Heidelberg 2007 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 201: Kosmische Strahlung I
T 201.6: Vortrag
Dienstag, 6. März 2007, 18:05–18:20, INF 308 Gr. HS
PEBS - Positron Electron Balloon Spectrometer — •Henning Gast, Philip von Doetinchem, Thomas Kirn, and Stefan Schael — I. Physikalisches Institut B, RWTH Aachen
The observation of a possible excess in the cosmic-ray positron spectrum has been suggested to originate from WIMP annihilations in the halo of the Galaxy. To measure this spectrum in the interesting energy range of 1-100 GeV with high precision for the first time, we are developing a dedicated balloon-borne spectrometer (PEBS).
It features an innovative tracking device based on scintillating fibres of 250 µ m diameter that are read out by Geiger-mode silicon avalanche photo diodes. A prototype of this system has recently been tested in a 10 GeV proton beam at CERN with great success.
The total material budget of the tracking system amounts to only 5% X0. To measure particle momenta, a magnetic field of 0.7 T is created by two superconducting Helmholtz coils. A lead-scintillating fibre sandwich serving as electromagnetic calorimeter and a transition radiation detector consisting of fleece layers interspersed with straw-tube proportional counters will achieve the suppression of the predominant proton background.
The geometrical acceptance of PEBS is 0.4 m2sr, exceeding that of the currently deployed satellite experiment PAMELA by a factor of 200. Its low weight of 1500 kg and power consumption of 900 W make it suitable for a high-altitude balloon. The design study, based on a full Geant4 simulation, will be presented.