DOCSLIB.ORG

Measuring Neutron Absorption Cross Sections of Natural Platinum Via Neutron Activation Analysis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Measuring Neutron Absorption Cross Sections of Natural Platinum Via Neutron Activation Analysis Measuring Neutron Absorption Cross Sections of Natural Platinum via Neutron Activation Analysis By Nick Petersen A thesis submitted to Oregon State University Department of Physics Corvallis, Oregon In partial fulfillment of the requirements for the degree of Bachelor of Science Presented June 11, 2012 Commencement June 17, 2012 Abstract: This thesis presents a measurement of the resonance integral and thermal cross section – which together represent the total neutron absorption cross section – of the naturally occurring isotopes of platinum that emit gamma radiation upon neutron absorption. The measurements were made via neutron activation analysis. Platinum samples were bombarded by neutrons produced in Oregon State University’s TRIGA nuclear reactor. Afterwards, the decay of the excited samples was measured to determine the activity of each isotope, yielding measurements of the cross sections for each. This experiment was repeated multiple times in different reactor locations to improve accuracy. Previous measurements of these values have been flawed by poor photon detector resolution, and evolving branching ratios, half-lives, natural abundances. A search of the literature reveals poor agreement and large error estimations. The results from this thesis are consistent, with one exception: there appears to be a systematic disagreement between the resonance integral measurements of samples bombarded in two different reactor locations. This discrepancy has now been seen in several experiments, which indicates inconsistent epithermal flux throughout OSU’s reactor. i TABLE OF CONTENTS 1 INTRODUCTION .......................................................................................................................................................... 1 1.1 MOTIVATION .............................................................................................................................................. 1 1.2 CROSS SECTION AND NEUTRON ENERGY .................................................................................................... 2 1.3 DECAY SCHEME AND NUCLEAR SPIN .......................................................................................................... 5 1.4 PLATINUM ISOTOPES ................................................................................................................................... 6 2 EXPERIMENTAL METHODS .................................................................................................................................... 8 2.1 EXPERIMENT OVERVIEW............................................................................................................................. 8 2.2 INDEPENDENT EXPERIMENTS ...................................................................................................................... 8 2.3 FLUX MONITORS ....................................................................................................................................... 11 2.4 CAPTURE OF GAMMA SPECTRA ................................................................................................................ 11 2.4 DATA ANALYSIS ....................................................................................................................................... 12 2.5 DETECTOR EFFICIENCY ............................................................................................................................. 14 3 RESULTS ...................................................................................................................................................................... 16 3.1 CLICIT RESULTS ...................................................................................................................................... 16 3.2 CADMIUM-ENCLOSED RABBIT RESULTS ................................................................................................... 17 3.3 NON CADMIUM-ENCLOSED RABBIT RESULTS........................................................................................... 19 3.4 THERMAL COLUMN RESULTS ................................................................................................................... 20 3.5 UNCERTAINTY CALCULATIONS ................................................................................................................. 21 4 DISCUSSION ............................................................................................................................................................... 22 4.1 PREVIOUS RESULTS .................................................................................................................................. 22 4.2 PT-190 → PT-191 CROSS SECTION ........................................................................................................... 23 4.3 PT-194 → PT-195M CROSS SECTION ........................................................................................................ 24 4.4 PT-196 → PT-197G CROSS SECTION ......................................................................................................... 24 4.5 PT-196 → PT-197M CROSS SECTION ........................................................................................................ 24 5.6 PT-198 → PT-199G CROSS SECTION ......................................................................................................... 24 5 CONCLUSION ............................................................................................................................................................. 