Nuclear-active Particles Research Articles

The Hypothesis of Strangelets in the Cosmic Rays

The experimental confirmation of the presence of a penetrating component in cosmic rays is presented. Unlike previous experiments, it is shown that the component is not born in the lead of the detectors, but is present in the primary radiation. In this case, the particles forming the penetrating component must be stable. Among the nuclear-active particles, there are only two stable variants. These are nuclei, among which the most penetrating are protons, and hypothetical particles of strange quark matter—strangelets (quasi-nuclei). The analysis of the muon component is not consistent with the proton variant.

Effects of meteoroid shape on cosmogenic nuclide production processes

AbstractThe shape of meteorites is one of the major factors influencing the production of cosmogenic nuclides. Numerical simulations using the Los Alamos Code System (LCS) particle production and transport codes were done to investigate particle fluxes and production rates of cosmogenic nuclides 10Be, 26Al, and 60Co in meteoroids of spherical, ellipsoidal, and cylindrical shapes. The calculations show that fluxes of nuclear active particles and also production rates of cosmogenic nuclides are sensitive to the shape of the irradiated parent body.

Production of anomalous Xe in nanodiamond in chondrites during the last supernova explosion predating the origin of the Solar System

Anomalous Xe enriched in both heavy and light isotopes (Xe-HL) was identified in the high-temperature Xe fraction in relict nanodiamond grains from chondrites, whereas the low-temperature Xe fraction (Xe-P3) typically has the normal isotopic composition. The paper presents a concise review of current models put forth to account for the genesis of nanodiamond with anomalous noble gas components and specifies a real process and major regularities during the generation of the isotopic relations of the anomalous Xe-HL component in relict nanodiamond grains. This component is demonstrated to be formed and captured simultaneously with the synthesis of nanodiamond, when shock waves induced by supernova explosions propagated. It is important that diamond synthesis during the passage of shock waves and the enrichment of this diamond in Xe-HL are also possible in the wave forefront region under extremal P-T conditions, in the pressure drop region behind the wave front (by means of nucleation), and by means of irradiation of carbonic grains with high-energy particles. The isotopic composition of Xe-HL results from an increase in the hardness of the spectrum of nuclear-active particles and its enrichment in heavy ions at acceleration in shock waves. Arguments are presented in support of the hypothesis that the nanodiamond population found in chondrites was produced during the latest supernova explosion before the development of the Solar System, with the supernova likely being a SnIa carbon detonation supernova. This furnishes evidence in support of recently advanced hypotheses that the nanodiamond population of chondrites is not presolar.

Effects of the diffusive acceleration of particles by shock waves in the primordial matter of the solar system

The effects of the shock wave diffusive acceleration of particles are considered in the case of formation of isotopic relations of the anomalous Xe-HL component of xenon in relic grains of nanodiamonds in chondrites. It is shown that this component could be formed and captured simultaneously with the nanodiamond synthesis in the conditions of the explosive shock wave propagation from supernova outbursts. The specificity of isotopic composition of Xe-HL is due to the high hardness of the spectrum of nuclear-active particles at the shock wave front and its enrichment with heavy isotopes. The spallogenic nature of both the anomalous and normal components of xenon is ascertained, and the role of the subsequent evolutionary processes in the change of their isotopic systems is shown. Experimental evidence of the formation of the power law spectrum of particles with the spectral index γ ∼ 1 by the supersonic turbulence during the carbon-detonation supernova SnIa explosion is obtained; this perhaps opens new perspectives in studying the problem of the origin of cosmic rays. It is shown that at the stage of free expansion of the explosive shock wave, the degree of compression of the matter at the wave front was σ = 31 (the corresponding Mach number M ∼ 97); this led to a 31-fold increase of the magnetic field as well as of the maximum energy of accelerated particles, so that even the energy of protons reached ∼ 3 × 1015 eV, i.e., the “knee” region.

