Possible attenuation of the radio signal from the cascade in solid medium at energies above 1020 eV

It was shown that the effect of plasma production during solid medium ionization by a developing cascade can shield excess-charge radiation in the radio range used for detecting particles at energies higher than 10²⁰ eV. Such a shielding effect is significant in Antarctic ice and is insignificant for lunar regolith. Hence, the LORD experiment on detection of cascades from ultrahigh-energy cosmic rays and neutrinos from circumlunar spacecrafts retains the capability of measurements up to the energies of 10²³ eV.     

Investigation of primary cosmic rays at energies above 10<Superscript>14</Superscript> eV

A search for sources of primary cosmic rays at energies of 10¹⁴–10¹⁵ eV was performed using the special independent KLARA+Khronotron unit at the Tien Shan Mountain Cosmic Ray Station in a joint experiment of the Lebedev Physics Institute (LPI) and the Central Research Institute for Physics (KFKI). A full data bank of standard events, consisting of 30 million extensive air showers (EASes), was analyzed. Analysis results are presented as maps of the directions of EAS arrival in equatorial coordinates in which the standard deviation of the number of events exceeds a certain value. These could be directions from which neutral primary cosmic particles (e.g., gamma ray photons) arrive from sources of primary cosmic rays. A match is found between separate directions with results, obtained on other stations, and the location of pulsars.     

The slowing down of atoms with energies ofE<10 eV in crystals

The line shape of the 773 keV emission line emitted by¹⁸⁷Re depends on the slowing down of the recoil the atom receives in the precedingβ transition. Using the nuclear resonance fluorescence method the line profile was studied for sources where the radioactive atoms are embedded in single crystals of W and WSe₂ and in polycrystalline samples of Nb. The experimental results for W and Nb are in complete agreement with predictions by a theory in which the slowing down is calculated starting from a Born-v. Karman lattice model. The temperature dependence of the line shape yields the phonon lifetimes in W and Nb (W) to beτ(300 K)=(2.4±0.3)ps andτ(300 K)=(1.7±0.2) ps, respectively. Measurements for the slowing down of the recoiling atoms perpendicularly to and along the hexagonal axis of WSe₂ yielded an anisotropy in qualitative agreement with expected values.     

Search for sources of primary cosmic radiation at energies above 10<Superscript>14</Superscript> eV

The results obtained at the separate installation of the Tien Shan station, intended for continuous studies, are analyzed with the aim of searching for local sources of primary cosmic radiation (PCR) at energies of 10¹⁴ − 10¹⁵ eV. Arrival directions in equatorial coordinates are determined for 35 millions of recorded extensive air showers (EAS) from PCR. The directions where the standard deviation of the number of events exceeds a certain value are separated. These can be the directions along which neutral primary cosmic particles (γ-rays and others) come from PCR sources. Some directions coincide with the results of other installations and pulsar positions.     

New method for determining energies of cosmic-ray nuclei

A new procedure for determining the energies of particles of primary cosmic radiation is described. The procedure is based on measuring the spatial density of the flux of secondary particles originating from the first event of nuclear interaction that have traversed a thin-converter layer. The use of the proposed method makes it possible to create equipment of comparatively small mass and high sensitivity. The procedure can be applied in balloon-and satellite-borne cosmic-ray experiments with cosmic nuclei for all types of nuclei over a wide energy range between 10¹¹ and 10¹⁶ eV per particle. Physical foundations of the method, results of a simulation, and the applicability range are described.     

Large-PT physics with cosmic-ray events

Summary Extensive Air Shower (EAS) experiments with high granularity have reported the detection of multicore events. On the other hand, multicluster and double-core events have been observed with emulsion chambers (EC) at mountain altitudes since the late '70s. A striking characteristic of these events is the large transverse momentum of the clusters. At accelerator energy region, it is known that jet production in deep inelastic hadronic processes is associated with the emission of large-P _T particles. In this paper we analyse the possibility that both EAS and EC events represent the same physical process, discussing the physical consequences of this fact and the possibilities offered by both techniques in integrating the accelerators data.     

