Cosmic-ray History Research Articles

Measuring Changes in the Atmospheric Neutrino Rate over Gigayear Timescales.

Measuring the cosmic ray flux over timescales comparable to the age of the Solar System, ∼4.5 Gyr, could provide a new window on the history of the Earth, the Solar System, and even our Galaxy. We present a technique to indirectly measure the rate of cosmic rays as a function of time using the imprints of atmospheric neutrinos in "paleo-detectors," natural minerals that record damage tracks from nuclear recoils. Minerals commonly found on Earth are ≲1 Gyr old, providing the ability to look back across cosmic ray history on timescales of the same order as the age of the Solar System. Given a collection of differently aged samples dated with reasonable accuracy, this technique is particularly well-suited to measuring historical changes in the cosmic ray flux at Earth and is broadly applicable in astrophysics and geophysics.

Measurements of cosmic-ray proton and helium spectra from the BESS-Polar long-duration balloon flights over Antarctica.

The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two long-duration balloon flights over Antarctica in December 2004 and December 2007, at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cosmic-ray antiprotons, positrons, and electrons from interactions of primary cosmic-ray nuclei with the interstellar gas, and to calculations of atmospheric muons and neutrinos. We report absolute spectra at the top of the atmosphere for cosmic-ray protons in the kinetic energy range 0.2-160 GeV and helium nuclei 0.15-80 GeV/nucleon. The corresponding magnetic rigidity ranges are 0.6-160 GV for protons and 1.1-160 GV for helium. These spectra are compared to measurements from previous BESS flights and from ATIC-2, PAMELA, and AMS-02. We also report the ratio of the proton and helium fluxes from 1.1 GV to 160 GV and compare to ratios from PAMELA and AMS-02.

From spontaneous ionization to subatomic physics: Some vignettes from cosmic ray history

In 1879 Crookes discovered that air seemed to ionize spontaneously. With the discovery in 1896 of radioactivity by Henri Becquerel, it appeared that the mystery was solved. However a number of physicists sought a quantitative agreement between the ”spontaneous ionization” and the radioactivity in the earth. The persistence of these physicists led to the discovery of another source of radiation which appeared to come from the heavens. The nature of this ”cosmic radiation” involved phenomena that were completely unknown. Coming to an understanding of the nature of this cosmic radiation took about 40years between 1912 and 1953. This history involves extraordinary scientists and the invention of dramatic new detection techniques. This story finishes with a remarkable conference organized by Patrick Blackett and Louis Leprince–Ringuet (1953) in the Pyrenees town of Bagnères de Bigorre. Following 1953 the cosmic ray researchers divided into two groups, those who continued the investigation of the new particles with the accelerators and those who continued with the search for the origin and the astrophysics of the cosmic rays.

