Stable Detector Research Articles

Steady-State Inverse-Temperature Crystallization Enabling Low Defect Perovskite Single Crystal and Efficient X-Ray Detectors.

Organic-inorganic halide perovskite single crystals (SCs) have shown great potential in radiation detection applications due to their large radiation stopping power and excellent carrier transport properties. The spatial-confined inverse-temperature crystallization (ITC) method has been widely adopted to obtain large-sized SCs. However, they usually face the problems of uneven stress distribution and high defect density due to the limited crystal growth space and varied growth rate with the increase in temperature, making it difficult to fabricate highly sensitive and stable radiation detectors. In this study, the steady-state inverse-temperature crystallization method (SS-ITC) is developed to regulate the growth process of SCs by controlling the growth speed precisely to achieve a constant rate of growth as the temperature increases. Compared with the conventional ITC-grown samples, the lattice spacing of SCs prepared by the SS-ITC method is reduced by 1.2% due to tensile stress relaxation, resulting in a lower defect density of 7.93×109cm-3 and a remarkable uniformity over a large area. As a result, the co-planar X-ray detectors based on these high-quality SCs exhibit a high sensitivity of 1.67×105 µC Gyair -1cm-2, representing the best performing MAPbBr3-based X-ray detectors reported to date.

Bottom-up construction of low-dimensional perovskite thick films for high-performance X-ray detection and imaging

Quasi-two-dimensional (Q-2D) perovskite exhibits exceptional photoelectric properties and demonstrates reduced ion migration compared to 3D perovskite, making it a promising material for the fabrication of highly sensitive and stable X-ray detectors. However, achieving high-quality perovskite films with sufficient thickness for efficient X-ray absorption remains challenging. Herein, we present a novel approach to regulate the growth of Q-2D perovskite crystals in a mixed atmosphere comprising methylamine (CH3NH2, MA) and ammonia (NH3), resulting in the successful fabrication of high-quality films with a thickness of hundreds of micrometers. Subsequently, we build a heterojunction X-ray detector by incorporating the perovskite layer with titanium dioxide (TiO2). The precise regulation of perovskite crystal growth and the meticulous design of the device structure synergistically enhance the resistivity and carrier transport properties of the X-ray detector, resulting in an ultrahigh sensitivity (29721.4 μC Gyair−1 cm−2) for low-dimensional perovskite X-ray detectors and a low detection limit of 20.9 nGyair s−1. We have further demonstrated a flat panel X-ray imager (FPXI) showing a high spatial resolution of 3.6 lp mm−1 and outstanding X-ray imaging capability under low X-ray doses. This work presents an effective methodology for achieving high-performance Q-2D perovskite FPXIs that holds great promise for various applications in imaging technology.

Mitigation of Parasitic and Drift Capacitance-Induced Nonlinear Current Responses for Stable and Sensitive Perovskite X-ray Detectors.

The development of perovskite direct X-ray detectors shows potential for advancing medical imaging and industrial inspection precision. To ensure the optimal energy conversion efficiency of X-rays for reducing radiation doses, it is necessary for perovskites with thicknesses reaching hundreds of micrometers or even several millimeters to be utilized. However, the nonlinear current response becomes uncertain with such high thicknesses. For instance, the prevailing theory regarding the rapid trapping and release of charges by shallow-level defects falls short in explaining the nonlinear current response observed in high-quality single-crystal samples. Moreover, a significant nonlinear current response can degrade the detection performance. Here, we elucidate peculiar parasitic and drift capacitance-induced nonlinear current responses in perovskites, which arise from bulk structural deficiencies and interface junction width variation in addition to shallow-level defects. Both theoretical analysis and experimental findings demonstrate the effective suppression of nonlinear current responses by establishing bulk heterojunctions and refining interface junctions. Consequently, we have successfully developed highly linear current-responsive detectors based on polycrystalline MAPbI3 thick films. Notably, these detectors achieve a record sensitivity of 2.3 × 104 μC·Gyair-1·cm-2 under 100 kVp X-ray irradiation with a low bias of 0.1 V/μm, enabling enduring and high-resolution X-ray imaging for high-density objects. Successful fabrication and testing of a 64 × 64-pixel flat-panel prototype detector affirm the widespread applicability of these strategies in rectifying nonlinear current responses in perovskite-based X-ray detectors.

