Local Oscillator Unit for HIFI

Local-Oscillator Developments for FIRST/HIFI

In Summer 99 the division took responsibility (as subsystem manager) for the local oscillator de­ve­lopment for HIFI (Heterodyne Instrument for HERSCHEL – formerly FIRST). HERSCHEL is ESA’s 4th cornerstone in the current Horizon 2000 science program, currently scheduled for launch in August 2008. HIFI is developed by a worldwide consortium of 25 scientific institu­tes, with the technological challenge to built a space-borne instrument of unique performance.

The major scientific objectives of HIFI

  • probing the physics, kinematics and energetic balance of the interstellar medium through the cooling lines of e.g. H2O, [CI], [NII] and [CII],
  • search for rotational and vibrational line transitions of hydrides and/or complex molecular species in unbiased line surveys from 500 to 1900 GHz,
  • studying the [CII] transition [158µm] - as the most luminous cooling line of star forming galaxies – in galaxies with various redshifts

will address key questions for our understanding of the star forming process, in the Galaxy and in galaxies of the earlier universe. Observations will provide insight into the overall interplay between the interstellar medium, newly formed stars, exhausted stars and super­novae, driving the chemical evolution of galaxies [for details, http://astro.estec.esa.nl/FIRST].

Instrument Specifications:

In order to meet these scientific objectives, the technical perfor­mance of HIFI must be far beyond current state-of-the-art submillimeter technology:

  • 480-1916 GHz full frequency coverage by 14 detector channels (SIS & HEB mixers)
  • lowest possible system noise (< 3 hn/k)
  • wide instantaneous bandwidth  (4-8 GHz)
  • high spectral resolution (R~107).    

The instrument is divided into several subsystems and institute responsibilities, the

  • Focal Plane Subsystem (SRON, The Netherlands)
  • Local Oscillator Subsystem (MPIfR, Germany)
  • High-Frequency Subsystem (JPL, USA)
  • Instrument Control Unit (IFSI, Italy)
  • High Resolution Spectrometer Subsystem (CNRS, France)
  • Wide Band Spectrometer Subsystem (KOSMA/MPAE, Germany)
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