Marietta Blau in the history of cosmic rays

Marietta Blau in the history of cosmic rays

Marietta Blau in the history of cosmic rays

Carlson replies: Ruth Lewin Sime correctly points out the important contributions to the nuclear emulsion technique by Marietta Blau, which are unfortunately often forgotten. Blau, together with Hertha Wambacher, observed cosmic-ray-induced “stars” in 1937. In my article, I pointed out that many results of fundamental importance were indeed obtained using nuclear emulsions, in particular the discovery of the pion that earned Cecil Powell the 1950 Nobel Prize in Physics.In 1950 Blau and Wambacher were nominated for the Nobel Prize in Physics for the method of exposing sets of emulsion plates at high altitude and for observing cosmic-ray-induced stars.11. Minutes of the Royal Swedish Academy of Sciences on Nobel Matters, Nobel Archives, Royal Swedish Academy of Sciences, Stockholm (1950), p. 391. Among the other 28 nominees that year was Cecil Powell, who received 16 nominations.Contrary to what Sime says, the names of Blau and Wambacher are not absent from the “Nobel texts.” In its 1950 recommendation to the Royal Swedish Academy of Sciences, the Nobel Committee for Physics included as an enclosure a nine-page detailed and accurate account, written by committee member Axel Lindh,22. Minutes of the Royal Swedish Academy of Sciences on Nobel Matters, Nobel Archives, Royal Swedish Academy of Sciences, Stockholm (1950), p. 132. on the work by Blau and Wambacher. Lindh wrote that without any doubt Blau and Wambacher were the first to use plates of emulsions to study cosmic rays and the first to use the technique to observe cosmic-ray-induced stars, a phenomenon earlier observed in cloud chambers. Lindh noted that Wambacher, in a 1938 paper,33. H. Wambacher, Phys. Z. 39, 883 (1926). wrote that E. G. Steinke was the one who had proposed using emulsions to study cosmic-ray stars. In his conclusion, Lindh acknowledged the pioneering work by Blau and Wambacher but noted that it was not of sufficient significance for a Nobel Prize.The committee report44. Minutes of the Royal Swedish Academy of Sciences on Nobel Matters, Nobel Archives, Royal Swedish Academy of Sciences, Stockholm (1950), p. 81. discussing the nomination of Blau and Wambacher states that among the notable descriptions of progress made using the emulsion technique are a 1925 article in which Blau says that protons also can be observed and one by Blau and Wambacher in 1937 reporting cosmic-ray-induced stars. The report ends with the proposal to award the 1950 Nobel Prize in Physics to Powell.REFERENCESSection:ChooseTop of pageREFERENCES <<CITING ARTICLES1. Minutes of the Royal Swedish Academy of Sciences on Nobel Matters, Nobel Archives, Royal Swedish Academy of Sciences, Stockholm (1950), p. 391. Google Scholar2. Minutes of the Royal Swedish Academy of Sciences on Nobel Matters, Nobel Archives, Royal Swedish Academy of Sciences, Stockholm (1950), p. 132. Google Scholar3. H. Wambacher, Phys. Z. 39, 883 (1926). Google ScholarCrossref4. Minutes of the Royal Swedish Academy of Sciences on Nobel Matters, Nobel Archives, Royal Swedish Academy of Sciences, Stockholm (1950), p. 81. Google Scholar© 2012 American Institute of Physics.

Early history of cosmic rays and solar wind – Some personal remembrances

The early history of solar wind was replete with prejudices and strong opposition to Parker’s formulation. It was only after conclusive evidence from satellite data was obtained that the idea of solar wind was accepted. Some personal experiences of mine during my stay at the University of Chicago in 1953–1954, including the encounter of Dr. Simpson with Dr. Biermann and the inconclusive discussion between them about a possible perpetual solar outflow of particles are presented and further developments when Parker came to Chicago in 1956 and formulated his idea of solar wind, as narrated to me later by Dr. Simpson, are described.

First measurements of cosmic-ray nuclei at high energy with CREAM

The balloon-borne cosmic-ray experiment CREAM-I (Cosmic-Ray Energetics And Mass) recently completed a successful 42-day flight during the 2004–2005 NASA/NSF/NSBF Antarctic expedition. CREAM-I combines an imaging calorimeter with charge detectors and a precision transition radiation detector (TRD). The TRD component of CREAM-I is targeted at measuring the energy of cosmic-ray particles with charges greater than Z ∼ 3. A central science goal of this effort is the determination of the ratio of secondary to primary nuclei at high energy. This measurement is crucial for the reconstruction of the propagation history of cosmic rays, and consequently for the determination of their source spectra. First scientific results from this instrument are presented.

6Li and Gamma Rays: Complementary Constraints on Cosmic‐Ray History

The rare isotope 6Li is made only by cosmic rays, dominantly in alpha+alpha fusion reactions with ISM helium. Consequently, this nuclide provides a unique diagnostic of the history of cosmic rays in our Galaxy. The same hadronic cosmic-ray interactions also produce high-energy gamma rays (mostly via neutral pion production). Thus, hadronic gamma-rays and 6Li are intimately linked. Specifically, 6Li directly encodes the local cosmic-ray fluence over cosmic time, while extragalactic hadronic gamma rays encode an average cosmic-ray fluence over lines of sight out to the horizon. We examine this link and show how 6Li and gamma-rays can be used together to place important model-independent limits on the cosmic-ray history of our Galaxy and the universe. We first constrain gamma-ray production from ordinary Galactic cosmic rays, using the local 6Li abundance. We find that the solar 6Li abundance demands an accompanying extragalactic pionic gamma-ray intensity which exceeds that of the entire observed EGRB by a factor of 2-6. Possible explanations for this discrepancy are discussed. We then constrain Li production using recent determinations of extragalactic gamma-ray background (EGRB). We note that cosmic rays created during cosmic structure formation would lead to pre-Galactic Li production, which would act as a "contaminant" to the primordial 7Li content of metal-poor halo stars. We find the uncertainties in the observed EGRB are so large that we cannot exclude a pre-Galactic Li which is comparable to primordial 7Li. Our limits and their more model-dependent extensions will improve significantly with additional observations of 6Li in halo stars, and with improved measurements of the EGRB spectrum by GLAST. (Abriged abstract)

