A&A Supplement series, Vol. 127, February I 1998, 497-504
Received March 20; accepted June 11, 1997
T. Peacock, P. Verhoeve, N. Rando, C. Erd, M. Bavdaz, B.G. Taylor, and D. Perez
Astrophysics Division, Space Science Department of the European Space Agency, ESTEC, PO Box 299,2200 AG Noordwijk, The Netherlands
Some recent results associated with the development of tantalum based
photon counting superconducting tunnel junctions (STJ) suitable for use
as broad-band low resolution spectrometers for optical and ultraviolet
astronomy are presented. A 
m square tantalum based STJ,
operated at a temperature of 0.3 K, has demonstrated a limiting resolution
of 
nm at 200 nm and 
nm at 1000 nm. The device is
extremely linear in response with photon energy, and covers the waveband
from 200 nm to 
while measuring the individual photon wavelength and
arrival time. The short wavelength limit is currently constrained by the
current experimental configuration (a fibre optic) as well as to some extent
the sapphire substrate. The estimated quantum efficiency for single photons
is over 
between 200 and 700 nm with a maximum of 
at
550 nm. Such an STJ when packaged into an array could contribute
significantly to many fields of near infrared, optical and ultraviolet
astronomy being able to provide efficiently and simultaneously the broad
band spectrum and photon arrival time history of every single object in the
field over a very wide dynamic range.
keywords: instrumentation: detectors -- photometry -- superconductors -- tunnel junctions -- optical/ultraviolet spectroscopy