Simulation of the dielectric charging-up effect in a GEM detector Alfonsi, M.; Croci, G.; Duarte Pinto, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2012, Letnik:
671
Journal Article
Recenzirano
Odprti dostop
The charging up effect is well-known in detectors containing dielectric materials and it is due to electrons and ions liberated in an avalanche and collected on the dielectric surfaces. In particular ...in Gas Electron Multiplier (GEM) based detectors, charges can be captured by the Kapton that separates top and bottom electrodes. The collection of a substantial number of charges on the dielectric surfaces induces a modification of the field inside the GEM holes that implies important consequences on some fundamental parameters such as the electron transparency and the effective gain. The correct simulation of this effect opens new ways to the detailed study of the processes that happens in a GEM-based detector and gives the possibility to optimise the GEM geometry in order to avoid it. This paper compares results of the measurements and the simulations, with and without the introduction of the charging-up effect, of the GEM electron transparency in the case of a single GEM detector. The introduction of the charging up effect in the simulation resulted to be crucial in order to get the proper agreement with the measurements. The measurements and simulations of the GEM effective gain will be the subject of a future work.
A pepperpot emittance meter was used to measure the transverse emittance of multiply charged beams from REXEBIS, an Electron Beam Ion Source (EBIS) used for charge breeding of radioactive ion beams. ...The emittance meter is equipped with a Micro Channel Plate (MCP), a phosphor screen and a CCD camera for detection of the ion signal. The pulsed beam structure of low duty cycle imposes challenging constraints on the detector settings. In this article we give a careful analysis of the optimal operating parameters of the pepperpot emittance meter for ion beams of varying intensities. Emittance values for mass-separated and non-separated beams for different operating modes of the EBIS are presented. Furthermore we report on aberrations created in our injection∕extraction system.
ABSTRACT The development of the Internet and the technologies associated with it has allowed disseminating and cheapening of communication equipment, prototyping services, electronic sensors, and all ...types of devices. Agriculture has benefited from these technological advances to boost its productivity and profitability. This study presents the development of a data acquisition and device control platform to obtain, in real-time and remotely, information from the field for decision-making and process automation. All electronic components are low-cost and “open hardware”, and the software is “open-source”. The developed platform was validated during a development cycle of two lettuce varieties (Japanese and crisp), in which the soil water matric potential was monitored at two depths (10 and 25 cm), while solar irradiation, air temperature, and soil temperature were evaluated only to monitor the cycle. The platform automatically and satisfactorily controlled the applied irrigation depths using only the data of matric potential by activating a solenoid valve and made the information from the sensors available on the ThingSpeak Internet of Things (IoT) platform.
Aim
Macroalgal habitats are believed to be the most extensive and productive of all coastal vegetated ecosystems. In stark contrast to the growing attention on their contribution to carbon export and ...sequestration, understanding of their global extent and production is limited and these have remained poorly assessed for decades. Here we report a first data‐driven assessment of the global extent and production of macroalgal habitats based on modelled and observed distributions and net primary production (NPP) across habitat types.
Location
Global coastal ocean.
Time period
Contemporary.
Major taxa studied
Macroalgae.
Methods
Here we apply a comprehensive niche model to generate an improved global map of potential macroalgal distribution, constrained by incident light on the seafloor and substrate type. We compiled areal net primary production (NPP) rates across macroalgal habitats from the literature and combined this with our estimates of the global extent of these habitats to calculate global macroalgal NPP.
Results
We show that macroalgal forests are a major biome with a global area of 6.06–7.22 million km2, dominated by red algae, and NPP of 1.32 Pg C/year, dominated by brown algae.
Main conclusions
The global macroalgal biome is comparable, in area and NPP, to the Amazon forest, but is globally distributed as a thin strip around shorelines. Macroalgae are expanding in polar, subpolar and tropical areas, where their potential extent is also largest, likely increasing the overall contribution of algal forests to global carbon sequestration.
Both diarrhea in calves and mastitis in cows limit cattle production. The bacteria involved in these diseases have shown multi-resistance to antimicrobials, however plant metabolites therefore can ...provide an alternative method of control. This study selected and characterized Cerrado plant extracts showing inhibitory effects against Escherichia coli and Staphylococcus spp. from cattle. Thirteen leaf extracts were initially screened and diameters of inhibition zones produced against the pathogens were recorded using an agar disk diffusion method. Total condensed tannin contents were determined and antibacterial activities were analyzed after tannin removal from the five selected extracts. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were evaluated by macro-dilution antimicrobial susceptibility tests, and the extracts were characterized by high performance liquid chromatography.
Inter- and intra-specific bacterial variations in the susceptibility to the extracts were detected. The aqueous extract (AE) from Caryocar brasiliense Cambess. leaves produced larger inhibition zones against E. coli strains than did other selected extracts. However, the AE from Schinopsis brasiliensis was the most effective against Staphylococcus spp. strains (P < 0.001). The MIC of ethanolic extracts (EE) from C. brasiliense (0.27 mg/mL) and S. brasiliensis (0.17 mg/mL) were lower than those of other extracts. The MIC and MBC of the Annona crassiflora EE were 6.24 mg/mL for all bacteria. Flavonoids were the main metabolites detected in the A. crassiflora EE as well as in the AE and EE from C. brasiliense, while tannins were the main metabolites in the S. brasiliensis leaf extracts.
The AE from C. brasiliense was more effective against Gram-negative bacteria, while the AE from S. brasiliensis was more effective against Gram-positive bacteria. A. crassiflora EE and S. brasiliensis extracts are potent bactericide. After removal of the tannins, no antimicrobial effects were observed, indicating that these metabolites are the main active antibacterial components.
THGEM based photon detector for Cherenkov imaging applications Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
We are developing a single photon detector for Cherenkov imaging counters. This detector is based on the use of THGEM electron multipliers in a multilayer design. The major goals of our project are ...ion feedback suppression down to a few per cent, large gain, fast response, insensitivity to magnetic fields, and a large detector size.
We report about the project status and perspectives. In particular, we present a systematic study of the THGEM response as a function of geometrical parameters, production techniques and the gas mixture composition. The first figures obtained from measuring the response of a CsI coated THGEM to single photons are presented.
Micropattern gaseous photon detectors for Cherenkov imaging counters Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
Recenzirano
We are developing a detector of single photons for application in Cherenkov imaging counters, based on the use of a multilayer architecture of THGEM electron multipliers coupled to a solid state CsI ...photocathode. The main goals of our project are ion feedback suppression down to a few per cent level, large gain, fast response, good time resolution, insensitivity to magnetic field and large detector size. We report about the project status and perspectives.
Activity of CERN and LNF groups on large area GEM detectors Alfonsi, M.; Bencivenni, G.; Brock, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report on the activity of CERN and INFN-LNF groups on the development of large area GEM detectors. The two groups work together within the RD51 Collaboration, to aim at the development of ...Micro-pattern Gas detectors technologies. The vast request for large area foils by the GEM community has driven a change in the manufacturing procedure by the TS-DEM-PMT laboratory, needed to overcome the previous size limitation of
450
×
450
mm
2
. Now a single-mask technology is used allowing foils to be made as large as
450
×
2000
mm
2
. The limitation in the short size, due to the definite width of the raw material, can be overcome by splicing more foils together. A
10
×
10
cm
2
GEM detector with the new single-mask foil has been tested with X-rays and the results are shown. Possible future applications for large area GEM are the TOTEM experiment upgrade at CERN, and the KLOE-2 experiment at the Dafne
Φ
-factory in Frascati.
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