Triple Gas Research Articles

Thin film thickness measurement with triple gas electron multiplier detector by 55Fe radiation transmission and background detection using energy distribution analysis

The quality control of thin film thickness measurements through the transmission and counting of beta and X-ray radiation has achieved very competitive precision with values to 0.2%. However, when the attenuated intensities by the thin film under measurement is above 90%, the method of counting beta or X-ray radiation generates a dramatic degradation in the precision to 30%. This work presents a new method to obtain and analyze thicknesses of aluminum and copper thin films using energy distribution information provided by a triple gas electron multiplier detector (3GEM). The method is based on the ratio of the peak of the Landau distribution generated by the background detection and the peak of the Gaussian distribution of soft X-ray photons generated by the radiation transmission through the thin films emitted by a 55Fe radiation source. The results improve the thickness measurement precision with respect to the radiation counting method when the intensity attenuated by the thin film is greater than 95% compared to precision values less than or equal to 30% obtained with the counting method to values below 10% achieved with the newly reported energy distribution method.

GRAAL: A novel package to reconstruct data of triple-GEM detectors

Micro-Pattern Gas Detectors (MPGDs) are the new frontier among the gas tracking systems. Among them, the triple Gas Electron Multiplier (triple-GEM) detectors are widely used. In particular, cylindrical triple-GEM (CGEM) detectors can be used as inner tracking devices in high energy physics experiments. In this contribution, a new offline software called GRAAL (Gem Reconstruction And Analysis Library) is presented: digitization, reconstruction, alignment algorithms and analysis of the data collected with APV-25 and TIGER ASICs are reported. An innovative cluster reconstruction method based on charge centroid, micro-TPC and their merge is discussed, and the detector performance evaluated experimentally for both planar triple-GEM and CGEM prototypes.

Assessing the annual power reliability of a residential building in relation to its ventilation system type: The case study of the off-grid container house in Shanghai.

In developing countries, electrification of rural and remote areas is an essential need for improving socio-economic conditions. However, increased access to adequate electricity and upgraded facilities may double or even triple present greenhouse gas emissions related to residential buildings operation. From both socio-economic and environmental perspective, implementation of solar-powered houses is widely considered as a sustainable. Power reliability is a key indicator used in assessing the annual performance of the off-grid housing operation. The primary objective of this article is to ascertain the impact of three main ventilation system types: natural (NV), mechanical with heat recovery (MV) and hybrid (HV) on annual power reliability of the case, off-grid building located in Shanghai. Firstly, three scenarios of hourly electricity loads profiles were calculated from an annual simulation via building performance software (BPS). Secondly, electrical load profiles were integrated into a developed model of alternating current (AC) coupled battery off-grid energy system model. The results indicate that the HV system provided the lowest annual electricity consumption (2847 kWh) and the best annual power reliability (98.6%) when compared to MV (2935kWh, 98.5%) and NV (2901kWh, 98.0%). The article discusses correlation between building ventilation scenarios, electrical loads and resultant annual power reliability. In conclusion economic viability of mechanical/hybrid ventilation implementation in off-grid housing is called into question.

Production performance analysis of fractured vertical wells with SRV in triple media gas reservoirs using elliptical flow

The stimulated reservoir volume (SRV) exists near hydraulic fractures in gas reservoirs after hydraulically fracturing stimulation, which creates one region with distinct gas reservoir properties from initial formation. Due to strong anisotropy, compared with radial flow model, the elliptical flow model is important for the optimal exploitation of triple media gas reservoirs (TMGR) consisting of matrix, vugs and fractures. The paper presents a composite elliptical flow model to analyse the fractured vertical well transient pressure and rate performance in TMGR with SRV. The inter-porosity flow from matrix to fractures is transient flow. Modified Mathieu functions is employed to solve the mathematical model. There are nine flow regimes based on dimensionless pseudo-pressure curves' characteristics and the comparison of transient inter-porosity flow with steady inter-porosity flow is illustrated. Sensitivity analysis for relevant parameters are conducted, such as well radius, SRV radius, mobility ratio, storativity ratio and inter-porosity flow coefficient.

