ترغب بنشر مسار تعليمي؟ اضغط هنا

Measurement of the cosmic-ray energy spectrum above $10^{16}$ eV with the LOFAR Radboud Air Shower Array

262   0   0.0 ( 0 )
 نشر من قبل Satyendra Thoudam Dr.
 تاريخ النشر 2015
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

The energy reconstruction of extensive air showers measured with the LOFAR Radboud Air Shower Array (LORA) is presented in detail. LORA is a particle detector array located in the center of the LOFAR radio telescope in the Netherlands. The aim of this work is to provide an accurate and independent energy measurement for the air showers measured through their radio signal with the LOFAR antennas. The energy reconstruction is performed using a parameterized relation between the measured shower size and the cosmic-ray energy obtained from air shower simulations. In order to illustrate the capabilities of LORA, the all-particle cosmic-ray energy spectrum has been reconstructed, assuming that cosmic rays are composed only of protons or iron nuclei in the energy range between $sim2times10^{16}$ and $2times10^{18}$ eV. The results are compatible with literature values and a changing mass composition in the transition region from a galactic to an extragalactic origin of cosmic rays.



قيم البحث

اقرأ أيضاً

There are some discrepancies in the results on energy spectrum from Yakutsk, AGASA, and HiRes experiments. In this work differential energy spectrum of primary cosmic rays based on the Yakutsk EAS Array data is presented. For the largest events value s of $S_{600}$ and axes coordinates have been obtained using revised lateral distribution function. Simulation of converters response at large distances showed no considerable underestimation of particle density. Complex shape of spectrum in region of $E > 10^{17}$ eV is confirmed. After adjustment of parameters and additional exposition at the Yakutsk array there are three events with energy $E > 10^{20}$ eV.
We report a measurement of the energy spectrum of cosmic rays for energies above $2.5 {times} 10^{18}~$eV based on 215,030 events recorded with zenith angles below $60^circ$. A key feature of the work is that the estimates of the energies are indepen dent of assumptions about the unknown hadronic physics or of the primary mass composition. The measurement is the most precise made hitherto with the accumulated exposure being so large that the measurements of the flux are dominated by systematic uncertainties except at energies above $5 {times} 10^{19}~$eV. The principal conclusions are: (1) The flattening of the spectrum near $5 {times} 10^{18}~$eV, the so-called ankle, is confirmed. (2) The steepening of the spectrum at around $5 {times} 10^{19}~$eV is confirmed. (3) A new feature has been identified in the spectrum: in the region above the ankle the spectral index $gamma$ of the particle flux ($propto E^{-gamma}$) changes from $2.51 pm 0.03~{rm (stat.)} pm 0.05~{rm (sys.)}$ to $3.05 pm 0.05~{rm (stat.)} pm 0.10~{rm (sys.)}$ before changing sharply to $5.1 pm 0.3~{rm (stat.)} pm 0.1~{rm (sys.)}$ above $5 {times} 10^{19}~$eV. (4) No evidence for any dependence of the spectrum on declination has been found other than a mild excess from the Southern Hemisphere that is consistent with the anisotropy observed above $8 {times} 10^{18}~$eV.
The Experimental complex NEVOD includes several different setups for studying various components of extensive air showers (EAS) in the energy range from 10^10 to 10^18 eV. The NEVOD-EAS array for detection of the EAS electron-photon component began i ts data taking in 2018. It is a distributed system of scintillation detectors installed over an area of about 10^4 m^2. A distinctive feature of this array is its cluster organization with different-altitude layout of the detecting elements. The main goal of the NEVOD-EAS array is to obtain an estimation of the primary particle energy for events measured by various detectors of the Experimental complex NEVOD. This paper describes the design, operation principles and data processing of the NEVOD-EAS array. The criteria for the event selection and the accuracy of the EAS parameters reconstruction obtained on the simulated events are discussed. The results of the preliminary analysis of experimental data obtained during a half-year operation are presented.
CHICOS (California HIgh school Cosmic ray ObServatory) is presently an array of more than 140 detectors distributed over a large area (~400 km^2) of southern California, and will consist of 180 detectors at 90 locations in the near future. These site s, located at area schools, are equipped with computerized data acquisition and automatic nightly data transfer (via internet) to our Caltech lab. The installed sites make up the largest currently operating ground array for ultra-high energy cosmic ray research in the northern hemisphere. The goal of CHICOS is to provide data related to the flux and distribution of arrival directions for ultra-high energy cosmic rays. We have performed detailed Monte-Carlo calculations to determine the density and arrival-time distribution of charged particles in extensive air showers for the CHICOS array. Calculations were performed for proton primaries with energies 10^18 to 10^21 eV and zenith angles out to 50 degrees. We have developed novel parameterizations for both distributions as functions of distance from the shower axis, primary energy, and incident zenith angle. These parameterizations are used in aperture calculations and reconstruction of shower data, enabling preliminary analysis of ultra-high energy shower data from CHICOS.
With the Akeno Giant Air Shower Array (AGASA), 581 cosmic rays above 10^19eV, 47 above 4 x 10^19eV, and 7 above 10^20eV are observed until August 1998. Arrival direction distribution of these extremely high energy cosmic rays has been studied. While no significant large-scale anisotropy is found on the celestial sphere, some interesting clusters of cosmic rays are observed. Above 4 x 10^19eV, there are one triplet and three doublets within separation angle of 2.5^o and the probability of observing these clusters by a chance coincidence under an isotropic distribution is smaller than 1 %. Especially the triplet is observed against expected 0.05 events. The cos(theta_GC) distribution expected from the Dark Matter Halo model fits the data as well as an isotropic distribution above 2 x 10^19eV and 4 x 10^19eV, but is a poorer fit than isotropy above 10^19eV. Arrival direction distribution of seven 10^20eV cosmic rays is consistent with that of lower energy cosmic rays and is uniform. Three of seven are members of doublets above about 4 x 10^19eV.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا