HAWC is an air-shower detector designed to study TeV gamma and cosmic rays. The observatory is composed of a 22000
m^2
m
2
array of 300 water Cherenkov tanks (4.5 m deep x 7.3 m diameter) with 4 ...photomultipliers (PMT) each. The instrument registers the number of hit PMTs, the timing information and the total charge at the PMTs during the event. From these data, shower observables such as the arrival direction, the core position at ground, the lateral age and the primary energy are estimated. In this work, we study the distribution of the shower age vs the primary energy of a sample of shower data collected by HAWC from June 2015 to June 2019 and employ a shower-age cut based on predictions of QGSJET-II-04 to separate a subsample of events dominated by H and He primaries. Using these data and a dedicated analysis, we reconstruct the cosmic ray spectrum of H+He from 6 to 158 TeV, which shows the presence of a softening at around 24 TeV with a statistical significance of 4.1
\sigma
σ
.
This work examines the strategies adopted by an arbuscular mycorrhizal symbiotic system to ameliorate environmental Pb stress by examining the concentrations of P, Fe, and Pb in the fungal ...microstructures and the host’s root. In vitro cultures of Ri-T DNA-transformed carrot (
Daucus carota
L.) roots were inoculated with
Glomus intraradices
and treated with Pb(NO
3
)
2
solution and the extraradical spores and mycelia (S/M) and the root with the vesicles, mycelia, and root cells were subsequently analyzed by polarized energy dispersive x-ray fluorescence (PEDXRF) spectrometry. Upon Pb treatment, within the root, the percentages of mycorrhizal colonization, the vesicles, and mycelia increased as well as the areas of the vesicles and the (extraradical) spores, although the number of spores and arbuscules decreased. The S/M and the mycorrhizal root showed enhanced concentrations of Pb, Fe, and P. These were particularly marked for Fe in the Pb-treated cultures. This indicates a synergistic relationship between the arbuscular mycorrhizal fungus and the host that confers a higher Pb tolerance to the latter by the induction of higher Fe absorption in the host. The intraradical vesicle, mycelia, and arbuscule numbers are interpreted as a “tactic to divert” the intraradical Pb traffic away from the root cells to the higher affinity cell walls of the arbuscular mycorrhizal fungi (AMF) microstructures in the apoplast. The results of this work show that the symbiosis between the AMF
G. intraradices
and the host plant
D. carota
distinctly improves the latter’s Pb tolerance, and imply that the appropriate metal tolerant host-AMF combinations could be employed in process designs for the phytoremediation of Pb.
The HAWC observatory is an air-shower detector, which is designed to study both astrophysical gamma-rays in the TeV region and galactic cosmic rays in the energy interval from 1 TeV to 1 PeV. This ...energy regime is interesting for cosmic ray research, since indirect observations overlap with direct measurements, which offers the opportunity for cross calibration and studies of experimental systematic errors in both techniques. One quantity that could help for this purpose is the all-particle energy spectrum of cosmic rays. In this work, we present an update of HAWC measurements on the total cosmic-ray energy spectrum between 10 TeV and 1 PeV. The spectrum was obtained from an unfolding analysis of almost two years of HAWC’s data, which was collected from January, 2018 to December, 2019. For the energy estimation, we employed the high-energy hadronic interaction model QGSJET-II-04. As in a previous work of HAWC, published in 2017, we observed the presence of a knee-like feature in the region of tens of TeV.
KASCADE and its extension array of KASCADE-Grande were devoted to measure individual air showers of cosmic rays in the primary energy range of 100 TeV to 1 EeV. The experiment has substantially ...contributed to investigate the energy spectrum and mass composition of cosmic rays in the transition region from galactic to extragalactic origin of cosmic rays as well as to quantify the characteristics of hadronic interaction models in the air shower development through validity tests using the multi-detector information from KASCADE-Grande. Although the data accumulation was completed in 2013, data analysis is still continuing. Recently, we investigated the reliability of the new hadronic interactions models of the SIBYLL version 2.3d only with the energy spectra from the KASCADE-Grande data. The evolution of the muon content of high energy air showers in the atmosphere is studied as well, using EPOS-LHC, SIBYLL 2.3, QGSJET-II-04 and SIBYLL 2.3c. In this talk, recent results from KASCADE-Grande and the update of the KASCADE Cosmic Ray Data Centre (KCDC) will be discussed.
