Primary Energy Spectrum Research Articles

The primary energy spectrum with the Linsley method correcting heavy primary effects in the LAAS experiments

The primary energy spectrum with the Linsley method correcting heavy primary effects in the LAAS experiments

The primary energy spectrum with the Linsley method correcting heavy primary effects in the LAAS experiments

The compact EAS Extensive Air Shower (EAS) array (200 m2 ) and the Linsley method have been used with the aim to observe the primary energy spectrum. The spectral indexes αproton and αiron are obtained as − 2.46 ± 0.17 and − 3.08 ± 0.24, respectively, in the primary energy region of 1016 eV − 1018.5 eV in the single observation of the compact EAS array. Additionally, αproton and αiron are obtained as − 3.12 ± 0.13 and − 3.52 ± 0.17, respectively, in the same primary energy region in the observation by restricting the zenith angle of EAS events.

The knee in the cosmic ray energy spectrum from the simultaneous EAS charged particles and muon density spectra

In this work we examine with the help of Monte Carlo simulation whether a consistent primary energy spectrum of cosmic rays emerges from both the experimentally observed total charged particles and muon size spectra of cosmic ray extensive air showers considering primary composition may or may not change beyond the knee of the energy spectrum. It is found that EAS-TOP observations consistently infer a knee in the primary energy spectrum provided the primary is pure unchanging iron whereas no consistent primary spectrum emerges from simultaneous use of the KASCADE observed total charged particle and muon spectra. However, it is also found that when primary composition changes across the knee the estimation of spectral index of total charged particle spectrum is quite tricky, depends on the choice of selection of points near the knee in the size spectrum.

Progenitor model of cosmic ray knee

The primary energy spectrum of cosmic rays exhibits a knee at about 3 PeV where a change in the spectral index occurs. Despite many efforts, the origin of such a feature in the spectrum is not satisfactorily solved yet. Here it is proposed that the steepening of the spectrum beyond the knee may be a consequence of the mass distribution of the progenitor of the cosmic ray source. The proposed speculative model can account for all the major observed features of cosmic rays without invoking any fine tuning to match flux or spectra at any energy point. The prediction of the proposed model regarding the primary composition scenario beyond the knee is quite different from most of the prevailing models of the knee, and thereby can be discriminated from precise experimental measurement of the primary composition.

Mass composition sensitivity of combined arrays of water cherenkov and scintillation detectors in the EeV range

We consider an array of scintillation detectors combined with an array of water Cherenkov detectors designed to simultaneously measure the cosmic-ray primary mass composition and energy spectrum at energies around 1EeV. In this work we investigate the sensitivity to primary mass composition of such combined arrays. The water Cherenkov detectors are arranged in a triangular grid with fixed 750m spacing and the configuration of the scintillation detectors is changed to study the impact of different configurations on the sensitivity to mass composition. We show that the performance for composition determination can be compared favorably to that of fluorescence measurements after the difference in duty cycles is considered.

Are the primary cosmic ray and EAS spectra the same or not?

Usually it is believed that the energy of extensive air showers (EAS) is equal or is proportional to the energy of primary particle. Of course, taking into account fluctuations in hadron interactions and in the EAS development, some difference between the energies of the EAS and PCR appears but the slopes of the spectra must be the same with a good accuracy. In this talk, an alternative approach, in which the model of PCR interaction at the knee energy is drastically changed, is considered. The consequences for interpretation of results on primary energy spectrum and composition in frame of this model are analyzed. The results agree with experimental data. Some possible experiments to check the predictions of this approach are discussed.

Estimating of Cherenkov Radiation in Extensive Air Showers Using CORSIKA Code for Tunka133 EAS Cherenkov Array

The simulation of Cherenkov light Lateral distribution function (LDF) in Extensive Air Showers (EAS) initiated primary particles such as primary calcium, argon, proton iron nuclei, neutron and nitrogen have been performed using CORSIKA program for conditions and configurations of Tunka133 EAS Cherenkov array. The simulation was fulfilled at the high energy range 1014-1016eV for four different zenith angles 0o, 10o, 15oand 30o. The results of the simulated Cherenkov light LDF are compared with the measurements of Tunka133 EAS array for the same particles and energy range mentioned above. This comparison may give the good ability to reconstruct the energy spectrum and mass composition of the primary cosmic ray particles in EAS. The main feature of the given approach consists of the possibility to make a library of Cherenkov light LDF samples which could be utilized for analysis of real events which can be detected with different EAS arrays and reconstruction of the primary cosmic rays energy spectrum and mass composition of EAS particles.