Optimization of the separation unit of methanol to propylene (MTP) process and its application

Abstract Based on a typical gas composition from a methanol-to-propylene (MTP) reactor, and guided by a requirement to recover both propylene and ethylene, three separation strategies are studied and simulated by using PROII package. These strategies are sequential separation, front-end dethanization, and front-end depropanization. The process does not involve an ethylene refrigeration system, using the separated stream as absorbent, and absorbing further the medium-pressure demethanization, and a proprietary technology by combining intercooling oil absorption and throttle expansion. Influences of different process streams as absorbent are studied on energy consumptions, propylene and ethylene recovery percentages, and other key-performance indicators of the separation strategies. Based on a commercial MTP plant with a methanol capacity of 1700 kt·a−1, the simulated results show that the front-end dethanization using the C4 mixture as absorbent is the optimal separation strategy, in which the standard fuel oil consumption (a key-performance indicator of energy consumption) is 18.97 kt·h−1, the total power consumption of two compressors is 22.4 MW, the propylene recovery percentage is 99.70%, and the ethylene recovery percentage is 99.70%. For a further improvement, the pre-dethanization and thermal coupling methods are applied. By using front-end pre-dethanization (partial cutting) with debutanizer-overhead, i.e. the C4 mixture, as absorbent, the power consumption of the compressors decreases to 19.9 MW, an 11% reduction compared with the clear-cutting method. The energy consumption for the dual compressors for crude gaseous product mixture and main product propylene refrigeration is 16.69 MW, 16.55% lower than that of the present MTP industrial plant with the same scale, and a total energy consumption of 20 MW for the triple compressors including product gas mixture compression, and ethylene and propylene refrigeration.

Dissipation behavior and dietary risk assessment of lambda-cyhalothrin, thiamethoxam and its metabolite clothianidin in apple after open field application

The dissipation dynamics and residue amounts of lambda-cyhalothrin, thiamethoxam and clothianidin in apple were investigated by using rapid resolution liquid chromatography triple quadrupole mass spectrometer (RRLC-MS/MS) and gas chromatography mass spectrometry (GC-MS). The developed method performed satisfactory recoveries of 88%–105% and the limit of quantitation (LOQ) was 0.01 mg kg−1. The suspension concentrate (SC) formulation of lambda-cyhalothrin and thiamethoxam was applied on apple field in accordance with good agricultural practice (GAP). The half-lives of two pesticides ranged from 7.01 d to 17.3 d and the terminal residues were <0.01–0.21 mg kg−1. Based on the Chinese dietary pattern, the dietary risk of lambda-cyhalothrin and total thiamethoxam were predicted by comparing intake amounts with the toxicological data, namely acceptable daily intake (ADI) and acute reference dose (ARfD). The chronic and acute risk quotients were 0.1080–0.4463 and 0.0008–0.2005, respectively, which showed negligible risk for general consumers. The pre-harvest interval (PHI) of 21 d was suggested for the formulation in compliance with maximum residue limit (MRL) and dietary risk assessment, meanwhile, the MRL of 0.1 mg kg−1 was recommended for thiamethoxam in apple. These results were vital for guiding reasonable usage of two insecticides and for approval of formulation use.

3D energy deposition measurements with the GEMPix detector in a water phantom for hadron therapy

In this paper we present 3D measurements of the energy deposition by a clinical carbon ion beam in a water phantom. Conventionally, these measurements are performed with an array of ionization chambers and used for quality assurance. The spatial resolution is typically not better than 5 mm. We used the GEMPix, a gaseous detector with a highly pixelated readout and much better spatial resolution. The GEMPix was obtained by coupling a triple Gas Electron Multiplier (GEM) to a quad Timepix ASIC with 512×512 pixels and 55 μm pitch. The Bragg curve, 2D images of the beam and a 3D reconstruction of the energy deposition are obtained from a single depth scan performed in approximately 15 minutes. A separate linearity check was also performed. The detector response is well linear and the measured Bragg curve is very smooth with uncertainties of a few percent. 3D energy deposition measurements in a water phantom with the GEMPix provide better spatial resolution than conventional devices. Systematic differences in the Bragg curve in comparison to the reference one are still too large for clinical use but work on several improvements is on-going.

A New Approach for Alpha Radiography by Triple THGEM using Monte Carlo Simulation and Measurement

In this research, alpha imaging in Self Quenching Streamer (SQS) mode is investigated using a triple Thick Gas Electron Multiplier (THGEM) detector by Monte Carlo method and experimental data. First, a semi-empirical equation is derived to represent the relation between the SQS voltage and the alpha energy in every hole of the triple THGEM. The accuracy of this equation is tested and confirmed by a high degree of consistency. Secondly, the images of objects that are irradiated by Am-241 alpha source (5.49 MeV) are recorded by a CMOS camera using triple THGEM detector in the SQS mode. The resolution of images in this paper is a function of the exposure time. For an alpha source with 150 kBq activity, an optimal time interval for exposure is about 30 sec. For exposure time less or more than 30 sec, the images are incomplete and ambiguous, respectively. The overall objective of this work is to facilitate the alpha radiography in nuclear imaging through a triple THGEM without any amplifier or complicated electrical equipment.

