Position Sensitive Detector Research Articles

Simultaneous Gamma-Neutron Vision device: a portable and versatile tool for nuclear inspections

This work presents GN-Vision, a novel dual γ-ray and neutron imaging system, which aims at simultaneously obtaining information about the spatial origin of γ-ray and neutron sources. The proposed device is based on two position sensitive detection planes and exploits the Compton imaging technique for the imaging of γ-rays. In addition, spatial distributions of slow- and thermal-neutron sources (<100 eV) are reconstructed by using a passive neutron pin-hole collimator attached to the first detection plane. The proposed gamma-neutron imaging device could be of prime interest for nuclear safety and security applications. The two main advantages of this imaging system are its high efficiency and portability, making it well suited for nuclear applications were compactness and real-time imaging is important. This work presents the working principle and conceptual design of the GN-Vision system and explores, on the basis of Monte Carlo simulations, its simultaneous γ-ray and neutron detection and imaging capabilities for a realistic scenario where a 252Cf source is hidden in a neutron moderating container.

Laser-enabled dual-state transformation on PANI:PSS/Si for wavelength-selective detection

Position-sensitive detectors are widely used in industry due to accurate sensing of changes in light position. The introduction of additional wavelength selectors can cause deviations in light position and affect the performance of the devices. In this work, an organic–inorganic heterojunction of polyaniline-poly (p-styrenesulfonic acid) (PANI:PSS)/p-Si is proposed to achieve selective detection at optical wavelengths using the lateral photovoltaic effect. The maximum reduction of sensitivity in the detection of 405 nm laser can reach up to 127.59 mV/mm, with a decrease in about 99%. When the device is exposed to blue-violet light, the absorption layer changes from a Si layer to a PANI:PSS layer, which weakens the photon utilization efficiency and charges carrier transport. The self-generated longitudinal voltage further enhances the absorption of the PANI:PSS layer for blue-violet light. PANI absorbs photon energy to generate electron–hole pairs and transitions from the reduced state to the oxidized state in the depletion region at the contact interface. The oxide layer hinders carrier separation and increases carrier recombination. Due to the inherent properties of the structure, the wavelength selection function is realized by the detector itself, enriching its original single function. The sensitivity in other light bands has been improved, including more than three times at 520 nm compared to p-Si. These results have provided the theoretical foundation for highly selective and tunable optoelectronic devices while helping to overcome the challenges of high manufacturing costs and customized application scenarios. They provide a viable solution for the intelligent development of optoelectronic devices.

Advanced picosecond precision Radio Frequency Timer

A new type of radio frequency (RF) timing technique is presented. It is based on a helical deflector, which performs circular or elliptical sweeps of photo- or secondary electrons, accelerated to keV energies, by means of RF fields in the 500–1000 MHz range. By converting a time distribution of the electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing, similar to streak cameras. Detection of the scanned electrons, using a position sensitive detector based on microchannel plates and a delay line anode, resulted in a timing resolution of 10 ps, which can be potentially improved to 1 ps. RF-Timer-based single photon and heavy ion detectors have potential applications in different fields of science and industry, which include high energy nuclear physics and imaging technologies. This technique could play a crucial role in developing of sub 10 ps Time-of-Flight Positron Emission Tomography.

Position Sensitive Detector Based on Microchannel Plates for Measuring the Characteristics of Fission Fragments at the MAVR Facility

Position Sensitive Detector Based on Microchannel Plates for Measuring the Characteristics of Fission Fragments at the MAVR Facility

Position-sensitive hybrid particle detector based on discrete-time readout

In this work a new readout scheme for scintillator-based detectors, using discrete time differences through a delay line is proposed, reducing the readout channels while maintaining the spatial resolution. A prototype was built using plastic scintillator blocks and MPPC sensors. Currently, the prototype produces discrete distributions with a dispersion <1.1ns which allows discriminating the different positions. The estimated spatial resolution is σ=1.456mm. This value presents a better resolution than that of Time-of-Flight detectors and of the order of Segmented detectors, but uses fewer readout channels. It is expected to improve this resolution using interpolation effects and testing with larger scale instruments.

A high-sensitivity SnSe/Si heterojunction position-sensitive detector for ultra-low power detection.

Position-sensitive detectors (PSDs) based on the lateral photovoltaic effect are crucial components in non-contact distance measurement, process control, guidance systems, and other related applications. However, PSDs are challenging due to the narrow spectral range and low sensitivity, limiting further practical application. Here, we present an ultra-sensitive SnSe/Si PSD device. A large-area uniform SnSe nanorod (NR) array film was grown on Si using a glancing-angle magnetron sputtering deposition technique and a SnSe/Si heterojunction PSD device was fabricated. PSDs exhibit an excellent photoresponse in a wide spectral range of 405-980 nm, showing an ultrahigh position sensitivity of 1517.4 mV mm-1 and an excellent spectral sensitivity of 4 × 104 V W-1. More importantly, the detection limit power of the device is as low as 10 nW, indicating the outstanding potential for weak light detection. Based on the unique structural features and interface effect, the mechanisms for the remarkable performance of the fabricated SnSe/Si PSD device are clarified. This work indicates the large potential of SnSe/Si heterojunctions as a promising material for ultrasensitive optical position-sensitive devices.