26 6 ACKNOWLEDGEMENTS ......................................................................................................................................... 27 7 REFERENCES ............................................................................................................................................................. 28 ii 1 INTRODUCTION 1.1 Motivation The neutron absorption cross sections of the naturally occurring isotopes of Pt (190, 192, 194, 196, 198) have not been adequately measured. Some of the values have been published in the literature only once or twice, and some of these measurements were done in the 1970s or earlier when technology (specifically photon detectors) was simply not good enough to do cross section measurements with a reasonable degree of accuracy. For example, the epithermal cross section (resonance integral)for neutron capture of Pt-198 to the metastable state of Pt-199 has been presented only twice in the literature and the average of the two is smaller than their standard deviation. See Tables 9 and 10 in Section 4.1 for more literature values. This thesis presents a methodical measurement of the neutron absorption cross sections of all natural Pt isotopes that produce radioisotopes following neutron capture (190, 194, 196, 198). Pt is noteworthy for the fact that when two of the stable isotopes (196 and 198) absorb a neutron, each product (197 and 199 respectively) has two possible product nuclei: a ground state and a more highly excited metastable state. The ground state of Pt-197 has a nuclear spin of 1/2 while the ground state of Pt-199 has nuclear spin of 5/2. In both cases, the excited metastable state product has a nuclear spin of 13/2. The ground and metastable states have different half-lives and emit different energy gamma rays upon decay, so the thermal neutron absorption cross section and epithermal resonance integral are considered separate for each state, even though the parent nucleus is the same. Pt-195 also has metastable and ground states with spins of 13/2 and 1/2 respectively. However, the ground state is stable and therefore cannot be probed with neutron activation analysis. Only the metastable state of Pt-195 was measured. For this experiment, the metastable state of Pt-199 could not be measured due to its extremely short half-life (13.6 s). It proved impossible to retrieve the samples and place them in front of a detector fast enough to record meaningful data. Also, the reaction Pt-192 → Pt-193 was not measured because Pt-192 has an extremely low natural abundance and Pt-193 emits very few characteristic gamma rays. 1 Pt is also a noteworthy element because the (admittedly flawed) current literature suggests that Pt- 190 has an epithermal cross section of a smaller value than the thermal cross section. This is highly unusual, as almost all nuclides have larger epithermal cross sections than thermal, usually an order of magnitude larger. It is important to verify these results to improve our understanding of nuclear systematics. 1.2 Cross Section and Neutron Energy The nuclear cross section is used to characterize the probability of a nuclear interaction with incident radiation. It has dimensions of area and is usually measured in units of barns, where 1 b is equal to 10-24 cm2. A larger cross sectional area means the effective nuclear area that incoming radiation sees is larger, making the probability of interaction greater. It can be used to describe the probability of absorption, elastic scattering, inelastic scattering, or the total of all three. In this paper, we are interested only in characterizing the probability of neutron absorption with subsequent emission of gamma rays; henceforward the neutron absorption cross section will simply be referred to as the “cross section.” The cross section is a function of specific nuclear characteristics and incident neutron energy. Slower neutrons with kinetic range in the range of 0 to 1 eV are referred to as thermal neutrons.
Load more

Recommended publications
  • Lecture 6: Spectroscopy and Photochemistry II
    Lecture 6: Spectroscopy and Photochemistry II Required Reading: FP Chapter 3 Suggested Reading: SP Chapter 3 Atmospheric Chemistry CHEM-5151 / ATOC-5151 Spring 2005 Prof. Jose-Luis Jimenez Outline of Lecture • The Sun as a radiation source • Attenuation from the atmosphere – Scattering by gases & aerosols – Absorption by gases • Beer-Lamber law • Atmospheric photochemistry – Calculation of photolysis rates – Radiation fluxes – Radiation models 1 Reminder of EM Spectrum Blackbody Radiation Linear Scale Log Scale From R.P. Turco, Earth Under Siege: From Air Pollution to Global Change, Oxford UP, 2002. 2 Solar & Earth Radiation Spectra • Sun is a radiation source with an effective blackbody temperature of about 5800 K • Earth receives circa 1368 W/m2 of energy from solar radiation From Turco From S. Nidkorodov • Question: are relative vertical scales ok in right plot? Solar Radiation Spectrum II From F-P&P •Solar spectrum is strongly modulated by atmospheric scattering and absorption From Turco 3 Solar Radiation Spectrum III UV Photon Energy ↑ C B A From Turco Solar Radiation Spectrum IV • Solar spectrum is strongly O3 modulated by atmospheric absorptions O 2 • Remember that UV photons have most energy –O2 absorbs extreme UV in mesosphere; O3 absorbs most UV in stratosphere – Chemistry of those regions partially driven by those absorptions – Only light with λ>290 nm penetrates into the lower troposphere – Biomolecules have same bonds (e.g. C-H), bonds can break with UV absorption => damage to life • Importance of protection From F-P&P provided by O3 layer 4 Solar Radiation Spectrum vs. altitude From F-P&P • Very high energy photons are depleted high up in the atmosphere • Some photochemistry is possible in stratosphere but not in troposphere • Only λ > 290 nm in trop.
