Extremely High Energy Research Articles

Constancy of the Half Value Layer of Cobalt-doped borate glasses with Lanthanum Oxide Additive at Extremely High Radiation Energy

Radiation shielding is essential for protecting workers, patients, and the environment from harmful effects of radiation. To achieve effective and non-toxic shielding, scientists are interested in developing lead-free materials with low thickness that can still attenuate radiation. This is where the concept of Half Value Layer (HVL) comes in. The aim of this study is to investigate the nature of the HVL of Cobalt-doped borate glasses with five different concentrations of Lanthanum oxide (La2O3) additive at various energy levels. Phy-X/PSD software was used to simulate radiation exposure and determined the HVL values for energies within the order of 0-10 keV, 10 – 100 keV, 100 keV – 1 MeV, 1 – 10, 10 – 100, 100 – 1,000, 1,000 – 10,000, and 10,000 - 100,000 MeV. The results showed that the HVL values fluctuated depending on the energy range of the incident radiation, but they remained constant within a mean value at extremely high energies. These findings can help manufacturers to determine the appropriate thicknesses and the amounts of (La2O3) additive for different applications of this glass system.

Harmonization of RBSP and Arase Energetic Electron Measurements Utilizing ESA Radiation Monitor Data

AbstractAccurate measurements of trapped energetic electron fluxes are of major importance for the studies of the complex nature of radiation belts and the characterization of space radiation environment. The harmonization of measurements between different instruments increases the accuracy of scientific studies and the reliability of data‐driven models that treat the specification of space radiation environment. An intercalibration analysis of the energetic electron flux measurements of the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron‐Proton Telescope (REPT) instruments on‐board the Van Allen Probes (VAP) Mission versus the measurements of the Extremely High Energy Electron Experiment (XEP) unit on‐board Arase satellite is presented. The performed analysis demonstrates a remarkable agreement between the majority of MagEIS and XEP measurements and suggests the rescaling of MagEIS HIGH unit and of REPT measurements for the treatment of flux spectra discontinuities. The proposed adjustments were validated successfully using measurements from ESA Environmental Monitoring Unit (EMU) on‐board GSAT0207 and the Standard Radiation Monitor (SREM) on‐board INTEGRAL. The derived results lead to the harmonization of science‐class experiments on‐board VAP (2012–2019) and Arase (2017–) and propose the use of the data sets as reference in a series of space weather and space radiation environment developments.

Characteristics of Glycerolized Chitosan: NH4NO3-Based Polymer Electrolyte for Energy Storage Devices with Extremely High Specific Capacitance and Energy Density Over 1000 Cycles.

In this work, plasticized polymer electrolyte films consisting of chitosan, ammonium nitrate (NH4NO3) and glycerol for utilization in energy storage devices was presented. Various microscopic, spectroscopic and electrochemical techniques were used to characterize the concerned electrolyte and the electrical double-layer capacitor (EDLC) assembly. The nature of complexation between the polymer electrolyte components was examined via X-ray diffraction analysis. In the morphological study, field emission scanning electron microscopy (FESEM) was used to investigate the impact of glycerol as a plasticizer on the morphology of films. The polymer electrolyte (conducting membrane) was found to have a conductivity of 3.21 × 10−3 S/cm. It is indicated that the number density (n), mobility (μ) and diffusion coefficient (D) of ions are increased with the glycerol amount. The mechanism of charge storing was clarified, which implies a non-Faradaic process. The voltage window of the polymer electrolyte is 2.32 V. It was proved that the ion is responsible for charge-carrying via measuring the transference number (TNM). It was also determined that the internal resistance of the EDLC assembly lay between 39 and 50 Ω. The parameters associated with the EDLC assembly are of great importance and the specific capacitance (Cspe) was determined to be almost constant over 1 to 1000 cycles with an average of 124 F/g. Other decisive parameters were found: energy density (18 Wh/kg) and power density (2700 W/kg).

A Method for Evaluation of Thermal Characteristics of Complex Heat-Shield Assembles at Extremely High Energy Fluxes

A suitable laboratory test procedure is developed where a small fragment of the relatively thick multilayer heat shield is exposed to the extreme heat flux of up to several kW/cm2 in order to evaluate its performance. A nearly one-dimensional test condition has been achieved, where thermal behavior of a small fragment of a large shield became representative for the large heat-shield panel. A cylindrical test sample made of carbon-carbon composite has been surrounded by high-temperature thermal isolation made of zirconia concrete. The high heat flux has been provided by a power CW-laser. The conditions of one-dimensional axial heat flux through the cylindrical fragment of the heat shield are confirmed by the mathematical modeling of the experiment using experimentally measured temperature excursions along the sample axis.

