Speaker
Description
The Alpha Magnetic Spectrometer (AMS-02), operating on the
International Space Station since 2011, measures cosmic rays in the
energy range from ~1 GV to several TV, providing precise determination
of particle charge, momentum, and matter–antimatter separation.
To enhance its performance before the expected retirement of the
International Space Station around 2030, the silicon tracking system
will be upgraded by installing a new top layer, AMS-L0. This L0 layer
is composed of two silicon microstrip planes mounted back-to-back with
a relative stereo angle of 45°. Each plane has an active area of 4 m²,
resulting in a total active area of 8 m², and each plane is further
subdivided into four quadrants of 1 m² each. The installation of AMS-L0
is planned for early 2027 and will be carried out by astronauts with
the assistance of the ISS robotic arm. After installation, AMS-L0 is
expected to increase the geometrical acceptance of AMS-02 by up to a
factor of three, while enabling early identification of nuclei before
fragmentation occurs.
This report briefly presents an overview of the AMS-L0 design and
status, with emphasis on the full AMS-L0 beam test scheduled for July
2026. In this test, the entire L0 detector will be operated on a
movable structure, with two additional tracking telescopes—each
composed of 6–8 similar detector layers—placed upstream and downstream
as beam monitors. The report also summarizes performance from completed
beam tests with a single L0 module and ground cosmic-ray measurements
with the full AMS-L0, highlighting key indicators such as signal-to-
noise ratio, stability, spatial resolution, and charge resolution.