Particle Identification Methods Research Articles

A gas-filled time-of-flight detector system and a new method for particle identification

In order to increase the power of isobaric identification in accelerator mass spectrometry (AMS) measurements, we built a new gas-filled time-of-flight (GF-TOF) detector system (Jiang et al.). The principle, construction and results of first on line tests with a Cu sample are described. Based on the GF-TOF detector system, we also propose a new particle identification method called energy-loss and time-of-flight ( ΔE– T) parabola. The principle of the method and the first test for the method with the 36 Cl AMS measurement are described.

Particle identification methods in high-energy physics

This paper deals with two major particle identification methods: d E/d x and Cherenkov detection. In the first method, we systematically compare existing d E/d x data with various predictions available in the literature, such as the Particle Data Group recommendation, and judge the overall consistency. To my knowledge, such comparison was not done yet in a published form for the gaseous detectors used in high-energy physics. As for the second method, there are two major Cherenkov light detection techniques: the threshold and the Ring imaging methods. We discuss the recent trend in these techniques.

Radiation monitoring with semiconductor spectrometers-dosimeters

We describe a spectrometer-dosimeter for simultaneous and independent measurements of the spectral and dose characteristics of α-, β-, and γ-radiations. The particle-identification method used in the spectrometers-dosimeters is based on simultaneous measurement of the particle energyE and its specific loss ΔE with semiconductor detectors. The dependences ΔE(E), preliminarily computed for each sort of particles, are stored in programmable read-only memories. Comparison of the expected and measured values of ΔE for the measured energyE completely defines the type of a particle. The method makes possible the determination of the spectral and dose characteristics of different types of radiation, as well as the radionuclide type and its concentration in the analyzed substance. It is shown that instruments based on this principle provide environmental radiation monitoring, including monitoring of radon, thoron, and their products.

A new method for charged particles identification with a CsI(Tl) crystal

A spectrometer for detecting and identifying light charged particles with low energies (>∼1 MeV) is described. The spectrometer consists of a thin CsI(Tl) crystal, an ФЭУ-176 photomultiplier, and a waveform digitizer. Digital oscillograms of anode pulses are stored and analyzed in off-line processing. In order to reconstruct the energy and specific energy losses, the two-component character of the scintillation fluorescence decay in a CsI(Tl) crystal and the dependence of the fast component on the specific loss value are used. A digital particle identification method is proposed. The results of experimental studies of the CsI(Tl) crystal scintillation properties and efficiency in identifying electrons, protons, and α-particles in an energy range of ∼1–10 MeV are presented. It is shown that the efficiency of the digital method for proton and α-particle identification is 1.5–2 times higher than that of the known analog methods.

Complementary particle ID: transition radiation and d E/d x relativistic rise

The Particle Identification (PID) methods using Transition Radiation (TR) and Relativistic Rise (RR) of the ionization losses are discussed as a complementary methods to a RICH technique. The comparative possibilities and limitations of these PID are considered. For the TR the modern high granularity detectors are described (ATLAS Transition Radiation Straw Tracker – TRT – as an example). The comparison is given between widely used Truncated Mean (TM technique) and a new approach based on Time over Threshold (ToT) measurements, which is more preferable due to the simplification of readout electronics and possibility of the fast triggering.

Detection of charged pions and protons in the segmented electromagnetic calorimeter TAPS

We present the characteristics of the segmented BaF 2 calorimeter TAPS for the measurement of charged pions and protons. The method of particle identification exploits the relation between the kinetic energy of a particle, its mass and the time-of-flight required to reach the detector. The detection efficiency is calculated using GEANT-GCALOR simulations. The analysis method is applied in the reaction 40Ar+ natCa at 0.8 A GeV. The simultaneous detection of charged pions and protons can be used to search for correlated pairs signalling the de-excitation of the Δ(1232) resonance.

Measurement of radiation tracks for particle and energy identification by using imaging plate

A new type of track counting method for particle identification was developed by using an Imaging Plate (IP). The distributions of the photo-stimulated luminescence (PSL) per track were measured after irradiation with 60Co gamma rays, 238U alpha particles, protons up to 12 MeV, carbon ions up to 290 MeV/ u and neon ions up to 400 MeV/ u. It was found that the PSL per track increases with energy loss per unit distance corresponding to linear energy transfer (LET).