Neutrinos from TXS 0506+056 prior to the 2017 gamma-ray flare

On 2017 September 22, IceCube released a public alert announcing the detection of a well-reconstructed, high-energy neutrino event. Such alerts issued through the Extremely High Energy (EHE) alert stream occur roughly four times a year. Subsequent multimessenger follow-up identified that the event was coincident in direction and time with a gamma-ray flare from the blazar TXS 0506+056. This association prompted an archival analysis searching for additional neutrinos from the direction of TXS 0506+056 using 9.5 years of IceCube neutrino observations. An excess of neutrino events with respect to atmospheric backgrounds was found between September 2014 and March 2015. The analysis yields 3:5σ evidence for neutrino emission from the direction of TXS 0506+056, independent of and prior to the 2017 emission.

High-resolution evaluation of the U5(n,f) cross section from 3 keV to 30 keV

235U neutron-induced fission cross-section is commonly used as reference for determining other isotope fission cross-section. However, below 150 keV this cross section is only included as Standard at the thermal point and recently its integral value between 7.8 eV and 11 eV [1]. The resolved resonance region, spanning up to 2.25 keV, has been reevaluated with high resolution in the last ENDF/B-VIII release [2] and a SAMMY resonance analysis was done by L. Leal et al. [3] including the CERN-nTOF experimental work of Paradela el al. [4] up to 10 keV, taken into account the IAEA Reference file. In this work the 235U(n,f) low-background and high-resolution experimental data obtained at the CERN-nTOF facility is combined with previous high-resolution experimental data, in order to produce a very fine grid dataset with normalisation to the IAEA Reference file. The extremelyhigh energy calibration required to reproduce the resonance sharp profiles is based on the nTOF DAQ system with a resolution below 0.1% with reference to the 8.78 eV resonance and to the sharp Al(n,g) capture dip at 5.904 keV. The comparison of the so-evaluated profile with the experimental data and with the evaluated ones will be discussed.

Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data

We report a quasi-differential upper limit on the extremely-high-energy (EHE) neutrino flux above $5\times 10^{6}$ GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above $10^{6}$ GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between $5 \times 10^{6}$ and $5 \times 10^{10}$ GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of $E_\nu^2\phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq2\times 10^{-8}\ {\rm GeV}/{\rm cm}^2\ \sec\ {\rm sr}$ at $10^9\ {\rm GeV}$. A significant part of the parameter-space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded.

Extremely high energy neutrinos in six years of IceCube data

The IceCube neutrino observatory is capable of detecting ultra-high-energy cosmic neutrinos even above PeV - EeV energies. These extremely high energy (EHE) neutrinos (≥ 10 PeV) are produced from interactions of the most energetic cosmic rays (≥ 1 EeV) and ambient photons/matter in the sources or diffuse photon fields such as the cosmic microwave background. Therefore, observations of these EHE neutrinos can be used to probe the origin of the highest energy cosmic rays with energies extending up to 100 EeV. We present the results of an updated analysis of the EHE neutrino sample with energies greater than ~ 1 PeV in 6 years of IceCube data (3 years of partially completed IceCube data (2008-2011) and 3 years of completed IceCube data (2011-2014)). While one event depositing an energy of 770±200 TeV was observed, it is incompatible with a hypothesis of cosmogenic origin. The resultant improvement in the upper limit corresponds to a factor of more than 2.5 from the previous study of two years of data from the nearly completed IceCube detector. Our limits disfavor the parameter space of sources of ultra-high-energy cosmic rays for which the cosmological evolution is stronger than the star formation rate, where the source candidate classes of active galactic nuclei (AGN) and gamma-ray bursts (GRB) belong, assuming the cosmic-ray composition is proton dominated. Results from a 7-year data analysis by adding another year’s worth of data to the current sample are also anticipated soon.