Structure formation cosmic rays: Identifying observational constraints

Shocks that arise from baryonic in-fall and merger events during the structure formation are believed to be a source of cosmic rays. These "structure formation cosmic rays" (SFCRs) would essentially be primordial in composition, namely, mostly made of protons and alpha particles. However, very little is known about this population of cosmic rays. One way to test the level of its presence is to look at the products of hadronic reactions between SFCRs and the ISM. A perfect probe of these reactions would be Li. The rare isotope Li is produced only by cosmic rays, dominantly in ?? ? 6Li fusion reactions with the ISM helium. Consequently, this nuclide provides a unique diagnostic of the history of cosmic rays. Exactly because of this unique property is Li affected most by the presence of an additional cosmic ray population. In turn, this could have profound consequences for the Big-Bang nucleosynthesis: cosmic rays created during cosmic structure formation would lead to pre-Galactic Li production, which would act as a "contaminant" to the primordial 7Li content of metalpoor halo stars. Given the already existing problem of establishing the concordance between Li observed in halo stars and primordial 7Li as predicted by the WMAP, it is crucial to set limits to the level of this "contamination". However, the history of SFCRs is not very well known. Thus we propose a few model-independent ways of testing the SFCR species and their history, as well as the existing lithium problem: 1) we establish the connection between gamma-ray and Li production, which enables us to place constraints on the SFCR-made lithium by using the observed Extragalactic Gamma-Ray Background (EGRB); 2) we propose a new site for testing the primordial and SFCR-made lithium, namely, low-metalicity High-Velocity Clouds (HVCs), which retain the pre-Galactic composition without any significant depletion. Although using one method alone may not give us strong constraints, using them in concert will shed a new light on the SFCR population and possibly give some answers about the pressing lithium problem. .

Cosmic-ray history derived from the 54Mn, 56Ni and 144Pm chronometers

Sources of 54 Mn, 55 Ni, and 144 Pm were placed at the center of the Gammasphere array and searches were made for the astrophysically interesting β + decay modes of these isotopes. The results of these searches are presented and the implications for cosmic-ray physics are discussed.

Production Cross Sections of Fragments from Beams of 400–650 MeV per Nucleon9Be,11B,12C,14N,15N,16O,20Ne,22Ne,56Fe, and58Ni Nuclei Interacting in a Liquid Hydrogen Target. I. Charge Changing and Total Cross Sections

We have measured the charge changing cross sections from 10 individual beams of isotopes from 8 different nuclei between Be and Ni which were accelerated to energies from 400-650 MeV nucleon-1 at the SATURNE Accelerator in France in 1993 and 1994. These nuclei interacted in a 1.52 g cm-2 thick liquid hydrogen target and the fragments were observed. This is the first use of a pure hydrogen target to measure cross sections that has a thickness approximating the amount of hydrogen traversed by cosmic rays in our Galaxy. Several of the beam charges such as 9Be,11B,15N, and 22Ne have not had their fragmentation cross sections measured previously. The cross sections from the 12C,14N,16O,20Ne,56Fe, and 58Ni beams are compared with earlier measurements by our group using a CH2 - C target subtraction technique to determine the hydrogen cross sections. The overall agreement between the new measurements and the earlier measurements using CH2 - C subtraction is excellent with a systematic consistency between measurements of 3%-5%. Using these new cross sections the predictions of both the B/C and Z = (21-23)/Fe ratios at ~1 GeV nucleon-1 now agree with HEAO measurements to ~1%-2%, thus obviating the need for truncation of the exponential path length distribution path length distribution that is expected from uniform propagation models. Also, these new charge changing cross sections along with the isotopic cross sections reported in paper two of this series, define the production of cosmic-ray beryllium and boron nuclei in the galaxy and also the secondary isotopes 10Be,13C,14N,15N,18O, and all of the Fe secondary isotopes to a level of precision of 3%-5% or better. These cross sections are important for determining the abundance of these rare isotopes and others in the cosmic-ray sources as well as tracing the detailed propagation history of cosmic rays in the Galaxy. These measurements also provide high precision cross sections for the study of the nuclear physics of the interaction process.

