Detector Box Research Articles

Periodic sampling and count rate correction of the low energy X-ray telescope on board the Insight- Hard X-ray modulation telescope

The Low Energy X-ray Telescope (LE) is an important instrument of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT), which performs scanning and point observation in the soft X-ray energy band (0.7–13 keV). Since its launch in 2017, it has conducted a large number of scientific observations and achieved significant astronomical discoveries. LE is composed of three detector boxes and an electronic control box. The data acquisition system of LE is designed to use periodic sampling, which solves the problem of unstable noise peaks. Data loss may occur when observing X-ray bursts, and periodic sampling provides a method of correcting light curves. In addition, in the South Atlantic Anomaly (SAA) or where the count rate of the particle monitor on the Insight-HXMT is very high, LE automatically switches into SAA operating mode, and only a small number of events are recorded. After data correction, the light curves can be estimated to expand the astronomical achievements of LE.

Large-volume CdZnTe bar detectors characterized by laser-induced transient currents

In this work, we studied the free-carrier transport properties and space-charge formation/polarization in a CdZnTe bar-shaped radiation detector using the Laser-Induced Transient Current technique. We found out that a steady-state space charge ranging from 8 × 108 to 2.1 × 109 cm−3 is formed throughout the detector at about 0.5 s following biasing. The measured current waveforms were modeled by Monte Carlo simulations after taking into account the electric and weighting fields inside the detector and shielding box. Modeling of the unpolarized waveforms revealed an exceptionally high electron mobility-lifetime product μeτe≥0.095cm2V−1. The observed formation of positive space charge in the biased detector and linear scaling of the current waveform shapes on applied bias revealed that the detector polarization is attributed to carrier injection at the anode. Measurements in pulsed and DC bias in modified electrode geometry proved the surface-charge formation.

Overview on the progress of the conceptual studies of a gamma ray spectrometer instrument for DEMO

The future DEMO tokamak will be equipped with a suite of diagnostics which will operate as sensors to monitor and control the position and operation parameters of DT plasmas. Among the suite of sensors, an integrated neutron and gamma-ray diagnostic system is also studied to verify its capability and performance in detecting possible DEMO plasma position variations and contribute to the feedback system in maintaining DEMO DT plasma in stable conditions. This work describes the progress of the conceptual study of the gamma-ray diagnostic for DEMO reactor performed during the first Work-Package contract 2015–2020. The reaction of interest for this Gamma-Ray Spectrometer Instrument (GRSI) consists of D(T, γ)5He with the emission of 16.63 MeV γ rays. Due to DEMO tokamak design constraints, the gamma and neutron diagnostics are integrated, both featuring multi-line of sight (camera type), viewing DEMO plasma radially with vertical (12) and horizontal (13) viewing lines to diagnose the γ and neutron emission from the DT plasma poloidal section. The GRSI design is based on the investigation of the reaction cross sections, on the calculations performed with GENESIS and MCNP simulation codes and on the physics and geometry constrains of the integrated instrument. GRSI features long collimators which diameters are constrained by the neutron flux at the neutron detectors of the Radial Neutron Camera (RNC) system placed in front, which are key to control DEMO DT plasma position. For these reasons, only few GRSI parameters can be independently selected to optimize its performance. Among these, the choice of the collimator diameters at the back side of the neutron detector box up to the GRSI detector, the use of LiH neutron attenuators in front of the GRSI detectors, the GRSI detector material and shielding. The GRSI detector is based on commercial LaBr3(Ce) inorganic scintillating crystal coupled with a photomultiplier tube or a silicon photomultiplier. They are designed to operate at high count rate although GRSI geometry constraints severely impact on this feature. The GRSI can also provide an independent assessment of DEMO DT fusion power and T burning.

The Low Energy X-ray telescope (LE) onboard the Insight-HXMT astronomy satellite

The low energy (LE) X-ray telescope is one of the three main instruments of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT). It is equipped with Swept Charge Device (SCD) sensor arrays with a total geometrical area of 384 cm2 and an energy band from 0.7 keV to 13 keV. In order to evaluate the particle induced X-ray background and the cosmic X-ray background simultaneously, LE adopts collimators to define four types of Field Of Views (FOVs). LE is constituted of three detector boxes (LEDs) and an electric control box (LEB) and achieves a good energy resolution of 140 eV at 5.9 keV, an excellent time resolution of 0.98 ms, as well as an extremely low pileup (<1% at 18000 cts/s). Detailed performance tests and calibration on the ground have been performed, including energy-channel relation, energy response, detection efficiency and time response.

