We report comprehensive, demonstrably contaminant‐free measurements of binary particle formation rates by sulfuric acid and water for neutral and ion‐induced pathways conducted in the European ...Organization for Nuclear Research Cosmics Leaving Outdoor Droplets chamber. The recently developed Atmospheric Pressure interface‐time of flight‐mass spectrometer was used to detect contaminants in charged clusters and to identify runs free of any contaminants. Four parameters were varied to cover ambient conditions: sulfuric acid concentration (105 to 109 mol cm−3), relative humidity (11% to 58%), temperature (207 K to 299 K), and total ion concentration (0 to 6800 ions cm−3). Formation rates were directly measured with novel instruments at sizes close to the critical cluster size (mobility size of 1.3 nm to 3.2 nm). We compare our results with predictions from Classical Nucleation Theory normalized by Quantum Chemical calculation (QC‐normalized CNT), which is described in a companion paper. The formation rates predicted by the QC‐normalized CNT were extended from critical cluster sizes to measured sizes using the UHMA2 sectional particle microphysics model. Our results show, for the first time, good agreement between predicted and measured particle formation rates for the binary (neutral and ion‐induced) sulfuric acid‐water system. Formation rates increase with RH, sulfuric acid, and ion concentrations and decrease with temperature at fixed RH and sulfuric acid concentration. Under atmospheric conditions, neutral particle formation dominates at low temperatures, while ion‐induced particle formation dominates at higher temperatures. The good agreement between the theory and our comprehensive data set gives confidence in using the QC‐normalized CNT as a powerful tool to study neutral and ion‐induced binary particle formation in atmospheric modeling.
Key Points
Atmospheric binary particle formation can be both kinetic and nucleation type
Both ion‐induced and neutral pathways are strong at free‐tropospheric conditions
Ion‐induced pathway dominates at midtroposphere, neutral at upper troposphere
A new design of a detector plane of sub-millimetre thickness for an electromagnetic sampling calorimeter is presented. It is intended to be used in the luminometers LumiCal and BeamCal in future ...linear e
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collider experiments. The detector planes were produced utilising novel connectivity scheme technologies. They were installed in a compact prototype of the calorimeter and tested at DESY with an electron beam of energy 1–5 GeV. The performance of a prototype of a compact LumiCal comprising eight detector planes was studied. The effective Molière radius at 5 GeV was determined to be (8.1 ± 0.1 (stat) ± 0.3 (syst)) mm, a value well reproduced by the Monte Carlo (MC) simulation (8.4 ± 0.1) mm. The dependence of the effective Molière radius on the electron energy in the range 1–5 GeV was also studied. Good agreement was obtained between data and MC simulation.
A prototype of a luminometer, designed for a future
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collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this ...beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Molière radius has been determined to be 24.0 ± 0.6 (stat.) ± 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.
The radiation-induced Bragg wavelength shift (BWS) was measured with type I gratings made of 12 fibers with very different composition, i.e., of fibers with an extremely different radiation-induced ...attenuation. With two of the fibers fabrication parameters like laser intensity, hydrogen loading, and annealing conditions after grating inscription were varied. With another fiber type I and type II gratings were made by a completely different process. With gratings made under identical conditions of the 12 fibers the radiation-induced BWS only varied by about a factor of three. Varying the fabrication parameters led to BWS differences up to nearly a factor of ten.
The Fast Beam Conditions Monitor, BCM1F, in the Compact Muon Solenoid, CMS, experiment was operated since 2008 and delivered invaluable information on the machine induced background in the inner part ...of the CMS detector supporting a safe operation of the inner tracker and high quality data. Due to the shortening of the time between two bunch crossings from 50 ns to 25 ns and higher expected luminosity at the Large Hadron Collider, LHC, in 2015, BCM1F needed an upgrade to higher bandwidth. In addition, BCM1F is used as an on-line luminometer operated independently of CMS. To match these requirements, the number of single crystal diamond sensors was enhanced from 8 to 24. Each sensor is subdivided into two pads, leading to 48 readout channels. Dedicated fast front-end ASICs were developed in 130 nm technology, and the back-end electronics is completely upgraded. An assembled prototype BCM1F detector comprising sensors, a fast front-end ASIC and optical analog readout was studied in a 5 GeV electron beam at the DESY-II accelerator. Results on the performance are given.
Fibre optic radiation sensor systems for particle accelerators Henschel, H.; Körfer, M.; Kuhnhenn, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2004, Letnik:
526, Številka:
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Journal Article
Recenzirano
Two different fibre optic dosimeter systems based on the radiation-induced increase of fibre attenuation are presented. The systems allow on-line measurement of the accumulated dose along accelerator ...beam lines (“distributed” sensor) as well as at fixed positions in selected accelerator sections (local sensors). Fibre properties, system layout and results of measurements obtained during operation of the TESLA
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Tera Electron Volt Energy Superconducting Linear Accelerator.
Test Facility (TTF) at DESY Hamburg are described.
Trophy hunting is widely used in Africa to generate funding for wildlife areas. In 2015, a global media frenzy resulted from the illegal killing of a radio‐collared lion, “Cecil,” by a trophy hunter ...in Zimbabwe. Trophy hunting is contentious and much of the media discourse is emotional and polarized, focusing on animal welfare and debating the value of hunting as a conservation tool. We use the Cecil incident to urge a change in the focus of discussion and make a call for global action. We highlight the dual challenge to African governments posed by the need to fund vast wildlife estates and provide incentives for conservation by communities in the context of growing human populations and competing priorities. With or without trophy hunting, Africa's wildlife areas require much more funding to prevent serious biodiversity loss. In light of this, we urge a shift away from perpetual debates over trophy hunting to the more pressing question of “How do we fund Africa's wildlife areas adequately?” We urge the international community to greatly increase funding and technical support for Africa's wildlife estate. Concurrently, we encourage African governments and hunters to take decisive steps to reform hunting industries and address challenges associated with that revenue generating option.
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