On the problem of Solar System origin: The regularities of noble gas fractionation in shock waves

The effects of the last supernova explosion before the formation of the Solar System are considered using noble gases as examples. Acceleration of generated supernova matter in the explosive shock wave led to its initial fractionation and to the formation of small-scale isotopic heterogeneity of primordial matter. This is fixed as some isotopic anomalies in high-temperature phases of the earliest condensates of carbonaceous chondrites, as well as in the isotopic systems of noble gases, and is the basis of the supernova phenomenon. Two main manifestations of shock-wave acceleration in noble gases are investigated: the change in the isotopic ratios of their cosmogenic components due to the increasing hardness of the spectrum of nuclear-active particles and the fractionation of gases, namely, the enrichment of their isotopic systems with heavier isotopes. The reality of the processes under consideration is demonstrated through the example of noble gases of solar corpuscular radiation in lunar ilmenites. The absence of r-process products among extinct radionuclides in Ca-and Al-rich inclusions (CAI) of carbonaceous chondrites with a formation interval of less than or equal to 1 Ma supports the idea that the last supernova was an Ia-type supernova, which possibly played an important role in the origin of the Solar System.

Two years of detecting dark matter objects: The solar system members

With a probability greater than 99% there are grounds to believe that our works on the detection of dark electric matter objects (daemons), which were launched in 1996, are crowned with success. The daemons are the relic elementary Planckian black holes $(m \approx 30\,\rmu \hbox {g})$ carrying a stable electric charge $Z = 10e$ . During the last 2 years, a detector made of two horizontal ZnS(Ag) screens of 1 m 2 area has been recording the correlated time-shifted scintillations corresponding to flux $f_{\oplus}\approx 10^{-5}\,\hbox{m}^{-2}\,\hbox {s}^{-1}$ of extraordinary penetrating nuclear-active particles which moved both downwards and upwards with a velocity of only about 5-30 km s −1 . The flux experiences seasonal variations with maxima supposedly corresponding to the Earth transition through the shadow and antishadow created by the Sun in its motion relative to the Galaxy disc daemon population. An accumulation of negative daemons, which stimulate the proton decay in about $1\,\rmu \hbox{s}$ ins...

Hadrons and other secondaries generated by cosmic-ray muons underground

The production of nuclear-active and electromagnetic particles, as well as long-lived isotopes in nuclear and electromagnetic showers generated by cosmic-ray muons at different depths underground is discussed. Characteristics of the secondary components and their dependence on the depth and the muon energy, obtained in experiments and calculations, are presented.

Propagation of nuclear-particle fluxes in the atmosphere

A Monte Carlo model of the development of a cascade of nuclear active particles initiated in the atmosphere by cosmic rays or by some other radiation source is developed. The model enables one to calculate the spatial distribution and energy spectra of fluxes of charged and nuclear particles in the air and in materials situated in the air.

Noble gases and the history of Jilin meteorite

Potassium and noble gases have been determined in more than twenty specimens from the largest known stone meteorite, the H5 chondrite Jilin. Thirteen specimens came from the surface of the present main mass, the remainder from various locations in the strewn field. The average K content is 802 ppm (29 samples from 23 specimens), maximum deviations from the mean are −7% and +11%. Whole-rock gas retention ages of different specimens are distinctly different; they vary between 2.22 and 3.90 AE for 40Ar 40K and between 0.44 and 2.0 AE for 4He U/Th. Severe losses of 4He and 40Ar (up to 95% and 80%, respectively) must have occurred (up to) less than 440 Ma ago; they cannot have happened during the fall of the meteorite, however. Differences in concentration of cosmic-ray-produced 3He, 21Ne, and 38Ar Me by factors of five, six, and seven, respectively, reflect a complex irradiation history; they are compatible with a short 4π irradiation and an extended one in 2π geometry at shallow depth (top samples were most probably located near the transition maximum of nuclear-active particles at around 15 cm depth; they definitely cannot have been buried deeper than 4 m). 3He/ 21Ne ratios in bulk samples are lowered by diffusion losses of 3He (25–61%) while 22Ne/ 21Ne ratios appear to be unaffected. 22Ne/ 21Ne values range between 1.060 and 1.086 (with a mean of 1.069) which is at variance with predictions for the particular irradiation conditions of Jilin. Low 36Ar/ 38Ar ratios (down to 0.553) in clean metal samples are interpreted as the combined effect of large size and the transient lowering of this ratio because of a sudden increase in production rates upon going from 2π to 4π irradiation.