The CNESM neutron imaging diagnostic for SPIDER beam source

The PRIMA project aims at the construction of two ITER-NBI facilities in Padova (Italy). The first one is called SPIDER which is negative H/D 100 keV RF source, while the second one (MITICA) will be a full scale 1 MeV deuterium beam injector as the one that will be used in ITER. In order to resolve the horizontal beam intensity profile in MITICA and one of the eight beamlets groups in SPIDER, the Close-contact Neutron Emission Surface Mapping (CNESM) system is being developed. The goal of this device is to reconstruct the D− beam evaluating the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. For this reason, the CNESM diagnostic, which is based on nGEM detectors for fast neutrons, will be placed right behind the SPIDER and MITICA beam dump, i.e. in an UHV (Ultra High Vacuum) environment. Since the nGEM detectors need to operate at atmospheric pressure a vacuum sealed detector box has been designed to be installed inside the vacuum vessel and able to sustain atmospheric pressure inside. This paper describes the status of the CNESM diagnostic and underlines the different phases followed during the realization and installation of the diagnostic on the SPIDER beam dump as well as its imaging performances.

Description of complex viewing geometries of fusion tomography diagnostics by ray-tracing.

Ray-tracing techniques are applied to bolometry, a diagnostic where the finite collection volume is particularly sensitive to the machine and detector configuration. A technique is presented that can handle arbitrarily complex aperture and collimator geometries, neglecting reflection effects. Sight lines from the ASDEX Upgrade bolometer foils were ray-traced with a path tracing algorithm, where the optical path is represented by a statistical bundle of ray paths connecting the foil surface with the slit geometry. By using the full 3D machine model for the detector box and first wall, effects such as occlusion and vignetting were included in the calculation of the bolometer's étendue. Inversion matrices calculated with the ray-tracing technique were compared with the more conventional single-ray approach and shown to be naturally more constrained, requiring less regularisation. The two models were tested on a sample radiation scenario, and the common single-ray approximation is shown to be insufficient. These results are particularly relevant for the divertor where strong emission gradients may be present. The technique developed generalises well to arbitrarily complex viewing geometries and collimators, opening up a new design space for bolometer configurations that might not normally have been considered.

English

The detection of leaf area in plants is a very important parameter to evaluate growth rates. Nowadays, this analysis is performed manually through a process of counting, cutting and weighing leaf that involves long periods of time, providing subjective results and with low repeatability. The purpose of this research was to develop a computational tool (leaf detector box) to detect leaf area through image processing techniques. The methodology implemented based on application of image processing techniques to segment leaves. Later, morphological operations were apply to eliminate objects that were not part of leaf. Finally, the leaf area was identified through a conversion of pixel to squared centimeter. The validation results showed a determination coefficient greater than 0.97 for four species of plants analyzed with regard to manual analysis by a technical expert. In addition, it validated in a set of 40 leaves precision of algorithm implemented carrying on three measurements for each one at different positions. The results showed a variance of 0.00024 for orange tree leaves, 0.007 for lemon tree leaves, 0.008 for almond tree leaves and 0.001 for mango tree leaves, indicating precision of algorithm providing similar results when it was applied in different opportunities to one leaf. Therefore, the tool becomes a reliable technological support in process of detection leaf area allowing reducing long periods of time and subjectivity in process. Likewise, the repeatability in results were increased. Key words: Leaf area, growth rates, computational tool, image processing, morphological operations, coefficient of determination.