A new setup for elastic recoil analysis using ion induced electron emission for particle identification

We describe a new setup for elastic recoil detection analysis (ERDA) using our recently developed particle identification method. Before the ions and elastic recoil atoms from the target reach a silicon surface barrier detector for energy analysis, they penetrate a set of thin foils (e.g. carbon). The ion induced electron emission yield from the foils depends on the nuclear charge of the penetrating ion and it is roughly proportional to the energy loss in the foil. The emitted electrons are accelerated towards a microchannel plate (MCP), which gives a signal amplitude proportional to the number of emitted electrons. This signal is measured in coincidence with the energy signal from the surface barrier detector using our dual-parameter multichannel analyzer system M2D. Since the energy resolution is not measurably deteriorated by the particle identification our setup offers optimum depth resolution for light elements. Due to the compact design large solid angles for high sensitivity can be achieved. A new measuring chamber has been built which offers considerable improvements. The ERDA scattering angle (30° or 45°) and the target orientation can be selected for optimum depth resolution or sensitivity. Element separation for light elements has been enhanced by several improvements: A new geometry of the foil setup improves the collection efficiency for ion induced electrons onto the MCP, coating of the carbon foils with insulators enhances the electron emission yield. Finally, a new data evaluation procedure has been developed in which the pulse height spectrum of the MCP is considered to be a linear combination of individual spectra from the incident ion and of the recoil atoms. The normalized shapes of these spectra are taken from calibration measurements, the intensities are then calculated using a linear fitting algorithm and finally give the depth profiles of the elements in the target. For hydrogen in near surface layers even isotopic separation is possible. Examples for 1H and 2H in a Be matrix will be given.

Identification of Spherical Virus Particles in Digitized Images of Entire Electron Micrographs

New methods are described that should facilitate high-resolution (5–10 Å) image reconstructions from low-dose, low-contrast electron micrographs of frozen-hydrated specimens and processing of large, digital images produced by new imaging devices and modern electron microscopes. Existing techniques for automatic selection of images of individual biological macromolecules from electron micrographs are inefficient or unreliable. We describe the Crosspoint method (CP), which produces good quality solutions with relatively small miss rates and few false hits, and an extension of this method along with a procedure for refining its solution. Two algorithms for processing large images, one based on image subsampling, the other on image decomposition, are described. A large image is first compressed (e.g., by subsampling) and the CP method is applied to the compressed image to produce an initial solution. The information gathered at this stage is used to cut the original image into subimages and then to refine the particle coordinates in each subimage. An interactive environment for experimenting with particle identification methods is described.

Identification of heavy ions in magnetic spectrograph measurements using a plastic phoswich

Abstract Plastic phoswich detectors, consisting of a 400 μm fast scintillator (BC400) and a 22 mm slow scintillator (BC444), were used for heavy ion identification in magnetic spectrograph measurements. While the light output from the phoswich in a fast time gate was sensitive to the Z separation when combined with a Bϱ measurement, the light output in a delayed-long time gate provided mass separation. The method of particle identification with the plastic phoswiches is described in detail.

A105 デローニー三角分割に基づく新しいPIV相関アルゴリズムの提案

In this paper, a new algorithm of particle identification based on Delaunay tessellation is proposed. Delaunay tessellation is a method which connects every scattered nodes to form triangles in either two-dimensional or three-dimensional space. Such a triangulation provides an essential step for spatial analysis of scattered data. Delaunay tessellation can be applied in PIV which deals with the particles in image. A new cross-correlation method for particle identification has been devised and tested by numerical simulation. Good result can be obtained.

Hydrogen content of C60 fullerenes, measured by elastic recoil detection

AbstractThe hydrogen content of thin films of C60 fullerenes, measured by elastic recoil detection (ERD), is investigated. In ERD analysis a new method for particle identification is employed using the ion‐induced electron emission from thin carbon foils. Since the electron emission yield depends on the nuclear charge of the penetrating particle, recoiled H ions and scattered He projectiles can be separated. The reliability and the sensitivity of the technique were checked by analysing a series of ion‐implanted H profiles in silicon. The sensitivity is better than 0.1 at.% H. In as‐grown fullerene films a hydrogen content of about 3 at.% has been found throughout the film. After doping of the fullerene films by ion implantation of K the hydrogen content increased up to 6 at.% in the implanted region.

