F. Badea

Bio: F. Badea is an academic researcher from Karlsruhe Institute of Technology. The author has contributed to research in topics: KASCADE & Air shower. The author has an hindex of 19, co-authored 104 publications receiving 1623 citations.

The cosmic-ray experiment KASCADE

Abstract: KASCADE has been designed to measure air showers of primary cosmic-ray energies in the PeV region and to investigate the knee phenomenon in the all-particle energy spectrum. Several observations are measured simultaneously for each event by different detector systems. The experiment started to take data in 1996 and has been completed and extended since then. The individual detector systems and their performances are described. Also, the experience in long-term operation of the experiment and the interplay between different components is outlined.

The KASCADE‐Grande Experiment

Abstract: The KASCADE-Grande experiment measures extensive air showers induced by primary cosmic rays in the energy range 1014 – 1018 eV. The major motivation for KASCADE-Grande is the investigation of the so called ”knee” in the energy spectrum of cosmic rays and its presumed rigidity dependence. A short overview of the experimental setup with focus on the Grande array and its new data acquisition system is given. As an example of analysis the reconstruction of the total muon number is presented.

Electron, Muon, and Hadron Lateral Distributions Measured in Air-Showers by the

Abstract: eV and extend from the inner coreregion to distances of 200 m. The electron and muon distributions are correctedfor mutual contaminations by taking into account the detector properties in theexperiment. All distributions are well described by NKG-functions. The scale radiidescribing the electron and hadron data best are ≃ 30 m and ≃ 10 m, respectively.We discuss the correlation between scale radii and ‘age’ parameter as well as theirdependence on shower size, zenith angle, and particle energy threshold.Key words: cosmic rays; air shower; lateral distributionPACS: 96.40.Pq

Test of high-energy interaction models using the hadronic core of EAS

Abstract: Using the large hadron calorimeter of the KASCADE experiment, hadronic cores of extensive air showers have been studied The hadron lateral and energy distributions have been investigated in order to study the reliability of the shower simulation program CORSIKA with respect to particle transport, decays, treatment of low-energy particles, etc A good description of the data has been found at large distances from the shower core for several interaction models The inner part of the hadron distribution, on the other hand, reveals pronounced differences among interaction models Several hadronic observables are compared with CORSIKA simulations using the QGSJET, VENUS and SIBYLL models QGSJET reproduces the hadronic distributions best At the highest energy, in the 10 PeV region, however, none of these models can describe the experimental data satisfactorily The expected number of hadrons in a shower is too large compared with the observed number, when the data are classified according to the muonic shower size

Tuning Monte Carlo Generators: The Perugia Tunes

Abstract: We present 9 new tunes of the p{sub perpendicular}-ordered shower and underlying-event model in Pythia 6.4. These 'Perugia' tunes update and supersede the older 'S0' family. The data sets used to constrain the models include hadronic Z{sup 0} decays at LEP, Tevatron min-bias data at 630, 1800, and 1960 GeV, Tevatron Drell-Yan data at 1800 and 1960 GeV, and SPS min-bias data at 200, 546, and 900 GeV. In addition to the central parameter set, called 'Perugia 0', we introduce a set of 8 related 'Perugia variations' that attempt to systematically explore soft, hard, parton density, and color structure variations in the theoretical parameters. Based on these variations, a best-guess prediction of the charged track multiplicity in inelastic, nondiffractive minimum-bias events at the LHC is made. Note that these tunes can only be used with Pythia 6, not with Pythia 8.

Annual report for 2010

Abstract: The following section, Management’s Discussion and Analysis of Operations, provides an overview of the consolidated financial statements of Fujitsu Limited (the “Company”) and its consolidated subsidiaries (together, the “Group”) for the year ended March 31, 2010 (fiscal 2009). Forward-looking statements in this section are based on management’s understanding and best judgment as of March 31, 2010. The impact of exchange rate movements is calculated by taking the average exchange rates in fiscal 2008 for the U.S. dollar, euro, British pound, Australian dollar, Korean won, and other currencies and applying them to foreign currencydenominated transactions in fiscal 2009.

On astrophysical solution to ultrahigh energy cosmic rays

Abstract: We argue that an astrophysical solution to the ultrahigh energy cosmic ray (UHECR) problem is viable. The detailed study of UHECR energy spectra is performed. The spectral features of extragalactic protons interacting with the cosmic microwave background (CMB) are calculated in a model-independent way. Using the power-law generation spectrum $\ensuremath{\propto}{E}^{\ensuremath{-}{\ensuremath{\gamma}}_{g}}$ as the only assumption, we analyze four features of the proton spectrum: the GZK cutoff, dip, bump, and the second dip. We found the dip, induced by electron-positron production on the CMB, to be the most robust feature, existing in energy range $1\ifmmode\times\else\texttimes\fi{}{10}^{18}\char21{}4\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{eV}$. Its shape is stable relative to various phenomena included in calculations: discreteness of the source distribution, different modes of UHE proton propagation (from rectilinear to diffusive), local overdensity or deficit of the sources, large-scale inhomogeneities in the universe, and interaction fluctuations. The dip is well confirmed by observations of the AGASA, HiRes, Fly's Eye, and Yakutsk detectors. With two free parameters (${\ensuremath{\gamma}}_{g}$ and flux normalization constant) the dip describes about 20 energy bins with ${\ensuremath{\chi}}^{2}/\mathrm{d}.\mathrm{o}.\mathrm{f}.\ensuremath{\approx}1$ for each experiment. The best fit is reached at ${\ensuremath{\gamma}}_{g}=2.7$, with the allowed range 2.55\char21{}2.75. The dip is used for energy calibration of the detectors. For each detector independently, the energy is shifted by factor $\ensuremath{\lambda}$ to reach the minimum ${\ensuremath{\chi}}^{2}$. We found ${\ensuremath{\lambda}}_{\mathrm{Ag}}=0.9$, ${\ensuremath{\lambda}}_{\mathrm{Hi}}=1.2$, and ${\ensuremath{\lambda}}_{\mathrm{Ya}}=0.75$ for the AGASA, HiRes, and Yakutsk detectors, respectively. Remarkably, after this energy shift the fluxes and spectra of all three detectors agree perfectly, with discrepancy between AGASA and HiRes at $Eg1\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{eV}$ being not statistically significant. The excellent agreement of the dip with observations should be considered as confirmation of UHE proton interaction with the CMB. The dip has two flattenings. The high energy flattening at $E\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{eV}$ automatically explains ankle, the feature observed in all experiments starting from the 1980s. The low-energy flattening at $E\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{18}\text{ }\text{ }\mathrm{eV}$ reproduces the transition to galactic cosmic rays. This transition is studied quantitatively in this work. Inclusion of primary nuclei with a fraction of more than 20% upsets the agreement of the dip with observations, which we interpret as an indication of the acceleration mechanism. We study in detail the formal problems of spectra calculations: energy losses (the new detailed calculations are presented), the analytic method of spectrum calculations, and the study of fluctuations with the help of a kinetic equation. The UHECR sources, AGN and GRBs, are studied in a model-dependent way, and acceleration is discussed. Based on the agreement of the dip with existing data, we make the robust prediction for the spectrum at $1\ifmmode\times\else\texttimes\fi{}{10}^{18}\char21{}1\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{eV}$ to be measured in the nearest future by the Auger detector. We also predict the spectral signature of nearby sources, if they are observed by Auger. This paper is long and contains many technical details. For those who are interested only in physical content we recommend the Introduction and Conclusions, which are written as autonomous parts of the paper.