Malte Henkel

The ALICE instrument and the measured cosmic ray elemental abundances

Abstract A Large Isotopic Composition Experiment (ALICE) is a balloon-borne spectrometer which can determine the elemental and isotopic composition of galactic cosmic rays with energies near 1 GeV/nucleon. ALICE was flown from Prince Albert, Canada in August 1987, and remained at float altitude (120000 feet) for 14.7 hours. In this paper, we describe the experimental methods and analysis which will be used for subsequent isotopic analysis. We obtained very precise charge resolution over the entire designed range: 0.10 and 0.16 charge units at neon and iron, respectively. Results on the galactic cosmic ray abundances and absolute fluxes of the elements from neon through nickel are reported.

A method to use drift chambers as track detectors for heavy ions

Abstract A drift chamber with 15 cm drift space has been exposed to the heavy ion beam at Berkeley, USA. Such a chamber will be used in a proposed cosmic ray isotope experiment. From these tests we conclude that amplitude discrimination against δ-rays which accompany the heavy ions is possible. It is recommended to run the chamber at a relatively low sense wire voltage (in our case below 1300 V) in order to avoid space charge effects. This technique works without loss of detection efficiency for particles with Z > 10, for lower charges the losses increase.

A drift chamber telescope for heavy ion track detection

Abstract A drift chamber telescope consisting of six individual drift chambers has been exposed to the heavy ion beam at the Lawrence Berkeley Laboratory, Ca, USA. This is a study for employing drift chambers in a cosmic ray isotope experiment. An amplitude discrimination against δ-rays which accompany the heavy ions is possible. The track detection efficiency for different nuclei is measured and discussed. It is recommended to run the chambers at low sense wire voltage in order to avoid space charge effects. The spatial resolution for Fe nuclei of 518 MeV/nucleon was measured to be σ = 0.3 mm.

A gas scintillation drift chamber for heavy ion detection

Abstract A gas scintillation drift chamber has been exposed to the heavy ion beam at Berkeley, Ca, USA. The drift velocity of an ar(98%)-N2 (2%) gas mixture as a function of the reduced electric field has been measured. The detector provided a spatial resolution of 500 μm and an energy resolution of 6% for penetrating 518 MeV / nuc Fe-particles.

An isotope experiment using Cherenkov range technique

Abstract The ALICE balloon experiment utilizes the Cherenkov-range technique to determine the isotopic composition of the cosmic radiation in the elemental range magnesium through iron. The instrument operates in the energy range 350 MeV/nucleon to 800 MeV/nucleon. Particle charge and energy are determined from scintillation and Cherenkov radiation emissions within light diffusion chambers. Trajectories of incoming particles are determined by means of large area gas drift chambers. The stopping range of the particles is measured in a cellulose nitrate range stack. This paper reports details of the experimental technique and results of the balloon flight.