Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX

Abstract

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 À1 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 9 Be, 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 À2 . The isotopic ratio at the top of the atmosphere for 10 Be/ 9 Be was measured to be 0:195 AE 0:036 (statistical) AE 0:039 (systematic) between 0.26 and 1.03 GeV nucleon À1 and 0:317 AE 0:109 (statistical) AE 0:042 (systematic) between 1.13 and 2.03 GeV nucleon À1 . This is the first measurement of its kind above 1 GeV nucleon À1 . 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 À1 ). The lithium and boron ratios agree well with existing data and model predictions at similar energies.

Propagation of cosmic rays in the AMS-02 era

“…9: 2σ bands of the 10 Be/ 9 Be ratios for different propagation models. The observational data are from: Ulysses [51], ACE [14], Voyager [52], IMP [53], ISEE-3 [53], and ISOMAX [54].…”

“…In order to have better constraints on the low energy behavior of the B/C ratio, we also employ the data from ACE-CRIS 2 with the same period as that of AMS-02. To constrain the lifetime of CRs in the Galaxy, we also use the 10 Be/ 9 Be data from some old measurements: Ulysses [51], ACE [14], Voyager [52], IMP [53], ISEE-3 [53], and ISOMAX [54]. The proton fluxes are employed to constrain the injection parameters of CRs.…”

A Markov Chain Monte Carlo technique to sample transport and source parameters of Galactic cosmic rays

“…For 10 Be/ 9 Be, the data are taken from balloon flights (Hagen et al 1977;Buffington et al 1978;Webber & Kish 1979), including the ISOMAX balloon-borne instrument (Hams et al 2004), and from the IMP-7/8 (Garcia-Munoz et al 1977), ISEE-3 (Wiedenbeck & Greiner 1980), Ulysses (Connell 1998), Voyager (Lukasiak et al 1999), and ACE spacecrafts (Yanasak et al 2001). For 26 Al/ 27 Al, the data consist of a series of balloon flights (Webber 1982), and the ISEE-3 (Wiedenbeck 1983), Voyager (Lukasiak et al 1994), Ulysses , and ACE spacecrafts (Yanasak et al 2001).…”

Evaluating the dark matter contribution to galactic synchrotron radiation

“…the diffusion coefficient, Alfvén velocity, convection velocity, and the galactic magnetic and radiation fields) must be correctly chosen in order to ensure that the Gal prop output provides a reasonable match for galactic synchrotron emission. However, not all of these input parameters are well constrained theoretically -thus it is important to ensure that any Gal prop simulation provides reasonable outputs by comparing the primary to secondary ratio observed at the solar position to that determined by the cosmic ray probes such as HEAO-3 [14], CRIS [15], and ISOMAX [16]. We pick a default model including a diffusion constant D 0 = 5 x 10 28 cm 2 s −1 , an Alfvén velocity v α = 25 km s −1 , a simulation height of 4 kpc and negligible convection, which provides a reasonable match to these cosmic ray constraints.…”