |
Editor |
|
Language |
English |
Summary Language |
English |
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0171-8630 |
ISBN |
|
Medium |
|
Area |
NE Atlantic |
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
refbase @ user @ 706 |
Serial |
4 |
Permanent link to this record |
|
|
|
Author |
Kostiuk, Theodor |
Title |
Heterodyne spectroscopy in the thermal infrared region: a window on physics and chemistry |
Type |
Conference Article |
Year |
2003 |
Publication |
Proc. International Thermal Detectors Workshop (TDW'03), session 7 (Heterodyne detectors) |
Abbreviated Journal |
|
Volume |
|
Issue |
|
Pages |
|
Keywords |
HgCdTe detector |
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
3501 University Boulevar East Adelphi, MD 20783 |
Editor |
University of Maryland Inn and Conference Center |
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
|
Serial |
372 |
Permanent link to this record |
|
|
|
Author |
Snyder Hale, David D. |
Title |
A thermal infrared heterodyne receiver with applications to astronomy |
Type |
|
Year |
2003 |
Publication |
|
Abbreviated Journal |
|
Volume |
|
Issue |
|
Pages |
|
Keywords |
|
Abstract |
|
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
Berkeley, CA 94720 |
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
|
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
|
Serial |
373 |
Permanent link to this record |
|
|
|
Author |
Sobolewski, R.; Verevkin, A.; Gol'tsman, G.N.; Lipatov, A.; Wilsher, K. |
Title |
Ultrafast superconducting single-photon optical detectors and their applications |
Type |
Journal Article |
Year |
2003 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
|
Volume |
13 |
Issue |
2 |
Pages |
1151-1157 |
Keywords |
NbN SSPD, SNSPD |
Abstract |
We present a new class of ultrafast single-photon detectors for counting both visible and infrared photons. The detection mechanism is based on photon-induced hotspot formation, which forces the supercurrent redistribution and leads to the appearance of a transient resistive barrier across an ultrathin, submicrometer-width, superconducting stripe. The devices were fabricated from 3.5-nm- and 10-nm-thick NbN films, patterned into <200-nm-wide stripes in the 4 /spl times/ 4-/spl mu/m/sup 2/ or 10 /spl times/ 10-/spl mu/m/sup 2/ meander-type geometry, and operated at 4.2 K, well below the NbN critical temperature (T/sub c/=10-11 K). Continuous-wave and pulsed-laser optical sources in the 400-nm-to 3500-nm-wavelength range were used to determine the detector performance in the photon-counting mode. Experimental quantum efficiency was found to exponentially depend on the photon wavelength, and for our best, 3.5-nm-thick, 100-/spl mu/m/sup 2/-area devices varied from >10% for 405-nm radiation to 3.5% for 1550-nm photons. The detector response time and jitter were /spl sim/100 ps and 35 ps, respectively, and were acquisition system limited. The dark counts were below 0.01 per second at optimal biasing. In terms of the counting rate, jitter, and dark counts, the NbN single-photon detectors significantly outperform their semiconductor counterparts. Already-identified applications for our devices range from noncontact testing of semiconductor CMOS VLSI circuits to free-space quantum cryptography and communications. |
Address |
|
Corporate Author |
|
Thesis |
|
Publisher |
|
Place of Publication |
|
Editor |
|
Language |
|
Summary Language |
|
Original Title |
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1051-8223 |
ISBN |
|
Medium |
|
Area |
|
Expedition |
|
Conference |
|
Notes |
|
Approved |
no |
Call Number |
|
Serial |
509 |
Permanent link to this record |