Primary cosmic ray flux

We discuss the primary cosmic ray flux from the point of view of particle interactions and production of atmospheric neutrinos. The overall normalization of the cosmic ray flux and its time variations and site dependence are major ingredients of the atmospheric neutrino predictions and the basis for the derivation of the neutrino oscillation parameters.     

Multiscaling of galactic cosmic ray flux

Multiscaling analysis of the differential flux dissipation rate of galactic cosmic rays (carbon nuclei) is performed in the energy ranges 56.3-73.4 MeV/nucleon and 183.1-198.7 MeV/nucleon, using the data collected by the ACE/CRIS spacecraft instrument for the year 2000. The analysis reveals strong (turbulencelike) intermittency of the flux dissipation rate for short-term intervals: 1-30 h. It is also found that the type of intermittency can be different in different energy ranges.     

Primary cosmic ray and muon measurements with CAPRICE

The WiZard Collaboration has performed several investigations of the cosmic ray muon component in the atmosphere. In this paper, we review the most recent results from the balloon-borne CAPRICE experiment and discuss their relevance in the context of the atmospheric neutrino observations.     

Prospects of experimental measurements at LHC to better understand cosmic ray induced air showers

In a few years, the LHC will provide proton-proton and nucleus-nucleus collisions at the highest c.m. energies available so far in the laboratory, up to 14 TeV in the case of proton-proton collisions. This regime corresponds to energies of cosmic rays of about 10¹⁷ eV, above the so-called “knee region” in the cosmic-ray flux. A summary of main features of the machine will be presented, concentrating on the various running scenarios foreseen. An overview of the approved experiments and their baseline coverage, as well as possibilities for extensions, will be given. The latter could provide a better coverage of the forward region (small angles with respect to the beam direction) and might give valuable information to help in our understanding of extended air showers induced by cosmic rays in the atmosphere of the Earth.     

Measurement of cosmic ray flux in the China JinPing underground laboratory

The China JinPing underground Laboratory (CJPL) is the deepest underground laboratory running in the world at present. In such a deep underground laboratory, the cosmic ray flux is a very important and necessary parameter for rare-event experiments. A plastic scintillator telescope system has been set up to measure the cosmic ray flux. The performance of the telescope system has been studied using the cosmic rays on the ground laboratory near the CJPL. Based on the underground experimental data taken from November 2010 to December 2011 in the CJPL, which has an effective live time of 171 days, the cosmic ray muon flux in the CJPL is measured to be (2.0±0.4)×10-10/(cm2 ·s). The ultra-low cosmic ray background guarantees an ideal environment for dark matter experiments at the CJPL.     

Determining the primary cosmic ray energy from the total flux of Cherenkov light measured at the Yakutsk EAS array

We present a method for determining the energy of the primary particle that generates an extensive air shower (EAS) of comic rays based on measuring the total flux of Cherenkov light from the shower. Applying this method to Cherenkov light measurements at the Yakutsk EAS array has allowed us to construct the cosmic ray energy spectrum in the range 10¹⁵ ? 3 × 10¹⁹ eV.     

Induction mechanism of cosmic ray production and kinks in the cosmic ray spectrum

Two kinks are observed in the energy spectrum of galactic cosmic rays. It is shown that the entire spectrum can be described, to a good approximation, by a single formula obtained on the basis of the hypothesis that the particles are produced and accelerated in plasma pinches by an induction mechanism under the assumption that three hierarchical groups of currents are present—interstellar, galactic, and metagalactic. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 4, 225–230 (25 August 1996)     

Change of primary cosmic ray mass composition at superhigh energies

The EAS MSU array experimental data are analyzed in relation to the primary cosmic ray composition in the energy range above 10¹⁷–10¹⁸ eV. The problem of the existence of an additional cosmic ray component, which cannot be explained in the framework of traditional mechanism of Galactic cosmic ray production, is considered. The fraction of gamma-quanta in the primary cosmic radiation is evaluated as well.     

Models for cosmic ray interactions

Contemporary models of hadronic interactions are reviewed. Basic phenomenological approaches are compared, with an emphasizes on the predicted air shower characteristics. Special attention is payed to the remaining discrepancies between present hadronic MC generators and cosmic ray data. Finally, future prospects concerning model improvements are discussed, in particular, regarding the possibilities to discriminate between different models on the basis of accelerator or cosmic ray measurements.     