Stable Ga2O3 soft x-ray detector with ultrahigh responsivity

Soft x-ray detectors play crucial roles in biology, chemistry, and lithography. Current soft x-ray detectors suffer from insufficient responsivity (R), excessively large cell area, and limited stability. Here, the β-Ga2O3 soft x-ray detector is constructed, and the effects of varying the sensitive layer thickness and voltage on the soft x-ray detection characteristics of the device are explored. Meanwhile, the mechanism of the multiplication ionization process from soft x-ray and the photoconductivity gain on the photoresponse performance of the device are analyzed. The device obtains the R up to 3.05 × 103 A/W under 300 eV soft x-ray irradiation at the synchrotron beamline, which is about 1.19 × 104 times higher than that of the conventional device. The Ga2O3 device also maintains stable operation under long-term irradiation and multicycle switching. These results indicate that Ga2O3 is an ideal candidate material for soft x-ray detection, which has great potential for applications such as imaging of biological cells.

High-Performance Flat-Panel Perovskite X-ray Detectors Enabled by Defect Passivation in Ruddlesden-Popper Perovskites.

Halide perovskites have emerged as promising candidates in X-ray detection due to their strong X-ray absorption and excellent optoelectronic properties. The development of sensitive and stable flat-panel X-ray detectors with high resolution is crucial for practical applications. In this paper, we introduce a novel flat-panel X-ray detector that integrates quasi-two-dimensional (2D) Ruddlesden-Popper (RP) perovskite with a pixeled thin film transistor (TFT) backplane. We incorporate 2,5-dibromopyrimidine (DBPM) as an additive to passivate the Lewis acid defects in the quasi-2D RP perovskite. This modification results in suppressed ion migration, improved optoelectronic performance, and enhanced operational stability of the device. Impressively, the activation energy of the RP perovskite increases from 0.96 to 1.35 eV with the DBPM additive. As a result, X-ray detectors exhibit a high sensitivity of ∼13,600 μC Gyair-1 cm-2, a low detection limit of 6.56 nGyair s-1, and excellent operational stability. Moreover, the flat-panel detectors demonstrate a high spatial resolution of 3.7 line pairs per millimeter and excellent X-ray imaging properties under a remarkably low X-ray dose of ∼50 μGyair, which is just half of the X-ray dose typically used in commercial equipment. This study opens new avenues for the development of flat-panel perovskite X-ray detectors with significant potential for various applications.

Structural, dielectric, and optical properties in Mn-modified CaSnO3

The CaSn0.95Mn0.05O3 (CSMO) was produced by using the sol-gel wet chemical process. The structural composition was examined using an X-ray diffraction (XRD) pattern, and the presence of an orthorhombic structure with the space group Pbnm was confirmed by Rietveld refinement. At different temperatures between 300 K and 773 K, the dielectric permittivity (ε), tangent losses (tanδ), and electrical conductivity of CSMO has been measured as a function of frequency from 100 Hz to 1 MHz .Dielectric permittivity (ε) is found to be independent of temperature up to 400K and very low tangent loss. Jonscher’s power law in the material’s frequency-dependent ac conductivity shows its semiconductor nature. Optical band gap of CSMO was observed by using UV-vis .absorption spectra. The optical band gap of CSMO, which was determined using Tauc plot measurements to be 2.42 eV, suggests that the sample is a semiconductor. The Arrhenius model is employed to perform an analysis of the dc conductivity of the material concerning both frequency and temperature. As a result of its semiconductivity, stable dielectric constant, and low tangent loss, CSMO is a suitable material for thermally stable capacitors, semiconductor devices, UV filter and UV detectors.

Cation-π interactions enabled water-stable perovskite X-ray flat mini-panel imager

Sensitive and stable perovskite X-ray detectors are attractive in low-dosage medical examinations. The high sensitivity, tunable chemical compositions, electronic dimensions, and low-cost raw materials make perovskites promising next-generation semiconductors. However, their ionic nature brings serious concerns about their chemical and water stability, limiting their applications in well-established technologies like crystal polishing, micro-processing, photolithography, etc. Herein we report a one-dimensional tryptamine lead iodide perovskite, which is stable in water for several months as the strong cation-π interactions between organic cations. The one-dimensional and two-dimensional tryptamine lead iodide perovskite tablets are switchable through thermal-annealing or water-soaking treatments to relax microstrains. The water-stable and microstrain-free one-dimensional perovskite tablets yield a large sensitivity of 2.5 × 106 μC Gyair−1 cm−2 with the lowest detectable dose rate of 5 nGyair s−1. Microelectrode arrays are realized by surface photolithography to construct high-performance X-ray flat mini-panels with good X-ray imaging capability, and a record spatial resolution of 17.2 lp mm−1 is demonstrated.

