No Arabic abstract
We discuss the acceptance and sensitivity of a small air-shower imaging system to detect earth-skimming ultrahigh-energy tau neutrinos. The instrument we study is located on top of a mountain and has an azimuthal field of view of $360^circ$. We find that the acceptance and sensitivity of such a system is close to maximal if it is located about 2 km above ground, has a vertical field of view of $5^circ$, allows the reconstruction of an at least $0.3^circ$ long air-shower image, and features an effective light-collection area of $10$ m$^2$ in any direction. After three years of operation, an imaging system with these features achieves an all-flavor neutrino flux sensitivity of $5times10^{-9}$ GeV cm$^{-2}$ s$^{-1}$ sr$^{-1}$ at $2times10^8$ GeV.
Efforts to detect ultrahigh energy neutrinos are driven by several objectives: What is the origin of astrophysical neutrinos detected with IceCube? What are the sources of ultrahigh energy cosmic rays? Do the ANITA detected events point to new physics? Shedding light on these questions requires instruments that can detect neutrinos above $10^7$ GeV with sufficient sensitivity - a daunting task. While most ultrahigh energy neutrino experiments are based on the detection of a radio signature from shower particles following a neutrino interaction, we believe that the detection of Cherenkov and fluorescence light from shower particles is an attractive alternative. Imaging air showers with Cherenkov and fluorescence light is a technique that is successfully used in several ultrahigh energy cosmic ray and very-high energy gamma-ray experiments. We performed a case study of an air-shower imaging system for the detection of earth-skimming tau neutrinos. The detector configuration we consider consists of an imaging system that is located on top of a mountain and is pointed at the horizon. From the results of this study we conclude that a sensitivity of $3cdot10^{-9}$ GeV cm$^{-2}$s$^{-1}$sr$^{-1}$ can be achieved at $2cdot10^8$ GeV with a relatively small and modular system after three years of observation. In this presentation we discuss key findings of our study and how they translate into design requirements for an imaging system we dub Trinity.
Trinity is a proposed air-shower imaging system optimized for the detection of earth-skimming ultrahigh energy tau neutrinos with energies between $10^7$ GeV and $10^{10}$ GeV. Trinity will pursue three major scientific objectives. 1) It will narrow in on possible source classes responsible for the astrophysical neutrino flux measured by IceCube. 2) It will help find the sources of ultrahigh-energy cosmic rays (UHECR) and understand the composition of UHECR. 3) It will test fundamental neutrino physics at the highest energies. Trinity uses the imaging technique, which is well established and successfully used by the very high-energy gamma-ray community (CTA, H.E.S.S., MAGIC, and VERITAS) and the UHECR community (Telescope Array, Pierre Auger)
Earth-skimming neutrinos are those which travel through the Earths crust at a shallow angle. For Ultra-High-Energy (E > 1 PeV; UHE) earth-skimming tau neutrinos, there is a high-probability that the tau lepton created by a neutrino-Earth interaction will emerge from the ground before it decays. When this happens, the decaying tau particle initiates an air shower of relativistic sub-atomic particles which emit Cherenkov radiation. To observe this Cherenkov radiation, we propose the Trinity Observatory. Using a novel optical structure design, pointing at the horizon, Trinity will observe the Cherenkov radiation from upward-going neutrino-induced air showers. Being sensitive to neutrinos in the 1-10,000 PeV energy range, Trinitys expected sensitivity will have a unique role to play filling the gap between the observed astrophysical neutrinos observed by IceCube and the expected sensitivity of radio UHE neutrino detectors.
To better understand the radio signal emitted by extensive air-showers and to further develop the radio detection technique of high-energy cosmic rays, the LOPES experiment was reconfigured to LOPES-3D. LOPES-3D is able to measure all three vectorial components of the electric field of radio emission from cosmic ray air showers. The additional measurement of the vertical component ought to increase the reconstruction accuracy of primary cosmic ray parameters like direction and energy, provides an improved sensitivity to inclined showers, and will help to validate simulation of the emission mechanisms in the atmosphere. LOPES-3D will evaluate the feasibility of vectorial measurements for large scale applications. In order to measure all three electric field components directly, a tailor-made antenna type (tripoles) was deployed. The change of the antenna type necessitated new pre-amplifiers and an overall recalibration. The reconfiguration and the recalibration procedure are presented and the operationality of LOPES-3D is demonstrated.
The Wide Field-of-View Cherenkov Telescope Array (WFCTA) and the Water Cherenkov Detector Arrays (WCDA) of LHAASO are designed to work in combination for measuring the energy spectra of various cosmic ray species over a very wide energy range from a few TeV to 10 PeV. The energy calibration of WCDA can be achieved with a proven technique of measuring the westward shift of the Moon shadow of galactic cosmic rays due to the geomagnetic field. This deflection angle $Delta$ is inversely proportional to the energy of the cosmic rays. The precise measurements of the shifts by WCDA allows us to calibrate its energy scale for energies as high as 35 TeV. The energy scale measured by WCDA can be used to cross calibrate the energy reconstructed by WFCTA, which spans the whole energy range up to 10 PeV. In this work, we will demonstrate the feasibility of the method using the data collected from April 2019 to January 2020 by the WFCTA array and WCDA-1 detector, the first of the three water Cherenkov ponds, already commissioned at LHAASO site.