The reactor antineutrinos are used for the precise measurement of oscillation parameters in the 3-neutrino model, and also used to investigate active-sterile neutrino mixing sensitivity in the
3
+
1
...neutrino framework. In the present work, we study the feasibility of sterile neutrino search with the indian scintillator matrix for reactor anti-neutrino (ISMRAN) experimental set-up using electron antineutrinos (
ν
¯
e
) produced from reactor as a source. The so-called
3
+
1
scenario is considered for active-sterile neutrino mixing, which leads to projected exclusion curves in the sterile neutrino mass and mixing angle plane. The analysis is performed considering both the reactor and detector related parameters. It is found that, the ISMRAN set-up can observe the active-sterile neutrino mixing sensitivity for
sin
2
2
θ
14
≥
0.064
and
Δ
m
41
2
=
1.0
eV
2
at
90
%
confidence level for an exposure of 1 ton-year by using neutrinos produced from the DHRUVA reactor with thermal power of
100
MW
th
. It is also observed that, there is a significant improvement of the active-sterile neutrino mixing parameter
sin
2
2
θ
14
to
∼
0.03 at the same
Δ
m
41
2
by putting the ISMRAN detector set-up at a distance of 20 m from the compact proto-type fast breeder reactor facility with thermal power of 1250
MW
th
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this work, we present an analysis of the sensitivity to the active-sterile neutrino mixing with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental setup at very short ...baseline. The 3 ( active ) + 1 (sterile) neutrino oscillation model is considered to study the sensitivity of the active-sterile neutrino in the mass splitting and mixing angle plane. In this article, we have considered the measurement of electron antineutrino induced events employing a single detector which can be placed either at a single position or moved between a near and far positions from the given reactor core. Results extracted in the later case are independent of the theoretical prediction of the reactor anti-neutrino spectrum and detector related systematic uncertainties. Our analysis shows that the results obtained from the measurement carried out at combination of the near and far detector positions are improved significantly at higher Δm412 compared to the ones obtained with the measurement at a single detector position only. It is found that the best possible combination of near and far detector positions from a 100 MWth power DHRUVA research reactor core are 7 m and 9 m, respectively, for which ISMRAN setup can exclude in the range 1.4 eV2 ≤ Δ m412 ≤ 4.0 eV2 of reactor antineutrino anomaly region along with the present best-fit point of active-sterile neutrino oscillation parameters. At those combinations of detector positions, the ISMRAN setup can observe the active sterile neutrino oscillation with a 95% confidence level provided that sin22θ14 ≥ 0.09 at Δm412 = 1 eV2 for an exposure of 1 ton-yr. The active-sterile neutrino mixing sensitivity can be improved by about 22% at the same exposure by placing the detector at near and far distances of 15 m and 17 m, respectively, from the compact proto-type fast breeder reactor (PFBR) facility which has a higher thermal power of 1250 MWth.
Image analysis and numerical simulation algorithms are introduced to analyze the micro‐structure, transport, and electrochemical performance of thin, low platinum loading inkjet printed electrodes. A ...local thresholding algorithm is used to extract the catalyst layer pore morphology from focused ion beam scanning electron microscopy (FIB‐SEM) images. n‐point correlation functions, such as auto‐correlation, chord length, and pore‐size distribution are computed to interpret the micro‐structure variations between different images of the same catalyst layer. Pore size distributions are in agreement with experimental results. The catalyst layer exhibits anisotropy in the through‐plane direction, and artificial anisotropy in the FIB direction due to low slicing resolution. Microscale numerical mass transport simulations show that transport predictions are affected by image resolution and that a minimum domain size of 200 nm is needed to estimate transport properties. A micro‐scale electrochemical model that includes a description of the ionomer film resistance and a multi‐step electrochemical reaction model for the oxygen reduction reaction is also presented. Results show that the interfacial mass transport resistance in the ionomer film has the largest effect on the electrochemical performance.
Abstract An experimental study has been performed using 14 MeV neutrons for imaging of low Z material (particularly composed of C, H, O elements) masked with thick layers of dense and high Z ...materials. The experimental setup consists of a D-T neutron generator, a metallic collimator and an imaging system. The imaging system is designed with a polypropylene zinc sulphide scintillator screen integrated with a lens coupled 16-bit ICCD camera. Imaging capability of the system was investigated using iron test samples with holes and line pair features. The minimum hole size of 2 mm could be imaged at a contrast of 36% and a line of 2 mm width visible at a contrast of 24% indicating the system's resolution of ∼ mm. Low Z samples such as water (H 2 O) and polyethylene (C 2 H 2 ) n placed behind thick layers of Pb (40 mm) and Uranium (35 mm), were imaged successfully. These images reveal the system's ability towards low Z material imaging in the presence of heavier metals. Good contrast images acquired at a lower neutron yield of ∼ 5 × 10 8 n/sec of D-T neutron generator has provided a possibility to realise fast neutron imaging having moderate resolution (∼ mm) with a smaller footprint and an economical system design for field applications.