Possible evidences in favour of a new type of cosmic-ray nuclear interaction named «centauro»

A new type of nuclear interaction named «Centauro» was found in chamber No. 15 of the Chacaltaya emulsion chamber and was reported at the Denver conference on cosmic rays. It shows the multiple production of more than fifty nuclear active particles without any accompanying neutral π-mesons. Chamber No. 17 of the continuing Chacaltaya experiment provided three events of the same character. The present paper gives the result of the highest-energy one of the three. It is found that the event is from an atmospheric interaction at ∼500 m above the chamber and is an emission of ∼100 nuclear active particles from a giant fireball of rest energy ∼270 GeV. The number of neutral π-mesons from the Centauro decay is estimated as 3±5, which is consistent with zero.

The NAP flux at mountain altitude 735 g cm-2

The energy spectrum of nuclear active particles (NAP) with energy Sigma Egamma greater than 3 TeV is obtained from an analysis of thick emulsion chamber (140 cu of Pb) exposed on Mount Norikura at 2770 m above sea level and the vertical flux is estimated to be (1.4+or-0.1)*10-10 cm-2 s-1 sr-1. Assuming that the energy spectrum and the zenith angle distribution of NAP are expressed by power functions proportional to E-( gamma +1) and cosn-2 theta respectively in differential form, the exponents gamma and n are obtained as 2.3+or-0.1 and 7.3+or-0.5 respectively. The collision mean free path and the ratio of constituents of NAP are discussed.

Barites: anomalous xenon from spallation and neutron-induced reactions

Sedimentary barites from South Africa and Western Australia (∼3 × 10 9 years old) contain spallogenic Xe isotopes produced by reactions of Ba with nuclear active particles in cosmic rays. “Surface residence time” of these samples was calculated from the observed concentrations of spallogenic 126Xe. Comparison of spallogenic ratios of 131Xe/ 126Xe in the two samples provides evidence for the reaction 130Ba(n,γ) → 131Xe , which is characterized by a large number of resonances for neutron absorption in the epithermal region. This observation lends additional support to the conclusions already arrived at, regarding the origin of anomalous 131Xe in lunar samples.

Monte Carlo calculations of nuclear cascades and associated Čerenkov radiation in extensive air showers

We present a Monte Carlo calculation, with observed cross sections and multiplicities, of the nuclear component of small extensive air showers (EAS) with primary energies ${E}_{0}\ensuremath{\ge}{10}^{3}$ GeV. The simulations were completely three-dimensional and were initiated by cosmic rays sampled from both their primary energy and mass spectra. Resulting particle spectra sampled at 564 g ${\mathrm{cm}}^{\ensuremath{-}2}$ agree with extrapolations from observations of EAS with ${E}_{0}>{10}^{4\ensuremath{-}6}$ GeV. The optical \ifmmode \check{C}\else \v{C}\fi{}erenkov radiation calculated for the nuclear-active particles and muons in these EAS is found to be comparable to that expected from the electrons and distinguishable for particular detector configurations. Implications for EAS observations of cosmic $\ensuremath{\gamma}$ rays and cosmic-ray composition are mentioned.

The momentum spectra of nuclear active particles in the cosmic radiation at sea level. II. A review of predictions

Computer simulations have been made of the propagation through the atmosphere of protons and pions using a model developed primarily for high energy air shower studies. The results are compared with those from other recent simulations and with measurement. There is little agreement between the results of the various simulations; the results of the present work based upon a simple model and assuming reasonable values for the primary intensity, are in broad agreement with the observational data.

The momentum spectra of nuclear active particles in the cosmic radiation at sea level. I. Experimental data

A cosmic ray spectrograph has been used to measure the momentum spectra of cosmic ray protons and pions in the momentum range 1-30 GeV/c in the near vertical direction at sea level. The observed intensities of both protons and pions are greater than those obtained in the previous measurements.

