Muon bundles produced by UHE cosmic rays at large zenith angles

The first experimental results on a new EAS observable, the local muon density spectra measured with a large area coordinate detector DECOR in a wide range of zenith angles, are presented. These data correspond to the interval of primary particle energies from 10¹⁵ to 10¹⁸ eV. Some features of local muon density phenomenology are considered on the basis of an analytical model. Expected distributions of the events in the muon density have been calculated by means of the CORSIKA code and compared with experimental data. The text was submitted by the authors in English.     

Paleoastrophysics and cosmic rays

Summary A discussion is given of the status and potential of studying the cosmic-ray flux level over long time scales by high-precision measurement of cosmogenic isotopes content in natural archives of cosmic radiation. Invited talk given at the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Origin of cosmic rays

Cosmic rays were discovered in 1911 but it is only now that some ideas are beginning to emerge as to their origin. This paper will examine the present evidence concerning the origin question over the whole energy range, from 10⁹ eV to 10²⁰ eV. At the lowest energies, (10⁹–10¹⁰ eV), the new subject of gamma ray astronomy plays a crucial role and a galactic origin is favoured. At higher energies (10¹²–10¹⁷ eV) recent measurements of the anisotropies in arrival directions also suggest a galactic origin, although the evidence is not as strong. At the very highest energies it seems likely that some, at least, of the particles come from outside the galaxy although the non-existence of the cut-off at about 6 × 10¹⁹ eV arising from interactions with the cosmological relict radiation provides a paradox. The likely future areas of advance in this fascinating subject will be indicated. Based on the B. B. Roy memorial lectures delivered at Calcutta University, February 1–3, 1978.     

Search for antihelium in cosmic rays

The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle Discovery during flight STS-91 in a 51.7° orbit at altitudes between 320 and 390 km. A total of 2.86×10⁶ helium nuclei were observed in the rigidity range 1 to 140 GV. No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of antihelium to helium of <1.1×10⁻⁶ is obtained.     

Search for anisotropy of ultrahigh-energy cosmic rays

It is shown that a statistically significant anisotropy exists in the arrival directions of cosmic rays with energies ∼1×10¹⁷ eV and 4×10¹⁸ eV. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 289–292 (10 September 1997)     

Lorentz violation for photons and ultrahigh-energy cosmic rays

Lorentz symmetry breaking at very high energies may lead to photon dispersion relations of the form omega2=k2+xink2(k/MPl)n with new terms suppressed by a power n of the Planck mass MPl. We show that first and second order terms of size |xi1|>orsimilar10(-14) and xi2相似文献   

A theory of cosmic rays

We present a theory of non-solar cosmic rays (CRs) in which the bulk of their observed flux is due to a single type of CR source at all energies. The total luminosity of the Galaxy, the broken power-law spectra with their observed slopes, the position of the ‘knee(s)’ and ‘ankle’, and the CR composition and its variation with energy are all predicted in terms of very simple and completely ‘standard’ physics. The source of CRs is extremely ‘economical’: it has only one parameter to be fitted to the ensemble of all of the mentioned data. All other inputs are ‘priors’, that is, theoretical or observational items of information independent of the properties of the source of CRs, and chosen to lie in their pre-established ranges. The theory is part of a ‘unified view of high-energy astrophysics’ — based on the ‘Cannonball’ model of the relativistic ejecta of accreting black holes and neutron stars. The model has been extremely successful in predicting all the novel properties of Gamma Ray Bursts recently observed with the help of the Swift satellite. If correct, this model is only lacking a satisfactory theoretical understanding of the ‘cannon’ that emits the cannonballs in catastrophic processes of accretion.     

Spectrum of ultrahigh-energy cosmic rays

Detailed calculation of the energy spectra of ultrahigh-energy cosmic rays has been performed. The spectral features related to the interaction of protons with cosmic microwave background have been analyzed. The calculated spectra are compared with the experimental data obtained at the giant detectors for ultrahigh-energy cosmic rays.     

Search for heavy particles in cosmic rays

A search for heavy, long-lived particles has been made in the cosmic rays. The observations may possibly be explained in terms of known particles, but they appear to be more easily explained in terms of a flux $\text{? 6.10}{}^{\mathrm{?9}}\text{cm}{}^{\mathrm{?2}}\text{sec}{}^{\mathrm{?1}}\text{sr}{}^{\mathrm{?1}}$ if singly charged particles having mass $\text{? 6 m}{}_{\mathrm{<mtext>p</mtext>}}$.     

