arXiv subjects

Tadeusz Wibig

Publications and source records attributed to Tadeusz Wibig.

At least 37 records · Page 2Linked to original sources

arXiv2010

Non-extensivity Parameter of Thermodynamical Model of Hadronic Interactions at LHC energies

The LHC measurements above SPS and Tevatron energies give the opportunity to test predictions of non-extensive thermodynamical picture of hadronic interaction to examine measured transverse momenta distributions for new interaction energy range. We determined Tsallis model non-extensivity parameter for the hadronization process before short-lived particles decayed and distort the initial p_t distribution. We have shown that it follows exactly smooth rise determined at lower energies below present LHC record. The shape of the q parameter energy dependence is consistent with expectations and the evidence of the asymptotic limit may be seen.

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arXiv2008

Ultra High-Energy Interaction of CR protons

The recent Auger results suggest that although coincidences of arrival directions with 'nearby' AGN and HiRes discovery of the GZK cut-off indicate protons, the measured longitudinal propagation characteristics indicate heavy nuclei, if the conventional interaction model is correct. Something has to change! Our own view is that it is possible that the AGN -implied proton identification is not correct and that the extra galactic particles are, in fact, mainly 'heavies', in which case the interaction problem goes away. However, here we assume that the particles ARE protons and examine the possible consequences. Parameters discussed include the interaction mean-free-path, inelasticities and 'exotic' possibilities.

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arXiv2008

On the Discovery of the GZK Cut-off

The recent claim of the '5 sigma' observation of the Greisen and Zatzepin and Kuzmin cut-off by the HiRes group based on their nine years data is a significant step toward the eventual solution of the one of the most intriguing questions which has been present in physics for more than forty years. However the word 'significance' is used in the mentioned paper in the sense which is not quite obvious. In the present paper we persuade that this claim is a little premature.

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arXiv2007

Heavy Cosmic Ray Nuclei from Extragalactic Sources above 'The Ankle'

A very recent observation by the Auger Observatory group claims strong evidence for cosmic rays above 56 EeV being protons from Active Galactic Nuclei. If, as would be expected, the particles above the ankle at about 2 EeV are almost all of extragalactic origin then it follows that the characteristics of the nuclear interactions of such particles would need to be very different from conventional expectation -- a result that follows from the measured positions of 'shower maximum' in the Auger' work. Our own analysis gives a different result, viz that the detected particles are still 'massive' specifically with a mean value of = 2.2 +- 0.8. The need for a dramatic change in the nuclear physics disappears.

astro-ph↗

arXiv2007

Comment on the "Second dip as a signature of ultrahigh energy proton interactions with cosmic microwave background radiation" by V.Berezinsky, A.Gazizov and K.Kachelriess

A new feature in the spectrum of ultra high energy cosmic rays (UHECR) has been announced in the paper by Berezinsky, Gazizov and Kachelriess. The ratio of the solution of the exact transport equation to its solution in the continuous energy loss limit shows intriguing features which, according to the Authors, are related to the very nature of the energy loss processes of UHECR:the very sharp second dip predicted at 6.3x10^19 eV can be used as an energy calibration point and also as the UHECR mass indicator for big future cosmic ray experiments. In the present paper we would like to advocate that this statement is an overinterpretation. The second dip is a result of an inapproriate approximation used, and thus it can't help to understand the nature of UHECR in any way.

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arXiv2005

Foreground contributions to the Cosmic Microwave Background

A detailed search has been made for evidence of foreground contributions to the Cosmic Microwave Background (CMB) WMAP, such foregrounds being related to our Galaxy. We find remarkable results. On the largest angular scales we find significant differences between the power in the fluctuations for positive and negative Galactic latitudes and between the four Galactic Quadrants. There are also differences between the power spectrum at latitudes within 10 deg of the Plane and at higher latitudes. The `slope' of the power spectrum has similar variations. In an effort to find the origin of these Galactic-style effects we have examined the evidence from Galactic gamma rays, specifically from the EGRET instrument. A correlation is found between gamma ray intensities and the CMB and other cosmic ray indicators. Most of the large scale Galactic asymmetries (eg north, south difference and Quadrant variations) have analogues in cosmic ray asymmetries and also in some other Galactic properties, such as the column density of gas. Thus, it is possible to hypothesise on direct cosmic ray-induced contributions, although it may be that cosmic rays are simply the indicators of Galactic `conditions' which are influencing the residual CMB fluctuations. Irrespective of the actual cause of the correlations we have endeavoured to extrapolate to the situation where the residual foreground is minimised. The effect on the usually-derived cosmological properties - universal matter content, ionization, the tensor contribution, tilt and curvature - is briefly examined.