Templated Synthesis of CsPbBr3 Nanowire Arrays Toward Low Current Drift and Stable X-ray Detector

All-inorganic halide perovskite CsPbBr3 with superior environmental stability, remarkable radiation hardness and great defect tolerance has emerged as a competitive material in radiation detection. However, the operation stability of CsPbBr3...

Computational modelling of graphene/aluminum nitride (GP/AlN) hybrid materials for the detection of 2,4 dichlorophenoxyacetic acid (DCP) pollutant.

Despite their efficacy in eliminating undesired crops and increasing yield, a range of environmental issues and chronic ailments arise when hazardous chemicals are highly concentrated in wastewater and then deposited into rivers, lakes or the air. Hence, the detection of these chemicals has become a cause of concern for researchers and scientists because they contribute largely to serious health problems. Herein, the potential of newly tailored nanomaterials for the detection of 2,4 dichlorophenoxyacetic acid (DCP) in humans was examined. The theoretical approach adopted in this work is within the framework of density functional theory (DFT) using the DFT/B3LYP-D3/def2SVP computational method. The reduction in the energy gap upon adsorption is indicative of good adsorbing properties. A chemisorption phenomenon was observed for DCP-GP/AlN. However, in most cases, physisorption occurs. Interestingly, the noncovalent nature of the interactions was observed in all the cases, indicating that the material was good. The green colour of the 3D RDG maps implies a significant intermolecular interaction. Sensor mechanisms confirmed that the nanocomposite materials exhibit excellent detection potential for DCP through greater charge transfer, better sensitivity, conductivity, and enhanced adsorption capacity. The potential of nanocomposite materials as stable and promising detectors for DCP pollutants was confirmed in this study. Hence, the studied GP/AlN nanocomposite material can be used in the engineering of future sensor devices for detecting DCP.

Lattice-Gradient Perovskite KTaO3 Films for an Ultrastable and Low-Dose X-Ray Detector.

Conventional indirect X-ray detectors employ scintillating phosphors to convert X-ray photons into photodiode-detectable visible photons, leading to low conversion efficiencies, low spatial resolutions, and optical crosstalk. Consequently, X-ray detectors that directly convert photons into electric signals have long been desired for high-performance medical imaging and industrial inspection. Although emerging hybrid inorganic-organic halide perovskites, such as CH3 NH3 PbI3 and CH3 NH3 PbBr3 , exhibit high sensitivity, they have salient drawbacks including structural instability, ion motion, and the use of toxic Pb. Here, this work reports an ultrastable, low-dose X-ray detector comprising KTaO3 perovskite films epitaxially grown on a Nb-doped strontium titanate substrate using a low-cost solution method. The detector exhibits a stable photocurrent under high-dose irradiation, high-temperature (200 °C), and aqueous conditions. Moreover, the prototype KTaO3 -film-based detector exhibits a 150-fold higher sensitivity (3150 µC Gyair -1 cm-2 ) and 150-fold lower detection limit (<40 nGyair s-1 ) than those of commercial α-Se-based direct detectors. Systematic investigations reveal that the high stability of the detector originates from the strong covalent bonds within the KTaO3 film, whereas the low detection limit is due to a lattice-gradient-driven built-in electric field and the high insulating property of KTaO3 film. This study unveils a new path toward the fabrication of green, stable, and low-dose X-ray detectors using oxide perovskite films, which have significant application potential in medical imaging and security operations.

