Isotopic Composition Of Cosmic Rays Research Articles

A Multiple Scattering-Based Technique for Isotopic Identification in Cosmic Rays

Analyzing the isotopic composition of cosmic rays (CRs) provides valuable insights into the galactic environment and helps refine existing propagation models. A particular interest is devoted to secondary-to-primary ratios of light isotopic components of CRs, the measurement of which can provide complementary information with respect to secondary-to-primary ratios like B/C. Given the complexity of the concurrent measurement of velocity and momentum required to differentiate isotopes of the same Z, a task typically accomplished using magnetic spectrometers, existing measurements of these ratios only effectively characterize the low-energy region (below 1 GeV/nucl). This study introduces a novel technique for isotopic distinction in CRs at high energies up to 100 GeV/nucl based on multiple scattering, which, combined with the proposed measurement of velocity, represent an interesting alternative to magnetic spectrometers. The performance of this technique was assessed through a dedicated simulation using the GEANT4 package, with specific emphasis on Z = 1 isotopes.

Iterative-Bayesian unfolding of cosmic-ray isotope fluxes measured by AMS-02

The measurement of the isotopic composition of cosmic rays (CRs) provides essential insights into the understanding of the origin and propagation of these particles, namely the CR source spectra, the propagation processes and the galactic halo size. The Alpha Magnetic Spectrometer (AMS-02), a CR experiment operating aboard the International Space Station since May 2011, has the capability of performing these measurements due to its precise determination of the velocity provided by its Time of Flight (TOF) and Ring Imaging Cherenkov (RICH) detectors. The correct interpretation of the data requires the measurements to be deconvoluted from the instrumental effects. The unique design of AMS-02, with more than one detector being used to measure the same particle flux, requires a novel approach to unfold the measured fluxes. In this work, we apply for the first time the so-called iterative-bayesian approach in the context of the direct measurement of the cosmic-ray fluxes. Moreover, we introduce a non-parametric regularization method for the detector response functions and a single, smooth flux prior covering the range of measurements from both detectors, TOF and RICH. The accuracy of the method is assessed using a simulated flux based on previous AMS-02 measurements and taking into account the full detector response. In addition, the estimation of the errors and a discussion about the performance of the method are also shown, demonstrating that the method is fast and reliable, allowing for the recovery of the true particle fluxes in the whole energy range.

Cosmic-ray propagation with DRAGON2: II. Nuclear interactions with the interstellar gas

Understanding the isotopic composition of cosmic rays (CRs) observed near Earth represents a milestone towards the identification of their origin. Local fluxes contain all the known stable and long-lived isotopes, reflecting the complex history of primaries and secondaries as they traverse the interstellar medium. For that reason, a numerical code which aims at describing the CR transport in the Galaxy must unavoidably rely on accurate modelling of the production of secondary particles. In this work we provide a detailed description of the nuclear cross sections and decay network as implemented in the forthcoming release of the galactic propagation code DRAGON2. We present the secondary production models implemented in the code and we apply the different prescriptions to compute quantities of interest to interpret local CR fluxes (e.g., nuclear fragmentation timescales, secondary and tertiary source terms). In particular, we develop a nuclear secondary production model aimed at accurately computing the light secondary fluxes (namely: Li, Be, B) above 1 GeV/n. This result is achieved by fitting existing empirical or semi-empirical formalisms to a large sample of measurements in the energy range 100 MeV/n to 100 GeV/n and by considering the contribution of the most relevant decaying isotopes up to iron. Concerning secondary antiparticles (positrons and antiprotons), we describe a collection of models taken from the literature, and provide a detailed quantitative comparison.

