Micro-pattern Gas Detectors Research Articles

3D printed imaging apertures for MicroPattern gas detector based full field of view X-ray fluorescence spectrometers

Additive Manufacturing, commonly referred as 3D printing, opened a new way to promptly produce cost-effective imaging apertures based on high-density materials, to be used in x-ray imaging systems, such as MicroPattern Gas Detector (MPGD) based Full Field X-ray Fluorescence (FF-XRF) spectrometers. These provide energy and spatially resolved information, allowing the mapping of large area samples. Traditionally, image formation is accomplished with pinhole apertures, devices of easy manufacturing that lead to sub-micrometre position resolution values. However, the sensitivity of the imaging system is severely hampered. To surpass this issue, alternative optical components, such as parallel multi-hole collimators, can be used.In this work, 3D printed multi-hole collimators with different geometries and material compositions are presented and applied to a FF-XRF spectrometer based on the 2D-THCOBRA gas detector. The system's performance parameters with different collimators, namely, relative sensitivity and position resolution, were experimentally determined and compared with the ones obtained with pinhole-based setups. The FF-XRF spectrometer was also simulated, to understand how different collimator geometries affect sensitivity and position resolution.

The state of art of μ-RWELL technology

The μ-RWELL is a single-amplification stage resistive Micro-Pattern Gaseous Detector (MPGD). The detector amplification element is realized with a single copper-clad polyimide foil micro-patterned with a blind hole (well) matrix and embedded in the readout PCB through a thin Diamond-Like-Carbon (DLC) sputtered resistive film. The introduction of the resistive layer, suppressing the transition from streamer to spark, allows to achieve large gains (≥ 104) with a single amplification stage, while partially reducing the capability to stand high particle fluxes. The simplest resistive layout, designed for low-rate applications, is based on a single-resistive layer with edge grounding. At high particle fluxes this layout suffers of a non-uniform response. In order to get rid of such a limitation different current evacuation geometries have been designed. In this work we report the study of the performance of several high rate resistive layouts tested at the CERN H8-SpS and PSI πM1 beam test facilities and with a high intensity 5.9 keV X-ray tube. These layouts fulfill the requirements for the detectors upgrades at the HL-LHC and for the experiments at the next generation colliders FCC-ee/hh and CepC.The possibility to realise the detector on flexible elements opens the way to use the technology for non-planar geometry such as the instrumentation of the Inner Tracker at future Charm-Tau factories. In addition, it must be stressed that the μ-RWELL device can be manufactured with full sequential-build-up technology, thus allowing a straightforward technology transfer of the manufacturing process to the industry.

Ready for LHC Run III: the ATLAS New Small Wheel and the MicroMegas chambers performances

The two New Small Wheels (NSW) for the upgrade of the ATLAS Muon Spectrometer are now installed in the experiment and ready to collect data in LHC Run III, started in July 2022. The NSW is the largest Phase-1 upgrade project of ATLAS. Its challenging completion and readiness for data taking is a remarkable achievement of the Collaboration. The two wheels (10 meters in diameter) replace the first muon stations in the high-rapidity regions of ATLAS and are equipped with multiple layers of two new detector technologies: the small strips Thin Gap Chambers (sTGC) and the MicroMegas (MM). The latter, belong to the family of Micro Pattern Gaseous Detectors (MPGD), for the first time used in such a large scale in HEP experiments. Each detector technology will cover more than 1200 m2 of active area. The new system is designed to assure high tracking efficiency, reduction of fake trigger rates and precision measurement of muon tracks, also in view of the higher background environment foreseen for Hi-Lumi LHC. In this presentation, the motivation of the NSW upgrade and the steps from the commissioning to the data taking together with the first results using the Run III data will be presented, focusing on the MicroMegasperformances.

Development and test of the Micromegas detector prototype and its readout electronics for the AMBER experiment at CERN

Several spectrometer upgrades are planned for future phases of the AMBER (NA66) experiment at CERN. Among these upgrades, the replacement of some aging Multi-Wire Proportional Chambers has motivated a R&D program to develop a Micro-Pattern Gaseous Detector and its front-end electronics. The results of testing the first small Micromegas prototype with the TIGER-based front-end are presented.