Production Cross Sections of Fragments from Beams of 400–650 MeV per Nucleon9Be,11B,12C,14N,15N,16O,20Ne,22Ne,56Fe, and58Ni Nuclei Interacting in a Liquid Hydrogen Target. II. Isotopic Cross Sections of Fragments

We have measured the isotopic cross sections of 130 secondary fragmentation isotopes from 10 different beam nuclei from 9Be to 58Ni that were accelerated to between 400 and 650 MeV nucleon-1 at the SATURNE Accelerator in France in 1993 and 1994. These beam nuclei interacted in a 1.52 g cm-2 thick liquid hydrogen target, and the isotopic fragments were observed. This is the first use of a pure hydrogen target with a thickness approximating the amount of hydrogen traversed by cosmic rays in our Galaxy to measure cross sections. Several of the beam charges such as 9Be,11B,15N, and 22Ne have not had their fragmentation cross sections measured previously. The isotopic cross sections from the 12C,14N,16O,20Ne,56Fe, and 58Ni beam interactions are compared with earlier measurements by our group using a CH2 - C target subtraction technique to determine the hydrogen cross sections. The overall agreement between the new measurements and the earlier measurements using a CH2 - C target subtraction is excellent with a systematic consistency between measurements ~3%-5%. These new isotopic cross sections define the Galactic production of the secondary isotopes 10Be,10B,11B,13C,14N,15N, and 18O as well as Fe and Ni secondary decay isotopes from Cl to Co to a level of precision of ~3%-5%. These cosmic-ray isotopes are important for understanding the nucleosynthesis in the cosmic-ray sources as well as tracing the detailed propagation history of cosmic rays in the Galaxy.

What are the Limits for Ace Galactic Cosmic-Ray Isotope Studies?

The CRIS experiment on ACE, with its excellent charge and mass resolution and a geometrical factor ∼10× that of any previous experiment, holds the promise of rewriting the book on galactic cosmic-ray abundance studies. Translating these measurements into precise cosmic-ray source abundances and using these measurements to determine more accurately the propagation history of cosmic rays is a different matter, however. In many important cases these studies will be limited by the accuracy of the nuclear cross- sections that determine how the cosmic-ray composition is modified as it traverses the interstellar matter. In this paper we will discuss these cross-sections and how well they are known as a function of the energy and the charge and mass of the cosmic-ray nuclei. This will then be used to discuss what new limits can be expected on several contemporary problems of interest in cosmic rays from the CRIS measurements.

10 Be: recent applications in Earth sciences

10 Be, a cosmogenic isotope produced by cosmic rays interacting with the Earth ’s atmosphere and surface, has chemical and physical properties that make it useful as a tracer for some terrestrial processes and a geological clock for a few substances. The rarity of the stable isotope, 9 Be, allows 10 Be to be detected in natural materials at extremely low levels with backgrounds for rocks, sediments etc. below 105 atom g -1 now attainable, a value to be com pared with an average annual global deposition rate of 1.3 x 10 6 atom cm -2. The affinity of Be for the components of soil and sediment is sufficiently high that its contact with them effectively immobilizes it, thereby allowing 10 Be to function as a tracer of sediment transport. The half-life of 1.5 Ma is convenient for some geological studies. Application has been found in cosmic-ray history, formation of manganese nodules, pelagic sedimentation, island-arc volcanism, soil evolution, soil erosion and rock weathering.

