Nuclear Detectors Research Articles

Detection and identification of Pu particles and HEU particles by nuclear detectors CR-39

Two parameter approach –a new technique has been devised and tested to identify and distinguish Pu–bearing particles from U-bearing particles. This technique can be used to select rare and microscopic Pu-bearing particles from environmental samples, such as in soil, water, air (aerosol) and swipe samples from the wall of buildings and surfaces of machines in nuclear factories. Some amount of Pu and U standard reference materials were respectively added to cellulose nitrate (CN) solution and dropped some quantity of the solution on mica plates and dried to from CN sheets. CR-39 track detectors were used to record tracks of α particles emitted from the Pu or U particles in CN sheets. After etching of CR-39 plates, α track stars were developed and can be seen under optical microscope. Tracks shapes of α particles in the stars were investigated. We found that at certain interval of etching time, the tip part of α tracks of Pu was very sharp, but the tip part of α tracks of U was blunted with spherical tips. The ratio Rt/Ro of the diameter (Rt) of tip point to the diameter (Ro) of the round track in center area of star is a superior parameter to identify Pu from U particles. The Rt/Ro measurements should be carried at a certain distance from the center point. The two parameter approach has been using in nuclear safeguards and nuclear forensics to analyze isotopic compositions and age of Pu samples.

Investigation on Cd1-xMnxTe grown by traveling heater method with redissolution process and Te inclusions on carrier transport uniformity of detector

Cd1-xMnxTe compound semiconductor is an ideal material for room-temperature nuclear detector. In this paper, the Traveling Heater Method (THM) with redissolution process has been adopted for the growth of Cd1-xMnxTe crystal. The as-grown Cd1-xMnxTe crystals have been investigated in the respects of crystalline size, Te inclusion distribution, resistivity, and carrier transport performance. The results show that redissolution process can increase the crystalline size and reduce the Te inclusions of crystal. The resistivity of crystal grown by THM with redissolution process is (2.7–5.6) × 109 Ω⋅cm, and it is (4.9–7.1) × 109 Ω⋅cm for crystal grown without redissolution process. The carrier mobility and lifetime product (μτ) of crystal grown with redissolution process is >10−3 cm2/V, which is about seven times larger than that of crystal grown without redissolution process. SEM and Cathodoluminescence (CL) tests were used to research the micro-morphology of Te inclusions and the distribution of defects induced by them, which show that the size of induced defect around Te inclusion is about 3.5 times that of Te inclusion. Accordingly, the effect of Te inclusions and induced defects on carrier transport uniformity of Cd1-xMnxTe detector was calculated by a proposed model.

Optimizing Thermal Detectors for Low-Threshold Applications in Neutrino and Dark Matter Experiments

Nuclear recoil detectors with low energy thresholds of 10–100 eV have applications in both neutrino physics (e.g. coherent elastic neutrino-nucleus scattering and neutrinoless double beta decay) as well as for $$\mathscr {O}$$ (GeV)-mass dark matter searches. Cryogenic crystal detectors are well suited for these applications, although some require very large masses which can be achieved with arrays of these detectors. An optimization of a design focusing on ease of fabrication and mass production while retaining low energy thresholds is presented. This is achieved by decoupling the complex lithography of the thermal sensor from the large crystal absorber/target, while optimizing the thermal time constants to retain the lowest threshold possible.

Correlated Production and Analog Transport of Fission Neutrons and Photons Using Fission Models FREYA, FIFRELIN, and the Monte Carlo Code TRIPOLI-4