Performance study of novel micro-Resistive WELL (μ-RWELL) detector in different gas mixtures

Versatility of micro-pattern gaseous detectors (MPGD) make them suitable for the use in various fields of study, e.g. nuclear physics, particle physics, dark matter physics along with a wide range of medical and security applications. Our primary interest was to implement the novel μ-RWELL (micro-Resistive WELL) detector as the gas amplification stage in TACTIC, a cylindrical active target time projection chamber (TPC) designed to study nuclear reactions with astrophysical significance. In preparation towards their installation inside TACTIC, the performance and characteristics of μ-RWELL were studied in a test chamber, a planar analogue of TACTIC. This work reports the high gas gains achieved in Ar:CH4 and He:CO2 and a study of the charging-up effect in He:CO2.

Observation on the bias current variation of a single mask triple GEM chamber

Gas Electron Multiplier (GEM) detector, one of the advanced members of the Micro Pattern Gas Detector (MPGD) group, is widely used in High Energy Physics (HEP) experiments. The high rate handling capability and spatial resolution make it a desired tracking detector for high rate HEP experiments. Investigation of the long-term stability is an essential criterion for any tracking device used in HEP experiments. To investigate the long-term stability of a Single Mask (SM) triple GEM detector prototype, it is irradiated continuously using a 55Fe X-ray source of energy 5.9 keV. The chamber is operated with Ar/CO2 gas mixture in continuous flow mode. The gain and energy resolution of the chamber are calculated from the 5.9 keV X-ray peak and studied as a function of time. The applied voltage, divider current and also the environmental parameters (ambient temperature, pressure and relative humidity) are recorded continuously. It is observed that at a fixed applied voltage, the divider current of the detector is changing with time and as a result, the gain of the detector also changes. A systematic investigation is carried out to understand the probable reasons behind the observed variation in divider current and also to find its possible remedies. The details of the experimental setup, methodology and results are discussed in this article.

Proportional Counter array (PCa) — a new concept and its realization

In this study, we introduce a new structure of micro-pattern gaseous detector, named proportional counter array (PCa). The standard Printed Circuit Board (PCB) process, which is cost-effective and easy to scale up, is used to manufacture the PCa prototypes. Both simulation and experimental studies were performed to characterise the prototypes, which demonstrated promising performance in terms of gas gain, rate capability, and ion backflow suppression. The prospects of the PCa technology are also discussed.

Study of hybrid micropattern gaseous detector with CsI photocathode for Super Tau-Charm facility RICH

Super τ-Charm facility (STCF) is a future electron-positron collider operating in the τ-Charm energy region with the aim of studying hadron structure and spectroscopy. The baseline design of the STCF barrel particle identification (PID) detector, which covers momentum up to 2 GeV/c, is provided by a Ring Imaging Cherenkov Counter (RICH). The RICH features an approximately focusing design with liquid perfluorohexane sealed in a quartz container as the radiator and a hybrid combination of CsI-coated THGEMs and Micromegas as the photo-electron detector. A 16×16 cm2 prototype with a quartz radiator has been built and tested at DESY and stably operated with an effective gain of 105. In this paper, the design, performance, and reconstruction algorithm of RICH detectors are discussed.

Reducing Ion Backflow with a novel MPGD structure using a bulked micro-mesh on a GEM

Due to their simplicity and accuracy for reconstructing particle trajectories, Micromegas (Micro-MEsh-GAseous Structure) and Gas Electron Multiplier (GEM) detectors are commonly used as readout systems in Time Projection Chambers (TPCs). The main limitation of these two types of detectors is the ion backflow (IBF), which may result in space charge in a TPC. We present in this article a new Micro-Pattern Gaseous Detector (MPGD) structure, which combines a micro-mesh and a set made of a GEM surmounted by a micro-mesh at only a few hundreds μm above. We report the performance results of two prototypes using this new structure, and compare them to a single Micromegas and a hybrid detector composed of a Micromegas and a GEM with a few millimeters gap. Finally, we show that this new detector is capable of reducing the ion backflow to less than 0.2% for a total gain of around 2000.

An automated testing system for the RD51 VMM hybrid and yield measurement of the first production batches

We present the development of an automated testing system for the VMM hybrid of the RD51 collaboration. The VMM hybrid is a new front-end board for the RD51 common readout system, the Scalable Readout System, and will become the workhorse for the next decade to read out Micro-Pattern Gaseous Detectors. It uses the VMM chip developed for the ATLAS New Small Wheel to convert charge signals from detectors to digital data. Our testing system automatically characterises the quality of the VMM chips on the hybrid after production during multiple tests. Results are evaluated to classify the chips and hybrids and uploaded to a database. We evaluated those results for the first two production batches to measure the production yield. The yield is better than the threshold below which chip testing on a wafer level offers financial benefits. Observations on prominent chip failures were propagated back to the hybrid production process to further increase the yield for future productions.

