Radiation Measurement System Research Articles

A High-Gain 1.75-GHz Dual-Inductor Transimpedance Amplifier With Gate Noise Suppression for Fast Radiation Detection

High-speed pulse-shape analysis can allow one to extract the physical parameters that govern radiation interaction. This brief presents a transimpedance preamplifier that can replace conventional configurations that contain a charge-sensitive preamplifier and shaping amplifier chain, particularly for high-speed radiation measurement systems. A transimpedance amplifier is a primary circuit of the preamplifier design based on a feedback structure with cascade inverting amplifiers and a feedback resistor, but it incorporates a bandwidth and gain enhancement technique that utilizes a series $LC$ circuit at the input of the amplifier. This configuration is designed to reduce the size, power consumption, and complexity of the front-end circuitry traditionally used in radiation measurements while enhancing pulse-shape analyses by preserving the temporal information of the carriers following radiation impingement. The preamplifier implemented in the 180-nm CMOS process exhibits an 83- $\mbox{dB}\Omega$ transimpedance gain and a 1.75-GHz bandwidth while consuming 48.6 mW using a 1.8-V supply.

Modelling of dynamic experiments in MCNP5 environment

The design of radiation measurement systems includes a modelling phase which ascertains the best 3D geometry for a projected gauge. To simulate measured counts by a detector, the widely-used rigorous phenomenological model is used. However, this model does not consider possible source or/and detector movement during a measurement interval. Therefore, the phenomenological model has been successfully modified in order to consider such a displacement during the time sampling interval in dynamic experiments. To validate the proposed model, a simple radiation system was accurately implemented in the MCNP5 code. The experiments confirmed the accuracy of the proposed model.

Development of radiation tolerance evaluation and measurement system for spaceborne D/A converter

Development of radiation tolerance evaluation and measurement system for spaceborne D/A converter

Enhanced light extraction efficiency of plastic scintillator by photonic crystal prepared with a self-assembly method

Plastic scintillators are extensively used in various radiation measurement systems. However the total internal reflection decreases the scintillation light output, leading to a low detection efficiency especially in these weak signal detection situations. In the present investigation, we have designed a light extraction scheme based on the photonic crystal formed with a monolayer periodic array of polystyrene nanospheres by a self-assembly method. The photonic crystal coated on the surface of plastic scintillator can significantly enhance the light extraction by 120% compared with the plain reference sample under X-ray excitation, which is achieved by the principle of the coupling of evanescent field near the scintillator-air interface with the photonic crystal.

Development of a radiation measurement system based on radiation and heat resistant materials

Development of a radiation measurement system based on radiation and heat resistant materials

Study of the radiated energy loss during massive gas injection mitigated disruptions on EAST

The MGI mitigated disruption experiments were carried out on EAST with a new fast gas controlling valve in 2012. Different amounts of noble gas He or mixed gas of 99% He+1% Ar are injected into plasma in current flat-top phase and current ramp-down phase separately. The initial results of MGI experiments are described. The MGI system and the radiation measurement system are briefly introduced. The characteristics of radiation distribution and radiation energy loss are analyzed. About 50% of the stored thermal energy Wdia is dissipated by radiation during the entire disruption process and the impurities of C and Li from the PFC play important roles to radiative energy loss. The amount of the gas can affect the pre-TQ phase. Strong poloidal asymmetry of radiation begins to appear in the CQ phase, which is possibly caused by the plasma configuration changes as a result of VDE. No toroidal radiation asymmetry is observed presently.