The RICH detector of AMS-02: 5 years of operation in space

AMS-02 is a high-energy particle physics magnetic spectrometer installed on the International Space Station since May 2011, and operating continuously since then. The AMS-02 Ring Imaging Čerenkov counter (RICH) is a specialised sub-detector for the precise measurement of the particle velocity β with a resolution of Δβ/β=0.7(2.4)×10−3 for helium nuclei passing through the Aerogel (NaF) radiator. From the emitted photon counting the particle absolute charge magnitude |Z| can be estimated with an uncertainty of 0.3 charge units for helium nuclei. In 5 years of operations the optical properties of the RICH had no significant degradation and the performances of the detector have been stable in time.By means of the simultaneous use of the Silicon Tracker and the RICH, AMS is able to investigate the isotopic composition of cosmic rays in the kinetic energy range from few GeV/n to ∼10GeV/n for elements with charge |Z| up to 4 with unprecedented statistics. The precise measurement of cosmic rays light nuclei isotopes ratio, such as 3He/4He and 10Be/9Be, provide important constraints to the free parameters in the models for cosmic rays propagation in our Galaxy. In particular the mass distinction between 3He and 4He needed for the measurement of the 3He/4He flux ratio is obtained by statistical methods. The excellent simulation of the AMS detector provides the precise description needed for this analysis. Moreover, the use of the geomagnetic field for selecting control samples of CRs with enhanced abundances of heavy isotopes provides an independent tool for the study of the light nuclei isotopic composition with AMS.

Array of scintillation detectors for the MONICA spectrometer

An array of scintillation detectors of the MONICA Spectrometer, whis is aimed at investigating fluxes of cosmic-ray ions (from H to Ni) in the extraterrestrial space within the energy range from 10 to 300 MeV per nucleon, is considered. The basic goal of the MONICA experiment is the measurement of the ionic and isotopic composition of cosmic rays of the galactic and solar origin, as well as the measurement of their energy spectrum. This problem was intensely studied by numerous investigators [1–10]; nevertheless, a lot of questions remain unsolved up to now, in this field of science. The array of scintillation detectors plays the important role in achieving the goals of the MONICA experiment. The composition of the array, tuning procedure, and characteristics of scintillation detectors are discussed in detail.

RELATIVE COMPOSITION AND ENERGY SPECTRA OF LIGHT NUCLEI IN COSMIC RAYS: RESULTS FROM AMS-01

Measurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined using the B/C ratio, the study of extended sets of ratios can provide stronger constraints on the propagation models. In this paper, the relative abundances of light-nuclei lithium, beryllium, boron, and carbon are presented. The secondary-to-primary ratios Li/C, Be/C, and B/C have been measured in the kinetic energy range 0.35–45 GeV nucleon−1. The isotopic ratio 7Li/6Li is also determined in the magnetic rigidity interval 2.5–6.3 GV. The secondary-to-secondary ratios Li/Be, Li/B, and Be/B are also reported. These measurements are based on the data collected by the Alpha Magnetic Spectrometer AMS-01 during the STS-91 space shuttle flight in 1998 June. Our experimental results are in substantial agreement with other measurements, where they exist. We describe our light-nuclei data with a diffusive-reacceleration model. A 10%–15% overproduction of Be is found in the model predictions and can be attributed to uncertainties in the production cross-section data.

Isotopic Composition of Cosmic Rays: Results from the Cosmic Ray Isotope Spectrometer on the ACE Spacecraft

The Cosmic Ray Isotope Spectrometer on the ACE spacecraft measures the isotopic composition of cosmic-ray elements from Li through Zn with an unprecedented combination of excellent mass resolution and high statistics. The results indicate a cosmic-ray source whose composition is remarkably similar to that of the solar system, but which is enriched in material that may have originated in Wolf-Rayet stars. The lack of ^(59)Ni is strong indication that the cosmic rays are accelerated at least 10^5 years after nucleosynthesis. We examine these results in the context of the superbubble model of cosmic-ray origin that has been described by Higdon and Lingenfelter.

Voyager measurements of the isotopic composition of cosmic-ray aluminum and implications for the propagation of cosmic rays