Fission modeling in general-purpose Monte Carlo transport codes often relies on average nuclear data provided by the international evaluation libraries. As such, only average fission multiplicities are available and correlations between fission neutrons and photons are missing. Whereas uncorrelated fission physics is usually sufficient for standard reactor core and radiation shielding calculations, correlated fission secondaries are required for specialized nuclear instrumentation and detector modeling. For coincidence counting detector optimization for instance, the precise simulation of fission neutrons and photons that remain correlated in time from birth to detection is essential. New developments were recently integrated into the Monte Carlo transport code TRIPOLI-4 to model fission physics more precisely, the purpose being to access event-by-event fission events from two different fission models: Fission Reaction Event Yield Algorithm (FREYA) and Fission Fragment Evaporation Leading to an Investigation of Nuclear Data (FIFRELIN). TRIPOLI-4 simulations can now be performed, either by connecting via an application programming interface to the Lawrence Livermore National Laboratory fission library including FREYA, or by reading the external fission event data files produced by FIFRELIN beforehand. These new capabilities enable us to easily compare results from the Monte Carlo transport calculations using the two fission models in a nuclear instrumentation application. In the first part of this paper, the broad underlying principles of the two fission models are recalled. We then present the experimental measurements of neutron angular correlations for 252Cf(sf) and 240Pu(sf). The correlations were measured for several neutron kinetic energy thresholds. In the latter part of this paper, simulation results are compared with the experimental data. Spontaneous fissions in 252Cf and 240Pu are modeled by FREYA or FIFRELIN. Emitted neutrons and photons are subsequently transported to an array of scintillators by TRIPOLI-4 in the analog mode to preserve their correlations. Angular correlations between fission neutrons obtained independently from these TRIPOLI-4 simulations, using either FREYA or FIFRELIN, are compared with the experimental results. For 240Pu(sf), the measured correlations were used to tune one of the FREYA model parameters. Similarly, different sets of parameters have been tested in FIFRELIN to try to improve the agreement with the experimental data.

Physical–chemical characterization of a GEM side-on 10B-based thermal neutron detector and analysis of its neutron diffraction performances

The synergic interplay between nuclear physics, detector technology and solid state and surface sciences is a fundamental aspect of the development of new neutron detection devices. The synthesis technique and the physical–chemical properties of the B4C films used as a neutron-to-charged particle converter are described in relation to the GEM side-on thermal neutron detector. Neutron detection is performed allowing scattered neutrons to be converted into charged particles by means of a series of sheets covered by 10B-enriched boron carbide (B4C) layers placed along their flight path inside the detector. The extremely interesting performance shown by the detector in neutron diffraction measurements at the ISIS spallation neutron sources are discussed and related to the chemical–physical properties of the converting layers.

Supernova neutrino physics with a nuclear emulsion detector

The existence of the coherent neutrino-nucleus scattering reaction requires to evaluate, for any detector devoted to WIMP searches, the irreducible background due to conventional neutrino sources and at same time, it gives a unique chance to reveal supernova neutrinos. We report here a detailed study concerning a new directional detector, based on the nuclear emulsion technology. A Likelihood Ratio test shows that, in the first years of operations and with a detector mass of several tens of tons, the observation of the supernova signal can be achieved. The determination of the distance of the supernova from the neutrinos and the observation of 8B neutrinos are also discussed.

P-MOSFET latch-based monolithic signal-processing circuit for nuclear event detector

This paper presents a p-MOSFET latch-based nuclear event detector signal-processing circuit which is implemented using a commercial standard 0.35-μm CMOS process. A positive-feedback loop consisting of a p-MOSFET with a common-source configuration and a photocurrent compensation MOSFET are used to offset the transient radiation effects. Additionally, a timer circuit containing an on-chip timer capacitor serves to reduce the response time. To mitigate the total ionizing dose effect, all n-MOSFETs are laid out using dummy gate-assisted n-MOSFETs.The measured response time of the fabricated chip is 12.2 ns. After measuring the electrical characteristics of the fabricated chip, the chip is exposed to 60Co gamma rays at a dose of 1.14 Mrad (Si). Even after exposure to radiation, the performance of the irradiated chip is nearly identical to that of a non-irradiated chip. To evaluate the upset threshold with regard to the dose rate of the fabricated chip, the chip is also exposed to prompt gamma rays with different dose rates, and the measured dose rate upset threshold is found to exceed 1.9×107rad(Si)/s.

Estimation of indoor radon levels using etched track detector

In this investigation, the activity levels of Indoor Radon-222, effective radium contents, exhalation rate of radon, and annual effective dose are reported for different indoor locations (Offices, Laboratories, Meeting rooms, and Storerooms) at two students divisions (boys, and girls) in science college, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia. Sealed-can technique based on CR-39 nuclear tracks detector was distributed to radon gas survey. The obtained results indicate normal levels of indoor radon concentration and effective radium content in all locations of the studied area. A strong correlation (R2 = 1) has been observed between effective radium content and radon exhalation rate. There is a slight increase in the values of exhalation rate at all locations. The average values of annual effective dose for boys division are 1.26, 1.51, 2.02, and 2.38 mSvy−1 for meeting rooms, offices, storerooms, and laboratories, respectively. For girls division, the average values of annual effective dose are 0.86, 0.95, 1.53, 0.78 mSvy−1 for meeting rooms, offices, storerooms, and laboratories, respectively.