Les collaborations CHG – neurologues libéraux : un mode de fonctionnement très divers. Une enquête du CNNHG

Coherent harmonic generation free-electron laser (CHG-FEL) acts as a harmonic amplifier of the seed laser. The spectral ratio, which is defined as the ratio of coherent radiation intensity and incoherent radiation intensity in infinitesimal bandwidth and solid angle aperture, can evaluate the performance of the CHG-FEL. In the experiment, we can only get the experimental integral ratio integrated over the actual bandwidth and solid angle aperture of the radiation measurement system. Because the coherent radiation and incoherent radiation are very different in the spatial and spectral structure, the experimental integral ratio is greatly influenced by the measurement system and cannot be directly used to evaluate the performance of the CHG-FEL. So, we must calculate the experimental spectral ratio according to the experimental integral ratio, the bandwidth and solid angle aperture of the measurement system and the parameters of the CHG-FEL. Our work provides a simple method for the calculation of experimental spectral ratio.

Twomey effect observed from collocated microphysical and remote sensing measurements over shallow cumulus

Clear experimental evidence of the Twomey effect for shallow trade wind cumuli near Barbados is presented. Effective droplet radius (reff) and cloud optical thickness (τ), retrieved from helicopter‐borne spectral cloud‐reflected radiance measurements, and spectral cloud reflectivity (γλ) are correlated with collocated in situ observations of the number concentration of aerosol particles from the subcloud layer (N). N denotes the concentration of particles larger than 80 nm in diameter and represents particles in the activation mode. In situ cloud microphysical and aerosol parameters were sampled by the Airborne Cloud Turbulence Observation System (ACTOS). Spectral cloud‐reflected radiance data were collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART‐HELIOS). With increasing N a shift in the probability density functions of τ and γλ toward larger values is observed, while the mean values and observed ranges of retrieved reff decrease. The relative susceptibilities (RS) of reff, τ, and γλ to N are derived for bins of constant liquid water path. The resulting values of RS are in the range of 0.35 for reff and τ, and 0.27 for γλ. These results are close to the maximum susceptibility possible from theory. Overall, the shallow cumuli sampled near Barbados show characteristics of homogeneous, plane‐parallel clouds. Comparisons of RS derived from in situ measured reff and from a microphysical parcel model are in close agreement.

An embedded read-out for GM counter

Cost effective embedded design for Geiger Mueller counter biasing and read-out, using a programmable system-on-chip is described in this paper. Geiger Mueller counters (GM-counters) are simple radiation detectors widely used in the area of detection of nuclear occurrences, which require read-out electronics to perform the functions of pulse counting and measurement data display. In addition to this, GM-tubes require high voltage biasing circuitry for their operation. A GM-tube based radiation counter has design requirements such as ruggedness, low power consumption and immunity against interference. These requirements are complex to achieve with conventional hardware circuit design of the read-out systems. In this paper a novel embedded design based on the cypress semiconductor’s single chip programmable-system-on-chip (PSoC), exploiting its mixed signal array of analogue and digital modules is described. Acquired data from GM counter has been communicated to a PC using UART protocol. Calibration procedures performed with the GM counter with the new read-out design is also discussed in this paper. The measurements from this design has been compared with those of existing commercial radiation measurement systems and found to be comparable with commercial off the shelf instruments. This reliable and accurate single-chip embedded design also has high-voltage biasing circuitry for the GM counter in addition to its read-out electronics.

空间目标的地基红外辐射特性测量技术研究

In order to precisely measure infrared radiation characteristics of space target, a radiometric calibration method is presented based on the internal calibration blackbody and external natural star with known infrared spectral characteristics, and on the basis of the proposed method corresponding radiation measuring mathematical model is established. Internal calibration blackbody is used to measure the responsivity of each detector pixel involving the back half light path of the telescope, and the external natural star is used to estimate equivalent transmittance of the atmosphere near target region with the first half light path of the telescope. A large number of infrared radiation intensity measurement experiment show that the accuracy can be better than 15% within 3~5 microns band on the 1.2-m ground based telescope when the target has strong infrared energy reference star and the exoatmosphere irradiance is higher than 11016 W/cm2 order of magnitude. The method can overcome the effects of the atmospheric path radiation, extinction and large diameter radiation calibration source on the measurement precision about infrared radiation intensity of exoatmosphere space target, and it is suitable for calibrating of the ground based infrared radiation measurement system with large diameter and measuring of the infrared radiation characteristics of exoatmosphere space target with high precision.

