Particle Detectors
type: Concept

CELIAS
type: Concept
in scheme: instruments
definition: 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 …