    [Show full text]
  • 7. Gamma and X-Ray Interactions in Matter
    Photon interactions in matter Gamma- and X-Ray • Compton effect • Photoelectric effect Interactions in Matter • Pair production • Rayleigh (coherent) scattering Chapter 7 • Photonuclear interactions F.A. Attix, Introduction to Radiological Kinematics Physics and Radiation Dosimetry Interaction cross sections Energy-transfer cross sections Mass attenuation coefficients 1 2 Compton interaction A.H. Compton • Inelastic photon scattering by an electron • Arthur Holly Compton (September 10, 1892 – March 15, 1962) • Main assumption: the electron struck by the • Received Nobel prize in physics 1927 for incoming photon is unbound and stationary his discovery of the Compton effect – The largest contribution from binding is under • Was a key figure in the Manhattan Project, condition of high Z, low energy and creation of first nuclear reactor, which went critical in December 1942 – Under these conditions photoelectric effect is dominant Born and buried in • Consider two aspects: kinematics and cross Wooster, OH http://en.wikipedia.org/wiki/Arthur_Compton sections http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=22551 3 4 Compton interaction: Kinematics Compton interaction: Kinematics • An earlier theory of -ray scattering by Thomson, based on observations only at low energies, predicted that the scattered photon should always have the same energy as the incident one, regardless of h or • The failure of the Thomson theory to describe high-energy photon scattering necessitated the • Inelastic collision • After the collision the electron departs
    [Show full text]
  • Neutron Scattering Facilities in Europe Present Status and Future Perspectives
    2 ESFRI Physical Sciences and Engineering Strategy Working Group Neutron Landscape Group Neutron scattering facilities in Europe Present status and future perspectives ESFRI scrIPTa Vol. 1 ESFRI Scripta Volume I Neutron scattering facilities in Europe Present status and future perspectives ESFRI Physical Sciences and Engineering Strategy Working Group Neutron Landscape Group i ESFRI Scripta Volume I Neutron scattering facilities in Europe - Present status and future perspectives Author: ESFRI Physical Sciences and Engineering Strategy Working Group - Neutron Landscape Group Scientific editors: Colin Carlile and Caterina Petrillo Foreword Technical editors: Marina Carpineti and Maddalena Donzelli ESFRI Scripta series will publish documents born out of special studies Cover image: Diffraction pattern from the sugar-binding protein Gal3c with mandated by ESFRI to high level expert groups, when of general interest. lactose bound collected using LADI-III at ILL. Picture credits should be given This first volume reproduces the concluding report of an ad-hoc group to D. Logan (Lund University) and M. Blakeley (ILL) mandated in 2014 by the Physical Science and Engineering Strategy Design: Promoscience srl Work Group (PSE SWG) of ESFRI, to develop a thorough analysis of the European Landscape of Research Infrastructures devoted to Neutron Developed on behalf of the ESFRI - Physical Sciences and Engineering Strategy Scattering, and its evolution in the next decades. ESFRI felt the urgency Working Group by the StR-ESFRI project and with the support of the ESFRI of such analysis, since many reactor-based neutron sources will be closed Secretariat down in the next years due to national decisions, while the European The StR-ESFRI project has received funding from the European Union’s Spallation Source (ESS) in Lund will be fully operative only in the mid Horizon 2020 research and innovation programme under grant agreement or late 2020s.
    [Show full text]
  • 12 Scattering in Three Dimensions
    12 Scattering in three dimensions 12.1 Cross sections and geometry Most experiments in physics consist of sending one particle to collide with another, and looking at what comes out. The quantity we can usually measure is the scattering cross section: by analogy with classical scattering of hard spheres, we assuming that scattering occurs if the particles ‘hit’ each other. The cross section is the apparent ‘target area’. The total scattering cross section can be determined by the reduction in intensity of a beam of particles passing through a region on ‘targets’, while the differential scattering cross section requires detecting the scattered particles at different angles. We will use spherical polar coordinates, with the scattering potential located at the origin and the plane wave incident flux parallel to the z direction. In this coordinate system, scattering processes dσ are symmetric about φ, so dΩ will be independent of φ. We will also use a purely classical concept, the impact parameter b which is defined as the distance of the incident particle from the z-axis prior to scattering. S(k) δΩ I(k) θ z φ Figure 11: Standard spherical coordinate geometry for scattering 12.2 The Born Approximation We can use time-dependent perturbation theory to do an approximate calculation of the cross- section. Provided that the interaction between particle and scattering centre is localised to the region around r = 0, we can regard the incident and scattered particles as free when they are far from the scattering centre. We just need the result that we obtained for a constant perturbation, Fermi’s Golden Rule, to compute the rate of transitions between the initial state (free particle of momentum p) to the final state (free particle of momentum p0).