Fluxes of cosmic-ray muons and atmospheric neutrinos at high energies

The problem of charm generation in the interactions of nucleons with nuclei of air atoms at energies inaccessible at present-day accelerators is discussed. Both experimental data on cosmic-ray muons and the predictions of QCD-based theoretical models are used in analyzing the behavior of the differential cross sections for charmed-particle production at high energies. The calculated fluxes of muons and neutrinos arriving at sea level both along the vertical and along the horizontal direction are presented, together with their approximations for the interval 2×10²–10¹⁰ GeV.     

On the problematic rising ratio of cosmic-ray positrons at ultra-high energies

Summary The rising ratio of cosmic-ray positrons at ultra-high energies of interactions seems to have puzzled the theorists to a great extent. We have made here a somewhat successful attempt to interpret the behaviour of this ratio,R=e⁺/(e⁺+e⁻), by putting into use the main physical ideas from our two previous works. The importance and the implications of this observation have also been highlighted and emphasized in the proper background.

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Riassunto Il crescente rapporto dei positroni dei raggi cosmici ad energie ultra-alte di interazioni sembra aver non poco confuso i teorici. Qui si tenta con un certo successo di interpretare il comportamento di questo rapportoR=e⁺/(e⁺+e⁻) usando i principali concetti fisici dei nostri due precedenti lavori. L'importanza e le implicazioni di questa osservazione sono state sottolineate ed enfatizzate nell'appropriato contesto.

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Резюме Увеличивающиеся отношение позитронов космических лучей при ультравыс оких энергиях, по-видимому, представляет загадку для теоретиков. В этой статье мы предпринимает отчасти успешную попытку интерпретировать поведение этого отношенияR=e⁺/(e⁺+e⁻), используя основные физические идеи из наших двух предыдущих публикаций. Отмчаются важностя и приложения полученных результатов.

     

Spectrographic investigations of the cosmic-ray events in December 2006

The Forbush decreases and ground-level enhancements in solar cosmic ray fluxes in December 2006 have been analyzed by the spectrographic method. The results showed a decrease in the cutoff rigidity and the spectrum power of variations during the main phase of Forbush decreases.     

Temperature effect of the integral flux of cosmic-ray muons at high energies

The temperature coefficients of the integral fluxes of cosmic-ray muons arriving at sea level vertically and horizontally with energies of 10², 10⁴, and 3 × 10⁶ GeV are calculated. Decays of pions, kaons, and charmed particles are considered as sources of muon generation in the atmosphere (according to current data on the generation cross sections of pions, kaons, and charmed particles in interactions between nucleons and the nuclei of atmospheric atoms, obtained in experiments on accelerators and in quantum chromodynamics models). The uncertainties in the generation cross sections of charmed particles are quite high.     

Determination of energies of cosmic-ray nuclei in the region above 1 TeV

A method is proposed for measuring energies of particles in the region above 1 TeV. The method is based on detecting the greatest specific energy deposition in hadronic cascades propagating in dense matter. This makes it possible to improve accuracy in measuring energy by thin calorimeters in studying the energy spectra of high-energy cosmic rays at high altitudes. Attainable accuracies in measuring energy are considered for protons and He nuclei. The results of a relevant simulation are compared with the results of a satellite-borne experiment with Kosmos-1713.     

Derivation of muon spectrum at high energies from the recent JACEE primary cosmic-ray spectrum using Fermilab data on meson production

Summary The energy spectrum of sea level muons in the range (10²÷10⁴) GeV has been calculated from the latest directly measured JACEE primary spectrum using Fermilab results on pp→π^± X and pp→K^± X inclusive reactions. The conventional pion atmospheric diffusion equation after Bugaevet al. has been used in this analysis to account the flux of muons emerged from the multiple generation of mesons in air. The derived muon spectrum has been compared with the earlier magnetic spectrograph data of Durham and Kiel groups. The latest BAKSAN scintillator telescope data is well in agreement with the calculated integral spectrum originated from the meson decays in the range (1÷10⁴) GeV.     