Abstract
Reactivity measurement using noise methods have been carried out in zero power subcritical system BRAHMMA, installed in BARC, India. During noise experiments, an Am-Be neutron source (1Ci) ...has been placed at the centre of the subcritical system. However, the proposed external neutron source in ADS, based on particle accelerator, is different from isotopic neutron source and the inherent fluctuations in beam current and accelerating voltage makes the source non-Poisson. In this context, Degweker and Rana had postulated a noise theory based on exponentially correlated Gaussian source characteristics for ADS. In noise experiments based on this postulate, a D-T neutron generator has been used in pulsed mode and source characterisation has been carried out to determine the distribution function, source correlation factor and D
+
beam pulse shape. It has been observed that the source is Gaussian in nature, the source correlation factor is very large compared to the prompt neutron decay constant and the pulsed D
+
beam is rectangular in shape. In noise experiments, the time stamped data have been analysed using various noise methods. The measured prompt neutron decay constant using Poisson source and correlated Gaussian source are in good agreement with theoretical value and amongst them.
The Indian Scintillator Matrix for Reactor Anti-Neutrino detection—ISMRAN experiment aims to detect electron anti-neutrinos ( e) emitted from a reactor via inverse beta decay reaction (IBD). The ...setup, consisting of 1 ton segmented Gadolinium foil wrapped plastic scintillator array, is planned for remote reactor monitoring and sterile neutrino search. The detection of prompt positron and delayed neutron from IBD will provide the signature of e event in ISMRAN. The number of segments with energy deposit (Nbars) and sum total of these deposited energies are used as discriminants for identifying prompt positron event and delayed neutron capture event. However, a simple cut based selection of above variables leads to a low e signal detection efficiency due to overlapping region of Nbars and sum energy for the prompt and delayed events. Multivariate analysis (MVA) tools, employing variables suitably tuned for discrimination, can be useful in such scenarios. In this work we report the results from an application of artificial neural network—the multilayer perceptron (MLP), particularly the Bayesian extension—MLPBNN, to the simulated signal and background events in ISMRAN. The results from application of MLP to classify prompt positron events from delayed neutron capture events on Hydrogen, Gadolinium nuclei and also from the typical reactor γ-ray and fast neutron backgrounds is reported. An enhanced efficiency of ∼91% with a background rejection of ∼73% for prompt selection and an efficiency of ∼89% with a background rejection of ∼71% for the delayed capture event, is achieved using the MLPBNN classifier for the ISMRAN experiment.
The present work, an intrinsic surface feature-based registration method, is used for the correction of lateral misalignments induced during scanning to acquire freeform sub-aperture data. Gaussian ...curvature is used as an intrinsic pattern which can be defined as one of the fundamental second-order geometric properties of a surface. Any shift in the peaks of Gaussian curvature of the reference and the measured sub-apertures corresponds to lateral misalignments in
X
and
Y
directions, which has to be minimized before registration of sub-apertures into global frame of reference. After precise registration, all the sub-apertures are stitched with consistent overlapping area by using least square fitting method. Numerical validation of the proposed scheme is carried out, and experimental verification demonstrates the effectiveness of the method to improve sub-aperture stitching accuracy.
Multiple Coulomb Scattering (MCS) based muon tomography technique has been considered to be a well-known tool to identify, discriminate, and to image the high-density objects placed inside closed ...volumes. The two most famous reconstruction algorithms are Point of Closest Approach (PoCA) and Maximum Likelihood Expectation Maximization (MLEM). PoCA is fast but purely geometrical and as a result of this, it gives a lot of false positives, i.e. sometimes the PoCA point lies outside the target object and hence it forms an envelope of false-positive which results in a smeared image. On the other hand, MLEM is an iterative algorithm and is much more computation-intensive. In this work a new and innovative method is proposed which is based on the concept of voxelization to handle the known problem of false positives of the PoCA algorithm, and hence provide a clear reconstructed image. These algorithms remove the false positives PoCA points from the 3D point cloud and will give useful information in terms of regions or voxels within a voxelized volume 'V' to do a clear image reconstruction. The advantages of the proposed algorithm to the existing algorithms are also discussed. The status of the experimental setup of the proposed facility using Resistive Plate Chamber(RPC) with spatial resolution of ∼ 1cm as muon detector, is also discussed. The preliminary data from the current experimental setup, showing detector performance and cosmic muon tracks are also shown. Since the experimental setup is not fully ready, the effectiveness of the developed algorithms and the results are evaluated using the data from the Geant4 simulation of the muon tomography setup.
In this article we explore neutron producing schemes using a compact accelerator for producing fast neutrons for nuclear data measurements relevant to GEN-IV reactors and Accelerator Driven Systems ...and also for other applications such as radioisotopes production. The compact accelerator which consists of an Electron Cyclotron Resonance ion source along with a Radio Frequency Quadrupole and Drift Tube Linac is expected to provide p,d and 7Li beams of energies in the range of 0.5–3 MeV/u. Two different neutron producing schemes are examined for their suitability for the above mentioned applications. In the first scheme, using the 7Li(d,n)2 4He reaction, a variety of neutron energies ranging from 1 MeV to 16 MeV with reasonable flux and energy-time characteristics can be generated making it suitable for studies in (n,cp), (n,f) and (n,Xn) reactions important for nuclear fusion technology, security applications and radioisotope production. In the second scheme, the p(7Li,n)7Be reaction can be used to produce quasi mono-energetic neutrons in inverse kinematics mode with very little background making it suitable for high precision nuclear data measurements relevant to GEN-IV reactors and Accelerator Driven Systems.
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