Search for toroids in excited nuclear material

Ground state nuclei usually have compact geometries. However, there have been theoretical predictions that excited nuclei can take on more extended shapes such as toroids or bubbles. There have been many attempts to identify signatures of such shapes in experimental data. One signature, both predicted by theory and reported in experimental data, is narrow resonances at high excitation energy in peripheral intermediate-energy heavy-ion collisions. This potential evidence for toroidal states was reported in the alpha particle disassembly of 28Si after collision with a 12C target at 35 MeV/nucleon. The prior work was limited by angular resolution and statistical uncertainties. The present work aims to measure the excitation energy distribution for these disassembly events with improved angular resolution and reduced statistical uncertainty using the Forward Array Using Silicon Technology (FAUST). FAUST is equipped with resistive dual-axis duo-lateral (DADL) position-sensitive silicon detectors capable of sub-millimeter position resolution. The measured excitation energy distributions of 7-α disassembly events showed no strong evidence for highly excited states at the cross section and widths suggested by previous experiment.

Position-sensitive Transformer aerial image object detection model

Position-sensitive Transformer aerial image object detection model

Development of a mosaic-type array formed by Si photodiodes for charged-particle detection in heavy-ion collisions

Silicon (Si) detectors find widespread application in heavy-ion collisions. In order to achieve a position-sensitive charged-particle detection with a relatively low cost, we have developed a mosaic-type array based on off-the-shelf Si photodiodes (Hamamatsu S13955-01). Its high modularity allows one to modify the geometric configuration of the array according to specific experimental requirements. In this contribution, characteristics of the photodiode tested with α source and experimental results of the α-decay spectroscopy are presented.

Noncontact Self-Vibration Compensated Position Sensitive Detector Based Low-Frequency Vibration Measurement

Noncontact Self-Vibration Compensated Position Sensitive Detector Based Low-Frequency Vibration Measurement

Non-contact position and orientation measurement system used one dimensional optical position sensor fusion

Non-contact position and orientation measurement system used one dimensional optical position sensor fusion

A high linearity and wide dynamic range readout circuit with saturation monitoring for position sensitive detection

A high linearity and wide dynamic range readout circuit with saturation monitoring for position sensitive detection

Position-sensitive non-destructive detection of charged-particle bunches in low-energy beamlines

We have developed and operated an electronic detection system for the non-destructive single-pass detection of bunches of charged particles in a beamline that allows for a measurement of their lateral position with respect to the central beamline axis on a shot-to-shot basis. It provides all features of our related development reported in Kiffer et al. (Rev Sci Instrum 90:113301, 2019), namely single-pass measurement of bunch length, kinetic energy and absolute charge, and is additionally designed to provide the lateral position of bunches with sub-mm accuracy. We show the setup, associated methods and provide characterizing measurements with bunches of highly charged ions in the keV regime of kinetic energy that demonstrate the capabilities and show a typical application.

Spatio-Temporal Processes in the Position-Sensitive Detector with Moving Current–Voltage Characteristic

Spatio-Temporal Processes in the Position-Sensitive Detector with Moving Current–Voltage Characteristic

Optical photon transport simulations for SiPM based PET scanner

Positrons emitted from radioisotope quickly annihilates to two collinear photons that are captured by the array of scintillator detectors to infer about the origin of radioactivity. Coincidence collection of pair of points from the detector modules makes a line of response, their large number reveals a radioactive region of interest. Most of the medical diagnostic research is conducted with position sensitive imaging device whose performance strongly depends on the optical light collection efficiency. A versatile Lutetium–Yttrium Oxyorthosilicate (LYSO) scintillator is used to mimic the optical photon production and transport processes followed by the light collection with Silicon PhotoMultiplier sensor. Charge spectrum from a 2 × 2 × 10 mm3 single LYSO bar is obtained in GEANT4, and reproduces well the scintillation characteristics of LYSO along with photons incidence angle distribution with a single SiPM pad. This excercise is followed by the simulation performance of two PET modules comprises of 12 × 12 SiPM tile coupled with mesh of LYSO bars. The preliminarly results shows the transverse position resolution (FWHM) as 7.82 mm for a point source. Objective of this study is to search for a cheaper detector solution which will have equivalent imaging performance.