Primary CR energy spectrum and mass composition by the data of Tunka-133 array

The Cherenkov light array for the registration of extensive air showers (EAS) Tunka-133 collected data during 5 winter seasons from 2009 to 2014. The differential energy spectrum of all particles and the dependence of the average maximum depth on the energy in the range of 6 · 10 15 -10 18 eV measured for 1540 hours of observation are presented.

Origin of Galactic Cosmic Rays from Supernova Remnants

We analyze the results of recent measurements of Galactic cosmic ray (GCRs) energy spectra and the spectra of nonthermal emission from supernova remnants (SNRs) in order to determine their consistency with GCR origin in SNRs. It is shown that the measured primary and secondary CR nuclei energy spectra as well as the observed positron-to-electron ratio are consistent with the origin of GCRs up to the energy 1017 eV in SNRs. Existing SNR emission data provide evidences for efficient CR production in SNRs accompanied by significant magnetic field amplification. In some cases the nature of the detected γ-ray emission is difficult to determine because key SNR parameters are not known or poorly constrained.

Sharp knee phenomenon of primary cosmic ray energy spectrum

Primary energy spectral models are tested in the energy range of 1-200 PeV using standardized extensive air shower responses from BASJE-MAS, Tibet, GAMMA and KASCADE scintillation shower arrays. Results point towards the two-component origin of observed cosmic ray energy spectra in the knee region (GAPS spectral model) consisting of a pulsar component superimposed upon rigidity-dependent power law diffuse galactic flux. The two-component energy spectral model accounts for both the sharp knee shower spectral phenomenon and observed irregularity of all-particle energy spectrum in the region of 50-100 PeV. Alternatively, tested multi-population primary energy spectra predicted by non-linear diffusive shock acceleration (DSA) models describe observed shower spectra in the knee region provided that the cutoff magnetic rigidities of accelerating particles are 6.0+/-0.3 PV and 45+/-2 PV for the first two populations respectively. Both tested spectral models confirm the predominant H-He primary nuclei origin of observed shower spectral knee. The parameters of tested energy spectra are evaluated using solutions of inverse problem on the basis of the corresponding parameterizations of energy spectra for primary H, He, O-like and Fe-like nuclei, standardized shower size spectral responses in the 550-1085 g/cm^2 atmospheric slant depth range and near vertical muon truncated size spectra detected by the GAMMA array.

A Monte Carlo study of the energy spectra and transmission characteristics of scattered radiation from x-ray computed tomography

Existing data used to calculate the barrier transmission of scattered radiation from computed tomography (CT) are based on primary beam CT energy spectra. This study uses the EGSnrc Monte Carlo system and Epp user code to determine the energy spectra of CT scatter from four different primary CT beams passing through an ICRP 110 male reference phantom. Each scatter spectrum was used as a broad-beam x-ray source in transmission simulations through seventeen thicknesses of lead (0.00–3.50 mm). A fit of transmission data to lead thickness was performed to obtain α, β and γ parameters for each spectrum. The mean energy of the scatter spectra were up to 12.3 keV lower than that of the primary spectrum. For 120 kVp scatter beams the transmission through lead was at least 50% less than predicted by existing data for thicknesses of 1.5 mm and greater; at least 30% less transmission was seen for 140 kVp scatter beams. This work has shown that the mean energy and half-value layer of CT scatter spectra are lower than those of the corresponding primary beam. The transmission of CT scatter radiation through lead is lower than that calculated with currently available data. Using the data from this work will result in less lead shielding being required for CT scanner installations.

Extensive Air Showers’ Arrival Direction Distribution by TBS Array

Arrival zenith angle distribution for the Extensive Air Showers (EAS) with a wide range of number of charged particles is studied using the experimental data obtained using the EAS 4-detector array TBS in Tbilisi. The station is a part of the GELATICA net in Georgia (GEorgian Large-area Angle and Time Coincidence Array). This experiment is devoted to the study of possible correlations in the arrival times and directions of separate EAS events over large distances and to the Primary Cosmic Ray energy spectrum investigation at very high energies. It is shown that the distribution function with the exponential dependence of showers’ flux on absorbing atmospheric depth provides a good approximation for the angular distribution despite the existing azimuth anisotropy of array. The dependence of the EAS absorption path estimation on the angular measure cutoff boundary is studied.