Current knowledge of the relative abundances and the energy spectra of the elemental mass groups of cosmic rays in the \(10\) TeV - \(1\) PeV interval is uncertain. This situation prevents carrying ...out precision tests that may lead to distinguish among the existing hypotheses on the origin and propagation of TeV cosmic rays in the galaxy. In order to learn more about the mass composition of these particles, we have employed HAWC data from hadron induced air showers in order to determine the spectra of three mass groups of cosmic rays: protons, helium and heavy nuclei with \(Z > 2\). The energy spectra were estimated by using the Gold unfolding technique on the 2D distribution of the lateral shower age against the estimated primary energy of events with arrival zenith angles smaller than 45 degrees. The study was carried out based on simulations using the QGSJET-II-04 model. Results are presented for primary cosmic-ray energies from \(10\) TeV to \(251\) TeV. They reveal that the aforementioned cosmic ray spectra exhibit fine structures within the above primary energy range.
We present a measurement of the energy spectrum of the light mass group of cosmic rays (protons and helium) with the High Altitude Water Cherenkov (HAWC) Observatory in the energy interval from ...\(10\) TeV to \(200\) TeV. The spectrum covers the energy range between direct and indirect measurements, where precision data on the composition of cosmic rays are needed. The spectrum was constructed by applying an unfolding technique on a proton plus helium enriched sub-sample (\(>90\%\) abundance) of cosmic ray air showers selected from the HAWC cosmic-ray data. The subset contains \(3.8 \times 10^{9}\) air shower events with primary energies in the interval \(1\) TeV to \(300\) TeV and zenith angles less than \(16.7\) degrees. Mass selection was performed using an analysis of the lateral age parameter of air shower events, based on both CORSIKA/QGSJET-II-03 simulations and event-by-event measurements on the lateral structure of the shower front and the primary energy of the showers.
We report on recent progress in the design of the proposed MATHUSLA Long Lived Particle (LLP) detector for the HL-LHC, updating the information in the original Letter of Intent (LoI), see ...CDS:LHCC-I-031, arXiv:1811.00927. A suitable site has been identified at LHC Point 5 that is closer to the CMS Interaction Point (IP) than assumed in the LoI. The decay volume has been increased from 20 m to 25 m in height. Engineering studies have been made in order to locate much of the decay volume below ground, bringing the detector even closer to the IP. With these changes, a 100 m x 100 m detector has the same physics reach for large c\(\tau\) as the 200 m x 200 m detector described in the LoI and other studies. The performance for small c\(\tau\) is improved because of the proximity to the IP. Detector technology has also evolved while retaining the strip-like sensor geometry in Resistive Plate Chambers (RPC) described in the LoI. The present design uses extruded scintillator bars read out using wavelength shifting fibers and silicon photomultipliers (SiPM). Operations will be simpler and more robust with much lower operating voltages and without the use of greenhouse gases. Manufacturing is straightforward and should result in cost savings. Understanding of backgrounds has also significantly advanced, thanks to new simulation studies and measurements taken at the MATHUSLA test stand operating above ATLAS in 2018. We discuss next steps for the MATHUSLA collaboration, and identify areas where new members can make particularly important contributions.
The observation of long-lived particles at the LHC would reveal physics beyond the Standard Model, could account for the many open issues in our understanding of our universe, and conceivably point ...to a more complete theory of the fundamental interactions. Such long-lived particle signatures are fundamentally motivated and can appear in virtually every theoretical construct that address the Hierarchy Problem, Dark Matter, Neutrino Masses and the Baryon Asymmetry of the Universe. We describe in this document a large detector, MATHUSLA, located on the surface above an HL-LHC \(pp\) interaction point, that could observe long-lived particles with lifetimes up to the Big Bang Nucleosynthesis limit of 0.1 s. We also note that its large detector area allows MATHUSLA to make important contributions to cosmic ray physics. Because of the potential for making a major breakthrough in our conceptual understanding of the universe, long-lived particle searches should have the highest level of priority.
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