Particle Detectors
CELIAS
The Charge, Element, and Isotope Analysis System (CELIAS) instrument is designed to study the composition of the solar wind (SW) and of solar and interplanetary energetic particles on SOHO. SOHO is a project of international cooperation between ESA and NASA. The CELIAS instrument consists of three different sensors with associated electronics, which are optimized each for a particular aspect of ion composition. These aspects are the elemental, isotopic, and ionic charge composition of SW or energetic ions emanating from the Sun. In addition, the Solar EUV Monitor (SEM) has been included into CELIAS for monitoring the absolute EUV flux from the Sun. The CELIAS instrument consists of three different sensor units (CTOF, MTOF, and STOF) coupled to a Digital Processing Unit (DPU). The energy ranges of the SOHO particle instruments, the CELIAS ion sensors together with the COSTEP /ERNE energetic particle experiments, cover a very wide range (large version) in nuclear mass and energy space. All three CELIAS sensors employ electrostatic deflection systems in combination with time-of-flight (TOF) measurements of the impinging particles. The CTOF and STOF sensors employ also silicon solid state detectors to determine the residual energy of particles. Thus for these two sensors the quantities energy per charge, E/Q, time-of-flight (TOF), and energy, E, are determined for the incoming particles. CTOF and STOF are aimed at different energy ranges, CTOF being devoted to solar wind and low energy suprathermal ions, while STOF is devoted to higher energy suprathermal and low energy solar energetic particles. The MTOF sensor is a high resolution retarding potential mass analyzer with a quadrupol electric field configuration, which will be able not only to measure the composition of the less abundant elements in the solar wind, but also the isotopic composition of the more abundant heavy ions. The solar EUV monitor, SEM, is structurally connected with STOF. SEM consists basically of a diffraction grating in front of a set of three absolutely calibrated silicon light diodes, which are covered with an aluminum filter. The diodes are placed at the zero - and first order diffraction image of the Sun in order to isolate the 30.4 nm He II line. The digital processing unit, DPU, serves all three sensors by fully handling the communications with the spacecraft. It receives rate and pulse-height data from each sensor, compresses, stores and formats it for conveying the data to the S/C telemetry. It also handles the experiment control through the commanding system and surveys the CELIAS housekeeping data. For more information, see: http://www.space.unibe.ch/soho/ Group: Instrument_Details Entry_ID: CELIAS Group: Instrument_Identification Instrument_Category: Solar/Space Observing Instruments Instrument_Class: Particle Detectors Short_Name: CELIAS Long_Name: Charge, Element, and Isotope Analysis System End_Group Group: Instrument_Associated_Sensors Short_Name: MTOF Short_Name: CTOF Short_Name: PM Short_Name: SEM/SOHO End_Group Group: Associated_Platforms Short_Name: SOHO End_Group Group: Spectral_Frequency_Information Wavelength_Keyword: Ultraviolet Spectral_Frequency_Coverage_Range: 17-70 nm End_Group Online_Resource: http://www.space.unibe.ch/soho/ Sample_Image: http://www.space.unibe.ch/soho/random/ctof.gif Group: Instrument_Logistics Instrument_Start_Date: 1995-12-02 Instrument_Owner: Max Planck Institut fur Extraterrestrische Physik Instrument_Owner: Universiy of Bern, Switzerland Instrument_Owner: Max Planck Institut fur Aeronomie Instrument_Owner: University of Maryland Instrument_Owner: Technische Universitat Braunschweig Instrument_Owner: University of Southern California End_Group End_Group