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arXiv2004

At what particle energy do extragalactic cosmic rays start to predominate?

We have argued [J. Szabelski et al. (2002)] that the well-known `ankle' in the cosmic ray energy spectrum, at logE (eV) ~ 18.7-19.0, marks the transition from mainly Galactic sources at lower energies to mainly extragalactic above. Recently, however, there have been claims for lower transitional energies, specifically from logE (eV) ~ 17.0 [G. Thompson et al. (2004)] via 17.2-17.8 [V.S. Berezinsky et al. (2004)] to 18.0 [A.M. Hillas (2004)]. In our model the ankle arises naturally from the sum of simple power law-spectra with slopes differing by ~ 1.8; from differential slope -3.8 for Galactic particles (near logE = 19) to ~ -2.0 for extragalactic sources. In the other models, on the other hand, the ankle is intrinsic to the extragalactic component alone, and arises from the shape of the rate of energy loss versus energy for the (assumed) protons interacting with the cosmic microwave background (CMB). Our detailed analysis of the world's data on the ultra-high energy spectrum shows that taken together, or separately, the resulting mean sharpness of the ankle (second difference of the log(intensity*E^3) with respect to logE) is consistent with our `mixed' model. For explanation in terms of extragalactic particles alone, however, the ankle will be at the wrong energy - for reasonable production models and of insufficient magnitude if, as seems likely, there is still a significant fraction of heavy nuclei at the ankle energy.

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arXiv2004

No 'cut off' in the High Energy Cosmic Ray Energy Spectrum

It is often claimed that there should be a 'GZK cut-off" in the flux of extragalactic cosmic rays, arising from interactions between the cosmic rays and the cosmic micro-wave background photons (e.g. 1 and 2). Some experiments (3 and 4) show particles of even higher energy than this value and this has led to claims for exotic processes (e.g. 5 and 6). We contend that such claims are unnecessary - there is no predicted cut-off, rather a continuation of the injection spectrum at reduced intensity. We have combined the world's data and shown that the prediction for a rather flat injection spectrum (exponent: 1.9 - 2.2) in the case of universal particle injection provides a reasonable fit to the data. Conventional forms for the particle attenuation in the intergalactic medium (e.g. 7 and 8) have been assumed. Either protons or iron nuclei (or a mixture) will suffice. Attention is drawn to another aspect, too, that of the losses on the infra-red radiation which may be intense near to strong sources and for sources in galaxy clusters. The attendant magnetic fields near the sources leads to significantly long diffusion times through the strong infra-red fields. Two 'case histories' are considered.

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arXiv2004

Propagation of Ultra-High Energy Cosmic Rays in Extragalactic Magnetic Fields

In this paper we will discuss the problem of Ultra High Energy Cosmic Rays (UHECR) and show that the idea of a Single Source Model established by Erlykin and Wolfendale (1997) to explain the features seen in cosmic ray energy spectra around the 10**15 eV region can be successfully applied also for the much higher energies. The propagation of UHECR (of energies higher than 10**19 eV) in extragalactic magnetic fields can no longer be described as a random walk (diffusion) process and the transition to rectilinear propagation gives a possible explanation for the so-called Greisen-Zatzepin-Kuzmin (GZK) cut-off which still remains an open question after almost 40 years. A transient "single source" located at a particular distance and producing UHECR for a finite time is the proposed solution.

astro-ph↗

arXiv2000

Alignment in hadronic interactions

The alignment of the products of very high energy interactions seen in mountain altitude experiments is one of the most puzzling phenomena in cosmic ray physics for quite a long time. The observations of the Pamir and Chacaltaya emulsion chamber groups and by the Tien-Shan extensive air shower experiment, together with a very clear event seen in the Concorde French-Japanese experiment in the stratosphere, makes the experimental basis very substantial. In the present paper a novel possible explanation is put forward.

