Pixelated resistive Micromegas detector for high-rate environment Alviggi, M.; Camerlingo, M.T.; Pietra, M. Della ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Letnik:
1041
Journal Article
Recenzirano
The R&D work reported in this paper has been devoted to the production and test of pixelated resistive micromegas detectors able to track particles in a high-rate environment, up to 10MHz/cm2, ...keeping a stable gain and a good spatial resolution. To pursue our goal, we had to reduce the occupancy by increasing the detector granularity and this has been done by changing the read-out anodes from the usual strips to pads. This minor change in the electrodes layout drastically increased the difficulty of implementing a resistive structure to protect the anodes from sparking. We present the results of the tests performed on four prototypes, with different protection schemes, showing it is possible to reach the desired rate with high gain, high efficiency and good position resolution. The response to X-rays from low (55Fe source) to high (X-rays generator) rates, as well as to beams of ionizing particles is reported.
High granularity small-pad resistive micromegas for rates above MHz/cm2 Alviggi, M.; Camerlingo, M.T.; D’Amico, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
March 2023, Letnik:
1048
Journal Article
Recenzirano
An R&D project has been recently started to consolidate the technology of resistive Micromegas for operations well beyond the actual operations at HEP experiments, aiming at stable, reliable, and ...high gain operation up to particle fluxes of the order of 10 MHz/cm2, over large surfaces.
To cope with these challenges, readout copper pads, of a few mm2 size, have been proposed to reduce the occupancy of the readout elements, calling for innovative solutions for the spark protection resistive scheme. It is known that single stage amplification Micro Pattern Gaseous Detectors suffer from sparks when operated under harsh environments. Resistive anodes drastically mitigate the spark intensities but, on the other hand, they reduce the rate capability when high currents flow into the detectors, generating a drop in the amplification voltage. Ad-hoc solutions must be adopted.
Two resistive schemes have been studied. The first one is based on a pad-patterned resistive double layer, superimposed to the readout pads, with an embedded resistor connecting the resistive pads. In this scheme, each pad is independent from the others. The second scheme exploits the recently developed Diamond-Like Carbon (DLC) resistive foils. A double layer of DLC is superimposed to the readout pads, with a grid of interconnecting vias to ground for a fast evacuation of the accumulated charge. In this case the pads are not completely independent since the charge can spread over more pads. For each of these resistive schemes, detectors with different configurations and construction techniques have been built.
All detectors have been thoroughly tested and fully characterized with radioactive sources, X-rays and with test beams carried out at CERN in 2021. The performance and achievements in terms of gains, rate capabilities, energy, space and time resolutions will be reported, along with a detailed comparison among the different schemes and configurations.
We present the development of resistive Micromegas aiming at operation under high rates, up to tens MHz/cm2, focusing on the optimisation of the spark protection resistive layer and the ...miniaturisation of the readout elements. Several Micromegas detectors have been built with an anode plane matrix of 48x16 rectangular readout pads, each pad 0.8x2.8 mm2. The detectors differ for the spark protection resistive schemes being realised with the following techniques: a pad-patterned embedded resistor by screen printing, and uniform DLC (Diamond Like Carbon structure) layers. Characterisation and performance studies of the detectors have been carried out by means of radioactive sources, X-Rays, and test beam. A comparison of the performance obtained with the different resistive layouts is presented, in particular focusing on the response under high irradiation and high rate exposure.
This work has the difficult task to deeply study the electrochemical processes that occur inside a 100 cm2 of Molten Carbonate Fuel Cells (MCFC) impedance spectra using the high resolution of ...Distribution of Relaxation Time (DRT) method. Using this method, it is possible to shed light on the different physicochemical processes occurring within these cells, identifying the characteristic relaxation times by means of an appropriate experimental campaign where temperature and gas compositions in anode and cathode were varied one at a time. The quality of the recorded spectra was verified by Kramers-Kronig relation before applying DRT calculations. In this work, five distinct and separated peaks with different time constants ranging from 0.01 to 500 Hz were identified and associated with physiochemical processes of the cell. Three peaks at high frequency represent the charge transfer processes in anode and cathode active sites. The other two, located at low frequency, are associated with the gas diffusion in the electrodes and to the gas conversion process. This study represents the first application of the DRT approach to this technology allowing to understand the physicochemical origin of the individual polarization processes controlling the cell performance and the degradation. The analysis of degradation processes using the DRT method and the physiochemical processes identification presented in this paper will be shown in part II of this work.
•The first application of DRT approach to MCFC impedance Spectra is presented.•Five processes controlling the cell performance are individuated using DRT method.•Repeatability and reproducibility of the DRT results in MCFCs are demonstrated.•Three peaks with a high-frequency domain are related to Charge Transfer Processes.•Two peaks with a low-frequency domain are associated with Mass Transfer Mechanisms.
Small-pads resistive Micromegas prototype Di Donato, C.; Alviggi, M.; Camerlingo, M.T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
Journal Article
Recenzirano
Detectors at future accelerators will require operation at rates up to three orders of magnitude higher than 15 kHz/cm2 the hit rates expected in the current upgrades forward muon detectors of LHC ...experiments. A resistive Micromegas detectors with modified readout system can achieve rate capability up to few MHz/cm2 low occupancy. We present the development of small-pad Micromegas detectors with a pad resistive readout of few mm2 in size, built with the spark protection resistive layer realized with different techniques.
We present the development of resistive Micromegas with small pad readout aiming at precision tracking without efficiency loss up to several MHz/cm2. Several prototypes have been built with the spark ...protection resistive layer deposited with different techniques: a pad-patterned embedded resistor layout with screen printing, and a uniform layer by sputtering (Diamond Like Carbon structure). All detectors consist of a matrix of 48 × 16 rectangular shaped pads with a pitch of (1 × 3) mm2. The active surface is (48 × 48) mm2 with a total number of 768 channels, routed off-detector for readout. Characterization and performance studies of all prototypes have been carried out by means of radioactive sources, X-rays, cosmic rays and high energy particle beams. A comparison of prototypes with different resistivity layout will be presented.
One of the biggest unresolved issues for fuel cells is to define a procedure to accelerate degradation phenomena occurring inside the cells in such a way as to obtain meaningful long-term results and ...information about the behaviour of the system in a shorter time. To define an accelerated testing protocol, a lot of different parameters have to be considered, all of them strongly dependent each other and concurring to determine the end of life of a fuel cell.
A preliminary literature review of the majors degradation phenomena was assessed to better understand the correlation of degradation mechanisms, occurring inside MCFCs, cell components and operative parameters, pointing out that electrolyte loss is the only degradation mechanism connected with all the operative parameters.
The aim of this work is to carry out a deep study of the electrolyte evaporation in a Molten Carbonate Fuel Cell (MCFC) and by this mechanism to evaluate the possibilities for inducing controlled acceleration of superimposed degradation phenomena, for this reason at the end of this experimental campaign, the effect of sulphur dioxide poisoning was evaluated, making possible a direct comparison between degradation coming from electrolyte loss and degradation coming from sulphur dioxide poisoning.
The first interpretation of long term tests carried out with MCFC button cells (3 cm2) will be presented in the attempt to better understand how evaporation loss takes place and could be accelerated.
•Voltage loss depending by electrolyte evaporation has been quantified.•Effectiveness of electrolyte refill was proved.•The separation of the effects due to two different degradation mechanisms has been approached.
PDF
