The experimental goal of the ISOMAX experiment are measurements of light
isotopes, especially the Be10/Be9 ratio, up to an energy of some GeV/n.
Because of the small fluxes of Beryllium, ISOMAX has a large geometry
factor of about 550 cmsr. The Balloon flights will be long-duration
flights lasting several days. For this purpose low-power electronics were
The ISOMAX magnet spectrometer consists of a superconducting double-coil magnet
and high-resolution driftchambers.
The driftchambers use the same driftcell structure as the chambers
used in the previous Balloon experiments. Ground myon tests showed a
resolution of about 60-70 m. The expected resolution for higher charged
particles is about 40-50 m.
With an average magnetic field of about 0.6 Tesla the MDR (Maximal Detectable
Rigidity) of the spectrometer
will be around 780 GV for single charged particles and more than 900 GV
for Beryllium. Therefore the spectra of particles up to energies of about
1 TeV can be measured.
For particle identification a Time-Of-Flight counter similar to the
experiment is used. The time-resolution
for single-charged particles should be 120-130 ps, for Beryllium we
expect around 60-80 ps.
To cover a higher energy range, an additional velocity measurement is
added using aerogel cherenkov counters. The construction will be similar
Since the delivery of the magnet was delayed, we had to wait for the first
flight from Lynn Lake, Manitoba until summer of 1998. ISOMAX was launched
on august 4th at 11:58 Z, and landed on august 5th near Peace River/Alberta
around 21:00 Z.
"ISOMAX: A Balloon-borne Instrument to Study Berlyllium and Other Light
Isotopes in the Cosmic Radiation",
R. E. Streitmatter, L. M. Barbier, M. Bremerich, E. R. Christian,
M. Hof, K. E. Krombel, W. Menn, R. A. Mewaldt, J. W. Mitchell,
J. F. Ormes, I. L. Rasmussen, S. M. Schindler, M. Simon,
Proc. 23th International Cosmic Ray Conference, (1993)
"A Telemetry/Frame Sync Board for Use in Balloon Payloads",
E. R. Christian, J. W. Mitchell, R. Baker, P. Goodwin, R. Nace, R. Smith,
Proc. 24th International Cosmic Ray Conference, (1995)
"Performance of CAMAC TDC and ADC in magnetic field",
S. K. Gupta, L. M. Barbier, E. R. Christian, S. Geier, J. F. Krizmanic, J. W. Mitchell, R. E. Streitmatter, P.
Nucl. Instr. and Meth. 400 (1997) 428-434