Charging-up effect and uniformity study of a single mask triple GEM detector

The Gas Electron Multiplier (GEM) detector is one of the advanced members of the Micro Pattern Gas Detector (MPGD) family, used in High Energy Physics (HEP) experiments as a tracking device due to its high rate handling capability and good spatial resolution. The uniformity in the performance of the detector is an essential criterion for any tracking device.The presence of the dielectric medium (Kapton) inside the active volume of the GEM chamber changes its behaviour when exposed to external irradiation. This phenomenon is known as the charging-up effect. In this article, the charging-up effect over the entire surface of a Single Mask (SM) triple GEM chamber of dimension 10 cm × 10 cm is reported. The study of uniformity in terms of gain, energy resolution and count rate for the same chamber is also presented before and after the charging-up of the GEM foils.

TPC Development by the LCTPC Collaboration for future Higgs factories

A future Higgs factory will impose demanding requirements on the detectors both in precision and in rate. To study the possibility of a time projection chamber as a central tracking detector at such a facility, the Linear Collider TPC (LCTPC) collaboration was founded in 2007. It is investigating various Micropattern Gaseous Detectors as a readout option for such a detector. A test setup was installed at the test beam area at DESY and many test beams campaigns have been performed since 2010. It was demonstrated that the required spatial resolutions could be reached.

The micro-RWELL detector for the phase-2 upgrade of the LHCb muon system

The micro-RWELL detector (μ-RWELL) is a single amplification stage resistive Micro Pattern Gaseous Detector (MPGD), based on a copper-clad polyimide foil patterned with a micro-well matrix coupled with the readout PCB through a DLC resistive film (10÷100MΩ/□). For the phase-2 upgrade of the LHCb experiment, proposed for the LHC Run-5, the excellent performance of the current muon detector will need to be maintained at 40 times the pile-up level experienced during Run-2. Requirements are challenging for the innermost regions of the muon stations: the detectors should exhibit a rate capability up to 1MHz/cm2 and they are supposed to integrate a charge up to ∼1C/cm2. In this framework an intense optimization program of the micro-RWELL technology has been launched in the last year, together with a technology transfer to the industry operating in the PCB field. In order to fulfill the requirements, a new layout of the detector with a very dense current evacuation grid of the DLC has been designed. The detector, co-produced by the CERN-EP-DT-MPT Workshop, lead by one of the authors, and the ELTOS Company, has been characterized in terms of rate capability exploiting a high intensity X-ray Philips 2217/20 gun with a spot size (10÷50mm diameter) larger than the DLC grounding-pitch. A rate capability exceeding 10MHz/cm2 has been achieved, in agreement with previous results obtained with m.i.p. at the Paul Scherrer Institute (PSI) in Villigen (CH). A long term stability test is in progress: a charge of about 5mC/cm2 has been integrated over a period of about 16 days. The test will continue, in harder conditions (larger gain and X-ray flux), with the goal to integrate about 1C/cm2 in one year, while a slice test of the detector is under preparation.

Upgrade to the focal-plane detector system of the S800 spectrograph at FRIB

The present work describes the ongoing upgrade of the focal-plane detector system and the associated data acquisition system of the large-acceptance S800 magnetic spectrograph. It includes the development of an innovative micro-pattern gaseous detector readout for the tracking system, a novel energy-loss detector concept for Z-identification, and a high resolution optical readout for the timing scintillator detector. The upgraded focal-plane detector system will allow for improved particle identification for heavy-ion beams above Z=100, at higher rate capability (> 25 kHz).

Gain measurements of [formula omitted]RWELLs in 3He-CF4 mixtures for thermal neutron detectors

μRWELLs are one of the latest Micro-Pattern Gas Detectors (MPGD) developed in the high-energy community and are widely used within the RD51 collaboration at CERN. Previously, they had only been tested as neutron detectors with the use of thin layers of boron as the neutron converter. Described here are the first ever measurements done with a μRWELL as a neutron detector using 3He gas as the conversion medium. In particular, gain measurements from a μRWELL operating in 3He gas combined with up to 6 bar of CF4 are presented. Among MPGDs, these operating pressures have previously only been achieved by Micro-Strip Gas Chambers (MSGCs).

