The global environmental crisis (characterized by declines in biodiversity, transboundary pollution, habitat degradation, and climate change) has inspired international environmental regimes, such as ...the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), to establish large‐scale networks of marine protected areas (MPAs) in areas beyond national jurisdiction.
The Southern Ocean surrounding Antarctica comprises roughly 10% of the global ocean and plays a crucial role in regulating global climate and marine ecosystems. Although the Antarctic marine environment currently remains one of the most intact on Earth, it is threatened by fishery expansion and a rapidly changing climate. In response, CCAMLR has been developing a representative network of MPAs to sustain ecosystem structure and function, protect areas vulnerable to human activities, and conserve biodiversity.
Whereas significant research has focused on the role of formal mechanisms and state power in international environmental regimes, very little is known about the role of non‐state actors and informal approaches, particularly in the negotiation of agreements to establish large‐scale networks of MPAs.
Case analysis of the 2016 Ross Sea Region MPA agreement reveals that CCAMLR is undergoing a significant period of learning and institutional evolution, as actors seek novel ways to negotiate a network of Southern Ocean MPAs. Key drivers of consensus include external political dynamics, internal leadership and group dynamics, and shared concern for the future of CCAMLR and Antarctic MPAs.
Actors also rely on informal principles of negotiation (such as increasing transparency, developing trust, and engaging in dialogue) to fill institutional gaps in both CCAMLR's formal structure and the current process for developing and negotiating MPAs.
As environmental threats grow in complexity and scale, non‐state actors and informal negotiations will become increasingly critical to support the ongoing success of formal international institutions dedicated to protecting the ecological integrity and function of the global environment.
Load capacity and recovery behaviour of ALD-coated MCP-PMTs Melikyan, Yu; Sýkora, T.; Komárek, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2020, Letnik:
949
Journal Article
Recenzirano
We report the saturation and recovery properties of ALD-coated MCP-PMTs produced by Hamamatsu Photonics K.K. and Photek Ltd. compared to a non-ALD device produced by Photonis, Inc. Similar study has ...been done previously for ALD-coated Photonis MCP-PMTs. The obtained results confirm that ALD-coated MCP-PMTs produced by any of these manufacturers feature an unexpectedly long time needed for the gain recovery once the saturation was reached (from few minutes up to more than an hour). Despite the saturation level in terms of the average anode current for such devices may reach 0.4 μA/cm2 their use in high load accelerator-based experiments requires additional precaution to avoid driving an MCP-PMT to a saturated mode even for a short time before the start of any data taking period.
We report the results of the measurements of three pieces of the new Photonis miniPLANACON microchannel-plate photomultipliers (MCP-PMTs) intended for use in the demanding environment of the Large ...Hadron Collider (LHC) beamline as a part of the AFP Time-of-Flight detector. These photomultipliers were modified in cooperation with the manufacturer by using a custom backend and were subjected to numerous tests, with the focus on the rate capability and crosstalk behaviour. We determined that the two of them with a lower MCP resistance are able to operate without significant saturation at an anode current density of 1μA/cm2. These two are, therefore, suitable for the intended use and are currently installed as part of the AFP detector packages.
We report here on a set of experiments that focus on measuring the timing performance of the Photonis miniPlanacon XPM85212/A1-S microchannel plate photomultiplier tubes along with the detector ...response at high event rates. The detector has a single photoelectron timing resolution of 30ps at low rates (10kHz). We show that both the gain and the timing start to deteriorate around 1MHz with 20 photoelectrons per channel at 104 target gain, giving the current per unit of area limits of 1.38 μA∕cm2 and 2.38 μA∕cm2 for the two tested devices. Photo-multiplier tubes with lower micro-channel plate resistivity exhibit a better rate capability due to the faster replenishment of the charge inside the microchannels. As we demonstrate, another method to improve the rate capability is to operate the photon detector tubes at a lower gain by reducing the supply voltage and compensating for the loss of amplitude by an additional amplification stage at the expense of the achieved timing resolution. The tube active area over which the beam is spread also plays a role since the same amount of light yields a better rate capability when spread over a larger area. The tubes exposed to high event rates showed an uncharacteristically slow recovery back to its initial gain with 80% of the initial gain recovered only after several tens of minutes.
•Nominal performance up to 1 MHz rates (20 photoelectrons per pulse, 104 gain).•Photomultipliers with lower resistivity can operate at higher rates.•Rate capability can be improved by reducing gain and adding another amplifier stage.•Extremely long time (minutes) to recover gain after exposure to high rates.
In this work we propose the Step Matrix Multiplication based Path Integration method (SMM-PI) for nonlinear vibro-impact oscillator systems. This method allows the efficient and accurate ...deterministic computation of the time-dependent response probability density function by transforming the corresponding Chapman–Kolmogorov equation to a matrix–vector multiplication using high-order numerical time-stepping and interpolation methods. Additionally, the SMM-PI approach yields the computation of the joint probability distribution for response and impact velocity, as well as the time between impacts and other important characteristics. The method is applied to a nonlinear oscillator with a pair of impact barriers, and to a linear oscillator with a single barrier, providing relevant densities and analysing energy accumulation and absorption properties. We validate the results with the help of stochastic Monte-Carlo simulations and show the superior ability of the introduced formulation to compute accurate response statistics.
Summary
An efficient numerical method is presented to analyze the moment stability and stationary behavior of linear stochastic delay differential equations. The method is based on a special kind of ...discretization technique with respect to the past effects. The resulting approximate system is a high dimensional linear discrete stochastic mapping. The convergence properties of the method is demonstrated with the help of the stochastic Hayes equation and the stochastic delayed oscillator.
We present the results of studies devoted to the development and optimization of the optical part of a high precision time-of-flight (TOF) detector for the Large Hadron Collider (LHC). This work was ...motivated by a proposal to use such a detector in conjunction with a silicon detector to tag and measure protons from interactions of the type p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The fast timing detector uses fused silica (quartz) bars that emit Cherenkov radiation as a relativistic particle passes through and the emitted Cherenkov photons are detected by, for instance, a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT). Several possible designs are implemented in Geant4 and studied for timing optimization as a function of the arrival time, and the number of Cherenkov photons reaching the photo-sensor.
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