Synthesis of Titanium Nanoparticles in Liquid Xenon by a High-Voltage Discharge

The formation of titanium nanoparticles (NPs) in a high-voltage electric discharge between titanium electrodes in liquid xenon at a temperature of –105°C has been observed. It has been shown that these titanium nanoparticles have a spherical shape with an average diameter of <50 nm and they possess high chemical activity. This makes it possible when a relative mass concentration of NP reaches ~10–6 to efficiently purify xenon from electronegative impurities for its use as a working medium for a new generation of high-efficiency nuclear radiation detectors.

Determination of the crystallographic orientation of SrI2 crystals

Single crystals of strontium iodide (SrI2), an important material for nuclear detector applications, are grown commercially in cylindrical ampoules using the Bridgman self-seeding method. As a result, the axial orientation of Bridgman boules varies from run to run. Most crystal growth methods benefit from the use of oriented seeds, which can be helpful in maximizing growth rates and crystal quality. However, it is very difficult to orient SrI2 crystals because they are deliquescent and their surfaces damage easily during cutting and polishing. In this study, unpolished facets formed on an edge-defined film-fed growth (EFG) boule were used to generate the first Laue patterns. The principal boule used in this study had a square cross section and was grown using a seed cut from along the growth axis of a Bridgman boule. X-ray analysis showed that the EFG boule grown from this seed grew along the b-axis and the side facets were the (1 0 0) and (0 0 1) faces. This work made possible the fabrication of oriented SrI2 seeds for use in future EFG and Czochralski growth experiments and allowed for the determination of the optic axes using polarized light.

Multifractal Analysis of Charged Particle Multiplicity Distribution in the Framework of Renyi Entropy

A study of multifractality and multifractal specific heat has been carried out for the produced shower particles in nuclear emulsion detector for16O-AgBr,28Si-AgBr, and32S-AgBr interactions at 4.5AGeV/c in the framework of Renyi entropy. Experimental results have been compared with the prediction of Ultra-Relativistic Quantum Molecular Dynamics (UrQMD) model. Our analysis reveals the presence of multifractality in the multiparticle production process in high energy nucleus-nucleus interactions. Degree of multifractality is found to be higher for the experimental data and it increases with the increase of projectile mass. The investigation of quark-hadron phase transition in the multiparticle production in16O-AgBr,28Si-AgBr, and32S-AgBr interactions at 4.5 AGeV/c in the framework of Ginzburg-Landau theory from the concept of multifractality has also been presented. Evidence of constant multifractal specific heat has been obtained for both experimental and UrQMD simulated data.

Capabilities of the Monte Carlo Simulation Codes for Modeling of a Small Animal SPECT Camera.

This study aims to compare Monte Carlo-based codes' characteristics in the determination of the basic parameters of a high-resolution single photon emission computed tomography (HiReSPECT) scanner. The geometry of this dual-head gamma camera equipped with a pixelated CsI(Na) scintillator and lead hexagonal hole collimator were accurately described in the GEANT4 Application for the Tomographic Emission (GATE), Monte Carlo N-particle extended (MCNP-X), and simulation of imaging nuclear detectors (SIMIND) codes. We implemented simulation procedures similar to the experimental test for calculation of the energy spectra, spatial resolution, and sensitivity of HiReSPECT by using 99mTc sources. The energy resolutions simulated by SIMIND, MCNP-X, and GATE were 17.53, 19.24, and 18.26%, respectively, while it was calculated at 19.15% in experimental test. The average spatial resolutions of the HiReSPECT camera at 2.5cm from the collimator surface simulated by SIMIND, MCNP-X, and GATE were 3.18, 2.9, and 2.62mm, respectively, while this parameter was reported at 2.82mm in the experiment test. The sensitivities simulated by SIMIND, MCNP-X, and GATE were 1.44, 1.27, and 1.38cps/μCi, respectively, on the collimator surface. Comparison between simulation and experimental results showed that among these MC codes, GATE enabled to accurately model realistic SPECT system and electromagnetic physical processes, but it required more time and hardware facilities to run simulations. SIMIND was the most flexible and user-friendly code to simulate a SPECT camera, but it had limitations in defining the non-conventional imaging device. The most important characteristics like time and speed of simulation, preciseness of results, and user-friendliness should be considered during simulations.