Outline Design of ITER Radial X-Ray Camera Diagnostic

The radial X-ray camera (RXC) is designed to measure the poloidal profile of plasma X-ray emission with high spatial and temporal resolution. Its primary diagnostic role includes measuring low (m, n) magnetohydrodynamic modes, sawteeth and disruption precursors, H-mode, edge-localized modes, and L-H transition. The RXC comprises two subsystems, i.e., in-port and ex-port cameras that view the outer and core regions, respectively, through vertical slots in the diagnostics shield module of an equatorial port plug. Detailed camera design is in progress including design of the camera structure, electronics, data acquisition and control, calibration, and pretest on the EAST tokamak. The sight path and neutron shielding have been optimized. The secondary vacuum, heat insulation, cooling, positioning, and calibration have been designed. The structure analysis results for the external camera indicate that even under five times gravity acceleration, the maximum stress was still below the allowable stress. The heat analysis results indicate that the maximum temperature on the detector box was ~56°C, which is within the detector operation temperature limit. The neutronics analysis results indicate that the detectors can be operated during the whole deuterium-deuterium phase without detector replacement. The electronics group and instrumentation and control group have also made good progress.

Laue Diffraction Using Scintillator Detectors

The Fast Acquisition Laue Camera for Neutrons (FALCON) is a thermal neutron Laue diffractometer at HZB in Berlin. The instrument comprises two scintillator plate detectors coupled to four iCCD cameras each. One detector is placed in the backscattering position, enabling neutrons to pass through the centre of the detector box. The second detector is free to be placed either in the direct transmission position, or rotated to positions around the sample. The image-intensified CCDs, supplied by Photonic Science Ltd as components of the detector units, are capable of obtaining 20-bit digitization Laue images in under ten seconds. Whilst our instrument will be used as a diffractometer primarily for crystal structure determination, the configuration of the detectors is similar to ICON at PSI in Switzerland, especially in their ‘double detector set-up’. In 2015 FALCON enters the commissioning phase whereby one of our activities will be to calibrate the detector units using CONRAD, the cold neutron imaging instrument of HZB. CONRAD will be used to characterise those factors which affect the total efficiency of the detectors i.e. cameras, lenses, CCD chips and the scintillators themselves e.g. homogeneity of the scintillator plate thickness.

The data aggregation problem in quantum hypothesis testing

We discuss the implications of quantum-classical Yule-Simpson effect for quantum hypothesis testing in the presence of noise, and provide an experimental demonstration of its occurrence in the problem of discriminating which polarization quantum measurement has been actually performed by a detector box designed to measure linear polarization of single-photon states along a fixed but unknown direction.

Multiple Modality $\gamma$-Ray Imager Using LaCl$_{3}$(Ce) Scintillators With Active Collimation Method

Multiple modality γ-ray imaging using mechanical and electronic collimation with different detection methods was proposed and tested by simulation. Although conventional mechanical collimators, which are made from high atomic number and density materials, passively filter the incident radiation, the mechanical collimator reported in this study consisted of LaCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (Ce) scintillators, which actively collimate the radiation and are used as the 1st detector of an electronic collimator to reconstruct a Compton image. A detector box made from six planar LaCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (Ce) scintillators was positioned behind the active collimator. The LaCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (Ce) scintillator arrays used as the active collimator and box detector consisted of voxels, each 2 mm × 2 mm × 5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in size. A combination of active collimators and box detectors can produce multiple modalities for both mechanical and electronic collimation. The information from each modality was combined effectively using the maximum likelihood expectation maximization (MLEM) method. Therefore, a reconstructed image from multiple modalities has inherently higher efficiency than each conventional modality. The reconstructed images were evaluated using the resolution-variance curve as a quantitative method. Although mechanical collimation is effective at low γ-ray energy and electronic collimation shows high performance at high γ-ray energy, multiple modalities are superior to the conventional single modalities for intermediate γ-ray energies (364 keV). The angular resolution and absolute efficiency were calculated for each modality and source energy.

Multiphoton adaptation of a commercial low-cost confocal microscope for live tissue imaging

The Nikon C1 confocal laser scanning microscope is a relatively inexpensive and user-friendly instrument. We describe a straightforward method to convert the C1 for multiphoton microscopy utilizing direct coupling of a femtosecond near-infrared laser into the scan head and fiber optic transmission of emission light to the three-channel detector box. Our adapted system can be rapidly switched between confocal and multiphoton mode, requires no modification to the original system, and uses only a few custom-made parts. The entire system, including scan mirrors and detector box, remain under the control of the user-friendly Nikon EZ-C1 software without modification.

