CEC Abstracts in PDF format (as of 7/3/07) - CEC-ICMC 2013

CEC 2007 - Abstracts
C2-M Instrumentation
C2-M-01 Operation of Superconducting Digital Receiver
Circuits on 2-Stage Gifford-McMahon Cryocooler
R.J. Webber, V. Dotsenko, A. Talalaevskii, R. Miller,
J. Tang, D. Kirichenko, I. Vernik, P. Schevchenko, D.
Gupta, O.A. Mukhanov, Hypres, Inc.
We have demonstrated the full operation of digital RF receivers on a
Hypres-designed cryostat, which couples a Nb-based superconducting
Rapid Single Flux Quantum (RSFQ) chip to a commercially available
100 mW 4 Kelvin Gifford-McMahon cryocooler. The electrical
performance at clock speeds in excess of 24 GHz is described as well
as the design of the electrical interfaces with room temperature
support electronics. The digital receiver chip is a 1cm x 1 cm chip
comprising ~ 11,000 Josephson junctions. Within the cryostat there is
the inevitable conflict between the need to minimize heat-leaks and
the need to minimize dissipation in input-output leads. The measured
cryogenic thermal and magnetic environments of the chip are
discussed and their impact on performance. Reception and direct
digital conversion of real signals in the HF-, VHF-, and X-bands
including signals from military satellite antennae shows the potential
of this system to replace large and power-hungry multiple analogue
receivers.
This work was supported in part by the Office of Naval Research, the
Army Small Business Innovation and Research Program and by the
US Air Force
C2-M-02 Level-detected characteristics of MgB2 sensor
for liquid hydrogen
M. Takeda, T. Akazawa, Y. Iwamoto, Kobe
University; H. Kumakura, A. Matsumoto, H. Uematsu,
C. Kazama, National Institute for Materials Science;
H. Iwashita, I. Kodama, Y. Matsuno, Iwatani
Industrial Gases Corporation.
In order to establish the storage and transportation system for liquid
hydrogen, it is important to develop a high sensitive liquid level
meter. A superconductive MgB2 level meter is expected to be a new
one. However, a research on the level-detected characteristics of the
MgB2 sensor has not been sufficiently carried out. Thus the
characteristics of the level sensor, which consists of a MgB2 wire (0.5
mm in diameter, 200 mm long) made by means of powder-in-tube
method, an electrical heater, and voltage/current taps, were
investigated by using the liquid hydrogen optical cryostat. The
linearity, resolution, repeatability, and heater current dependence of
the sensor reading with varying liquid levels are discussed.
This work was supported in part by Hyogo Prefecture (COE
Program), Japan.
C2-M-03 Cryogenic Fiber Optic Sensors Based on Fiber
Bragg Gratings
P.R. Swinehart, M. Maklad, S.S. Courts, Lake Shore
Cryotronics, Inc.
Fiber optic sensing has many favorable characteristics - a single fiber
can be used to interrogate multiple sensors along the length of the
fiber, fiber optic sensing is immune to electromagnetic noise and is
inherently safe for combustible liquids and atmospheres. Previously,
fiber optic sensors based on fiber Bragg gratings (FBGs) have been
demonstrated for cryogenic use for both temperature and strain
sensing, but often little data is supplied as to the reproducibility or
unit-to-unit uniformity of these sensors. Lake Shore Cryotronics has
manufactured fiber optic cryogenic temperature and strain sensors
based on Bragg gratings using novel packaging techniques. The
reproducibility and uniformity characteristics of the cryogenic strain
sensor is reported for 295 K and 77K. The temperature response,
reproducibility, and uniformity of wide range temperature sensors is
reported from 20K to 480K.
C2-M-04 A Commercial Ruthenium Oxide Thermometer
For Use to 10 mK
S.S. Courts, J.K. Krause, Lake Shore Cryotronics, Inc.
The adoption of the PLTS-2000 has given the ultra low temperature
community a recognized temperature scale with which to work.
However, the defining instrument, the He-3 melting curve
thermometer, is not well suited for transferring this scale. Primary
thermometers are available for ultra low temperatures, namely nuclear
orientation and noise thermometry, but they are statistical in nature
and require long averaging times for a single measurement limiting
their practical use. Resistance thermometers are easy to use, provide
fast measurements allowing active feedback temperature control, and
have extremely high sensitivities at ultra low temperatures allowing
for microkelvin level control. However, resistance thermometry for
use below 50 mK requires rethinking the standard packaging. Many
common materials used in packaging cryogenic sensors limit the
thermal connection to the sensor thus limiting the allowable excitation
used for measurement. This research examines the use of a
commercially available ruthenium oxide thick film chip resistor for
thermometry to 10 mK. Data was acquired for sample sensors
fabricated using two package styles. The temperature was measured
using a Co-60 nuclear orientation thermometer in conjunction with
PTB-calibrated germanium thermometers. Resistance as a function of
temperature, self-heating and time response data are presented.
C2-M-05 The Effect of Small Helium Leaks into Low
Temperature Systems
J. Panek, E. Canavan, M. DiPirro, J. Francis, S.
Riall, P. Shirron, NASA.
Recent experience with small helium leaks (