hep-ph↗

arXiv1999

Depth of maximum of extensive air showers and cosmic ray composition above 10**17 eV in the geometrical multichain model of nuclei interactions

The depth of maximum for extensive air showers measured by Fly's Eye and Yakutsk experiments is analysed. The analysis depends on the hadronic interaction model that determine cascade development. The novel feature found in the cascading process for nucleus-nucleus collisions at high energies leads to a fast increase of the inelasticity in heavy nuclei interactions without changing the hadron-hadron interaction properties. This effects the development of the extensive air showers initiated by heavy primaries. The detailed calculations were performed using the recently developed geometrical multichain model and the CORSIKA simulation code. The agreement with data on average depth of shower maxima, the falling slope of the maxima distribution, and these distribution widths are found for the very heavy cosmic ray mass spectrum (slightly heavier than expected in the diffusion model at about 3*10**17 eV and similar to the Fly's Eye composition at this energy).

hep-ph↗

arXiv1998

Proton-nucleus cross section at high energies

Cross sections for proton inelastic collision with different nuclei are described within the Glauber and multiple scattering approximations. A significant difference between approximate `Glauber' formula and exact calculations with a geometrical scaling assumption for very high-energy cross section is shown. Experimental values of proton-proton cross sections obtained using extensive air shower data are based on the relationship of proton-proton and respective proton-air absorption cross sections. According to obtained results values reported by the Akeno and Fly's Eye experimental groups are about 10% overestimated. The proper energy dependence of absorption cross section for collisions with air nuclei is of a great importance for studies of high energy cosmic rays using the Monte Carlo technique.

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arXiv1998

Three steps in intranuclear cascading

Between the initial excitation of nucleons by the passing throughout each other and the final cascading of newly created hadrons there should be considered one more step. We call it the second step cascading process. It acts as an interaction of wounded nucleon from one nucleus with another nucleon from the same nucleus. This mechanism leads to the significant increase on the inelasticity for nuclei collisions without changing the hadron-hadron interaction characteristics.

hep-ph↗

arXiv1998

Nuclei cross sections in Extensive Air Showers

Cross sections for proton inelastic collision with different nuclei are described within the Glauber approximation. The significant difference between approximate ``Glauber'' formula and exact calculations with geometrical scaling assumption is shown for very high energy cross section calculations. According to obtained results values of proton-proton cross section reported by the Akeno and Fly's Eye experimental groups are about 10 % overestimated.

hep-ph↗

arXiv1998

On the Extensive Air Shower density spectrum

In search for new methods of determining the primary energy spectrum of Cosmic Rays, the attention was paid to the density spectrum measurement. New methods available at present warrant an accurateness of conclusions derived from the density spectrum measurements. The general statement about the change of the spectral index of the charged particle density spectrum is confirmed very clearly. Results concerning the shower size and primary energy spectra are also presented and discussed. Interesting future prospects for applications of the density spectrum method are proposed.

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arXiv1997

Inelasticity and intranuclear cascading in geometrical multichain model

The inelasticity in nucleus-nucleus collisions at high energies is calculated in the framework of geometrical multichain model. The very fast increase of the inelasticity is found as a result of a second-stage cascading process. The same behaviour is expected for all the models using the wounded nucleon idea. The simple formula for the number of wounded nucleons inside colliding nuclei does not need to be exact.

hep-ph↗

arXiv1997

Extension of the Geometrical Two-Chain Model to high energies

In the paper the extension of the Geometrical Two-Chain model to higher energies is presented. The agreement with experimental data is achieved using pre-hadronization chain breakups due to coloured dipole radiation mechanism and the discretization of the soft gluon emission process.

hep-ph↗

arXiv1996

The Artificial Neural Networks as a tool for analysis of the individual Extensive Air Showers data

In that paper we discuss possibilities of using the Artificial Neural Network technic for the individual Extensive Air Showers data evaluation. It is shown that the recently developed new computational methods can be used in studies of EAS registered by very large and complex detector systems. The ANN can be used to classify showers due to e.g. primary particle mass as well as to find a particular EAS parameter like e.g. total muon number. The examples of both kinds of analysis are given and discussed.

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