Effect of final state interactions on neutrino energy reconstruction at DUNE

We quantitatively study the percentage of fake events present in CCQE and CCRes interactions and the impact of final state interactions on the neutrino oscillation parameters at DUNE. The effect of final-state interactions for DUNE oscillation physics is analyzed in an ideal and realistic detector scenario. Resonance interaction will be the most dominant interaction in the oscillation sensitive region of DUNE. The νμ-disappearance oscillation channel is studied using LAr detector. We find that nuclear effects and detector threshold play a significant role in CCQE and CCRes interactions and these nuclear effects induce a significant bias in the determination of atmospheric neutrino oscillation parameters. The impression of nuclear effects on the determination of θ23 is quantified in this work, which will help in reducing the systematic error at DUNE.

Performance test of radiation detectors developed for ITER-TBM

The validation of calculation tools used for the nuclear design and analysis of future fusion machines requires the availability of nuclear instrumentation able to measure the nuclear quantities of interest in the harsh environments typical of tokamaks (e.g. ITER) characterized by high radiation level and high temperature. This instrumentation needs to be developed and properly tested under reactor-relevant working conditions. In the EU the activities to develop advanced nuclear detectors for the ITER-TBM are coordinated and supported by F4E and carried out under a collaborative effort between ENEA and KIT performed under the European Consortium on “Nuclear Data and Experimental Techniques”.In this paper the activities carried out at ENEA Frascati to develop nuclear sensors (diamond and self-powered detectors) able to operate “in-core” under the harsh working conditions of the ITER-TBM are discussed. Furthermore, the performance of diamond detectors operated at T >300 °C, as well as the performance of a self-power neutron detector (SPND) made with Cr emitter are presented.The open issues and the technological challenges to be faced to further develop the detectors are also addressed.

A high-impedance detector-array glove for magnetic resonance imaging of the hand.

Densely packed resonant structures used for magnetic resonance imaging (MRI), such as nuclear magnetic resonance phased-array detectors, suffer from resonant inductive coupling, which restricts coil design to fixed geometries, imposes performance limitations, and narrows the scope of MRI experiments to motionless subjects. Here, we report the design of high-impedance detectors, and the fabrication and performance of a wearable detector array for MRI of the hand, that cloak themselves from electrodynamic interactions with neighboring elements. We experimentally verified that the detectors do not suffer from signal-to-noise degradation mechanisms typically observed with the use of traditional low-impedance elements. The detectors are adaptive and can accommodate movement, providing access to the imaging of soft-tissue biomechanics with unprecedented flexibility. The design of the wearable detector glove exemplifies the potential of high-impedance detectors in enabling a wide range of applications that are not well suited to traditional coil designs.

Alternative Approach to Extract the Bulk Etching Rate of PADC Nuclear Detector

The paper aims to propose the maximum track length (L max ) measurement as an alternative approach to evaluate and extract the bulk etch rate (V b ) of the nuclear detector PADC CR-39, and compare it with the results obtained by the removal layer thickness measurement of the etched detector. The alternative L max -method mainly relies on the measuring the length of the etched tracks, their maximum values and saturation times from the obtained track profile images. The detectors were irradiated with different energies of alpha particles emitted from the 241 Am source and then etched in a 6.5 N NaOH solution at 70�1 o C for different successive time intervals. In order to calculate V b , the maximum length of the tracks and their saturation times were determined corresponding to the energies of the alpha particles used. A direct proportion between the maximum length of the tracks and the energy of the alpha particle was observed. However, the value of V b is found to be 1.344�0.0202 mm h -1 obtained using the L max -method, and it was consistent with that computed by the method based on the measurement of the thickness difference of the etched detector which was 1.354�0.065 mm h -1 .

A Nuclear Emulsion Detector for the Muon Radiography of a Glacier Structure

Cosmic ray muons can be used to image the interior of geological sites provided that one employs detectors able to operate in the specific harsh conditions of the mountain environment. We designed and developed a detector exploiting the nuclear emulsion technique to assess the bedrock profile underneath an alpine glacier. Nuclear emulsions do not need any electric power supply or maintenance and allow for the measurement of the muon flux and direction behind a large target volume. The 3D density distribution of the material traversed by muons can then be assessed, bringing relevant information on the shape of the boundary between the glacial ice and the underlying bedrock. This new methodology in the geological field was recently tested in a campaign of measurements in the Jungfrau region of the central Swiss Alps. It was shown that the bedrock surface position can be measured with a resolution of about 5 % when the traversed target is about 100 m thick. Characteristics and performance of the method are reported here and demonstrate that muon radiography based on emulsion detectors represents a powerful tool for the geological study of glaciers.

