Gas Avalanche Research Articles

Secondary scintillation properties of multi-layer THGEMs operated in low-pressure CF4 and Ar/5%Xe

We present a measurement of the secondary scintillation yield produced by two-layer Thick Gas Electron Multipliers (M-THGEMs) in pure Tetrafluoromethane (CF4) gas and in Ar mixed with 5% Xe in low-pressures down to 20 Torr. The detector was irradiated with 5.49 MeV alpha particles from a low-rate 241-Am source. The secondary scintillation light generated during the gas avalanche process was read out by a Hamamatsu photomultiplier tube (model R8520-406), sensitive to a broad wavelength range (160–650 nm). The avalanche charge was collected on the bottom electrode of M-THGEM and correlated to the scintillation light on an event-by-event basis. We observed that, for both gas types, the value of the photon to electron production ratio (0.4 ph/el in CF4 and 0.1 ph/el in Ar/5%Xe) increases with the thickness of the M-THGEM electrodes and varies significantly with the pressure, being higher at lower values. The decrease in electroluminescence yield at higher pressures is much more pronounced in the Ar/Xe mixture. In addition, because of a larger gas avalanche volume, the electroluminescence light yield is larger in thicker M-THGEM structures. Presented results are particularly useful for designing the next generation of Optical-readout Time Projection Chambers (O-TPCs) operated at low-pressure CF4; applications include experimental nuclear physics with rare isotope beams, dark matter detection with directional sensitivity and observation of the Migdal effect in a low-pressure Optical TPC.

Gap uniformity study of a resistive Micromegas for the Multi-purpose Time Projection Chamber (MTPC) at Back-n white neutron source

A Multi-purpose Time Projection Chamber prototype based on a resistive Micromegas technique has been proposed, designed and fabricated at China Spallation Neutron Source to measure the cross sections of neutron-induced light-charged particle emission reactions and fission reactions at the Back-n white neutron source. For the requirements of working stability with high voltage and high granularity of readout, the prototype is fabricated by applying a resistive Micromegas with high-density pixelated anode plane. In order to fully understand the process of charge spreading and signal induction on the anode plane covered by a resistive layer, a simulation method is developed and the energy correction function is then obtained, which can be used in the further energy correction in the experimental data analysis. Measured with a 55Fe X-ray source, the uniformity of gain and avalanche gap are specially analyzed by combining the simulated gas avalanche parameters with fitting of experimental data in which the parallel plate avalanche model is adopted.

Development of the TIP-HOLE gas avalanche structure for nuclear physics/astrophysics applications with radioactive isotope beams: preliminary results.

We discuss the operational principle and performance of new micro-pattern gaseous detectors based on the multi-layer Thick Gaseous Electron Multiplier (M-THGEM) concept coupled to a needle-like anode. The new gas avalanche structure aims at high-gain operation in nuclear physics and nuclear astrophysics applications with radioactive isotope beams. It is thereafter named TIP-HOLE gas amplifier, and consists of a THGEM or a two-layers M-THGEM mounted in a WELL configuration. The avalanche electrodes are collected by thin conductive needles (with up to a few ten μm radius and a height of 100 μm), located at the center of the hole and acting as a point-like anode. The bottom area of the needle could be surrounded by a cylindrical cathode strip in order to increase the electron collection efficiency. The electric field lines from the drift region above the M-THGEM are focused into the holes, and then forced to converge on the needle tip. An extremely high field is reached at the top of the needle, creating a point-like avalanche process. Stable, high-gain operations in a wide range of pressures can be achieved at relatively low operational voltage, even in pure quencher gas at atmospheric pressure (e.g. pure isobutene). The TIP-HOLE structure may be produced by the innovative scalable additive manufacturing technology for large-area, multiple-layer printed circuit boards, recently developed by the UHV technology company (USA) and discussed for the first time in this work.

