Abstract
The application of muon tomography method in small scale, for the imaging of a five-centimeter side lead cube, is being examined in the present work. The representation of the object is ...being achieved by using the transmission muography technique, in which the “free-sky” muon flux is compared to the muon flux measured within the acceptance of the detector. This comparison yields information about the absorption of the muons as they pass through the object under investigation. Also, a projective reconstruction method called “Back Projection” is tested by being applied on the data, providing information about the location of the object and its dimensions. This project has been carried out within the frame of EKATY programme, which aims to the innovative imaging of the subsurface of archaeological sites and the interior of structural elements of monuments in three and four dimensions.
Abstract
Within the frame of the EKATϒ programme, whose purpose is the innovative imaging of the subsurface of archaeological sites and the interior of structural elements of monuments in “three” and ...“four” dimensions, the applicability of Muon Tomography technique in the representation of a tumulus is tested in the present work. The scanning of its internal structure is accomplished by measuring the flux deficit of cosmic muon tracks in the presence of an object inside the tumulus, compared to the muon flux when traversing a uniform tumulus (transmission muography). The feasibility study of the method is achieved with a simulation of the tumulus geometry and the structure under investigation. Following the simulation process, a tracking telescope, consisting of four MicroMegas detectors and two trigger plastic scintillators, will be placed near Apollonia’s tumulus to collect data. For the specific latitude where the Apollonia’s tumulus is located, the energy and angular muon distribution at sea level is studied. Implementing the dimensions of the telescope in the simulation, the back-projection method is examined for the localization of the hidden object and the estimation of its dimensions. The method is tested for the telescope optimal position, placed under the tumulus, and the realistic one, placed near the tumulus at the level of its base.
The steadily increasing luminosity of the LHC requires an upgrade with high-rate and high-resolution detector technology for the inner end cap of the ATLAS muon spectrometer: the New Small Wheels ...(NSW). In order to achieve the goal of precision tracking at a hit rate of about 15 kHz/cm2 at the inner radius of the NSW, large area Micromegas quadruplets with 100µm spatial resolution per plane have been produced. IRFU, from the CEA research center of Saclay, is responsible for the production and validation of LM1 Micromegas modules. The construction, production, qualification and validation of the largest Micromegas detectors ever built are reported here. Performance results under cosmic muon characterization will also be discussed.
Resonance parameters for neutron induced reactions in 106,108,110,111,112,113,114,116Cd have been evaluated. The parameters are the result of an analysis of experimental data available in the ...literature together with a parameter adjustment to transmission and capture data obtained at the time-of-flight facility GELINA. The parameters derived from the GELINA data are in reasonable agreement with those quoted in the literature. From the analysis of the GELINA transmission data a thermal neutron total cross section equal to 2450±40b has been deduced for natCd at 300K. This value is in agreement with results of previous measurements which have been performed at thermal reactor beams using different techniques. It differs by about 1.5% from the value 2413b which was recently deduced from an adjustment to results of an integral experiment. The GELINA transmission and capture data in the low energy region are not fully consistent with resonance parameters recommended in evaluated data files. The impact of the resonance parameters obtained in this work on cadmium transmission factors and on the interpretation of an integral experiment is discussed.
Monte Carlo simulation of the n_TOF Total Absorption Calorimeter Guerrero, C.; Cano-Ott, D.; Mendoza, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2012, Letnik:
671
Journal Article
Recenzirano
The n_TOF Total Absorption Calorimeter (TAC) is a 4π BaF2 segmented detector used at CERN for measuring neutron capture cross-sections of importance for the design of advanced nuclear reactors. This ...work presents the simulation code that has been developed in GEANT4 for the accurate determination of the detection efficiency of the TAC for neutron capture events. The code allows to calculate the efficiency of the TAC for every neutron capture state, as a function of energy, crystal multiplicity, and counting rate. The code includes all instrumental effects such as the single crystal detection threshold and energy resolution, finite size of the coincidence time window, and signal pile-up.
The results from the simulation have been validated with experimental data for a large set of electromagnetic de-excitation patterns: β-decay of well known calibration sources, neutron capture reactions in light nuclei with well known level schemes like natTi, reference samples used in (n,γ) measurements like 197Au and experimental data from an actinide sample like 240Pu. The systematic uncertainty in the determination of the detection efficiency has been estimated for all the cases. As a representative example, the accuracy reached for the case of 197Au(n,γ) ranges between 0.5% and 2%, depending on the experimental and analysis conditions. Such a value matches the high accuracy required for the nuclear cross-section data needed in advanced reactor design.
A new set of measurements for the total and capture cross section determination of W isotopes was done using GELINA (GEel LINear Accelerator), a neutron Time-Of-Flight facility at the Institute for ...Reference Materials and Measurements (IRMM). Measuring stations at different flight path lengths were used in order to cover a broad neutron energy range with high resolution demands. Experimental techniques adopted for both transmission and capture measurements are well established using a ^6Li glass detector and C_6D_6 scintillation arrays as detections systems respectively. As target samples highly enriched ^(182,183,184,186)W metallic discs were used. KCI Citation Count: 4
A data format for time-of-flight spectra (transmission, reaction andself-indication yields) and their covariance matrices based on the AGS(Analysis of Geel Spectra) format is discussed in ...collaboration betweenEC-JRC IRMM and IAEA-NDS for the EXFOR library. Experimentalists areencouraged to consider the uncertainty propagation following the AGSprinciple and submission of their data to the International Networks NuclearReaction Data Centres (NRDC) for EXFOR compilation using a proposedtemplate. KCI Citation Count: 10
Cross section measurements have been performed at the time-of-flight facility GELINA to determine the average capture cross section for
197
Au in the energy region between 3.5 keV and 84 keV. Prompt ...γ-rays, originating from neutron-induced capture events, were detected by two C
6
D
6
liquid scintillators. The sample was placed at about 13m distance from the neutron source. The total energy detection principle in combination with the pulse height weighting technique was applied. The energy dependence of the neutron flux was measured with a double Frisch-gridded ionization chamber based on the
10
B(n,α) reaction. The data have been normalized to the well-isolated and saturated
197
Au resonance at 4.9 eV. Special care was taken to reduce bias effects due to the weighting function, normalization, dead time and background corrections. The total uncertainty due to normalization, neutron flux and weighting function is 1.0%. An additional uncertainty of 0.5% results from the correction for self-shielding and multiple interaction events. Fluctuations due to resonance structures have been studied by complementary measurements at a 30m flight path station. The results reported in this work deviate systematically by more than 5% from the cross section that is recommended as a reference for astrophysical applications. They are about 2% lower compared to an evaluation of the
197
Au(n, γ) cross section, which was based on a least squares fit of experimental data available in the literature prior to this work. The average capture cross section as a function of neutron energy has been parameterized in terms of average resonance parameters. Maxwellian average cross sections at different temperatures have been calculated.
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