view Abstract Citations (27) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Voyager Measurements of the Isotopic Composition of Cosmic-Ray Aluminum and Implications for the Propagation of Cosmic Rays Lukasiak, A. ; McDonald, F. B. ; Webber, W. R. Abstract We report a new measurement of the cosmic-ray isotopic composition of aluminum in the low-energy range form 75 to 206 MeV per nucleon.This measurement was made using the high-energy telescope of the CRS experiment on the Voyager 1 and 2 spacecraft during the time period from 1977 to 1993 with an average solar modulation level about 497 MV, roughly the same as at Earth near sunspot minimum. We obtain approximately 430 Al events of which approximately 35 are Al-26 and 395 are Al-27. The Al isotopes were separated with an average mass resolution sigma of 0.35 amu. Our interpretation of the isotopic composition of cosmic-ray aluminum is based on a standard Leaky-Box model for the interstellar propagation of cosmic-ray nuclei using the latest cross sections of the New Mexico-Saclay collaboration as well as a disk-halo diffusion model. From our observed ratio Al-26/Al-27 of 8.3 +/- 2.4 % we deduce an average interstellar density of about 0.52 (+0.26, -0.2) atoms per cu cm. This density is larger than the value of 0.28 (+0.14, -0.11) atoms per cu cm we found from an analysis of the observed abundance of the longer lived Be-10 made using data from the Voyager detectors over almost the same time interval and using essentially the same propagation program. Publication: The Astrophysical Journal Pub Date: July 1994 DOI: 10.1086/187440 Bibcode: 1994ApJ...430L..69L Keywords: Abundance; Aluminum Isotopes; Beryllium Isotopes; Cosmic Rays; Interstellar Matter; Energy Distribution; Mass Distribution; Mass Ratios; Mass Spectrometers; Voyager 1 Spacecraft; Voyager 2 Spacecraft; Space Radiation; ISM: ABUNDANCES; ISM: COSMIC RAYS full text sources ADS |

Cosmic-ray isotopic composition of C, N, O, Ne, Mg, SI nuclei in the energy range 50-200 MeV per nucleon measured by the Voyager spacecraft during the solar minimum period

The isotopic composition of C, N, O, Ne, Mg, Si cosmic ray nuclei has been measured in the energy range 50-200 MeV per nucleon using data collected by the High-Energy Telescope of the cosmic-ray subsystem experiment on the Voyager 1 and 2 spacecraft. These data were collected during the period of minimum solar activity in 1986-1988 at an average distance of 27 AU with an effective solar modulation that was much less than at the Earth. The isotope analysis, based on the energy loss - total energy method, has a mass resolution of 0.2 amu for carbon and 0.4 amu at silicon. We find a (C-13)/(C-12) ratio slightly lower and a (O-18)/(O-16) ratio slightly enhanced over their solar system value. We also observe the previously reported enhancement of the (Ne-22)/(Ne-20) ratio relative to solar at the cosmic-ray source but only a weak, if any, enhancement of the (Mg-25)/(Mg-24), (Mg-26)/(Mg 24), and (Si-30)/(Si-28) ratios.

The isotopic composition of cosmic-ray beryllium and its implication for the cosmic ray's age

We report a new measurement of the cosmic-ray isotopic composition of beryllium in the low-energy range from 35 to 113 MeV per nucleon. This measurement was made using the High Energy Telescope of the CRS experiment on the Voyager 1 and 2 spacecraft during the time period from 1977 to 1991. In this overall time period of 14 years the average solar modulation level was about 500 MV. The cosmic-ray beryllium isotopes were completely separated with an average mass resolution sigma of 0.185 amu. The isotope fractions of Be-7, Be-9, and Be-10 obtained are 52.4 +/- 2.9%, 43.3 +/- 3.7%, and 4.3 +/- 1.5%, respectively. The measured cosmic-ray abundances of Be-7 and Be-9 are found to be in agreement with calculations based on standard Leaky-Box model for the interstellar propagation of cosmic-ray nuclei using the recent cross sections of the New Mexico-Saclay collaboration. From our observed ratio Be-10/Be = 4.3 +/- 1.5% we deduce an average interstellar density of about 0.28 (+0.14, -0.11) atoms/cu cm, and a cosmic-ray lifetime for escape of 27 (+19, -9) x 10<SUP>6</SUP> years. The surviving fraction of Be-10 is found to be 0.19 +/- 0.07. Modifications to the conclusions of the Leaky-Box model when a diffusion + convection halo model for propagation is used are also considered.

Chemical and isotopic composition of cosmic rays

Important progress has been made in deriving the composition of the Galactic cosmic rays at their source. This is largely due to a systematic effort made in measuring the fragmentation cross sections necessary to correct the observed cosmic ray abundances for propagation effects between their source and the Earth. This paper presents up-to-date chemical and isotopic abundances at the source of cosmic rays, taking advantage of the improved cross sections and of the latest cosmic ray measurements. Some of the models proposed for the cosmic ray sources are also discussed in relation with these observations.