Study of the ecological gas for MRPCs

The Multigap Resistive Plate Chamber (MRPC) is a gaseous detector; the performance depends very much on the gas mixture as well as the design. MRPCs are used as a timing device in several collider experiments and cosmic ray experiments thanks to the excellent timing performance. The typical gas mixtures of RPC-type detectors at current experiments are based on the gases $\rm C_2F_4H_2$ and $\rm SF_6$. These gases have very high Global Warming Potential (GWP) values of 1430 and 23900 respectively. The present contribution has been performed as a part of efforts to reduce the amount of greenhouse gases used in high energy experiments. The performance of MRPC has been measured with two different gas mixtures; $\rm C_2F_4H_2$ based gas mixtures and the ecological $\rm C_3F_4H_2$ (HFO-1234ze). A small MRPC was used for the tests. It has an sensitive area of 20 $\times$ 20 $\rm cm^2$; it was been built with 6 gaps of 220 $\mu$m. In normal operation, the strong space charge created within the gas avalanche limits the avalanche's growth. $\rm SF_6$ plays an important part in the process due to its high attachment coefficient at low electric fields. It is thus necessary to find another gas that has a similar attachment coefficient. $\rm CF_{3}I$ is a possible candidate. Tests were performed with this gas added to $\rm C_3F_4H_2$.

The Focal-Plane Detector Package on the TUNL Split-Pole Spectrograph

A focal-plane detector for the Enge split-pole spectrograph at the Triangle Universities Nuclear Laboratory has been designed. The detector package consists of two position-sensitive gas avalanche counters: a gas proportionality energy loss section and a residual energy scintillator. This setup allows both particle identification and focal-plane reconstruction. In this paper, we will detail the construction of each section along with their accompanying electronics and data acquisition. Effects of energy loss throughout the detector, ray-tracing procedures, and resolution as a function of fill pressure and bias voltage are also investigated. A measurement of the 27Al $(d,p)$ reaction is used to demonstrate a detector performance and to illustrate a Bayesian method of energy calibration.

The Focal-Plane Detector Package on the TUNL Split-Pole Spectrograph

A focal plane detector for the Enge Split-pole Spectrograph at Triangle Universities Nuclear Laboratory has been designed. The detector package consists of two position sensitive gas avalanche counters, a gas proportionality energy loss section, and a residual energy scintillator. This setup allows both particle identification and focal plane reconstruction. In this paper we will detail the construction of each section along with their accompanying electronics and data acquisition. Effects of energy loss throughout the detector, ray tracing procedures, and resolution as a function of fill pressure and bias voltage are also investigated. A measurement of the $^{27}\!$Al$(d,p)$ reaction is used to demonstrate detector performance and to illustrate a Bayesian method of energy calibration.

A concept for laboratory studies of radiation detectors over a broad dynamic-range: instabilities evaluation in THGEM-structures

A simple methodology for evaluating the dynamic-range of gas avalanche detectors in the laboratory is presented and discussed. It comprises two tools: a charge injector of tunable gain which transfers radiation-induced amplified electron swarms to the investigated detector to mimic events with well defined primary-ionization spectra, and a systematic approach for measuring the detector's discharge probability. The methodology, applicable to a broad range of detectors, is applied here for instability studies in various single-stage THGEM and THGEM-WELL structures. The results indicate upon a somewhat larger attainable dynamic range in a single-stage THGEM operated with additional multiplication in the induction gap.

Numerical statistical modelling algorithms for electron avalanches in gases

A three-dimensional parallel algorithm of the Monte Carlo method (ELSHOW) is developed for simulation of electron avalanches in gases. The parallel implementation is performed with the use of the well- proven PARMONC library, which accelerates the calculations of such integral characteristics as the number of particles in an avalanche, the coefficient of impact ionization, the drift velocity, and the others, as well as ways to select an appropriate size of the time step using the technique of dependent statistical tests. The algorithm consists of special methods of distribution modelling, a lexicographic implementation scheme for ‘branching’ of trajectories, a ‘Russian roulette’, justified construction of histograms and a polygon of frequencies, and the calculation of probabilistic error estimate of functionals. A comparison of the obtained results for nitrogen with previously published theoretical and experimental data is presented.

Эффективное использование многоядерных сопроцессоров при суперкомпьютерном статистическом моделировании электронных лавин

Three-dimensional parallel Monte Carlo algorithm for modelling the electron avalanches in gases is developed. Parallel Implementation is made on supercomputers with MPP architecture and on hybrid supercomputers with Intel Xeon Phi coprocessors. The well-working library PARMONC is used to implement parallel computations. The use of the library enables fast calculation of functionals such as the number of particles in avalanche, first Townsend coefficient, drift velocity, etc.