Descriptive Study of Electromagnetic Wave Distribution for Various Seating Positions

To better understand environmental electromagnetic wave exposure during the use of digital textbooks by elementary school students, we measured numeric values of the electromagnetic fields produced by tablet personal computers (TPCs). Specifically, we examined the distribution of the electromagnetic waves for various students' seating positions in an elementary school that uses digital textbooks. Electric and magnetic fields from TPCs were measured using the HI-3603 Visual Display Terminal/ Very Low Frequency (VDT/VLF) radiation measurement system. Electromagnetic field values from TPCs measured at a student's seat and at a teacher's computer were deemed not harmful to health. However, electromagnetic field values varied based on the distance between students, other electronic devices such as a desktop computers, and student posture while using a TPC. Based on these results, it is necessary to guide students to observe proper posture and to arrange seats at an appropriate distance in the classroom.

An Antenna Measurement System Based on Optical Feeding

A radiation measurement system by using optical feeding is proposed. The system replaces conventional electrical feeding to antennas by the optical feeding which is composed of an electrical/optical (E/O) converter, a graded-index (GI) optical fiber, and an optical/electrical (O/E) converter. The GI fiber is used so as the O/E converter becomes very compact by using a simple means of coupling between the fiber and the photo-diode in the converter. A vertical surface emitting laser (VCSEL) is used in the E/O converter to make the system available till 6 GHz. This combination also makes the system cost-effective. The validity as well as the advantage of the system is demonstrated by measuring an ultra-wideband (UWB) antenna both by the optical and electrical feeding systems and comparing with a calculated result. Ripples in radiation pattern due to the electrical feeding are successfully suppressed by the optical feeding. For example, in a radiation measurement on the azimuth plane at 3 GHz, ripple amplitude of 1.0 dB that appeared in the electrical feeding is reduced to 0.3 dB. In addition, a circularly polarized (CP) antenna is successfully measured by the proposed system to show that the system is available not only for amplitude but also phase measurements.

Development of transportable gamma-ray tomographic system for industrial application

This paper introduces a gamma-ray tomographic system which is transportable and can be used for on-line systems such as a pipeline operation. In a previous study, a feasibility study on a gamma-ray tomographic system with a scanning geometry of Electron Beam CT was carried out by Monte Carlo simulation. This paper contains a successive work on a previous study by developing and evaluating a real system. To construct a gamma-ray CT, 137Cs was used as a gamma-ray source and radiation measurement system with 72 channel CsI detectors whose crystal is a 12mm×12mm×20mm rectangular parallelepiped was developed to operate jointly with a motion control system. ML-EM algorithm was used for image reconstruction of experimental data. Using the developed transportable gamma-ray system, laboratory and field experiments were carried out successfully. The field experiment results show that a gamma-ray CT with an Electron Beam CT scanning geometry can be a transportable gantry for objects which are parts of processes.

Development of a portable survey meter system for the studies of uranium discovery

In this study, a portable radiation measurement system which has a microprocessor-controller was developed for uranium discovery. The developed system has the feature of saving the counting data from a Geiger–Mueller detector and position data from a global positioning system. The pulses obtained from the detector were transferred into a counting input of a microprocessor via a pulse shaper. Evaluation of the pulses has been performed by microprocessor’s software. The results obtained from the developed radiation detection system were compared with those of a calibrated reference detector system. The developed system has some important features such as low current consumption, low cost, small size and lightness.