Assessment of Photon Propagation through Fatby Monte Carlo Simulation and Experimental Work in Linear Accelerator of Imam Reza Hospital

The aim of radiation therapy is to maximise the dose to the tumour, while minimising the dose to healthy tissue. Monte Carlo (MC) methods are now widely used to model radiotherapy systems for accurate treatment planning and evaluate the accuracy of the dose distributions in a variety of clinical situations involving highly heterogeneous media, such as lung or head and neck treatments. This study aimed to simulate the photon propagation in tissue using MC technique.The MC simulation was written in Fortran 77 program. Moreover, emigration of photons in tissue was determined using MCNP-4C code. The tally F5: P, 9 MeV photons beam as a source and point detector was utilized to calculate the flux of photon at various depths of tissue. Neptun 10 PC linear accelerator of Imam Reza Hospital with 9 MeV photon beam energy was used to determine experimental results.The result of MC methodwas evaluated withthose of MCNP-4C code and experimental result performed by clinical treatment planning system. The result of MC method shows a good consistent with those of MCNP-4C code and experimental result. The results of this research provide a method to characterize the primary radiation energy spectrum produced by a linear accelerator.

DETECTION OF A CHANGE OF SLOPE IN THE SPECTRUM OF HEAVY MASS COSMIC RAYS PRIMARIES BY THE KASCADE-GRANDE EXPERIMENT

KASCADE-Grande is an extensive air shower experiment devoted to the study of cosmic rays in the 1016 ÷ 1018 eV energy range. The array is composed by different detectors allowing independent measurements of the number of muons (Nμ) and charged particles (Nch) of extensive air showers (EAS). These two observables are then used to study the primary energy spectrum, separating the events in two samples, on the basis of the shower size ratio, corrected for attenuation in the atmosphere, lnNμ/ lnNch. The two samples represent the light and heavy mass groups of the primaries. In the studied energy range only the spectrum of heavy primaries shows a significant change of slope, the energy (estimated using the QGSJET II hadronic interaction model) of this feature is in agreeement with the expectations of a rigidity dependent knee feature.

DETECTION OF A CHANGE OF SLOPE IN THE SPECTRUM OF HEAVY MASS COSMIC RAYS PRIMARIES BY THE KASCADE-GRANDE EXPERIMENT

KASCADE-Grande is an extensive air shower experiment devoted to the study of cosmic rays in the 1016 ÷ 1018 eV energy range. The array is composed by different detectors allowing independent measurements of the number of muons (Nμ) and charged particles (Nch) of extensive air showers (EAS). These two observables are then used to study the primary energy spectrum, separating the events in two samples, on the basis of the shower size ratio, corrected for attenuation in the atmosphere, lnNμ/ lnNch. The two samples represent the light and heavy mass groups of the primaries. In the studied energy range only the spectrum of heavy primaries shows a significant change of slope, the energy (estimated using the QGSJET II hadronic interaction model) of this feature is in agreeement with the expectations of a rigidity dependent knee feature.

Observation of a muon excess following a gamma-ray burst event detected at the International Space Station

On April 24, 2012, at 16:47:14 UT, the Gas Slit Camera (GSC) of the Japanese Monitor of All-sky X-ray Image (MAXI) instrument on the International Space Station detected a short x-ray transient lasting about 34 seconds. The MAXI/GSC transient was most likely a gamma-ray burst (GRB), because of the high Galactic latitude, spectral hardness ratio, and the absence of known bright x-ray sources at the detected position. In addition, the MAXI/GSC transient GRB 120424A coordinates were in the field of view of the inclined Tupi muon telescope located at ground level (3 m above sea level) at ($22.9\ifmmode^\circ\else\textdegree\fi{}\text{ }\mathrm{W}$, $43.2\ifmmode^\circ\else\textdegree\fi{}\text{ }\mathrm{S}$) in the South Atlantic Anomaly region. We report here that the Tupi telescope registered a muon excess with a signal significance $6.2\ensuremath{\sigma}$ within the MAXI/GSC transient time period. Assuming a power law function with a spectral index of $\ensuremath{\gamma}=\ensuremath{-}1.54$ in the tail of the primary gamma-ray energy spectrum, we can conclude that the fluence obtained from the muon excess detected by the Tupi telescope is consistent with the preliminary value obtained by the MAXI team. This result agrees with an assumption that the muons were produced in photonuclear reactions in the Earth's atmosphere. In addition, we show also that the South Atlantic Anomaly region can be a favorable place at ground for the detection of the tail of the energy spectrum (the GeV counterpart) of some GRBs.

