Small-pads resistive Micromegas prototype

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. © 2019 Elsevier B.V

Pixelated resistive bulk micromegas for tracking systems in high rate environment

One of the main objectives within the community of the Micro-Pattern-Gaseous-Detectors (MPGD) is the design of new detectors for operation with a very high particle flow. This research path is driven mainly by future upgrades of existing experiments at high-luminosity LHC or next generation accelerators where gaseous detectors will be operated at rates up to few MHz/cm2, three orders of magnitude higher than nowadays. The goal of our R&D project, started few years ago, is to develop a new generation of single amplification stage resistive MPGD based on Micromegas technology with the following characteristics: Stable and efficient operation up to particle fluxes of 10 MHz/cm2; high granularity readout, with pixels of order mm2 and fully integrated electronics; reliable and cost-effective production process. We present here the development status of our small-pads resistive Micromegas prototypes, focusing on the optimization of the spark protection resistive layer. Characterization and performance studies of the prototypes have been carried out by means of radioactive sources, X-Rays and test beams. A comparison of the performance obtained with the different resistive layout realized until now is presented, studying in particular the response under high rate irradiation. © 2020 IOP Publishing Ltd and Sissa Medialab

The role of CD44+/CD24-/low biomarker for screening, diagnosis and monitoring of breast cancer

Cancer stem cells (CSCs) have been defined as 'a cell within a tumor that possesses the capacity to self-renew and to cause the heterogeneous lineages of cancer cells that comprise the tumor'. The CSC hypothesis postulates that a small subpopulation of cancer cells drives tumor initiation, growth and metastasis. CSCs have been isolated from breast cancer using CD44+/CD24-/low phenotype. The purpose of the present study was to evaluate the expression of CD44+/CD24-/low in two diverse breast carcinomas (ductal and lobular), and to determine the correlation between expression of CD44+/CD24-/low, and clinicopathological characteristics starting from human fresh breast cancer specimens. We analyzed specimens from 57 patients using CD44 and CD24 markers by flow cytometry and immunohistochemistry and correlated the CD44+/CD24-/low phenotype with clinicopathological characteristics. Moreover, mammosphere formation was tested. In all specimens tested, CD44+/CD24-/low phenotype was detectable with mean percentage of 4.73% as confirmed also by immunohistochemical analyses. A significant statistical association was found among these phenotypic groups and age, grade G3, estrogen and progesterone receptor, Ki-67 as well as lymph node metastasis. No correlation was found for histological type. In conclusion, our data showed that CD44+/CD24-/low phenotype was found at a high frequency in tumors pT2, G3, pN3, positive for Ki-67, and negative for estrogen and progesterone receptors highlighting the hypothesis that CD44+/CD24-/low profile correlates with the more aggressive clinical-pathological features of the disease

Rate capability and stability studies on small-Pad resistive Micromegas

Micromegas are among the most promising micro pattern gaseous detector (MPGD) technologies for applications in high energy physics (HEP). Micromegas are very versatile. They can be used for precision tracking and trigger, in particle flow sampling calorimetry, as anode planes for RICH detectors or for time projection chambers. Driven mainly by future upgrades of existing experiments at high-luminosity LHC (HL-LHC) and for applications at future accelerators, we started an R&D; project to push further this technology for operations under very high particle flow up to rates of tens MHz/cm$^{2}$, three orders of magnitude higher than current applications. The miniaturization of the readout elements and the optimization of the spark protection system, as well as the stability and robustness under operation, are the primary challenges of the project

Small-pad Resistive Micromegas: Comparison of patterned embedded resistors and DLC based spark protection systems

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. © 2020 Published under licence by IOP Publishing Ltd

Small-Pad Resistive Micromegas: Rate capability for different spark protection resistive schemes

Started few years ago, the goal of this R&D project is to develop a new generation of single amplification stage resistive MPGD based on Micromegas technology with the following characteristics: stable and efficient operation up to 10 MHz/cm2 particle flows; high granularity readout with small pads of the order of mm2; reliable and cost-effective production process. The miniaturization of the readout elements and the optimization of the spark protection system, as well as the stability and robustness under operation, are the primary challenges of the project. Several Micromegas detectors have been built with similar anode planes, segmented with a matrix of 48 × 16 readout pads with a rectangular shape (0.8 × 2.8 mm2) and with a pitch of 1 and 3 mm in the two coordinates. The active surface is 4.8 × 4.8 cm2 with a total number of 768 channels, routed off-detector for readout. With this anode/readout layout, the spark protection resistive layer has been realized with two different techniques: a pad-patterned embedded resistor with screen printing, and a uniform DLC (Diamond Like Carbon structure) layer by sputtering. For each technique different configurations and resistivity values have been adopted. For the DLC series, the most recently built prototype exploits the availability of copper clad DLC foils to improve the construction. Characterization 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 layout and different configurations are presented, in particular focusing on the response under high irradiation and high rate exposure. © 2020 IOP Publishing Ltd and Sissa Medialab

High rate performance of small-pad resistive micromegas. Comparison of different resistive protection concepts

Motivated mainly by future detector upgrades at HL-LHC and at future colliders, most of the HEP R&D collaborations have been focusing on the design of new prototypes of particle detectors for operation under very high particle flow. In the field of Micro-Pattern-Gaseous-Detectors, the Small-pad resistive MICROMEGAS prototypes were designed to overcome the actual limitations of more standard strip resistive MICROMEGAS. In these new prototypes, small pads with a few mm2 area replace the readout strips to reduce the occupancy, and the spark protection resistive layer has been redesigned and optimized with different techniques to permit a safe behaviour of the detector, without efficiency loss, at rates of the order of MHz/cm2 over large surfaces. The firstly-developed design exploits a pad-patterned (PAD-P) embedded resistor layout by screen-printing while the most recent technique involves uniform sputtered DLC (Diamond Like Carbon structure) layers, where the current evacuates through vias to ground. Comparative studies have been conducted on the performances of the prototypes with different resistive layouts or different values of DLC resistivity and vias pitch. The preliminary results of the tests done with high-rate X-rays and with high energy charged particle beams will be presented. © Owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0)

High rate performance of Small-pad Resistive Micromegas. Comparison of different resistive protection concepts.

Motivated mainly by future detector upgrades at HL-LHC and at future colliders, mostof the HEP R&D; collaborations have been focusing on the design of new prototypes ofparticle detectors for operation under very high particle flow. In the field of Micro-Pattern-Gaseous-Detectors, the Small-pad resistive MICROMEGAS prototypes were designed toovercome the actual limitations of more standard strip resistive MICROMEGAS. In thesenew prototypes, small pads with a few mm$^{2}$ area replace the readout strips to reduce theoccupancy, and the spark protection resistive layer has been redesigned and optimizedwith different techniques to permit a safe behaviour of the detector, without efficiencyloss, at rates of the order of MHz/cm$^{2}$ over large surfaces. The firstly-developed designexploits a pad-patterned (PAD-P) embedded resistor layout by screen-printing while themost recent technique involves uniform sputtered DLC (Diamond Like Carbon structure)layers, where the current evacuates through vias to ground. Comparative studies havebeen conducted on the performances of the prototypes with different resistive layouts ordifferent values of DLC resistivity and vias pitch. The preliminary results of the tests donewith high-rate X-rays and with high energy charged particle beams will be presented