The charge spectrum of heavy cosmic ray nuclei measured in the Biostack experiment aboard Apollo 16 using plastic...

In the Biostack experiment flown aboard Apollo 16 plastic detectors were used to select those individual biological objects which were hit by single heavy cosmic-ray nuclei during the 266 hours of space flight. The energy loss deposited in the biological object can be determined. This method needs a separate calibration in every experiment, i.e. an individual track etching rate as function of the energy loss. This calibration is given. An area of 36 cm2 of eight cellulose nitrate sheets was scanned for tracks of heavy cosmic-ray particles that stopped in the sheets. About 200 particles could be evaluated. Calibration was achieved using the oxygen isotope 16O of the cosmic-ray ions and the charge spectrum of all measured particles (Z=5-16) could be obtained.