The scintillating optical fiber isotope experiment: Bevalac calibrations of test models

The Scintillating Optical Fiber Isotope Experiment (SOFIE) is a Cherenkov d E/d x-range experiment being developed to study the isotopic composition of cosmic rays in the iron region with sufficient resolution to resolve isotopes separated by one mass unit at iron. This instrument images stopping particles with a block of scintillating optical fibers coupled to an image intensified video camera. From the digitized video data the trajectory and range of particles stopping in the fiber bundle can be determined; this information, together with a Cherenkov measurement, is used to determine mass. To facilitate this determination, a new Cherenkov response equation was derived for heavy ions at energies near threshold in thick Cherenkov radiators. Test models of SOFIE were calibrated at the Lawrence Berkeley Laboratory's Bevalac heavy ion accelerator in 1985 and 1986 using beams of iron nuclei with energies of 465 to 515 MeV/ nucleon. This paper presents the results of these calibrations and discusses the design of the SOFIE Bevalac test models in the context of the scientific objectives of the eventual balloon experiment. The test models show a mass resolution of σ A ≈ 0.30 amua nd a range resolution of σ R ≈ 250 μm. These results are sufficient for a successful for a successful cosmic ray isotope experiment, thus demonstrating the feasibility of the detector system. The SOFIE test models represent the first successful application in the field of cosmic ray astrophysics of the emerging technology of scintillating optical fibers.

Total charge and mass changing cross sections of relativistic nuclei in hydrogen, helium, and carbon targets.

This is the first in a series of papers describing the results of a systematic study of total, elemental, and isotopic cross sections measured in hydrogen, helium, and carbon targets. These fragmentation studies are based on measurements using 42 beams of 12 separate nuclei from $^{12}\mathrm{C}$ to $^{58}\mathrm{Ni}$. This has resulted in the measurement of more than 100 secondary elemental cross sections and over 300 secondary isotopic cross sections in addition to the total charge changing and mass changing cross sections reported in this paper. These measurements have been made at energies from 300 to 1700 MeV/nucleon and include ten separate energies for $^{56}\mathrm{Fe}$, for example. The measurements have been made with the objective of interpreting the production of secondary nuclei during cosmic-ray propagation in the galaxy in order to better estimate the source elemental and isotopic composition of cosmic rays. At the same time they provide a valuable data base for nuclear physics and the understanding of peripheral interactions of energetic heavy nuclei. In the work reported in this paper \ensuremath{\sim}100 total charge changing and mass changing cross sections have been measured for various targets and energies. The mass changing cross sections we measure are found to agree with earlier cross section measurements using energetic protons incident on targets composed of heavier elements to within \ensuremath{\sim}2% in cases where a comparison can be made. The systematics of this new data set are described and a new, more accurate cross section formula is presented and discussed.

The isotopic composition of cosmic rays

Observations of the isotopic composition of the elements carbon, nitrogen, oxygen, neon, magnesium, silicon, sulfur, calcium, iron and nickel are reviewed and “best” values of selected isotope ratios are derived from the collected data. A simple model of cosmic ray propagation is employed to deduce cosmic ray source abundance ratios both from these best values and from the observations made in a recent high resolution satellite experiment. General features of the cosmic ray source composition are discussed, with emphasis on the enhanced abundances of various neutron rich nuclides and on the distinctly non-solar character of the nitrogen isotopic abundances.

Nucleosynthesis in Wolf-Rayet stars and galactic cosmic-ray isotopic composition

An explanation of the isotopic composition of Galactic Cosmic Rays could provide some clues to the mystery of their origin. It seems now that the strong stellar winds of Wolf-Rayet stars could account for most of the isotopic anomalies that have been observed in Cosmic Rays. Some results are presented, obtained by detailed nucleosynthesis computations.