Model of cosmic ray generation

It is shown that the two bends observed in the cosmic ray energy spectrum can be well approximated by equations derived by assuming that cosmic rays can be generated and accelerated in plasma pinches. Zh. éksp. Teor. Fiz. 111, 385–403 (February 1997)     

New physics, the cosmic ray spectrum knee, and pp cross section measurements

We explore the possibility that a new-physics interaction can provide an explanation for the knee just above 10⁶ GeV in the cosmic ray spectrum. We model the new-physics modifications to the total proton–proton cross section with an incoherent term that allows for missing energy above the scale of new physics. We add the constraint that the new physics must also be consistent with published pp cross section measurements, using cosmic ray observations, an order of magnitude and more above the knee. We find that the rise in cross section required at energies above the knee is radical. The increase in cross section suggests that it may be more appropriate to treat the scattering process in the black disc limit at such high energies. In this case there may be no clean separation between the standard model and new-physics contributions to the total cross section. We model the missing energy in this limit and find a good fit to the Tibet III cosmic ray flux data. We comment on testing the new-physics proposal for the cosmic ray knee at the Large Hadron Collider.     

宇宙射线和α放射线的地质作用

对采集到的矿物样品结合理论计算结果进行了详细分析.阐明了矿物样品上的菱形腐蚀坑,可能是宇宙射线粒子和天然放射线中的α粒子与矿物晶格碰撞后,在晶格中留下的损伤经过地层中腐蚀性液体长期腐蚀扩大形成的.讨论了这些腐蚀坑对地质作用的影响.指出这些射线对地质作用的影响,应当是地质作用研究中不可忽视的因素.     

Stationary cosmic jets as accelerators of ultrarelativistic cosmic ray particles

A model of a cosmic jet working in the mode of a magnetohydrodynamic nozzle and unipolar inductor is considered. It is shown that the “solid-state” rotation of screw magnetic field lines leads to acceleration of small fractions of plasma particles up to ultrarelativistic energies with the spectrum dq/d? ～ ? ^?n , the exponent n being close to the experimental value.     

Identification of the primary cosmic ray

The nature of the primary particle giving rise to an atmospheric shower may be, to some extent, inferred from the observable properties: longitudinal profile (especially position of the maximum of the number of charged particles) or shape at ground level (lateral distribution, curvature and thickness of the shower front, muonic component). Distinguishing different nuclei cannot be performed unambiguously on a single shower, because of the random fluctuations in the first steps of the cascade; however, it is possible to study the composition of the incident flux on a statistical basis: showers from heavier nuclei have a faster development, and contain more muons. The uncertainties on the hadronic interactions at the highest energies limit the reliability of the identification. Other primaries, if they exist, could be easier to distinguish. Photons would give a slower development than protons, especially at highest energies, and a very reduced muonic component; neutrinos would be characterized by deep interactions in the atmosphere, or even within the Earth, giving almost horizontal showers with a large electromagnetic component, clearly different from the muonic tail of showers induced in the upper atmosphere by nuclei. Such ‘exotic’ primaries have not yet been observed. To cite this article: P. Billoir, P. Sommers, C. R. Physique 5 (2004).     

Ultra high-energy cosmic ray proton interactions

The recent Auger results suggest that the coincidences of arrival directions with ‘nearby’ AGN, and the HiRes discovery of the GZK cut-off, indicate protons to be at least the strongly dominant component of primary extra galactic cosmic ray flux. The measured longitudinal extensive air shower propagation characteristics, however, indicate at least a mixed composition, if the conventional interaction model is correct. For the present work we assume that the particles are indeed protons and examine the consequences for the high-energy interaction physics. We have found that such a supposition requires strong violation of the so-called Feynman scaling.     

Calculation of LET-spectra of heavy cosmic ray nuclei at various absorber depths

The calculation is based on a factorization of fragmentation cross-sections into a projectile-depending and a target-depending part, which was found at Bavalac for high energy C and O ions. With this the known cross-sections for the fragmentation of heavy ions in collision with protons can be extrapolated to heavier targets. Considering the fragmentation and the energy loss of heavy nuclei the energy spectra of individual elements are calculated for different depths of absorber. This energy spectra can easily be converted to LET (linear energy transfer) spectra. The changes of the isotopic composition with absorber depth and its influence on the shape of the LET-spectra are discussed. The calculated results are compared with experimental data.