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Published 2001 | Published
Book Section - Chapter Open

A Measurement of the ^(10)Be/^9Be ratio above 1.0 GeV/nucleon: Results from the 1998 Flight of ISOMAX


The Isotope Magnet Experiment, ISOMAX, was a balloon-borne instrument designed to measure the isotopic composition of the light elements in cosmic rays (3 ≤ Z ≤ 8), with a particular emphasis on the measurement of the radioactive isotope 10 Be. ISOMAX, flown in August 1998 from Lynn Lake, Manitoba, Canada, measured isotope mass with excellent resolution by combining velocity measurements from a time-of-flight (TOF) system and two Cherenkov detectors with magnetic rigidity (charge/momentum) measurements from the magnetic spectrometer. Velocity from the TOF can be used to resolve isotopes of beryllium from ˜0.2 GeV/nucleon to just above 1 GeV/nucleon. The Cherenkov counters employed silica-aerogel radiators with indices of refraction n=1.14, corresponding to an energy threshold of ˜1 GeV/nucleon. Thus, the velocity measurement from the Cherenkov counters complements and extends the energy range covered by the TOF. We discuss improvements to the mass resolution above Cherenkov threshold and present results for the 10 Be/9 Be and 7 Be/Be ratios in the energy range covered by the Cherenkov counters (1.1-2.0 GeV/nucleon).

Additional Information

© Copernicus Gesellschaft 2001. This work was supported by grant NAG5-5227 ac Caltech and by NASA RTOP 353-87-02 at Goddard and DFG Si290/8 at the University of Sicgeu. We would also like to t11ank the many engineers and technicians that made ISOMAX a success as well as Lhe National Scientific Balloon Facility.

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August 19, 2023
October 20, 2023