Strategies and policies to reach a land-degradation neutral world

Despite the difficulties in quantifying the extent and degree of land degradation or restoration, evidence shows that continued land degradation will be an impediment to meeting several SDGs. The United Nations states that it aims for land degradation neutrality (LDN) which in 2015 became firmly established as an agreed-upon objective in the realm of international environmental politics. First, as part of the SDGs whose Target 15.3 calls to “combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradationneutral world” by 2030 (UNGA, 2015). The Conference of Parties (COP) of the United Nations Convention to Combat Desertification (UNCCD) took the decision to align the implementation of the Convention with SDG 15.3 and invited its Parties to set voluntary LDN targets (UNCCD, 2015). From that point onwards, the key question is how to implement these global aspirations at the national level and what is needed to operationalize the LDN concept and translate it into concrete strategies to meet LDN at scale..

A 16 Parts per Trillion Comparison of the Antiproton-to-Proton q/m Ratios

The Standard Model (SM) of particle physics is both incredibly successful and glaringly incomplete. Among the questions left open is the striking imbalance of matter and antimatter in the observable universe which inspires experiments to compare the fundamental properties of matter/antimatter conjugates with high precision. Our experiments deal with direct investigations of the fundamental properties of protons and antiprotons, performing spectroscopy in advanced cryogenic Penning-trap systems. For instance, we compared the proton/antiproton magnetic moments with 1.5 ppb fractional precision, which improved upon previous best measurements by a factor of >3000. Here we report on a new comparison of the proton/antiproton charge-to-mass ratios with a fractional uncertainty of 16ppt. Our result is based on the combination of four independent long term studies, recorded in a total time span of 1.5 years. We use different measurement methods and experimental setups incorporating different systematic effects. The final result, $-(q/m)_{\mathrm{p}}/(q/m)_{\bar{\mathrm{p}}}$ = $1.000\,000\,000\,003 (16)$, is consistent with the fundamental charge-parity-time (CPT) reversal invariance, and improves the precision of our previous best measurement by a factor of 4.3. The measurement tests the SM at an energy scale of $1.96\cdot10^{-27}\,$GeV (C$.$L$.$ 0.68), and improves 10 coefficients of the Standard Model Extension (SME). Our cyclotron-clock-study also constrains hypothetical interactions mediating violations of the clock weak equivalence principle (WEP$_\text{cc}$) for antimatter to a level of $|\alpha_{g}-1| < 1.8 \cdot 10^{-7}$, and enables the first differential test of the WEP$_\text{cc}$ using antiprotons \cite{hughes1991constraints}. From this interpretation we constrain the differential WEP$_\text{cc}$-violating coefficient to $|\alpha_{g,D}-1|<0.030$

Ultra-thin polymer foil cryogenic window for antiproton deceleration and storage

We present the design and characterization of a cryogenic window based on an ultra-thin aluminized biaxially oriented polyethylene terephthalate foil at T < 10 K, which can withstand a pressure difference larger than 1 bar at a leak rate < 1 × 1 0 − 9 mbar l/s. Its thickness of ∼1.7 μm makes it transparent to various types of particles over a broad energy range. To optimize the transfer of 100 keV antiprotons through the window, we tested the degrading properties of different aluminum coated polymer foils of thicknesses between 900 and 2160 nm, concluding that 1760 nm foil decelerates antiprotons to an average energy of 5 keV. We have also explicitly studied the permeation as a function of coating thickness and temperature and have performed extensive thermal and mechanical endurance and stress tests. Our final design integrated into the experiment has an effective open surface consisting of seven holes with a diameter of 1 mm and will transmit up to 2.5% of the injected 100 keV antiproton beam delivered by the Antiproton Decelerator and Extra Low ENergy Antiproton ring facility of CERN

Ultra thin polymer foil cryogenic window for antiproton deceleration and storage

We present the design and characterisation of a cryogenic window based on an ultra-thin aluminised PET foil at T < 10K, which can withstand a pressure difference larger than 1bar at a leak rate < $1\times 10^{-9}$ mbar$\cdot$ l/s. Its thickness of approximately 1.7 $\mu$m makes it transparent to various types of particles over a broad energy range. To optimise the transfer of 100keV antiprotons through the window, we tested the degrading properties of different aluminium coated PET foils of thicknesses between 900nm and 2160nm, concluding that 1760nm foil decelerates antiprotons to an average energy of 5 keV. We have also explicitly studied the permeation as a function of coating thickness and temperature, and have performed extensive thermal and mechanical endurance and stress tests. Our final design integrated into the experiment has an effective open surface consisting of 7 holes with 1 mm diameter and will transmit up to 2.5% of the injected 100keV antiproton beam delivered by the AD/ELENA-facility of CERN

BASE-STEP: A transportable antiproton reservoir for fundamental interaction studies