Background biomonitoring of residue levels of 137 pesticides in the blood plasma of the general population in Beijing.

Due to the widespread use of pesticides, human exposure to pesticides is possible and can potentially cause adverse impacts on public health. We measured 137 pesticides including organophosphorus, organochlorine, pyrethroid and carbamate pesticides together with various herbicides in 100 human blood samples collected from the general population in Beijing. The samples were analysed by triple quadrupole tandem gas chromatography-mass spectrometry. In total, 24 organochlorine pesticides, 5 pyrethroid pesticides and 6 organophosphorus pesticides were detected. The detection rates of HCB, α-HCH, β-HCH, γ-HCH, p,p'-DDE and quintozene were 99, 96, 74, 72, 96 and 95%, respectively. No statistically significant gender difference in the blood concentrations of the pesticides was found. Consistent with the trend of the increasing β-HCH, p,p'-DDE and quintozene concentrations with age, a strong positive correlation between the age and concentrations of β-BHC, p,p'-DDE and quintozene was observed.

A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.

SXR measurement and W transport survey using GEM tomographic system on WEST

Measuring Soft X-Ray (SXR) radiation (0.1–20 keV) of fusion plasmas is a standard way of accessing valuable information on particle transport. Since heavy impurities like tungsten (W) could degrade plasma core performances and cause radiative collapses, it is necessary to develop new diagnostics to be able to monitor the impurity distribution in harsh fusion environments like ITER. A gaseous detector with energy discrimination would be a very good candidate for this purpose. The design and implementation of a new SXR diagnostic developed for the WEST project, based on a triple Gas Electron Multiplier (GEM) detector is presented. This detector works in photon counting mode and presents energy discrimination capabilities. The SXR system is composed of two 1D cameras (vertical and horizontal views respectively), located in the same poloidal cross-section to allow for tomographic reconstruction. An array (20 cm × 2 cm) consists of up to 128 detectors in front of a beryllium pinhole (equipped with a 1 mm diameter diaphragm) inserted at about 50 cm depth inside a cooled thimble in order to retrieve a wide plasma view. Acquisition of low energy spectrum is insured by a helium buffer installed between the pinhole and the detector. Complementary cooling systems (water) are used to maintain a constant temperature (25̂C) inside the thimble. Finally a real-time automatic extraction system has been developed to protect the diagnostic during baking phases or any overheating unwanted events. Preliminary simulations of plasma emissivity and W distribution have been performed for WEST using a recently developed synthetic diagnostic coupled to a tomographic algorithm based on the minimum Fisher information (MFI) inversion method. First GEM acquisitions are presented as well as estimation of transport effect in presence of ICRH on W density reconstruction capabilities of the GEM.

Results and performances of X-ray imaging GEM cameras on FTU (1-D), KSTAR (2-D) and progresses of future experimental set up on W7-X and EAST Facilities

The triple Gas Electron Multiplier (GEM) is a good candidate for the observation of the plasma volume emitting X-rays photons in the energy band up to 30 keV . The GEM camera system can be simply installed outside the port of a fusion device and it's a micropattern proportional gas detector which consists of an ionization gap, where X-rays photon conversion occurs, three consecutive foils working as amplification stage and finally a dedicated printed circuit board. Its simple experimental setup can be made in different configurations with 1D or 2D imaging possibilities: perpendicular GEM camera allows a 1D emissivity profile reconstruction instead a tangential GEM camera allows a poloidal cross-section image. Moreover, they offer high sensitivity, noise free, optical flexibility (zooming and tilting, magnification 10× up to 30×), high contrast, high dynamic range (6 orders of magnitude) and good time resolution (submillisecond). In this work several experimental results already observed on the Frascati Tokamak Upgrade (FTU) and the Korean Superconducting Tokamak Advanced Research (KSTAR) devices will be presented. The perpendicular installation on FTU allows a 1D radial profile with 128 lines of sight, while thanks to the 2D tangential view of the plasma, the reconstruction of the cross section has been done on KSTAR. Between them there are dynamic and precursors of sawtooth, effects of Edge Localized Mode (ELM) in the core and possible interplay between core and edge in ELMs (high m modes), effects of plasma rotation in the core, dynamic of injected impurities in the outer part of the plasma or also impurity accumulation and localized effects of additional heating. Installation of GEM systems is planned on Wendelstein 7-X (W7-X) and the Experimental Advanced Superconducting Tokamak (EAST) also for their robustness and flexibility X-rays detection in presence of high radiative environments (neutrons and gammas). In future applications on the above mentioned fusion devices, another possibility under evaluation is to use standard tomographic methods using two orthogonal GEM camera systems.