Effective Gain and Ion Back Flow study of triple and quadruple GEM detector

Gas electron Multipliers (GEM) are a new generation of gaseous avalanche devices in the Micro Pattern Gaseous Detector (MPGD) category. GEMs are widely used in both nuclear and high energy experiments as well as in medical science. Several parameters define the performance of these types of devices under various experimental conditions. This article focuses on the study of effective gain and Ion Back Flow (IBF) in both triple and quadruple GEM detectors. Effective gain and IBF are two of the most important parameters in determining the performance of GEM detectors.

Development of a high-rate scalable readout system for gaseous detectors

The RD51 collaboration developed the Scalable Readout System (SRS) as part of its R&D activities on Micro-Pattern Gaseous Detectors. This common multi-purpose readout system allows to read out small R&D detectors (0.2k channels) up to mid-sized experiments with multiple detectors (2.5k to 5k channels). To cope with increased demands on detectors, electronics and readout speed, a new front-end ASIC—the VMM3a—was integrated into the SRS. This led to the development of a scalable, self-triggered high-rate readout system that provides energy, space and time information of the interacting particles at the same time.

Test-beam and simulation studies towards RPWELL-based DHCAL

Digital Hadronic Calorimeters (DHCAL) were suggested for future Colliders as part of the particle-flow concept. Though studied mainly with RPC, studies focusing on sampling elements based on Micro-Pattern Gaseous Detector have shown the potential advantages; they can be operated with environment-friendly gases and reach similar detection efficiency at lower average pad multiplicity. We summarize here the experimental test-beam results of a small-size DHCAL prototype, incorporating six Micromegas and two RPWELL sampling elements, interlaced with steel-absorber plates. It was investigated with 2–6 GeV pion beams at the CERN/PS beam facility. The data permitted validating a GEANT4 simulation framework of a DHCAL, and evaluating the expected pion energy resolution of a full-scale RPWELL-based calorimeter. The pion energy resolution derived for the RPWELL concept is competitive to that of glass RPC and Micromegas sampling techniques.

Muon detector for a Muon Collider

A Muon Collider represents a promising possibility to combine the high energy and luminosity of hadron machines with very precise measurements of lepton colliders. The main challenges, that impact both the machine and detector design, arise from the short muon lifetime and the harsh Beam-induced Background (BIB).Therefore, a full simulation is crucial to understand the feasibility of the experiment implementation. Focusing in particular on the muon system, a preliminary simulation of sensitivity and hit rate reveals that the technology inherited from CLIC, i.e. glass Resistive Plate Chambers, is already at the limit of its rate capability. Thus, alternative MicroPattern Gaseous Detector solutions are under investigation to try to match the required performance. In parallel, studies of muon reconstruction are ongoing.Results of the muon reconstruction efficiency and BIB sensitivity are presented for multimuon final state processes at a centre-of-mass energy of 1.5TeV. Besides, PICOSEC technology, based on a Micromegas detector coupled to a Cherenkov radiator and equipped with a photocathode, is discussed.

Design and simulation of a MPGD-based hadronic calorimeter for Muon Collider

The project of a Multi-TeV Muon Collider represents a unique opportunity to explore the high energy physics frontier and to measure with high precision the Higgs coupling with the other particles of the Standard Model as well as the trilinear and quadrilinear Higgs self-coupling, leading to a precise determination of the Higgs potential, in order to confirm the theoretical predictions of the SM and possibly to find evidences for new physics. One of the major challenges for the design and optimization of the technologies suitable for a Muon Collider experiment is represented by the high background induced by the decay of the muons coming from the beam. This contribution present the design of an innovative MPGD-based hadronic calorimeter (HCAL). The detector consists of a sampling calorimeter exploiting the Micro Pattern Gas Detectors (MPGDs) as active layers: MPGDs offer a fast and robust technology for high radiation environments and a high granularity for precise spatial measurements. Moreover, the detector is designed to optimize the jet reconstruction and for background suppression. The calorimeter is simulated using the Geant4 toolkit to support the detector R&D. The detector design and layout optimization supported by the simulation is described.