Monte Carlo simulations of a high-resolution X-ray CT system for industrial applications

An X-ray computed tomography (CT) model based on the GEANT4 Monte Carlo code was developed for simulation of a cone-beam CT system for industrial applications. The full simulation of the X-ray tube, object, and area detector was considered. The model was validated through comparison with experimental measurements of different test objects. There is good agreement between the simulated and measured projections. To validate the model we reduced the beam aperture of the X-ray tube, using a source–collimator, to decrease the scattered radiation from the CT system structure and from the walls of the X-ray shielding room. The degradation of the image contrast using larger beam apertures is also shown. Thereafter, the CT model was used to calculate the spatial distribution and the magnitude of the scattered radiation from different objects. It has been assessed that the scatter-to-primary ratio (SPR) is below 5% for small aluminum objects (approx. 5 cm path length), and in the case of large aluminum objects (approx. 20 cm path length) it can reach up to a factor of 3 in the region corresponding to the maximum path length. Therefore, the scatter from the object significantly affects quantitative accuracy. The model was also used to evaluate the degradation of the image contrast due to the detector box.

Soft x-ray measurement of the toroidal pinch experiment RX reversed field pinch plasma using transition edge sensor calorimeter

A superconductive transition edge sensor (TES) calorimeter is for the first time applied for the diagnostics of the reversed field pinch plasma produced in the toroidal pinch experiment RX (TPE-RX), and the instrumental system is fully described. The first result from the soft x-ray spectroscopy in 0.2–3keV with an energy resolution ∼50eV are also presented. The TES calorimeter is made of a thin bilayer film of titanium and gold with a transition temperature of 151mK and its best energy resolution at our laboratory is 6.4eV, while it was significantly degraded by about a factor of eight during the plasma operation. The TES microcalorimeter was installed in a portable adiabatic demagnetization refrigerator (ADR), which is originally designed for a rocket experiment. The detector box is carefully designed to shield the strong magnetic field produced by the ADR and TPE-RX. The ADR was directly connected to TPE-RX with a vacuum duct in the sideway configuration, and cooled down to 125mK stabilized with an accuracy of 10μK rms using an improved proportional, integral, and derivative (PID) control method. Thin aluminized Toray Lumirror or Parylene-N films were used for the IR to UV blocking filters of the incident x-ray window to allow soft x-rays coming into the detector with good efficiency. TPE-RX was operated with the plasma current of Ip=220kA, and the wave forms of the TES output for every plasma shot lasting ∼80ms were obtained with a digital oscilloscope. The wave forms were analyzed with the optimal filtering method, and x-ray signals were extracted. A total of 3472 counts of x-ray signals were detected for 210 plasma shots during the flat-top phase of t=35–70ms. Combined with the data measured with a lithium drifted silicon detector in the 1.3–8keV range, spectral features are investigated using a spectral fitting package XSPEC. The obtained spectrum is well explained by thermal plasma emission, although an impurity iron-L line emissions at variously ionized states are dominant around 0.7–1.2keV. At least three different temperature components ranging T=350–900eV are required to account for the spectral shape, while the average temperature is consistent with the ruby laser Thomson scattering measurement.

First application of a TES microcalorimeter to a thermonuclear fusion plasma experiment

We report the first application of a superconductive transition edge sensor (TES) microcalorimeter to a thermonuclear fusion plasma experiment in the toroidal pinch experiment RX (TPE-RX). The TES microcalorimeter was installed in a portable adiabatic demagnetization refrigerator (ADR), which is originally designed for a rocket experiment. The ADR was directly connected to TPE-RX with a vacuum duct, and thin Toray–Lumirror or parylene films were used for entrance windows to allow soft X-rays coming into the detector with good efficiency. The detector box was designed to shield the strong magnetic field produced by ADR and TPE-RX. A total of 3472 counts of X-ray signals were detected in 0.2–3.0 keV for 210 plasma shots during the flat-top phase (35–70 ms) after discarding pile-up events. Combining the data with that measured in the energy range of 1.3–8 keV using a SiLi detector, we examined a wide band X-ray spectrum of the plasma. The obtained spectrum is dominated by thermal plasma emission, although at least four different temperature components are required to account for the whole band spectral shape. Impurities in the deuterium plasma are also investigated.