Applications of Accelerator Mass Spectrometry

(1 .5 x 106 yr half-life), 26 Al (7.2 x 105 yr), and 36CI (3.0 x 105 yr), are now routinely observable using accelerator mass spectrom­ etry and are finding increasing use in earth and planetary sciences. Their use for radioactive dating, an idea that figured prominently in the papers reporting the first experiments, has been a small part of subsequent work, but their use as tracers has developed rapidly, with the result that this review covers areas unsuspected in 1977. The application to radiocarbon has proved arduous owing to the need to determine isotopic ratios to a precision of 1%, a restriction that has seldom hampered the method when applied to the other isotopes, which are generally measured to accuracies of 5 to 10%. The precision desired for radiocarbon, implying an age uncertainty of 83 yr, although trivial by the standards of low-energy mass spectrometry, has only recently been achieved for sustained periods of machine operation. The technique has been applied to research on the atmosphere, the cosmic-ray history found in Arctic ice, manganese nodules,

Cosmic-ray elemental abundances

The elemental composition of the cosmic radiation as function of particle energy is one of the major sources of information concerning the origin and life history of cosmic rays. The Danish-French spectrometer on the HEAO-3 satellite /1/ has recently provided new and detailed data on the composition and energy spectra of the cosmic rays for the elements between beryllium and germanium in the energy range between 0.7 and 25 GeV/nucleon. The analysis of these data appear to be consistent with the following assumptions: 1) a source composition similar to that of the Solar System, 2) an injection process favouring elements with low values of the first ionization potential, 3) a rapid acceleration proces yielding identical energy spectra for all species, and 4) a diffusive propagation in the Galaxy with the average amount of matter traversed before escape from the confinement volume being a decreasing function of the particle rigidity. Despite the consistency of the HEAO-data with this set of assumptions it is unfortunately too early to regard these as well established facts of general validity. Observations of the hydrogen-helium component of the cosmic radiation have yielded constraints on the source composition, the injection and acceleration processes, and the propagation history which seems to be at variance with the picture described above.

The history of cosmic rays in a dynamical halo - A retrodictive probability approach

We examine a particular model of cosmic-ray propagation in the Galaxy that contains convective outflow in the halo. When this convection is important, the solutions for the cosmic-ray density are quite different from those obtained by considering diffusion alone. We derive an equation for propagating, backward in time, the particle population that is the disk at the present time and find that, unlike the bulk of the cosmic rays, these particles have never been very far from the disk. We may therefore define an effective halo thickness D* which is smaller than the actual halo thickness D and conclude that particles in the disk have little to do with those that venture farther into the halo than D*. This fact can, perhaps, reconcile radio evidence for an extensive halo with the evidence from ..gamma..-ray data that the distribution of cosmic rays in the disk is strongly source-dominated.

Origin of energetic cosmic rays. III. One-dimensional diffusion from random sources

For pt.II see ibid., vol.7, no.3, 437 (1974). The model of cosmic ray propagation by one-dimensional diffusion along randomly wandering field lines proposed by Jones in 1971 is developed by considering the effect of random discrete sources on the concentration, anisotropy and mean age of cosmic rays along a line of magnetic flux. This mode of propagation is taken to be valid in the energy range 1011 eV to 1014 eV. The experimental information on the galactic anisotropy, mean age and constancy of the cosmic ray flux is briefly stated. The probability of our being at a time in the earth's cosmic ray history when the fluctuating anisotropy is by chance at its relatively low observed value is evaluated for a number of values of the parameters of propagation.

The History of Cosmic Rays

The history of developments in the cosmic-ray field is traced back to the time when there was uncertainty about the origin of ionization in closed vessels. We then pass through the period when, through the high-altitude experiments of Victor F. Hess, we were forced to admit the existence of a radiation coming from outside our atmsophere. The controversy as to whether the rays are photons or charged particles is sketched and leads through the results of geomagnetic effects to the conclusion that the primaries are positively charged particles, mostly hydrogen, but that in addition there is about 15% of helium, and representatives of probably all elements are to be found in amounts diminishing with increase of atomic number. The effect on the detailed study of cosmic ray phenomena (as observed in the atmosphere) of the discovery of the mesotron and the positron is traced, as is the part played by such theoretical discoveries as “pair production.” Brief reference is made to “large showers,” and the paper concludes with a brief summary of our knowledge of the origin of the primary cosmic radiation and of the part played by “island magnetic fields” existing in our galaxy and even in our solar system.