A Study of Nuclear Active Particles in Extensive Air Shower

The high energy nuclear active particles (NAP) of more then 200 GeV, associated with EAS, have been studied by means of the large area scintillation detectors under water tank, at the mountain altitude of 2770 m a.s.l. We have obtained the following results; (1) The energy spectrum of NAP has a knee at about 500 GeV where the spectrum index changes from -1.0 to -1.8, (2) The lateral distribution of NAP can be expressed as A exp (- r / r 0 ) with r 0 of 1∼2 m, (3) The number of NAP is much smaller than the results of the Monte Calro simulations assuming the ordinary interaction model, and (4) The mean transverse momentum of NAP is about 2 GeV/c which is much higher than generally accepted value in the nuclear interactions.

Ratio of pions to protons and ratio of neutral to charged interacting particles at mountain altitude of 800 gm/cm2

Using a combined set-up of a multiplate cloud chamber, an air Cerenkov counter and a total absorption spectrometer, the ratio of pions to protons not associated with large air showers has been determined to be 0·50 ± ·07 in the energy region 20–40 GeV at an altitude of 800 gm/cm2. In the same energy region the ratio of neutral to charged particles is found to be 0·66 ± ·07. From the ratio of neutrons to protons deduced from these measurements (i.e., 0·99 ± ·11), it is concluded that most of the charge excess of nuclear active particles of energies > 20 GeV at mountain altitudes and sea-level is due to pions.

Monte Carlo Simulation on Propagation of Cosmic-Rays in the Atmosphere

A simulation study is made on propagation and multiplication of the high energy cosmic-ray components in their passage through the atmosphere. The study is planned to simulate observation of high energy cosmic-ray phenomena by the emulsion chambers exposed at high altitude laboratories and to make clear how the observation of such kind will disclose unknown mechanism of the extremely high energy interactions-multiple production of mesons. In particular, the following two models of the multiple meson production are examined in the present simulation: 1) Two-fire-ball model,l> abbreviated as 2F; 2) H-quantum model,2> abbreviated as HQ. The outline of our simulation is as follows. A high energy primary cosmic-ray particle collides with an air nucleus of the upper atmosphere and causes the multiple meson production according to mechanism of the assumed models. The secondary nuclear-active particles, charged n-mesons and an outgoing nucleon, among the generated particles collide in their turn with air nuclei and they develop the so-called nuclear cascade processes while passing through the atmosphere. Gamma-rays, being the decay products of n°-mesons produced by the successive nuclear collisions, are the source of the atmospheric electromagnetic cascade showers. We make a record of particles with energies above a certain threshold energy both of the nuclear-active component and of the electro-magnetic component, which arrived at the observation level. The record consists of data of the arriving particles together with those on the primary particle. The present simulation calculation corresponds to observation of high energy cosmic-ray particles by the emulsion chamber exposed at the mountain altitudes. In particular, it provides us data of the artificial families: identity, energy and spatial distribution of member particles of the families. It is instructive to learn what kind of pattern the artificial families show at the observation plane under a certain assumption. This is indispensable for

Monte Carlo studies on the hadronic component of extensive air showers

Three-dimensional Monte Carlo calculations have been performed on the development of the hadronic component of extensive air showers using a semi-empirical model of high-energy nuclear interactions. Results include integral energy spectra and lateral distribution of nuclear active particles as well as total hadronic energy flux. The probability of multi-core showers is discussed. The contribution of pionization tends to mask the dependence of this probability on primary atomic number. Fluctuations of total and central hadronic energy flux are investigated. Maps of hadronic energy flux in the core region of individual showers are presented.

Nuclear-active energetic particles and extensive air showers at sea level

The particle number distributions of the showers accompanying nuclear-active particles of definite energies at sea level have been calculated. Comparison of the calculated and observed distributions makes it possible to conclude that the nuclear-active particles interact differently with nuclei depending on their energies.