Matter from outside our solar system–new insights Part II. Experimental measurements and interpretation

One of the prerequisites for the study of cosmic-ray isotopic composition was the development of detector technology capable of providing measurements of the required precision. This was accomplished during the 1970s, and these technological advances are described in the next section. This description is between different experiments and extrapolation of the data to the cosmic-ray source, unfolding the effects of galactic propagation and solar modulation. The comparison between cosmic-ray source matter and solar-system material is given and several models for the nucleosynthesis and the evolution of cosmic-ray source matter are also presented. (AIP)

The elemental and isotopic composition of cosmic rays - Silicon to nickel

The reported observations were made with the aid of the Cosmic Ray Isotope Instrument System (CRISIS) which had been designed to detect and resolve the isotopes of cosmic ray nuclei with atomic numbers equal to or greater than 10. The CRISIS detector was flown on a balloon launched from Aberdeen, South Dakota on 1977 May 20. The period 1977 May 19-22 has been classified by Mason et al. (1979) as one of 'superquiet' solar activity, characterized by the lowest fluxes of low-energy solar particles ever observed. The obtained results are presented in a number of graphs and tables. It was found that the elemental and isotopic abundances of Si are solar-like. Elemental S is underabundant in the cosmic rays by a factor of approximately 3 relative to the solar system, but its isotopic composition resembles the solar composition with S-32 being the dominant isotope. Elemental Ar is virtually absent in the source, and the observed isotopic composition is consistent with a secondary origin. Elemental Ni has a solar-like abundance.

Anomalous isotopic composition of cosmic rays

Recent measurements of nonsolar isotopic patterns for the elements neon and (perhaps) magnesium in cosmic rays are interpreted within current models of stellar nucleosynthesis. One possible explanation is that the stars currently responsible for cosmic-ray synthesis in the Galaxy are typically super-metal-rich by a factor of 2-3. Other possibilities include the selective acceleration of certain zones or masses of supernovae or the enhancement of Ne-22 in the interstellar medium by mass loss from red giant stars and planetary nebulae. Measurements of critical isotopic ratios are suggested to aid in distinguishing among the various possibilities. Some of these explanations place significant constraints on the fraction of cosmic-ray nuclei that must be fresh supernova debris and the masses of the supernovae involved.

The mean mass of the abundant cosmic-ray nuclei from boron to silicon at 1.2 GeV per atomic mass unit

view Abstract Citations (38) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The mean mass of the abundant cosmic-ray nuclei from boron to silicon at 1.2 GeV per atomic mass unit. Dwyer, R. Abstract Results are presented for an investigation of cosmic-ray isotopic composition in which a balloon-borne instrument was used to perform an isotopic analysis of the abundant elements from B through Si in the energy range from 1.0 to 1.6 GeV/amu. The technique employed, which depends on the effect of earth's magnetic field on incoming cosmic rays, and reduction of the observational data are described in detail. Mean masses of the elements B, C, N, O, Ne, Mg, and Si are extracted from normalized Cerenkov spectra and evaluated in terms of the 'leaky box' model of galactic propagation and confinement. The implications of the results for cosmic-ray sources are shown to be consistent with the nucleosynthesis of certain isotopes in the cosmic rays in explosive carbon burning under the conditions of peak temperature, density, and neutronization expected in an explosion of a massive highly evolved star. The possibility of alternate interpretations is noted. Publication: The Astrophysical Journal Pub Date: September 1978 DOI: 10.1086/156417 Bibcode: 1978ApJ...224..691D Keywords: Abundance; Cosmic Rays; Heavy Nuclei; Isotope Effect; Nuclear Fusion; Balloon Sounding; Boron; Carbon; Cerenkov Radiation; Energy Methods; Nitrogen; Oxygen; Space Radiation; Cosmic Rays:Isotopic Abundances; Cosmic Rays: Nuclei full text sources ADS |

The isotopic composition of cosmic rays with Z between 5 and 26

Results are reported for a high-altitude balloon flight which measured the isotopic composition of cosmic rays by using a Cerenkov-range technique to determine the masses of arriving cosmic rays with charges between 5 and 26 for kinetic energies around 450 MeV/amu. Event-selection criteria are discussed, and the mass-determination technique is outlined. Some of the mass histograms resulting from the analysis are presented along with the mean masses calculated from the data, and the derived isotopic compositions. It is found that: (1) C, N, and O are consistent with pure C-12, N-14, and O-16 sources; (2) Mg seems to require some neutron-rich component at the source; (3) Ne appears to require a source isotopic composition that is even more neutron-rich than the universal abundances; and (4) the source may be somewhat enriched in Fe-54. It is suggested that the fundamental nuclear physics which governed the synthesis of solar-system material may also be responsible for cosmic rays, implying that the solar system is probably an average sample of galactic matter.