Three-Dimensional PTV Based on Binary Cross-Correlation Method. Algorithm of Particle Identification.

The present study proposes a new method of particle identification in three-dimensional particle-tracking velocimetry (3D PTV) using binary image data. It is based on the necessary condition for particle identification and the 3D cross-correlation method for evaluating the similarity of particle distribution patterns in two spaces. Computer simulations are carried out to investigate the effects of the sizes of particles, search subregion and identification subregion on the particle identification performance. The method has two key advantages. One is quick and accurate particle identification performance and the other is that the computer memory required for the computation of particle identification is generally small compared to other methods.

二値化相関法による3D-PTVの気泡噴流撹拌流計測への応用

The authors already developed three-dimensional particle tracking velocimetry (3D-PTV) based on a binary correlation method for high speed particle identification. The technique of the 3D-PTV is applied to the measurement of the flows of water and air bubbles in a cylindrical bath with a bottom blowing air bubbling jet.The performance of the stereo matching and reconstruction for threedimensional particle positions and the measurement accuracy of velocity vectors of water flow are discussed. Besides, the trajectories of air bubbles are investigated and discussed.

Identification of particles in air showers using tracking chambers and a thin absorber

Results are presented from a test of the particle identification method used in the GRAND extensive air shower array. This method uses position sensitive chambers to determine the effect of a thin absorber on the trajectories of individual shower particles. The test utilizes actual cosmic ray secondaries which are preselected as muons or as electrons. The results indicate that most muons penetrate the absorber with little scattering while most electrons either stop in the absorber or are scattered. Based on a simple algorithm, 3.4% of muons and 4.4% of electrons are misidentified.

Three-Dimensional PTV Based on Binary Cross-Correlation Method. (Algorithm of Particle Identification).

The purpose of the present study is to propose a new method of particle identification in three-dimensional particle-tracking velocimetry (3D PTV) using binary image data. It is based on the necessary condition for particle identification and the 3D cross-correlation method for evaluating the similarity of particle distribution patterns in two spaces. Computer simulations are carried out to investigate the effects of particle size, search subregions and identification subregions on the performance of particle identification. The method has two key advantages: One is a quick and high efficiency particle identification performance and the other is that the computer memory required for the computation of particle identification is generally smaller compared to the other methods.

45 3次元2値化相関法によるPTVとその必要条件

The purpose of the present study is to propose a new high efficiency particle identification method for 3D PTV, based on a binary cross correlation method and its necessary condition. The effects of sizes of imaginary particle, search subregion, and identification subregion on the particle identification efficiency are discussed through numerical simulation.

Particle identification by modified Bragg-curve centroid detection

A new particle identification method based on the measurement of Bragg-curve centroids using a gas-filled ionization chamber has been improved for detection of low-energy particles around 1 MeV per nucleon by introducing a nonuniform distribution of resistance on the anode electrode. Almost the same quality of Z-resolutions as in the conventional ΔE− E method could be obtained up to Z = 19.

Light particle discrimination using CR-39

A method of light particle identification is proposed to simplify measurements on the products of nuclear reactions. The method is based on etch pit radius measurements in the phase of track development V g t 1 . An appropriate calibration for CR-39 is given. Application of the proposed method was made on the products of negative pion absorption from 7 Li.

プラズマ荷電による微粒子の分級と物質の同定

A plasma-assisted fine particle classification and identification method has been developed by using a Geisler tube with a coneshape electrode. A particle is charged in plasma, in which its surface is covered with the sheath made of double layer of negative and positive ions. The charged particle flies to the positive electrode under high voltage. The flying mode, however, is influenced by the gravity, the collision of plasma ions with the flying particles and the viscosity of the constituent non-charged gas molecules. The newly-developed classification setup is made with three main parts; the Geisler tube, a powder supplier and an evacuation system. The fine powders such as alumina, silica, silicon carbide were classified under the condition of DC voltage of 500V and the tube current of 30mA at 2.0Torr (2.7×102Pa). It is found from the experiments that the finer particles fall down near the upper side of cone electrode, but the coarser ones fly apart from it and that the grains with different mechanical and physical properties can be identified.