    [Show full text]
  • Photon Cross Sections, Attenuation Coefficients, and Energy Absorption Coefficients from 10 Kev to 100 Gev*
    1 of Stanaaros National Bureau Mmin. Bids- r'' Library. Ml gEP 2 5 1969 NSRDS-NBS 29 . A111D1 ^67174 tioton Cross Sections, i NBS Attenuation Coefficients, and & TECH RTC. 1 NATL INST OF STANDARDS _nergy Absorption Coefficients From 10 keV to 100 GeV U.S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS T X J ". j NATIONAL BUREAU OF STANDARDS 1 The National Bureau of Standards was established by an act of Congress March 3, 1901. Today, in addition to serving as the Nation’s central measurement laboratory, the Bureau is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To this end the Bureau conducts research and provides central national services in four broad program areas. These are: (1) basic measurements and standards, (2) materials measurements and standards, (3) technological measurements and standards, and (4) transfer of technology. The Bureau comprises the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Center for Radiation Research, the Center for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation’s scientific community, industry, and com- merce. The Institute consists of an Office of Measurement Services and the following technical divisions: Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic and Molec- ular Physics—Radio Physics -—Radio Engineering -—Time and Frequency -—Astro- physics -—Cryogenics.
    [Show full text]
  • Calculation of Photon Attenuation Coefficients of Elements And
    732 ISSN 0214-087X Calculation of photon attenuation coeffrcients of elements and compound Roteta, M.1 Baró, 2 Fernández-Varea, J.M.3 Salvat, F.3 1 CIEMAT. Avenida Complutense 22. 28040 Madrid, Spain. 2 Servéis Científico-Técnics, Universitat de Barcelona. Martí i Franqués s/n. 08028 Barcelona, Spain. 3 Facultat de Física (ECM), Universitat de Barcelona. Diagonal 647. 08028 Barcelona, Spain. CENTRO DE INVESTIGACIONES ENERGÉTICAS, MEDIOAMBIENTALES Y TECNOLÓGICAS MADRID, 1994 CLASIFICACIÓN DOE Y DESCRIPTORES: 990200 662300 COMPUTER LODES COMPUTER CALCULATIONS FORTRAN PROGRAMMING LANGUAGES CROSS SECTIONS PHOTONS Toda correspondencia en relación con este trabajo debe dirigirse al Servicio de Información y Documentación, Centro de Investigaciones Energéticas, Medioam- bientales y Tecnológicas, Ciudad Universitaria, 28040-MADRID, ESPAÑA. Las solicitudes de ejemplares deben dirigirse a este mismo Servicio. Los descriptores se han seleccionado del Thesauro del DOE para describir las materias que contiene este informe con vistas a su recuperación. La catalogación se ha hecho utilizando el documento DOE/TIC-4602 (Rev. 1) Descriptive Cataloguing On- Line, y la clasificación de acuerdo con el documento DOE/TIC.4584-R7 Subject Cate- gories and Scope publicados por el Office of Scientific and Technical Information del Departamento de Energía de los Estados Unidos. Se autoriza la reproducción de los resúmenes analíticos que aparecen en esta publicación. Este trabajo se ha recibido para su impresión en Abril de 1993 Depósito Legal n° M-14874-1994 ISBN 84-7834-235-4 ISSN 0214-087-X ÑIPO 238-94-013-4 IMPRIME CIEMAT Calculation of photon attenuation coefíicients of elements and compounds from approximate semi-analytical formulae M.