Two-dimensional hybrid perovskite crystals for highly sensitive and stable UV light detector

Two-dimensional metal halide perovskites (2D MHPs) are promising candidates for ultraviolet (UV) light detection due to their narrow band gap and high stability in the air atmosphere. MHP crystals, with fewer defects and grain boundaries than polycrystalline films, are more suitable for photodetectors and other advanced semiconductor devices. In this paper, aimed to fabricate high-performance UV light detector, a series of high-quality and large-sized 2D perovskite crystals with the composition of (BA)2Pb(ClxBr1-x)4 were prepared and the best UV responsibility was found in the (BA)2Pb(Cl0.1Br0.9)4 crystal. Despite the detector was fabricated by the simple silver brushing method, it exhibits high responsivity of 3.19 mA/W, high detection rate of 3.87 × 1011 Jones, and fast response speed to UV light of 340 nm under the bias of 20 V. Moreover, the detector shows remarkable light sensitivity even under extremely weak UV illumination of 5.4 μW/cm2 and satisfactory stability during a long-duration switching operation. The excellent light response performance of the (BA)2Pb(Cl0.1Br0.9)4 detector was ascribed to the very low dark current (0.84 pA) of the detector, which highly relies on the crystal quality of the light-absorbing perovskites. The relationship between the structural and the compositional characteristics of (BA)2Pb(Cl0.1Br0.9)4 and its light response property was analyzed. This work provides a promising candidate material for sensitive UV detection and high-performance photodetectors.

Multiband spectral response inspired by ultra-high responsive thermally stable and self-powered Sb2Se3/GaN heterojunction based photodetector

Hetero-structuring of dissimilar materials provides an exciting pathway to achieve unique electrical and optical properties based on application demand. A combination of Sb2Se3 and GaN is a potential candidate for optoelectronic applications owing to the notable carrier mobilities and absorption coefficient. The thermal stability, low optical signal detection capabilities, and broad range spectral response of Sb2Se3/GaN heterostructure self-powered photodetector are assessed. A stable Sb2Se3/GaN heterostructure-based two-terminal device with excellent photoresponsivity of 1210 mAW−1 (self-power) and 2.3 × 106 mAW−1 (photoconductive @ 12V) with extremely low optical signal detection capability (650 nW) is designed. The devices can detect optical radiation across a broad spectrum from Deep Ultraviolet (250 nm) to Short Wave Infrared (1250 nm). Additionally, the assessment of the device revealed a distinct high-temperature resilience limit that allowed it to work as a thermally stable broadband photodetector. The heterostructure-based optical device demonstrates ultrahigh responsivities of 844 mAW−1 and 1.2 × 106 mAW−1 at 250 °C in the photovoltaic (0V) and photoconductive (12V) modes, respectively. The Sb2Se3/GaN heterostructure-based detector provides an excellent perspective for the next generation of thermally stable optoelectronic devices. The analysis better explains how heterostructure provides thermal stability and offers a viable approach for developing high-performance, self-powered, thermally stable broadband optical detectors.

Reversible capacitive Frisch grid TlBr detectors

A reversible capacitive Frisch grid detector was fabricated using a thallium bromide (TlBr) crystal with a symmetrical electrode design. The device operates by switching the polarity of the applied voltage, which is necessary for a stable TlBr detector operation. A 2 mm × 2 mm × 5 mm bar-shaped TlBr crystal was used to construct the detector, which exhibited an (full width at half maximum) energy resolution of 1.9% for 662 keV γ-rays measured using a depth correction method at RT. The TlBr detector also showed a stable operation for 8 h of with hourly bias switching.

Domain Agnostic Post-Processing for QRS Detection Using Recurrent Neural Network.

Deep-learning-based QRS-detection algorithms often require essential post-processing to refine the output prediction-stream for R-peak localisation. The post-processing involves basic signal-processing tasks including the removal of random noise in the model's prediction stream using a basic Salt and Pepper filter, as well as, tasks that use domain-specific thresholds, including a minimum QRS size, and a minimum or maximum R-R distance. These thresholds were found to vary among QRS-detection studies and empirically determined for the target dataset, which may have implications if the target dataset differs such as the drop of performance in unknown test datasets. Moreover, these studies, in general, fail to identify the relative strengths of deep-learning models and the post-processing to weigh them appropriately. This study identifies the domain-specific post-processing, as found in the QRS-detection literature, as three steps based on the required domain knowledge. It was found that the use of minimal domain-specific post-processing is often sufficient for most of the cases and the use of additional domain-specific refinement ensures superior performance, however, it makes the process biased towards the training data and lacks generalisability. As a remedy, a domain-agnostic automated post-processing is introduced where a separate recurrent neural network (RNN)-based model learns required post-processing from the output generated from a QRS-segmenting deep learning model, which is, to the best of our knowledge, the first of its kind. The RNN-based post-processing shows superiority over the domain-specific post-processing for most of the cases (with shallow variants of the QRS-segmenting model and datasets like TWADB) and lags behind for others but with a small margin ( ≤ 2%). The consistency of the RNN-based post-processor is an important characteristic which can be utilised in designing a stable and domain agnostic QRS detector.