Similar structure of solution for triple media shale gas reservoir

In view of the limitations of the traditional shale gas reservoir model when used in describing the process of shale gas flow, this paper establishes the seepage model of a triple media shale gas reservoir, and takes the adsorption and desorption process into account. By combining the use of Laplace transforms with similar structure theory, pseudo pressure solutions under three different outer boundary conditions having similar structures are obtained in Laplace space. The pseudo pressures are then inverted into real space with the Stehfest numerical inversion logarithm. In addition, the characteristic curves are drawn, and impact of the variation of the main parameters on them are analyzed. The results show that three different outer boundary conditions of the pseudo pressures are only different at the kernel functions. Furthermore, under the similar structure theory, portraying the characteristic curves of three different outer boundary conditions only requires a change to the kernel functions. Therefore, the similar structure theory replaces the complex calculation process of seepage equations in the simple algebraic calculation. At the same time, the similar structure theory tremendously simplifies the drawing process of the characteristic curves. This will have a profound influence on the development of well testing analysis software in the future as well.

Measurements of 55Fe activity in activated steel samples with GEMPix

In this paper we present a novel method, based on the recently developed GEMPix detector, to measure the 55Fe content in samples of metallic material activated during operation of CERN accelerators and experimental facilities. The GEMPix, a gas detector with highly pixelated read-out, has been obtained by coupling a triple Gas Electron Multiplier (GEM) to a quad Timepix ASIC. Sample preparation, measurements performed on 45 samples and data analysis are described. The calibration factor (counts per second per unit specific activity) has been obtained via measurements of the 55Fe activity determined by radiochemical analysis of the same samples. Detection limit and sensitivity to the current Swiss exemption limit are calculated. Comparison with radiochemical analysis shows inconsistency for the sensitivity for only two samples, most likely due to underestimated uncertainties of the GEMPix analysis. An operative test phase of this technique is already planned at CERN.

SINGLE ANODE TRIPLE GEM TISSUE EQUIVALENT PROPORTIONAL COUNTER AS THE BASIS FOR A PERSONAL NEUTRON DOSIMETER.

This paper reports on a tissue-equivalent proportional counter (TEPC) based on a triple gas electron multiplier structure, with a single pad readout, as a basis for a personal neutron dosimeter. Its dosimetric response was studied using the 252Cf neutron source at the Health Physics Generator Facility of the Canadian Nuclear Laboratories. Measured lineal energy spectra were found to be in agreement with numerical simulations performed with Monte Carlo N-Particle eXtended (MCNPX). Both simulations and measurements showed that the mean pathlength of secondary charged particles in the TEPC gas was best represented by the thickness of the drift region of the device. It was determined that the Cauchy Theorem, used to calculate the mean chord length in spherical and cylindrical TEPCs, overestimated the simulated mean chord length by nearly a factor of two. Important operational characteristics of the device were investigated, including gas gain, sensitivity and dosimetric response, as functions of tissue-equivalent gas pressure. This work demonstrates that the proposed design can serve as the basis for a personal neutron dosimeter device, which would satisfy the angular dosimetric response criteria of the personal dosimeter standard IEC61526.

Multi-objective optimization of a triple shaft gas compressor station using Imperialist Competitive Algorithm

Triple-shaft gas turbine is one of the most commonly used gas compressor driven in natural gas compressor stations. In this work, exergy equilibrium formula of each components of a gas compressor station was specified and modeled using several mathematical models. The models predicted different parameters based on the environmental and operational conditions. A multivariate linear regression and ANOVA technique were employed to develop high precision models. Exergy analysis showed that the heater and combustion chamber have the lowest exergy efficiency in gas compressor stations. A significant exergy destruction occurs in the combustion chamber and approximately 13MW of the available energy is lost in exhaust. Imperialist Competitive Algorithm was used for single-objective and multi-objective optimizations based on the socio-political relationship of countries. Results of this optimization revealed that application of this novel algorithm, can lead to a significant decrease in the computational time. This algorithm can be applied to the most of the industrial subjects, especially energy issues. Finally, a Matlab graphical user interface program was developed in order to make the modeling and optimization simpler to use. The best gas compressor operating conditions of all gas compressor stations driven by triple-shaft gas turbines can be determined using this algorithm.