    [Show full text]
  • PGNAA Neutron Source Moderation Setup Optimization
    Submitted to ‘Chinese Physics C PGNAA neutron source moderation setup optimization Zhang Jinzhao1（张金钊）Tuo Xianguo1（庹先国） (1.Chengdu University of Technology Applied Nuclear Techniques in Geoscience Key Laboratory of Sichuan Province，Chengdu 610059，China) Abstract: Monte Carlo simulations were carried out to design a prompt γ-ray neutron activation analysis (PGNAA) thermal neutron output setup using MCNP5 computer code. In these simulations the moderator materials, reflective materials and structure of the PGNAA 252Cf neutrons of thermal neutron output setup were optimized. Results of the calcuations revealed that the thin layer paraffin and the thick layer of heavy water moderated effect is best for 252Cf neutrons spectrum. The new design compared with the conventional neutron source design, the thermal neutron flux and rate were increased by 3.02 times and 3.27 times. Results indicate that the use of this design should increase the neutron flux of prompt gamma-ray neutron activation analysis significantly. Key word: PGNAA; neutron source; thermal neutron; moderation; reflection 1. Introduction study, Monte Carlo calculation was carried out for the Prompt gamma ray neutron activation analysis design of a 252Cf neutron source moderation setup for the (PGNAA) is a rapid, nondestructive, powerful analysis cement samples[7]. The model of Monte Carlo multielemental analysis technique, large samples of some simulation was verified by experiment[8, 9].We improve minor, trace light elements and is used in industrial the thermal neutron source yield rate of 252Cf neutron by control[1-5]. In a PGNAA analysis, the sample nuclear the PGNAA neutron source structure to the design. The composition is determined from prompt gamma rays calculation results for the new design were compared which produced through neutron inelastic scattering and with the previous, example: themal neutron flux rate, fast thermal neutron capture.
    [Show full text]
  • Sonie Applications of Fast Neutron Activation Analysis of Oxygen
    S E03000182 CTH-RF- 16-5 Sonie Applications of Fast Neutron Activation Analysis of Oxygen Farshid Owrang )52 Akadenmisk uppsats roir avliiggande~ av ilosofie ficentiatexamen i Reaktorf'ysik vid Chalmer's tekniska hiigskola Examinator: Prof. Imre PiAst Handledare: Dr. Anders Nordlund Granskare: Bitr. prof. G~iran Nyrnan Department of Reactor Physics Chalmers University of Technology G6teborg 2003 ISSN 0281-9775 SOME APPLICATIONS OF FAST NEUTRON ACTIVATION OF OXYGE~'N F~arshid Owrang Chalmers University of Technology Departmlent of Reactor Physics SEP-1-412 96 G~iteborg ABSTRACT In this thesis we focus on applications of neutron activation of oxygen for several purposes: A) measuring the water level in a laboratory tank, B) measuring the water flow in a pipe system set-up, C) analysing the oxygen in combustion products formed in a modern gasoline S engine, and D) measuring on-line the amount of oxygen in bulk liquids. A) Water level measurements. The purpose of this work was to perform radiation based water level measurements, aimed at nuclear reactor vessels, on a laboratory scale. A laboratory water tank was irradiated by fast neutrons from a neutron enerator. The water was activated at different water levels and the water level was decreased. The produced gamma radiation was measured using two detectors at different heights. The results showed that the method is suitable for measurement of water level and that a relatively small experimental set-up can be used for developing methods for water level measurements in real boiling water reactors based on activated oxygen in the water. B) Water flows in pipe.
    [Show full text]
  • 3 Scattering Theory
    3 Scattering theory In order to find the cross sections for reactions in terms of the interactions between the reacting nuclei, we have to solve the Schr¨odinger equation for the wave function of quantum mechanics. Scattering theory tells us how to find these wave functions for the positive (scattering) energies that are needed. We start with the simplest case of finite spherical real potentials between two interacting nuclei in section 3.1, and use a partial wave anal- ysis to derive expressions for the elastic scattering cross sections. We then progressively generalise the analysis to allow for long-ranged Coulomb po- tentials, and also complex-valued optical potentials. Section 3.2 presents the quantum mechanical methods to handle multiple kinds of reaction outcomes, each outcome being described by its own set of partial-wave channels, and section 3.3 then describes how multi-channel methods may be reformulated using integral expressions instead of sets of coupled differential equations. We end the chapter by showing in section 3.4 how the Pauli Principle re- quires us to describe sets identical particles, and by showing in section 3.5 how Maxwell’s equations for electromagnetic field may, in the one-photon approximation, be combined with the Schr¨odinger equation for the nucle- ons. Then we can describe photo-nuclear reactions such as photo-capture and disintegration in a uniform framework. 3.1 Elastic scattering from spherical potentials When the potential between two interacting nuclei does not depend on their relative orientiation, we say that this potential is spherical. In that case, the only reaction that can occur is elastic scattering, which we now proceed to calculate using the method of expansion in partial waves.