Plasma wakefield acceleration for ultrahigh-energy cosmic rays

A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfvén shocks in a relativistically flowing plasma. We show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f(epsilon) proportional, variant 1/epsilon(2). As an example, we discuss the possible production in the atmosphere of gamma ray bursts of ultrahigh-energy cosmic rays (UHECR) exceeding the Greisen-Zatsepin-Kuzmin cutoff. The estimated event rate in our model agrees with that from UHECR observations.     

The search for antimatter in cosmic rays

The search for antimatter in the universe is a page in the history of the Ioffe Physicotechnical Institute (IPTI). Experiments on spacecraft and high-altitude balloons, begun in the 1960s, yielded information on to the presence or absence of antimatter stars or galaxies according to evidence arising in explosive processes in these objects. Antiprotons with energies of 2–5 GeV in galactic cosmic rays were observed at the end of the 1970s in balloon experiments by the Cosmic Spectrometry Laboratory at the IPTI. These studies were done using a magnetic spectrometer at altitudes with a residual pressure of 10 g/cm² with a threshold geomagnetic rigidity of 3 GV. High-latitude experiments in the 1980s, yielding the first measurements of the flux of galactic antiprotons with energies of 0.2–2 GeV, gave some indication of the mechanism by which they are generated. The measured ratios of the fluxes of antiprotons and protons in the cosmic rays are 2.4 _−1.3 ^+2.4 ×10⁻⁴ and 6 ₋₅ ⁺¹⁴ ×10⁻⁵ at energies of 2–5 and 0.2–2 GeV, respectively. Subsequent balloon-borne experiments employing magnetic spectrometers by groups from the USA and Japan have confirmed the results obtained by the IPTI. Experimental and theoretical work on the search for antiparticles in cosmic rays is summarized and the astrophysical consequences of this research are discussed. Experimental data on the detection of antiparticles in galactic cosmic rays indicate that there are no objects made of antimatter within the local group of galaxies. Zh. Tekh. Fiz. 69, 99–103 (September 1999)     

Ultra-high-energy cosmic rays and inflation relics

There are two processes of matter creation after inflation that may be relevant to the resolution of the puzzle of cosmic rays observed with energies beyond GZK cut-off: 1) gravitational creation of superheavy (quasi)stable particles, and 2) non-thermal phase transitions leading to the formation of topological defects. We review both possibilities.     

Search for extragalactic sources of ultrahigh-energy cosmic rays

Possible extragalactic sources of cosmic rays with energies above 4 × 10¹⁹ eV detected at the Yakutsk EAS array are sought. The correlation of the shower arrival directions with objects from Véron’s catalog that are located closer than 100 Mpc from the Earth confirms the observations at the Pierre Auger Observatory, as well as the Greisen-Zatsepin-Kuzmin effect on the spectrum of cosmic rays. The detailed analysis of the data reveals the classes of objects belonging to the active galactic nuclei that are the most probable sources of ultrahigh-energy cosmic rays.     

Spinning neutron stars and cosmic rays

Spindown of magnetic neutron stars in close binaries by the propeller mechanism, and spinup by accretion are revised. Spindown is more efficient than sometimes claimed. Cosmic rays are probably generated by the propeller mechanism rather than in (single) pulsar winds.     

Search for new massive particles in cosmic rays

In this paper, some unusual cosmic ray events are reviewed. They are the Yunnan event recorded in 1972 using a cloud chamber at Yunnan Cosmic Ray Station (YCRS) near Kunming, the south-west of China; the six exotic events (Kolar events) collected during 1965 to 1975 in the Kolar Gold Mine Field (KGF) in south India; and a double-core event obtained also in KGF in 1979 at a depth different from that where the other six were obtained. In addition, some interesting phenomena were also noticed: the abnormal upward muon flux observed by the MINI collaboration, and several intriguing signals seen in the proton detector in KGF. A careful kinematics analysis has shown that all these exotic events are likely to be related to a kind of heavy and slow-moving (i.e. with a Lorentz factor γ ≈ 2–5) particles produced from cosmic ray interactions. Besides, the rough flux estimates in these experiments seem to indicate that the event rate does not depend on the depth. Thus a natural hypothesis is that there is a heavy and neutral component in the cosmic rays which might be related with the long-sought weakly interacting massive particle (WIMP) - one of the most promising candidates of the dark matter of our Universe. Moreover, from the tracks seen in these events, there is also a signal of the possible existence of a kind of heavy and charged particles with a relatively long lifetime (say, longer than 10⁻⁹s) which might be the interacting products of the unknown cosmic ray particles mentioned above. We then turn to the question of how to search for these exotic particles in cosmic rays, and propose to build a dedicated magnetic spectrometer for identifying them.