Stable perovskite single-crystal X-ray imaging detectors with single-photon sensitivity

A major thrust of medical X-ray imaging is to minimize the X-ray dose acquired by the patient, down to single-photon sensitivity. Such characteristics have been demonstrated with only a few direct-detection semiconductor materials such as CdTe and Si; nonetheless, their industrial deployment in medical diagnostics is still impeded by elaborate and costly fabrication processes. Hybrid lead halide perovskites can be a viable alternative owing to their facile solution growth. However, hybrid perovskites are unstable under high-field biasing in X-ray detectors, owing to structural lability and mixed electronic–ionic conductivity. Here we show that both single-photon-counting and long-term stable performance of perovskite X-ray detectors are attained in the photovoltaic mode of operation at zero-voltage bias, employing thick and uniform methylammonium lead iodide single-crystal films (up to 300 µm) and solution directly grown on hole-transporting electrodes. The operational device stability exceeded one year. Detection efficiency of 88% and noise-equivalent dose of 90 pGyair are obtained with 18 keV X-rays, allowing single-photon-sensitive, low-dose and energy-resolved X-ray imaging. Array detectors demonstrate high spatial resolution up to 11 lp mm−1. These findings pave the path for the implementation of hybrid perovskites in low-cost, low-dose commercial detector arrays for X-ray imaging.

PF6 - Pseudohalides Anion based Metal-Free Perovskite Single Crystal for Stable X-ray Detector to Attain Record Sensitivity.

Metal-free perovskites (MFPs) possess excellent photophysical properties of perovskites while avoiding the introduction of toxic metal ions and organic solvents, and have been expanded to X-ray detection. However, iodine-based high-performance MFPs are tended to oxidation, corrosion and uncontrolled ion migration, resulting in poor material stability and device performance. Herein, the strongly electronegative PF6 - pseudohalide is used to fabricate the large-size MDABCO-NH4 (PF6 )3 (MDBACO = methyl-N'-diazabicyclo[2.2.2]octonium) single crystals (SCs) for solving the problems of iodine ions. After the introduction of PF6 - pseudohalides, the Coulomb interaction and hydrogen bonding strength are enhanced to alleviate the ion-migration and stability problems. Moreover, combined with theoretical calculations, PF6 - pseudohalides increase the ion-migration barrier, and affect the contribution of its components to energy band for a broadening band gap. Meanwhile, the improved physical properties, such as large activation energy of ionic migration, high resistivity and low current drift, further expand its application in low-dose and sensitive X-ray detection. Finally, the X-ray detector based on MDABCO-NH4 (PF6 )3 SCs achieves a sensitivity of 2078 μC Gyair -1 cm-2 (highest among metal-free SCs-based detectors) and the lowest detectable dose rate (16.3 nGyair s-1 ). This work has expanded the selection of MFPs for X-ray detectors and somewhat advanced the development of high-performance devices. This article is protected by copyright. All rights reserved.

Ferroelectric dipole-MAPbI3 coupled x-ray detector

Blade coating offers a low-cost production method for fabricating perovskite thick-film x-ray detectors. However, due to the preferential nucleation at the gas–liquid interface of a perovskite solution, high-quality perovskite thick films are in such a dilemma, sacrificing either the density of the thick film by forming a porous structure or the thickness of the film through depositing a compact structure. The porous structure will lead to carrier recombination and ion migration while low thickness will cause insufficient x-ray absorption, which will increase the dark current or reduce the sensitivity of the corresponding x-ray detector. In the present work, a scalable ferroelectric dipole–methylamine lead iodide (MAPbI3) coupled x-ray detector is proposed, where the x-ray photoconductor in situ formed on indium tin oxide shows a dense fibrous mesoscopic structure oriented along the charge-carriers transport direction. It is demonstrated that ferroelectric dipoles promise not only strong coupling effects with MAPbI3, driving better crystallinity and denser assemblies, but also excellent passivation to MAPbI3 interfaces, decreasing trap-state densities, leading to improved direct x-ray detection performance. In addition, the enhanced operational stability of the corresponding device suggests a strategy of introducing the localized polarization field for stable perovskite direct x-ray detectors.

