A Caltech Library Service

Measurement of the Abundance of Radioactive ^(10)Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon^(-1) with the Balloon-Borne Instrument Isomax

Hams, T. and Barbier, L. M. and Bremerich, M. and Christian, E. R. and de Nolfo, G. A. and Geier, S. and Göbel, H. and Gupta, S. K. and Hof, M. and Menn, W. and Mewaldt, R. A. and Mitchell, J. W. and Schindler, S. M. and Simon, M. and Streitmatter, R. E. (2004) Measurement of the Abundance of Radioactive ^(10)Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon^(-1) with the Balloon-Borne Instrument Isomax. Astrophysical Journal, 611 (2). pp. 892-905. ISSN 0004-637X.

[img] PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


The Isotope Magnet Experiment (ISOMAX), a balloon-borne superconducting magnet spectrometer, was designed to measure the isotopic composition of the light isotopes (3 ≤ Z ≤ 8) of cosmic radiation up to 4 GeV nucleon^(-1) with a mass resolution of better than 0.25 amu by using the velocity versus rigidity technique. To achieve this stringent mass resolution, ISOMAX was composed of three major detector systems: a magnetic rigidity spectrometer with a precision drift chamber tracker in conjunction with a three-layer time-of-flight system, and two silica-aerogel Cerenkov counters for velocity determination. A special emphasis of the ISOMAX program was the accurate measurement of radioactive ^(10)Be with respect to its stable neighbor isotope ^9Be, which provides important constraints on the age of cosmic rays in the Galaxy. ISOMAX had its first balloon flight on 1998 August 4–5 from Lynn Lake, Manitoba, Canada. Thirteen hours of data were recorded during this flight at a residual atmosphere of less than 5 g cm^(-2). The isotopic ratio at the top of the atmosphere for 10Be/9Be was measured to be 0:195 ± 0:036 (statistical) ± 0:039 (systematic) between 0.26 and 1.03 GeV nucleon^(-1) and 0:317 ± 0:109 (statistical) ± 0:042 (systematic) between 1.13 and 2.03 GeV nucleon^(-1). This is the first measurement of its kind above 1 GeV nucleon^(-1). ISOMAX results tend to be higher than predictions from current propagation models. In addition to the beryllium results, we report the isotopic ratios of neighboring lithium and boron in the energy range of the time-of-flight system (up to ~1 GeV nucleon^(-1)). The lithium and boron ratios agree well with existing data and model predictions at similar energies.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Additional Information:© 2004 The American Astronomical Society. Received 2004 March 9; accepted 2004 May 4. This experiment was supported by grant NASA RTOP 353-87-02 at Goddard, by NAG5-5227 at Caltech, and by DFG Si 290/8 at the University of Siegen, Germany. We would like to thank the many engineers and technicians that made ISOMAX a success, as well as the National Scientific Balloon Facility. In particular, we thank Donald L. Righter for his invaluable, dedicated work on balloon payloads. Thanks to A. Molnar at the University of Siegen for providing the beryllium and lithium spectra.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASARTOP 353-87-02
Deutsche Forschungsgemeinschaft (DFG)Si 290/8
Subject Keywords:balloons — cosmic rays — nuclear reactions, nucleosynthesis, abundances
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2004-08
Record Number:CaltechAUTHORS:20150323-152504814
Persistent URL:
Official Citation:Measurement of the Abundance of Radioactive 10Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon–1 with the Balloon-borne Instrument ISOMAX T. Hams et al. 2004 ApJ 611 892
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55992
Deposited By: Deborah Miles
Deposited On:24 Mar 2015 17:03
Last Modified:04 Oct 2016 23:39

Repository Staff Only: item control page