Studi Distribusi Fluks Neutron Termal dan Energi yang Dihasilkan Linac Menggunakan Detektor CR-39 pada Medium Air

Linac surgery is required in radiotherapy activities. However, if Linac operated more than 8 MV can cause additional radiation of neutrons, as well as triggers forming secondary cancer. The study was conducted to determine the distribution of thermal neutron flux and energy responses on the trace. One method to detect neutrons is to use a nuclear trace detector. Measurements were made using a CR-39 detector coated with a Boron radiator. A number of detectors were placed on the surface of the sphere and entered into a 30×30×30 cm 3 fantom. Irradiation is done by placing fantom under Linac gantry with 100cm SSD distance. After irradiation, then etching. The results of the measurements showed that the distribution of thermal neutron fluxes spread in all directions. Linac 10 MV neutron flux value varies, starting at 0° of 1,637×10 3 n/cm 2 .s and decrease at 135°of 1.285×10 3 n/cm 2 s. The highest Linac 15 MV at detector position 0° of 10.723x10 4 n/cm 2 .s and decreased at 135° of 5.142x10 4 n/cm 2 s. This proves that the farther from the source the less the thermal neutron flux value due to the collision process. While Linac 10 MV and 15 MV produce range of diameter ranging from 8.21-16.75 (μm) and 9.21-17.45 (μm), with energy response value 0.5-3.5 MeV. The larger the energy response, the smaller the diameter and vice versa, this is due to the effect of penetration on the depth of the distance resulting in smaller track.

Studi Distribusi Fluks Neutron Termal dan Energi yang Dihasilkan Linac Menggunakan Detektor CR-39 pada Medium Air

Linac surgery is required in radiotherapy activities. However, if Linac operated more than 8 MV can cause additional radiation of neutrons, as well as triggers forming secondary cancer. The study was conducted to determine the distribution of thermal neutron flux and energy responses on the trace. One method to detect neutrons is to use a nuclear trace detector. Measurements were made using a CR-39 detector coated with a Boron radiator. A number of detectors were placed on the surface of the sphere and entered into a 30×30×30 cm 3 fantom. Irradiation is done by placing fantom under Linac gantry with 100cm SSD distance. After irradiation, then etching. The results of the measurements showed that the distribution of thermal neutron fluxes spread in all directions. Linac 10 MV neutron flux value varies, starting at 0° of 1,637×10 3 n/cm 2 .s and decrease at 135°of 1.285×10 3 n/cm 2 s. The highest Linac 15 MV at detector position 0° of 10.723x10 4 n/cm 2 .s and decreased at 135° of 5.142x10 4 n/cm 2 s. This proves that the farther from the source the less the thermal neutron flux value due to the collision process. While Linac 10 MV and 15 MV produce range of diameter ranging from 8.21-16.75 (μm) and 9.21-17.45 (μm), with energy response value 0.5-3.5 MeV. The larger the energy response, the smaller the diameter and vice versa, this is due to the effect of penetration on the depth of the distance resulting in smaller track.

Palladium(II) Picoline Thiourea Complex as Homogenous Catalyst in Heck Cross-Coupling Reaction in the Formation of C=C Bond

Palladium (II) complex containing picoline thiourea (Pd-PTu) was prepared by reacting bis (benzonitrile) palladium (II) chloride (Pd-PhCN) withN’-2-(5-picolyl)-N-4-bromobenzoylthiourea (PTu). All synthesized compounds have been characterized via several selected typical spectroscopic and analytical techniques namely elemental analysis, Infrared (IR) spectroscopy, Ultraviolet-visible (UV-Vis) spectroscopy, Nuclear Magnetic Resonance (1H and13C NMR) and gas chromatography-flame ionization detector (GC-FID). For Pd-PTu, IR spectrum showed significant shift in the ν (C=N) on the pyridine ring and ν (C=S) stretching vibration at around 30cm-1compared to the free ligand. The finding indicated that the expected coordination of ligand to the palladium metal centre took place via N and S atoms. The catalytic reaction was monitored using GC-FID with conversion of 83.81 %, proved that Pd-PTu can be used as an ideal homogenous catalyst in any Heck cross-coupling reactions in the near future.