The Atmospheric Monitoring System of the JEM-EUSO space mission

An Atmospheric Monitoring System (AMS) is a mandatory and key device of a space-based mission which aims to detect Ultra-High Energy Cosmic Rays (UHECR) and Extremely-High Energy Cosmic Rays (EHECR) from Space. JEM-EUSO has a dedicated atmospheric monitoring system that plays a fundamental role in our understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. Our AMS consists of a very challenging space infrared camera and a LIDAR device, that are being fully designed with space qualification to fulfil the scientific requirements of this space mission. The AMS will provide information of the cloud cover in the FoV of JEM-EUSO, as well as measurements of the cloud top altitudes with an accuracy of 500 m and the optical depth profile of the atmosphere transmittance in the direction of each air shower with an accuracy of 0.15 degree and a resolution of 500 m. This will ensure that the energy of the primary UHECR and the depth of maximum development of the EAS ( Extensive Air Shower) are measured with an accuracy better than 30\% primary energy and 120 $g/cm^2$ depth of maximum development for EAS occurring either in clear sky or with the EAS depth of maximum development above optically thick cloud layers. Moreover a very novel radiometric retrieval technique considering the LIDAR shots as calibration points, that seems to be the most promising retrieval algorithm is under development to infer the Cloud Top Height (CTH) of all kind of clouds, thick and thin clouds in the FoV of the JEM-EUSO space telescope.

Radiodetection of Neutrinos

Despite 100 years of effort, we still know very little about the origin of ultra-high energy cosmic rays. The observation of neutrinos produced when cosmic-ray protons with energies above 4×1019 eV interact with the cosmic microwave background radiation, or in the neutrino sources, would tell us much about the origin and composition of these particles. Over the past decade, many experiments have searched for radio waves emitted from the charged particle showers produced when Extremely High Energy (EHE) neutrinos interact with Antarctic or Greenland ice or the moon. These experiments have not yet observed a neutrino signal. Two groups are now proposing to instrument 100 km3 of Antarctic ice with radio antennas, producing a detector large enough to observe a clear EHE neutrino signal in a few years of operation.

Erratum: Constraints on the extremely-high energy cosmic neutrino flux with the IceCube 2008-2009 data [Phys. Rev. D83, 092003 (2011)

We report on a search for extremely-high energy neutrinos with energies greater than $10^6$ GeV using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half completed IceCube array. The absence of signal candidate events in the sample of 333.5 days of livetime significantly improves model independent limit from previous searches and allows to place a limit on the diffuse flux of cosmic neutrinos with an $E^{-2}$ spectrum in the energy range $2.0 \times 10^{6}$ $-$ $6.3 \times 10^{9}$ GeV to a level of $E^2 \phi \leq 3.6 \times 10^{-8}$ ${\rm GeV cm^{-2} sec^{-1}sr^{-1}}$.

Constraints on the extremely-high energy cosmic neutrino flux with the IceCube 2008-2009 data

We report on a search for extremely-high energy neutrinos with energies greater than 10(6) GeV using the data taken with the IceCube detector at the South Pole. The data was collected between April 2008 and May 2009 with the half-completed IceCube array. The absence of signal candidate events in the sample of 333.5 days of live time significantly improves model-independent limits from previous searches and allows to place a limit on the diffuse flux of cosmic neutrinos with an E-2 spectrum in the energy range 2.0 x 10(6) - 6.3 x 10(9) GeV to a level of E-2 phi <= 3.6 x 10(-8) GeV cm(-2) sec(-1) sr(-1).

First search for extremely high energy cosmogenic neutrinos with the IceCube Neutrino Observatory

We report on the results of the search for extremely-high energy (EHE) neutrinos with energies above $10^7$ GeV obtained with the partially ($\sim$30%) constructed IceCube in 2007. From the absence of signal events in the sample of 242.1 days of effective livetime, we derive a 90% C.L. model independent differential upper limit based on the number of signal events per energy decade at $E^2 \phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq 1.4 \times 10^{-6}$ GeV cm$^{-2}$ sec$^{-1}$ sr$^{-1}$ for neutrinos in the energy range from $3\times10^7$ to $3\times10^9$ GeV.

Identification of extremely-high energy starting neutrino events with the IceCube observatory

The IceCube neutrino observatory is capable of detecting Extremely High Energy (EHE) neutrinos with energies beyond 108 GeV originated in the highest energy cosmic rays. The high energy muon bundles associated with cosmic ray air showers constitute a major background and a reliable rejection mechanism must be developed. A possible approach is to identify events induced by neutrinos inside the detector instrumentation volume. The initial simulation study is briefly reported.

