Variations in water use by a mature mangrove of Avicennia germinans, French Guiana

In the tropical intertidal zones, little is known on water uptake by mangroves. Transpiration rates are generally measured at leaf level, but few studies exist on water use at tree or stand levels. The objective of this study was to measure sap flow in trees of different sizes to appreciate the range of variation in water use that may exist in a site dominated by 80% mature Avicennia germinans. The results showed that from the dry to the wet season the mean water use increased from 3.2 to 5.3 dm3 d−1 in small trees (DBH ∼ 13 cm), from 11.5 to 30.8 dm3 d−1 in medium trees (∼24 cm) and from 40.8 to 64.1 dm3 d−1 in large ones (∼45 cm). Sapwood remained active up to a depth of 8 cm with radial variations within the stem. Weak correlations were obtained with VPD and net radiation. This study confirmed that transpiration was larger under low levels of salinity. Water use at stand level (∼1900 living stems ha−1) was estimated to be in the range of 5.8 to 11.8 m3 ha−1 d−1 according to the season

Energy loss of pions and electrons of 1 to 6 GeV/c in drift chambers operated with Xe,CO2(15%)

We present measurements of the energy loss of pions and electrons in drift chambers operated with a Xe,CO2(15%) mixture. The measurements are carried out for particle momenta from 1 to 6 GeV/c using prototype drift chambers for the ALICE TRD. Microscopic calculations are performed using input parameters calculated with GEANT3. These calculations reproduce well the measured average and most probable values for pions, but a higher Fermi plateau is required in order to reproduce our electron data. The widths of the measured distributions are smaller for data compared to the calculations. The electron/pion identification performance using the energy loss is also presented.Comment: 15 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth.

Toward High Energy Neutrino Detection with the Radar Echo Telescope for Cosmic Rays (RET-CR)

The Radar Echo Telescope for Cosmic Rays (RET-CR) is a pathfinder experiment for the Radar Echo Telescope for Neutrinos (RET-N), a next-generation in-ice detection experiment for ultra high energy neutrinos. RET-CR will serve as the testbed for the radar echo method to probe high-energy particle cascades in nature, whereby a transmitted radio signal is reflected from the ionization left in its wake. This method, recently validated at SLAC experiment T576, shows promising preliminary sensitivity to neutrino-induced cascades above the energy range of optical detectors like IceCube. RET-CR intends to use an in-nature test beam: the dense, in-ice cascade produced when the air shower of an ultra high energy cosmic ray impacts a high-elevation ice sheet. This in-ice cascade, orders of magnitude more dense than the in-air shower that preceded it, is similar in profile and density to the expected cascade from a neutrino-induced cascade deep in the ice. RET-CR will be triggered using surface scintillator technology and will be used to develop, test, and deploy the hardware, firmware, and software needed for the eventual RET-N. We present the strategy, status, and design sensitivity of RET-CR, and discuss its application to eventual neutrino detection

The Radar Echo Telescope for Cosmic Rays

The Radar Echo Telescope for Cosmic Rays (RET-CR) was deployed in May 2023. RET-CR aims to show the in-nature viability of the radar echo method to probe in-ice particle cascades induced by ultra high energy cosmic rays and neutrinos. The RET-CR surface system detects ultra-high-energy cosmic ray air showers impinging on the ice using conventional methods. The surface detector then triggers the in-ice component of RET-CR, that is subsequently used to search for a radar echo off of the in-ice continuation of an ultra high energy cosmic ray air shower. The two systems independently reconstruct the energy, arrival direction, and impact point of the particle cascade. Here we present RET-CR, its installation in Greenland, and the first operations and results of RET-CR

Simulation and Optimisation for the Radar Echo Telescope for Cosmic Rays

The SLAC T-576 beam test experiment showed the feasibility of the radar detection technique to probe high-energy particle cascades in dense media. Corresponding particle-level simulations indicate that the radar method has very promising sensitivity to probe the > PeV cosmic neutrino flux. As such, it is crucial to demonstrate the in-situ feasibility of the radar echo method, which is the main goal of the current RET-CR experiment. Although the final goal of the Radar Echo Telescope is to detect cosmic neutrinos, we seek a proof of principle using cosmic-ray air showers penetrating the (high-altitude) Antarctic ice sheet. When an UHECR particle cascade propagates into a high-elevation ice sheet, it produces a dense in-ice cascade of charged particles which can reflect incoming radio waves. Using a surface cosmic-ray detector, the energy and direction of the UHECR can be reconstructed, and as such this constitutes a nearly ideal in-situ test beam to provide the proof of principle for the radar echo technique. RET-CR will consist of a transmitter array, receiver antennas and a surface scintillator plate array. Here we present the simulation efforts for RET-CR performed to optimise the surface array layout and triggering system, which affords an estimate of the expected event rate

Investigating signal properties of UHE particles using in-ice radar for the RET experiment

The Radar Echo Telescope (RET) experiment plans to use the radar technique to detect Ultra-High Energy (UHE) cosmic rays and neutrinos in the polar ice sheets. Whenever an UHE particle collides with an ice molecule, it produces a shower of relativistic particles, which leaves behind an ionization trail. Radio waves can be reflected off this trail and be detected in antennas. It is critical to understand such a radar signal's key properties as that will allow us to do vertex, angular and energy reconstruction of the primary UHE particle. We will discuss various simulation methods, which will fundamentally rely on ray tracing, to recreate the radar signal and test our reconstruction methods

The Radar Echo Telescope for Neutrinos (RET-N)

We present the Radar Echo Telescope for Neutrinos (RET-N). RET-N focuses on the detection of the cosmic neutrino flux above PeV energies by means of the radar detection technique. This method aims to bridge the energy gap between the diffuse neutrino flux detected by IceCube up to a few PeV and the sought for cosmogenic neutrinos at EeV energies by the in-ice Askaryan detectors, as well as the air-shower radio detectors. The radar echo method is based on the detection the ionization trail in the wake of a high-energy neutrino-induced particle cascade in ice. This technique, recently validated in a beam test (T576 at SLAC) is also the basis for the RET-N pathfinder experiment, RET-CR, which is currently under development. Based on the T-576 results, we show that the radar echo method leads to very promising sensitivities to detect cosmic neutrinos in the PeV-EeV region and above. We present the RET-N project and the results of our sensitivity studies