    [Show full text]
  • Neutron Capture Cross Sections of Cadmium Isotopes
    Neutron Capture Cross Sections of Cadmium Isotopes By Allison Gicking A thesis submitted to Oregon State University In partial fulfillment of the requirements for the degree of Bachelor of Science Presented June 8, 2011 Commencement June 17, 2012 Abstract The neutron capture cross sections of 106Cd, 108Cd, 110Cd, 112Cd, 114Cd and 116Cd were determined in the present project. Four different OSU TRIGA reactor facilities were used to produce redundancy in the results and to measure the thermal cross section and resonance integral separately. When the present values were compared with previously measured values, the differences were mostly due to the kind of detector used or whether or not the samples were natural cadmium. Some of the isotopes did not have any previously measured values, and in that case, new information about the cross sections of those cadmium isotopes has been provided. Table of Contents I. Introduction………………………………………………………………….…….…1 II. Theory………………………………………………………………………...…...…3 1. Neutron Capture…………………………………………………….….……3 2. Resonance Integral vs. Effective Thermal Cross Section…………...………5 3. Derivation of the Activity Equations…………………………………....…..8 III. Methods………………………………………………………….................…...…...12 1. Irradiation of the Samples………………………………………….….....…12 2. Sample Preparation and Parameters………………..………...………..……16 3. Efficiency Calibration of Detectors…………………………..………....…..18 4. Data Analysis…………………………………...…….………………...…..19 5. Absorption by 113Cd……………………………………...……...….………20 IV. Results………………………………………………….……………..……….…….22
    [Show full text]
  • Determination of Uranium and Thorium by Neutron Activation Analysis Applied to Fossil Samples Dating
    2011 International Nuclear Atlantic Conference - INAC 2011 Belo Horizonte,MG, Brazil, October 24-28, 2011 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-04-5 DETERMINATION OF URANIUM AND THORIUM BY NEUTRON ACTIVATION ANALYSIS APPLIED TO FOSSIL SAMPLES DATING Regina B. Ticianelli 1, Ana Maria Graciano Figueiredo 1, Guilherme S. Zahn 1, 2,3 2 Angela Kinoshita , Oswaldo Baffa 1 Instituto de Pesquisas Energéticas e Nucleares –IPEN-CNEN/SP, C.P. 11049, 05422-970, São Paulo, SP. [email protected] 2 Departamento de Física, FFCRLP- USP, Ribeirão Preto, SP 3 Universidade Sagrado Coração, Bauru, SP ABSTRACT Electron Spin Resonance (ESR) dating is based on the fact that ionizing radiation can create stable free radicals in insulating materials, like tooth enamel and bones. The concentration of these radicals - determined by ESR - is a function of the dose deposed in the sample along the years. The accumulated dose of radiation, called Archeological Dose, is produced by the exposition to environmental radiation provided by U, Th, K and cosmic rays. If the environmental dose rate in the site where the fossil sample is found is known, it is possible to convert this dose into the age of the sample. The annual dose rate coming from the radioactive elements present in the soil and in the sample itself can be calculated by determining the U, Th and K concentration. Therefore, the determination of the dose rate depends on the concentration of these main radioactive elements. Neutron Activation Analysis has the sensitivity and the accuracy necessary to determine U, Th and K with this objective.
    [Show full text]
  • LENS Report Low Energy Accelerator-Driven Neutron Sources
    LENS Report Low Energy Accelerator-driven Neutron Sources LENS Ad-hoc Working Group CANS Nov. 2020 2 www.lens-initiative.org Table of Content 1 Foreword ................................................................................................................................6 2 Executive summary .................................................................................................................8 3 Neutrons for science and industry ......................................................................................... 12 4 Neutron production and landscape of neutron Infrastructures in Europe .............................. 16 4.1 Neutron production ........................................................................................................... 16 4.2 Situation in Europe ............................................................................................................ 16 4.3 Situation outside Europe ................................................................................................... 18 5 Capabilities of CANS .............................................................................................................. 22 5.1 What is a CANS ? ............................................................................................................... 22 5.2 What are the different types of facilities that can be considered? ...................................... 22 5.3 What performances can be achieved on a CANS for neutron scattering ............................. 23 6 Advantages / limitations
    [Show full text]