Simulation of gas avalanche in a micro pixel chamber using Garfield++

A micro pixel chamber (μ-PIC), the development of which started in 2000 as a type of a micro pattern gas detector,has a high gas gain greater than 6000 in stable operation, a large detection area of 900 cm2, and a fine position resolution of about 120 μm.However, for its development, simulation verification has not been very useful,because conventional simulations explain only part of the experimental data.On the other hand, some μ-PIC applications require precise understanding of the fluctuation of the gas avalanche and signal waveform for their improvement;therefore, there is a need to update the μ-PIC simulation.Hence, we adopted Garfield++, which is developed for simulating a microscopic avalanche in an effort to explain experimental data.The simulated avalanche size was well consistent with the experimental gas gain.Moreover, we calculated a signal waveform and successfully explained the pulse height and time-over-threshold.These results clearly indicate that the simulation of μ-PIC applications will improveand that Garfield++ simulation will easily facilitate the μ-PIC development.

Deadtime calibration in high-rate microstrip gas counters

The advent of the microstrip gas chamber (MSGC) has permitted the development of position-sensitive gas avalanche detectors, which combine sub-millimeter spatial resolution with multi-MHz global rate capabilities not attainable with traditional types of gas counters. Based on massively parallel electronic readout, the need to keep down electronic channel costs imposes a simple front-end design without in-built deadtime compensation. In this report we show that insitu calibration of the deadtime of the detector system is straight-forward and reliable. Methods are described for applications to X-ray and neutron detection.

Radiation hardness of gas discharge tubes and avalanche diodes used for transient voltage suppression

The widespread use of gas discharge tubes (GDTs) and avalanche diodes for transient voltage suppression (TVS) in many cases results in their exposure to ionizing radiation. The aim of this paper is to investigate the influence of irradiation on these TVS devices’ characteristics, by exposing them to a combined neutron/gamma radiation field. Experimental results show that irradiation of TVS diodes causes a lasting degradation of their protective characteristics. On the other hand, GDTs exhibit a temporary change of performance. The observed effects are presented with the accompanying theoretical interpretations, based on the interaction of radiation with materials constituting the investigated devices.

Recombination: An important effect in multigap resistive plate chambers

We have simulated the gas avalanche in a multigap resistive plate chamber (MRPC). The results were then compared with our data from the MRPC [1]. Up to now, the total amount of charge produced in a gas gap is considered to be given by the total number of positive ions generated by the gas avalanches. However, the total charge generated by the simulation program is much too large and is in conflict with our data. Our data indicate that nearly 100% of the negative ions recombine with the positive ions. The recombination effect dramatically reduces the amount of charge in the gas gap: a very important feature for MRPC technology especially for the rate capability.

Charge amplitude distribution of the Gossip gaseous pixel detector

The Gossip gaseous pixel detector is being developed for the detection of charged particles in extreme high radiation environments as foreseen close to the interaction point of the proposed super LHC. The detecting medium is a thin layer of gas. Because of the low density of this medium, only a few primary electron/ion pairs are created by the traversing particle. To get a detectable signal, the electrons drift towards a perforated metal foil (Micromegas) whereafter they are multiplied in a gas avalanche to provide a detectable signal. The gas avalanche occurs in the high field between the Micromegas and the pixel readout chip (ROC). Compared to a silicon pixel detector, Gossip features a low material budget and a low cooling power. An experiment using X-rays has indicated a possible high radiation tolerance exceeding 10 16 hadrons/cm 2. The amplified charge signal has a broad amplitude distribution due to the limited statistics of the primary ionization and the statistical variation of the gas amplification. Therefore, some degree of inefficiency is inevitable. This study presents experimental results on the charge amplitude distribution for CO 2/DME (dimethyl-ether) and Ar/iC 4H 10 mixtures. The measured curves were fitted with the outcome of a theoretical model. In the model, the physical Landau distribution is approximated by a Poisson distribution that is convoluted with the variation of the gas gain and the electronic noise. The value for the fraction of pedestal events is used for a direct calculation of the cluster density. For some gases, the measured cluster density is considerably lower than given in literature.