Enhanced Ar-K X-ray emission observed in EBIT at electron energies around 6,500 eV

Recently (2015) at the Institute of Physics of the Jagiellonian University, a commercial electron beam ion source (Dresden EBIT, DREEBIT Co.) was installed for teaching and scientific purposes. The first experiments were focused on observation of radiative recombination and dielectronic recombination (DR). A good resolution of the X-ray spectra for DR in argon encouraged a more detailed search. An investigation of higher order resonances, namely, trielectronic recombination (TR: KK-LLL, KK-LLM,…) in argon ions, was initiated. The present experiment was conducted while scanning the electron beam energy of the EBIT over the region 5,700–7200 eV. This electron energy region was expected to manifest an enhancement of the Ar-K X-ray emission due to TR processes mentioned above. Indeed, a maximum-like behavior of the radiation intensity was observed.     

Quark-gluon state of matter and positive excess of cosmic-ray muons at high energies

The problem of the relationship between the numbers of positively and negatively charged particles in the flux of cosmic-ray muons arriving at sea level with energies in excess of 0.1 TeV (up to 100 TeV) is discussed. It is shown that the formation of quark—gluon matter as the result of high-energy nuclear interactions leads to a reduction of the positive excess in cosmic-ray muons at the above energies. At the present time, the quark-gluon state of matter is studied in accelerator experiments at colliding-particle energies of up to √s = 200 GeV per nucleon. Estimates presented in this article for the positive excess of muons having energies of up to 3 or 4 TeV are based on available data from accelerator experiments; at higher muon energies, the respective estimates are based on extrapolating these data.     

Derivation of vertical muon spectra at superhigh energies from our predicted primary cosmic-ray spectrum using machine interaction parameters and Feynman scaling hypothesis

Summary The vertical differential and integral, muon spectra at super-high energies,viz. up to 10 TeV have been estimated from our predicted primary spectrum of the formN(E)dE=2.4E ^−2.7dE (cm²s sr GeV)⁻¹. The accelerator data of Johnsonet al., Elbertet al. have been used for the evaluation of fractional hadronic energy moments. By using the conventional Feynman scaling hypothesis and the meson atmospheric diffusion equation after Bugaevet al., the differential and integral muon spectra have been estimated and the results are well in accord with the experimental data of Bakeret al., Allkoferet al., Ayreet al., Aminevaet al., Menon and Ramana Murthy, and Sheldonet al. in the spectral range (0.1÷10) TeV.     

Sputtering yield of chromium by argon and xenon ions with energies from 50 to 500 eV

A radioactive tracer technique is described for the quantitative measurement of the sputtering yield of a target material electroplated on a copper substrate. Sputtering yields of chromium by argon and xenon ions with energies from 50 to 500 eV are reported. The ion beams, having a current density ranging from 0.01 to 0.1 mA/cm² at an operating pressure of 2×10^–5 Torr, were produced by a low-energy ion gun. The sputtered atoms were collected on an aluminum foil surrounding the target. ⁵¹Cr was used as the tracer isotope. The results indicate that the radioactive tracer technique is sensitive enough in measuring the extremely small amount of sputtered material at low ion currents and low ion energies.     

Variations in the cosmic-ray rigidity spectrum during events of January 2005

Variations in the cosmic-ray (CR) rigidity spectrum during events of January 2005 have been investigated on the basis of the ground-based observations of the CR intensity performed at the world network of stations using spectrographic global survey. The parameters of the CR rigidity spectrum reflecting the electromagnetic characteristics of heliospheric fields during the events under study have been determined in the combined analysis of ground-based and satellite measurements of protons with energies from several megaelectronvolts to several tens of gigoelectronvolts. The CR variations in a wide energy range are explained on the basis of the analysis performed.