Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8175260 | Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | 2014 | 4 Pages |
Abstract
AMS-02 was successfully installed on the International Space Station (ISS) in May 2011, to perform precise measurements of galactic cosmic rays in the 100Â MV to few TV magnetic rigidity range. Among several specialized sub-detectors, AMS-02 includes a Ring Imaging Cherenkov detector (RICH), which provides a precise measurement of the particle charge and velocity. The Cherenkov light is produced in a radiator made of silica aerogel and sodium fluoride and collected by means of an array of photomultiplier tubes. Since its launch to space, the detector has been taking data without failures; its functionality and data integrity are monitored and show stable response. In order to achieve the optimal detector performance, calibrations have been performed to account for the dependence of the photodetectors response on temperature and for effective non-uniformities in the detector. The knowledge gathered of the photon yield at the percent level resulted in a charge resolution of 0.3 charge units for He and 0.5 charge units for Si ions. The required precision in the measurements of the particle velocity at the per mil level demanded a more accurate determination of the aerogel refractive index. A map of the aerogel radiator refractive index has been directly inferred from in-flight high statistics data with a precision of În/n<2Ã10â5 on average and its stability with time has also been checked. Finally, a velocity resolution of ~0.8Ã10â3 for He and ~0.5Ã10â3 for Z>5 ions has been obtained.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Instrumentation
Authors
F. Giovacchini, On behalf of the AMS02-RICH Collaboration On behalf of the AMS02-RICH Collaboration,