Electron-hole avalanches in semiconductors

An analytical theory of the development of electron-hole avalanches in semiconductors, which qualitatively differ from the electron avalanches in gases, is proposed and the spatiotemporal distributions of the field and charge in such avalanches are determined. It is suggested to identify the onset of the avalanche-streamer transition as the moment (t a) corresponding to a 20% decrease in the impact ionization coefficient α at the avalanche center. A transcendent equation is obtained for the calculation of t a as a function of the unperturbed coefficient α(E ext) determined by the external field E ext. It is established that, as the α(E ext) value is increased in from 103 to 105 cm−1, the total number of electron-hole pairs generated by the t a moment decreases by almost three orders of magnitude.

High resolution β-imager: a new tool for characterizing 2D peptide distribution on biomimetic materials?

A common theme in engineering cell and tissue behavior at device surfaces is the biomimetic modification of the material in which peptides containing the adhesion domains of the extracellular matrix proteins are attached to the base material. Since the biological responses (e.g. the strength of the cell attachment, the cell migration rate and the extent of cytoskeletal organization formation) are dependent on several factors such as the receptor-ligand affinity, the density of ligand, and the spatial distribution of ligand, considering these parameters is important for the design of biomimetic materials. Consequently, this work deals with the presentation of a convenient and highly resolvent technique (High Resolution β-imager) allowing biomimetic surface modification to be analysed qualitatively and quantitatively. This gas avalanche imager was employed to characterize several biomimetic modification routes of titanium, showing the real interest of this system as a new imaging device for biomaterial surface characterization. It is presented by means of the determination of the RGDC peptide density and the homogeneity of the layout onto titanium at once. β activity was given by [ 35S]-cysteine that standed for RGDC peptide and the resulting amino-acid layout was characterized by High Resolution β-imager and X-Ray photoelectron Spectroscopy. Cysteine density was finally determined and results were discussed considering threshold densities governing biological events governing biological responses.

A gas avalanche light detector for multi-kiloton liquid argon TPC

We are developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate down to liquid nitrogen temperature (77 K). It has to be able to produce fast signals for timing and triggering purposes in multi-kiloton liquid argon time projection chambers. We studied the possibility to couple a standard photocathode to a suitable electron multiplication system in gas. In the first part of the programme the gas avalanche multiplication at cryogenic temperature and low pressure was studied. The second part of the programme foresees the production of a photocathode able to operate at low temperature. A complete detector prototype is going to be set up. It will consist of a simple CsSb photocathode and a multiplication stage made of 100 μ m stainless steel wires. We present the results of the evaluation of the gain attainable with different gas mixtures.

Development of gas avalanche photodetector operating at cryogenic temperature

We are interested in developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate in cryogenic environment down to liquid nitrogen temperature (77 K). It has to be a simple, cheap and compact device, with a photocathode surface comparable to that of photomultipliers, and it has to be able to produce fast signals for timing and triggering purposes. It could offer a cheap alternative to the photomultiplier use in large volume time projection chambers operating in liquid noble gas. We studied the possibility to couple a standard photocathode to a suitable electron multiplication system in gas. The results of the evaluation of the maximum gain attainable in gas employing pure argon and argon/methane mixture at low temperature are presented.

Study of electron avalanche multiplication in gaseous argon detectors at low pressure and operating at cryogenic temperature

We are developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate down to liquid nitrogen temperature (77 K). It has to be a simple, cheap and compact device, with a photocathode surface comparable to that of photomultipliers and it has to be able to produce fast signals for timing and triggering purposes. We studied the possibility of coupling a standard photocathode to a suitable electron multiplication system in gas; this would offer a cheap alternative to the use of photomultipliers. Gas avalanche multiplication at cryogenic temperatures and low pressure was observed in a small prototype chamber. Gains of the order of 10 3 were obtained in pure argon, while gains up to 10 5 were achieved using argon/methane mixture in cryogenic environment.

Simulation study on the operation of a multi-gap resistive plate chamber

The main features of a multi-gap resistive plate chamber (MRPC) are studied by Monte Carlo simulation with the gas avalanche model developed by Legler and Riegler et al (1961 Z. Naturforsch. 16a 253). A simple model of signal readout including FEE and noise effect is introduced in the simulation. The results of detection efficiency and time resolution are compared with those from experiments, under different working conditions. Good agreements are achieved.