Simulation of the ALTEA experiment on the International Space Station with the Geant 3.21 program

The ALTEA (Anomalous Long Term Effects in Astronauts) project is aimed at the study of the transient and long term effects of cosmic particles on the astronauts’ cerebral functions. The detector will fly on the International Space Station in 2005. Due to the complexity of the detector (12 double silicon detector boxes arranged around the head of the astronaut) it is necessary to have a detailed simulation of the apparatus response to cosmic ray nuclei in order to assess the detector response and its observational capabilities. The ALTEA detector was therefore simulated by using the Geant 3.21 program, by the astronauts’ head described by 64 cubes of water. By using Creme96 program to evaluate the cosmic rays fluxes within the International Space Station we obtained the events distribution and the energy lost in the cubes of water, as well as the expected interaction rates. Furthermore, we calculated the triggered events number per unit of time in the detector. The simulation was also used to develop a technique to recognize the cosmic rays nuclei.

Development of a Gamma-Ray Box (GARBO)

Isomer decays, β–γ and electron–γ spectroscopy, α–γ fine structure studies, and Coulomb excitation are cases of nuclear structure experiments where the ideal detector is a compact, highly segmented, very efficient germanium (Ge) detector box. In order to develop such a structure, we are working on the R&D of large, segmented, high-purity planar Ge strip detectors (HPGeDSSD) which form the walls of such a box. We have developed a 92mm×92mm×20mm HPGeDSSD, which has 16×16 orthogonal strips of 5mm width. We are in the process of designing a focal plane detector for the Argonne fragment mass analyzer which consists of a five-sided box, each side having a HPGeDSSD backed by a large segmented clover HPGe detector. MCNP simulations indicate this detector would have an efficiency of ∼60% for 122keV gamma rays and ∼15% for 1.33MeV radiation, which is ideal for studying the decays of nuclei far from stability that are usually produced with very low cross-sections.

An Inexpensive Detector for Gas Chromatography

We have developed a low-cost (parts cost approximately $70) detector that can be used in a freshman level class to demonstrate the fundamental principles of gas chromatography (GC). The detector box can be used in a modification of experiments available in the literature which do not enable a quantitative method of analysis. We have used it with success in a freshman class of approximately 450 students in an experiment to separate chlorinated hydrocarbons via GC. Natural gas is used as the carrier gas, a commercial GC column packing is the separating medium, and a Beilstein detector generates a green flame when the halocarbon is burned as it exits the column. The detector box is equipped with a CdS detector selective for the green light emitted and gives a signal that is quantitatively measured by an appropriate means such as a strip chart recorder or computer interfaced terminal panel.The detector box has a limit of detection on the order of 0.5 to 5 mg and shows a linear response over a sixfold change i...

Detector system of the first focal plane of the spectrometer SMART at RIKEN

A detector system of the first focal plane of SMART, the 135 MeV/u high-resolution spectrometer at RIKEN Accelerator Research Facility, is described. It consists of a pair of multi-wire drift chambers and a trigger scintillator hodoscope contained in a He-filled detector box. A major subject using this system is the measurement of the (d, 2He) reaction making the most of its large angular and momentum acceptances. Without seriously sacrificing the detection efficiency, reasonably good energy and angular resolutions for 2He, 460 keV and 9 mrad (FWHM), respectively, have been achieved after optimizing the optics property of the spectrometer.

Design of a new CCD-camera neutron radiography detector

A new electronic neutron radiography detector has been designed at the Paul Scherrer Institute with the aim of providing a tool for scientific and industrial radiography applications requiring high-quantitative precision. The basic principle of the detector is the combination of a CCD-camera with a neutron-sensitive scintillator screen. The light from the screen is reflected to the camera by a mirror and focused on the CCD-chip by a lens. Shielding components to protect the camera from radiation damage include radiation protection windows located in the optical path between mirror and lens. The whole assembly is placed in a detector box which functions as a positioning device and light-tight enclosure. The detector has been optimized for use at the future neutron radiography station at the continuous spallation source SINQ but can also be moved easily to other neutron sources. The detector has been tested at several facilities and its performance has been studied regarding dynamic range and spatial resolution as well as the reduction of interference factors.