Currently, the only worldwide source of low-energy antiprotons is the AD/ELENA facility located at CERN. To date, all precision measurements on single antiprotons have been conducted at this facility and provide stringent tests of the fundamental interactions and their symmetries. However, the magnetic field fluctuations from the facility operation limit the precision of upcoming measurements. To overcome this limitation, we have designed the transportable antiproton trap system BASE-STEP to relocate antiprotons to laboratories with a calm magnetic environment. We anticipate that the transportable antiproton trap will facilitate enhanced tests of CPT invariance with antiprotons, and provide new experimental possibilities of using transported antiprotons and other accelerator-produced exotic ions. We present here the technical design of the transportable trap system. This includes the transportable superconducting magnet, the cryogenic inlay consisting of the trap stack and the detection systems, and the differential pumping section to suppress the residual gas flow into the cryogenic trap chamber.Comment: To be submitted to Rev. Sci. Instrument

Scientific Conceptual Framework for Land Degradation Neutrality: A Report of the Science-Policy Interface

At the 12th Conference of the Parties to the UN Convention to Combat Desertification, Parties were invited to formulate voluntary targets to achieve land degradation neutrality (LDN). This “Conceptual Framework for Land Degradation Neutrality” is intended to provide a scientifically-sound basis for understanding and implementing LDN, and to inform the development of practical guidance for pursuing LDN and monitoring achievement of LDN for those UNCCD Parties that choose to pursue a LDN target. The LDN conceptual framework focuses on the goal of LDN and the supporting processes required to deliver this goal, including biophysical and socio-economic aspects, and their interactions

Future Program of the BASE Experiment at the Antiproton Decelerator of CERN

This report outlines the future program of the BASE antiproton experiment at the Antiproton Decelerator (AD) facility of CERN. We describe methods and future developments to improve the precision of the antiproton-to-proton charge-to-mass ratio to the parts-per-trillion (p.p.t.) level and the precision of the antiproton magnetic moment to a level of 100 p.p.t. on the short term. Our proposal includes the application of phase sensitive detection techniques, the implementation of measurements on co-trapped particles, the development of more advanced Penning-trap systems, and the invention of a novel type of trap — a cooling trap. In order to further improve experimental precision beyond these limits, we will develop a transportable trap for antiprotons to move the particles out of the AD-facility. This will become necessary since accelerator operation imposes electrical and magnetic noise which makes high-precision Penning-trap measurements beyond the p.p.t. level impossible in the current location of BASE. We request additional offline laboratory space on the CERN campus in which a second high-precision Penning-trap experiment will be con- structed and operated. The transportable trap will supply this second exper- iment with antiprotons. In the new laboratory we will further advance our high-precision studies by applying classical measurement methods in calmer environment and by implementing quantum-logic inspired methods for sym- pathetic cooling and spin-state readout of single trapped antiprotons

Technical Design Report of BASE-STEP

BASE-STEP is a transportable antiproton trap system with the purpose to improve tests of CPT invariance based on antiproton precision measurements. The magnetic field fluctuations in the AD/ELENA facility impose a major limitation in upcoming antiproton CPT invariance tests, and BASE-STEP enables to circumvent these limitations and relocate antiproton precision measurements into a calm magnetic environment. This documents describes the technical design of the BASE-STEP apparatus and its proposed implementation in the AD/ELENA facility

Sympathetic cooling of a trapped proton mediated by an LC circuit

Efficient cooling of trapped charged particles is essential to many fundamental physics experiments, to high-precision metrology and to quantum technology. Until now, sympathetic cooling has required close-range Coulomb interactions, but there has been a sustained desire to bring laser-cooling techniques to particles in macroscopically separated traps, extending quantum control techniques to previously inaccessible particles such as highly charged ions, molecular ions and antimatter. Here we demonstrate sympathetic cooling of a single proton using laser-cooled Be+ ions in spatially separated Penning traps. The traps are connected by a superconducting LC circuit that enables energy exchange over a distance of 9 cm. We also demonstrate the cooling of a resonant mode of a macroscopic LC circuit with laser-cooled ions and sympathetic cooling of an individually trapped proton, reaching temperatures far below the environmental temperature. Notably, as this technique uses only image–current interactions, it can be easily applied to an experiment with antiprotons, facilitating improved precision in matter–antimatter comparisons and dark matter searches

Sympathetic cooling of a trapped proton mediated by an LC circuit

Efficient cooling of trapped charged particles is essential to many fundamental physics experiments, to high-precision metrology and to quantum technology. Until now, sympathetic cooling has required close-range Coulomb interactions, but there has been a sustained desire to bring laser-cooling techniques to particles in macroscopically separated traps, extending quantum control techniques to previously inaccessible particles such as highly charged ions, molecular ions and antimatter. Here we demonstrate sympathetic cooling of a single proton using laser-cooled Be+ ions in spatially separated Penning traps. The traps are connected by a superconducting LC circuit that enables energy exchange over a distance of 9 cm. We also demonstrate the cooling of a resonant mode of a macroscopic LC circuit with laser-cooled ions and sympathetic cooling of an individually trapped proton, reaching temperatures far below the environmental temperature. Notably, as this technique uses only image–current interactions, it can be easily applied to an experiment with antiprotons, facilitating improved precision in matter–antimatter comparisons and dark matter searches