GEM detectors for WEST and potential application for heavy impurity transport studies

In tokamaks equipped with metallic walls and in particular tungsten, the interplay between particle transport and MagnetoHydroDynamic (MHD) activity might lead to impurities accumulation and finally to sudden plasma termination called disruption. Studying such transport phenomena is thus essential if stationary discharges are to be achieved. On WEST a new SXR diagnostic is developed in collaboration with IPPLM (Poland) and the Warsaw University of Technology, based on a triple Gas Electron Multiplier (GEM) detector. Potential application of the WEST GEM detectors for tomographic reconstruction and subsequent transport analysis is presented.

The influence of the evaporator inlet conditions on the performance of a diffusion absorption refrigeration cycle

The purity of the condensate at the evaporator inlet on the performance of a diffusion absorption refrigeration cycle is examined under three configurations of sub-cooling. Three sub-cooling configurations were studied numerically: the no sub-cooling (nSC) configuration where the condensate flows directly to the evaporator inlet without sub-cooling, the partial sub-cooling (pSC) configuration where the condensate is sub-cooled by the refrigerant heat exchanger before the evaporator inlet and the full sub-cooling (fSC) configuration where the condensate is sub-cooled both by the refrigerant heat exchanger and the evaporator. It was found that for the same heat input the pSC configuration shows the highest cooling effect at the evaporator and therefore the highest COP. The influence of the evaporator inlet condition on the triple tube gas heat exchanger was also studied. It was found that the temperature at the evaporator inlet has to be as low as possible. Finally, the influence of the purity of the vapor phase at the rectifier outlet on the cycle performance was also studied. It was found that less effort has to be invested in the purification of the hot refrigerant vapor in the rectifier.

複合粒子により作製された SOFC カソードの電極特性評価

The composite particles were prepared by one-step mechanical processing of the starting raw powders of La0.8Sr0.2MnO3 （LSM） and scandia stabilized zirconia （ScSZ） fine particles. In this paper, volume percentage of ScSZ in composite particles was set as 50 vol％ and 62 vol％, respectively. The SOFC cathodes using the composite particles were prepared by sintering at 1200℃. Sintering time was selected as 2h and 3h. As results of electrochemical examinations by AC impedance measurements, the increased content of ScSZ （62 vol％） and the shorter sintering time （2h） contributed to improving the polarization resistance （Rp） of cathodes. Three factors such as conductivity of oxygen ion, formation of triple phase boundaries and gas diffusivity were discussed for the improvement of Rp using the Bode plots which showed the relationship between the absolute value of imaginary part of impedance and the frequency.

Optimization of in-cell accelerated solvent extraction technique for the determination of organochlorine pesticides in river sediments

Organochlorine pesticides (OCPs) are ubiquitous environmental contaminants with adverse impacts on aquatic biota, wildlife and human health even at low concentrations. However, conventional methods for their determination in river sediments are resource intensive. This paper presents an approach that is rapid and also reliable for the detection of OCPs. Accelerated Solvent Extraction (ASE) with in-cell silica gel clean-up followed by Triple Quadrupole Gas Chromatograph Mass Spectrometry (GCMS/MS) was used to recover OCPs from sediment samples. Variables such as temperature, solvent ratio, adsorbent mass and extraction cycle were evaluated and optimized for the extraction. With the exception of Aldrin, which was unaffected by any of the variables evaluated, the recovery of OCPs from sediment samples was largely influenced by solvent ratio and adsorbent mass and, to some extent, the number of cycles and temperature. The optimized conditions for OCPs extraction in sediment with good recoveries were determined to be 4 cycles, 4.5g of silica gel, 105°C, and 4:3 v/v DCM: hexane mixture. With the exception of two compounds (α-BHC and Aldrin) whose recoveries were low (59.73 and 47.66% respectively), the recovery of the other pesticides were in the range 85.35–117.97% with precision <10% RSD. The method developed significantly reduces sample preparation time, the amount of solvent used, matrix interference, and is highly sensitive and selective.