Spacecraft and observatory web pages

• The radiation monitor on-board Herschel is called SREM for Standard Radiation Environment Monitor. SREM raw and calibrated data products are delivered with the Herschel observations as part of the auxiliary context, inside the observation context. The SREM units detect and count electrons, protons and cosmic rays with a coarse spectral resolution and ±20◦ angular resolution. The measurements are based on silicon diodes polarized in reverse by a high voltage. The SREM consists of three detectors, D1, D2 and D3, mounted in two heads. One head consists of a single silicon diode (D3) and its main entrance window is covered with an aluminium plate of 0.7mm, defining a lower energy threshold of ~0.5MeV for electrons and ~10MeV for protons. The other head uses to silion diodes (D1/D2) arranged in a telescope configuration. The main entrance window is covered with an aluminum plate of 2mm providing a threshold of 1.5MeV for electrons and 20MeV for protons.