Remote detection of bovine serum albumin (BSA) using cantilever beam magnetometer

Detection of bovine serum albumin (BSA) is important to comprehend the severity of a certain diseases. Here, we report on the remote detection of bovine serum albumin (BSA) using modified cantilever beam magnetometery (CBM). A magnetostrictive Fe70Ga30 cantilever in combination with optical detection technique allowed us to detect BSA concentration up to 1 mg/mL in a remote way. Essentially, a position sensitive detector (PSD) is used to detect reflected light from cantilever without any optical mirrors. Apart from the above, magnetostriction of Fe70Ga30 cantilever estimated as 80 ppm at 180 mT. We ascertain that our method is easy and efficient in estimating the magnetostriction of thin films up to 10-6 order. We believe that CBM technique that we developed would be helpful in estimating magnetostriction of bulk and thin films apart from the detection of bio – molecules.

One-dimensional position-sensitive detector for alpha particles using an outer-layer scintillating fiber

For applications of detecting alpha contamination and identifying its location over a wide area at a time in nuclear plants and radiation facilities, a position-sensitive detector for α-rays based on an outer-layer scintillating (OLS) fiber with silicon photomultiplier (SiPM) readout was developed. While a standard scintillating fiber is unable to detect α-rays due to their short range, the OLS fiber has a thin scintillation layer on its surface that enhances its potential for α-ray measurements. We initially performed measurements using an Am-241 source to compare the α-ray-detection capability of the OLS fiber with that of a conventional scintillating fiber. Subsequently, a position-sensitive detector employing the time-difference method was developed to measure the radiation distribution along the fiber in a one-dimensional format. The time and spatial resolutions of the measurement system, which used a single 2.2-m-long fiber, were estimated to be approximately 3.6 ns and 290 mm full width at half maximum (FWHM), respectively. Results from two Am-241 sources placed simultaneously indicated that the resolving capability to distinguish the two sources of the measurement system was <300 mm.

A new detector concept based on the prompt gamma radiation analysis for In vivo boron monitoring in BNCT.

The problem of boron concentration monitoring during the boron neutron capture therapy (BNCT) therapy is one of the main challenges of this type of radiotherapy and is directly related to the nature of the interaction of neutrons with mater. Among the available in vivo methods of boron monitoring positron emission tomography seems to be very promising but it requires a new boron carrier with a β+ emitter, which is not yet clinically available. An alternative solution may be the prompt gamma radiation analysis (PGRA) based on the secondary radiation emitted in the interaction of neutrons with the patient's tissues. This method requires, however, compact gamma radiation detection systems sustaining high counting rates and characterized by very good energy resolution. In this contribution, we present state-of-the-art solutions for monitoring in BNCT based on PGRA. Moreover, we describe a new concept of such a system based on position-sensitive scintillator detectors equipped with an anti-Compton shield and data analysis supported with modern artificial intelligence algorithms.

Analysis of Error Sources in the Lissajous Scanning Trajectory Based on Two-Dimensional MEMS Mirrors

Deviations or distortions in the trajectoy of MEMS-based Lissajous scanning imaging platforms might be detrimental to imaging quality. These deviations often arise from differences in MEMS mirror frequency response characteristics and asymmetry in parameters within the measurement and control circuit. This study concentrated on the measurement and control circuit unit as it identified and analyzed four error sources: the MEMS mirror frequency response error, the AD acquisition synchronization error, the drive source error, and the cross-coupling error between the MEMS mirror axes. This study constructed a Lissajous trajectory test platform based on oscilloscopes and a position sensitive detector. Consequently, its experimental results guided the error processing methods to access the feasibility of the compensation methods by combining measured trajectories. Overall, regarding MEMS-based Lissajous scanning platforms for biomedical imaging, this study could provide quantitative numerical references for error analysis, image reconstruction, and aberration correction.

Development and evaluation of laser acoustic measurement system for supersonic jet noise

Acoustic measurements in the near field are significant to suppress the noise generated by a supersonic jet. The microphone measurement is commonly used to measure noise, but it is not appropriate for the jet noise measurement in the near field, because it may be broken or disturb the sound field. In this study, we propose an optical acoustic measurement method using a laser and a 2-D position sensitive detector. This system can measure the propagating direction and the spectra of acoustic waves by detecting the angle and direction of laser path deflection by acoustic wave passing. To evaluate this laser measurement method, it was applied to various supersonic jet noise phenomena, such as Mach waves and screech tones, and then the results were compared with those of microphone measurements. The spectra measured by the laser measurement show good agreement with those by microphone measurements, and the difference in OASPL was less than 0.7 dB. As for the propagating direction, it is calculated using the principal component analysis in the laser measurement, and its results also show good agreement with those of acoustic intensity vector measurement.