Flux of antinucleons induced by cosmic rays in the atmosphere

This work is devoted to the calculation of the fluxes of the atmospheric antiprotons and antineutrons generated at various atmospheric depths, lying from 5 to 300 g/cm2. The simulations are carried out with the help of CORSIKA package involving a primary energy spectrum starting at the energy threshold of antiparticle production up to 1 PeV. The obtained results match well with the atmospheric antiproton spectra measured by the BESS-2001 experiment in the kinetic energy range 1-3 GeV.

Scaling behaviour of lateral distribution of electrons in EAS

From a Monte Carlo simulation study of cosmic ray air showers around the knee of the primary energy spectrum it is shown that, despite a strong radial dependence of the lateral shower age parameter, the lateral density distribution of electrons in cosmic ray EAS displays universality when expressed in terms of local age parameters. The nature of the radial variation of local age is found to depend on the choice of the effective Moliere radius, particularly for radial distances below about 400 m. The possible use of shower age parameters in a multi-parameter study of EAS for extracting information about the nature of the shower initiating particles, has been re-examined.

SU‐E‐T‐678: Monte Carlo Investigation on Dose Perturbations in the Lung Due to Constant Magnetic Fields during MRIgRT

Purpose: Magnetic resonance image‐guided radiotherapy (MR‐IGRT) has emerged as a promising new technology to reduce tumor position uncertainty during photon radiotherapy treatments of lung cancer. MRIGRT improves upon traditional IGRT techniques by providing real‐time intrafraction imaging of tumor motion. However, the use of MRI during beam delivery complicates treatment planning since the magnetic field will perturb the radiation dose distribution especially in fields prescribed in heterogeneous regions of the body such as the lung. In this study we used Monte Carlo methods to investigate the magnetic field effects on dose distributions near interfaces of high‐ and low‐density regions where the influence of magnetic fields will be significant. Methods: The Monte Carlo code EGS4nrc was used for all simulations performed in this study. We investigated dose distributions from both Co‐60 and 6‐MV photon beam energy spectra in simple heterogeneous phantoms. The phantoms consisted of alternating slabs of PMMA and air or lung material with different thicknesses. Homogeneous transverse magnetic fields of varying strengths were applied to the phantom during the simulations. Results: Large perturbations in the dose distributions near PMMA‐air or PMMA‐lung interfaces were recorded when a transverse magnetic field was applied to the phantom, which can be attributed to electron return effect. It was demonstrated that the size of the perturbation at an interface depends not only on the magnetic field strength, but also on the primary photon beam energy spectrum and the length of the air cavity within the phantom. Conclusions: Preliminary results demonstrated that magnetic fields alter the delivered dose distributions near interfaces of high‐ and low‐density regions. Therefore, accurate planning for MR‐IGRT treatments of lung cancer may need to consider magnetic field effects on the dose distribution. Future work will use Monte Carlo methods to investigate dose perturbations due to magnetic fields in 4D patient geometry.

Primary energy reconstruction from the charged particle densities recorded at 500 m distance from shower core with the KASCADE-Grande detector

Previous EAS investigations have shown that for a fixed primary energy the charged particle density becomes independent of the primary mass at certain (fixed) distances from the shower axis. This feature can be used as an estima- tor for the primary energy. We present results on the recon- struction of the primary energy spectrum of cosmic rays from the experimentally recorded S(500) observable (the density of charged particles at a distance of 500 m to the shower core as measured in a plane normal to the shower axis) using the KASCADE-Grande detector array. The KASCADE-Grande experiment is hosted by the Karlsruhe Institute for Technol- ogy - Campus North, Karlsruhe, Germany, 110 m a.s.l. and