Airborne hyperspectral observations of surface and cloud directional reflectivity using a commercial digital camera

Abstract. Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements with the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer) showed an agreement within the uncertainties of both instruments (6% for both). The directional reflectivity in terms of the hemispherical directional reflectance factor (HDRF) was obtained for sea ice, ice-free ocean and clouds. The sea ice, with an albedo of ρ = 0.96 (at 530 nm wavelength), showed an almost isotropic HDRF, while sun glint was observed for the ocean HDRF (ρ = 0.12). For the cloud observations with ρ = 0.62, the cloudbow – a backscatter feature typically for scattering by liquid water droplets – was covered by the camera. For measurements above heterogeneous stratocumulus clouds, the required number of images to obtain a mean HDRF that clearly exhibits the cloudbow has been estimated at about 50 images (10 min flight time). A representation of the HDRF as a function of the scattering angle only reduces the image number to about 10 (2 min flight time). The measured cloud and ocean HDRF have been compared to radiative transfer simulations. The ocean HDRF simulated with the observed surface wind speed of 9 m s−1 agreed best with the measurements. For the cloud HDRF, the best agreement was obtained by a broad and weak cloudbow simulated with a cloud droplet effective radius of Reff = 4 μm. This value agrees with the particle sizes derived from in situ measurements and retrieved from the spectral radiance of the SMART-Albedometer.

1P1-E07 自律移動ロボットによる放射線測定システムの検討(車輪型/クローラ型移動ロボット(3))

1P1-E07 自律移動ロボットによる放射線測定システムの検討(車輪型/クローラ型移動ロボット(3))

방사선 측정기의 품질관리 기법에 대한 고찰

In this study, radiation measurement system has been investigated to set up for the radioisotopes analysis in the radioactive waste samples after selecting the radiation counters of alpha beta and gamma nuclides. The counting efficiencies for alpha, beta and gamma measurement systems were calibrated. To obtain stability of the radiation detectors, quality control program has been established. Also, minimum detectable activities (MDAs) depending on the type of samples were calculated for increasing the confidence level for analytical result.

Transfiguration of extracting mirror in synchrotron radiation system at SSRF

The first extracting mirror is very important for synchrotron radiation monitor (SRM). The SRM system of SSRF (Shanghai Synchrotron Radiation Facility) should extract the visible light with low optical distortion. The analysis of SR power spectrum and heat transfiguration based on Matlab is introduced in this paper, which will be used in calibration. One beryllium mirror with water-cooling is used to transmit X-ray and reflect visible light to satisfy the measurement request. The existing system suffers from a dynamic problem in some beam physics study. The system includes optics, image acquisition and interferometers. One of the instruments is a digital camera providing the image of the beam transverse profile. The hardware configuration will be summarized. The synchrotron radiation measurement system has been in operation in SSRF for more than one year.

A new natural gamma radiation measurement system for marine sediment and rock analysis

A new high-efficiency and low-background system for the measurement of natural gamma radioactivity in marine sediment and rock cores retrieved from beneath the seabed was designed, built, and installed on the JOIDES Resolution research vessel. The system includes eight large NaI(Tl) detectors that measure adjacent intervals of the core simultaneously, maximizing counting times and minimizing statistical error for the limited measurement times available during drilling expeditions. Effect to background ratio is maximized with passive lead shielding, including both ordinary and low-activity lead. Large-area plastic scintillator active shielding filters background associated with the high-energy part of cosmic radiation. The new system has at least an order of magnitude higher statistical reliability and significantly enhances data quality compared to other offshore natural gamma radiation (NGR) systems designed to measure geological core samples. Reliable correlations and interpretations of cored intervals are possible at rates of a few counts per second.

Measurement of natural background radiation intensity on a train

This work aims to measure different components of natural background radiation on a train. A radiation measurement system consisting of four types of radiation detectors, namely, a Berkeley Lab cosmic-ray detector, moderated (3)He detector, high-pressure ionisation chamber and NaI(Tl) spectrometer, associated with a global positioning system unit was established for this purpose. For the commissioning of the system, a test measurement on a train along the railway around the northern Taiwan coast from Hsinchu to Hualien with a distance of ∼ 275 km was carried out. No significant variation of the intensities of the different components of natural background radiation was observed, except when the train went underground or in the tunnels. The average external dose rate received by the crew of the train was estimated to be 62 nSv h(-1).