COSMIC RAYS AT THE HIGHEST ENERGIES — FIRST DATA FROM THE PIERRE AUGER OBSERVATORY

The southern Pierre Auger Observatory, presently under construction in Malargüe, Argentina, is nearing completion. The instrument is designed to measure extensive air-showers with energies ranging from 1018-1020 eV and beyond. It combines two complementary observation techniques; the detection of particles at ground and the coincident observation of associated fluorescence light generated in the atmosphere above the ground. This is being realized by employing an array of 1600 water Cherenkov detectors, distributed over an area of 3000 km2, and operating 24 wide-angle Schmidt telescopes, positioned at four sites at the border of the ground array. The Observatory will reach its full size only in 2007 but data are routinely recorded already and have started to provide relevant science results. This talk will focus on the detector characterizations and presents first results on the arrival direction of extremely-high energy cosmic rays, their energy spectrum, and on the upper limit of the photon fraction.

The EHE Neutrino Search Capability of the IceCube Observatory

An initial study of the extremely high energy (EHE) physics capability of the IceCube neutrino observatory is demonstrated by considering a GZK mechanism neutrino production model, which is a guaranteed source for EHE neutrinos. We study EHE event properties in the energy range 10 5 E 10 11 GeV observed by IceCube using detailed Monte Carlo simulation. Results of a simulation study shows that about 0.7 EHE neutrino events per year is expected with the full IceCube configuration over a 0.03 atmospheric muon background which passed an EHE event criteria. It is also shown that with the present partial IceCube detector with the same criteria is capable of studying EHE physics and the sensitivity improves with the number of deployed strings in the ice.

INVESTIGATION OF EVENT RATES FOR DIFFERENT DETECTOR ARRAYS AND VARIOUS EXTREMELY HIGH ENERGY MODELS

New detection methods for extremely high energy (EHE) neutrinos are being discussed. In this paper, the comparison of different detection methods at energies E &gt; 107.5 GeV are examined, using various neutrino flux predictions. Arrays for acoustic and radio signals from neutrino induced electromagnetic cascades as well as the IceCube array with additional strings ("IceCube Plus") are investigated with effective volumes as given in 5,6. The depth of the detector below the Earth's surface are examined with respect to the absorption of a potential neutrino signal by the Earth. It can be shown that absorption plays an important role and that an array of acoustic and radio antennas should preferably be put at shallow depths of ~ 500 m depth. The detection potential at this depth ranges from several up to tens of events at EHEs depending on the source of the neutrino flux.

The LPM showers traversing the atmosphere

We simulate the LPM showers due to Extremely-High-Energy(EHE) neutrinos traversing atmosphere horizontally without colliding with the Earth. We calculate the LPM showers with energies of 1017eV to 1022eV, using the hybrid method as exactly as possible. Reffecting the complicated change in the air density along the trajectories of the shower developments, the variety of the LPM showers is shown to depend on their starting points and their heights. The EHE LPM showers in atmosphere are exclusively produced by EHE neutrinos. Therefore, the studies on the LPM showers are very important for EHE neutrino astrophysics. As an example, the air fluorescence photon profiles of the LPM showers are also given for the future satellite-based experiment.

Investigation of the characteristics of air showers produced by extremely high energy gamma-rays

The technique of adjoint cascade equations has been applied to calculate the properties of air showers produced by extremely high energy (EHE) γ-rays in the energy range 10 18 ÷ 10 22 eV. The high intrinsic accuracy, combined with very modest (compared with the traditional Monte Carlo codes) computational time requirements, make this method to be an effective tool for detailed study of development of EHE showers in the Earth's atmosphere. Parameters of γ-ray induced air showers are analysed with taking into account two independent effects which become crucial for the cascade development in the EHE regime — the LPM effect and the interaction of primary γ-rays with the geomagnetic field. We show that the total number of muons in the γ-ray induced shower is less, by a factor of 5 to 10, than this number for the proton induced shower. The lateral distribution of muons in the γ-ray shower is considerably narrower than that for the proton shower.

Telescope Array Project for Extremely High Energy Cosmic Rays

The existence of extremely high energy cosmic rays (EHECRs) with energies exceeding 10 2 0 eV has been reported by the AGASA experiment. These cosmic rays may be produced in the active astronomical object in the outer galaxy and propagated a long distance toward the Earth. Such high energy 'stars have been searched in the arrival direction of these events but no clear candidates were found. A new experiment, Telescope Array (TA), is planned to unveil the enigmatic origin of the EHECRs. The physics motivation of TA is reviewed and its present status is reported.