Low-Dose and Stable X-ray Detection Enabled by Ferroelectric Perovskite Oxides

Ferroelectric perovskites are recognized as promising candidates for use in optoelectronics due to the efficient electron and hole extraction enabled by the spontaneous electric polarization induced depolarization electric field. Ferroelectric perovskite oxides also show good stability in harsh chemical, mechanical, and thermal conditions and can be fabricated by using robust and scalable methods. However, the small photocurrent of the typical ferroelectric oxide optoelectronics greatly limits their applications, such as in photovoltaics and photocatalysis. Here, we show that ferroelectric perovskite oxides are suitable for low-dose X-ray detection (ultraweak radiation detection). Ferroelectric plate-like perovskite-type CaBi2Ta2O9 (CBTa), prepared by a solid-state sintered reaction method, displays a spontaneous polarization (Ps) of 6.5 μC cm–2, a remanent polarization (Pr) of 4.9 μC cm–2, and a high Curie temperature (Tc) of 1196 K. Large resistivity and high Pr of CBTa enable a good response to low-dose X-rays under zero bias, resulting in a detection limit of 30 nGyair s–1 for the detector, which is much lower than the requirement for X-ray diagnostics (5.5 μGyair s–1). The CBTa detectors also exhibit ultralow noise and good operation stability. This study will motivate new strategies to explore low-dose and stable X-ray detectors with ferroelectric oxides.

A new indium-based MOF as the highly stable luminescent ultra-sensitive antibiotic detector

A novel luminescent double-interpenetrated metal-organic framework (MOF), named {[In6(O)3(BTB)4]·3H2O}n (1), is designed and synthesized using the tritopic linkers (1,3,5-tris(4-carboxyphenyl)benzene (H3BTB)) and tetranuclear clusters [In4O2(COO)8]. 1 features 3,8-connected dual-wall “cage-in-cage” and exhibits excellent chemical stability owing to its high connectivity and double-interpenetrated architectures. Moreover, it could rapidly detect thiamphenicol (THI), nitrofurazone (NFZ), and nitrofurantoin (NFT) antibiotics in N,N-dimethylformamide (DMF) with superior detection sensitivity (KSV) and low detection limits (LOD) of 4.52 × 103 M−1 and 348.6 ppm, 1.43 × 105 M−1 and 13.8 ppm, and 1.47 × 105 M−1 and 12.1 ppm for THI, NFZ, and NFT, respectively. Additionally, compound 1 exhibits good selectivity and recyclability. It is also effectively used to detect NFT in the milk sample. Furthermore, the mechanism of luminescence quenching was revealed through the experimental results and the density functional theory calculations. The occurrence of photo-induced electron transfer (PET) affects the fluorescence quenching effect of NFT and NFZ. The design of indium-based MOFs has the potential to detect antibiotic residues in food.

Performance studies of RPC detectors operated with C2H2F4 and CO2 gas mixtures

Resistive Plate Chambers detectors are largely employed at the CERN LHC experiments thanks to their excellent trigger performances and contained costs. They are operated with a gas mixture made of 90%–95% of C2H2F4, that provides a high number of ion–electron pairs, about 5% of i-C4H10, that ensures the suppression of photon-feedback effects, and 0.3% of SF6, used as an electron quencher to further operate the detector in streamer-free mode. C2H2F4is known to be a Greenhouse gas, with a global warming potential (GWP) of 1430. CERN has identified several strategies to reduce the consumption of greenhouse gas emissions from particle detectors at LHC experiments. One research line is focused on the study of alternatives to C2H2F4. In this context, a conservative approach for the next years of LHC operation could be to focus on reducing the GWP of the RPC gas mixture by only adding CO2 and not using new gases, whose effects on detector long-term operation have to be studied. The RPC performance with standard gas mixture with the addition of 30%–50% of CO2 (and SF6 concentration between 0.3 and 0.9%) were studied both in laboratory set-up and at the CERN Gamma Irradiation Facility in presence of muon beam and gamma background radiation. Encouraging results were obtained showing that the addition of CO2 to the standard gas mixture can represent a mid-term solution to reduce emissions and lower operational costs by keeping stable detector performance and safe long-term operation.