MINERALS RESOURCES Student Projects for 2016-17 The CSIRO On-line Analysis (OLA) Group offers opportunities for students to undertake applied physics research projects at our Lucas Heights laboratories. We offer industrial traineeships (vacation projects and honours projects). Vacation projects, typically of 10-12 weeks duration, are normally completed full-time during the summer vacation, but may be undertaken on a full- or part-time basis at other times during the year. Honours projects are normally undertaken on a part-time basis over a period of about 6-7 months during the academic year. A daily stipend is paid to all students. In 2016/17, CSIRO is offering the following vacation and Honours projects all related to our research based on X-rays: Vacation projects V1. Characterising X-ray detector (SDD) spatial response with polycapillary optic V2. Study of Compton tails on X-ray fluorescent lines as a function of sample matrix V3. Characterising X-ray tube target PSF to improve X-ray imaging Honours projects H1. 3D printed X-ray fluorescence analyser H2. High accuracy measurements of heavy elements using XRF H3. High accuracy measurements of light elements using XRF H4. X-ray spectroscopy with consumer-grade imaging sensors All laboratory work would be undertaken under the supervision of experienced CSIRO staff. The student will be enrolled in the ANSTO radiation monitoring service. Students will be required to prepare a report and give a presentation on their findings. In addition, students will be given the opportunity to assist in the preparation of a paper to discuss the findings in a journal. About the CSIRO Lucas Heights Group The OLA group develops novel instruments for minerals and security industry applications. We focus on carrying new ideas from the basic research stage through to industrial demonstration and commercialisation. Our group comprises a mix of students, postdoctoral fellows, scientists, and mechanical, electronic and software engineers. Currently we have 28 staff including 8 students and Post-Doctoral Fellows. The group is led by Mr Michael Millen and is within the Ore sensing and sorting Program lead by Dr Nick Cutmore. Students would join the X-Ray team led by Dr Yves van Haarlem. The team focuses on inventing, designing and building X-ray and nuclear-based measurement and imaging systems. The projects listed above would allow the student to develop a diverse range of skills, including: 1
Computer modelling of X-ray behaviour in materials, using Monte Carlo simulation tools; Designing, building and operating experimental equipment; Using radiation sources and detectors, including X-ray tubes and high-resolution solid-state detectors; Data collection and analysis using packages such at Matlab; and Report writing. Students would be based at CSIRO s Lucas Heights laboratories. There are excellent opportunities for interested students to continue their studies by undertaking a PhD project with the group. 2
V1. Vacation project - Characterising X-Ray Detector (SDD) Spatial Response with a Polycapillary Optic Supervisor: Dr Yves Van Haarlem (yves.vanhaarlem@csiro.au) Skills required: This introductory project would suit students from a wide range of science backgrounds. General physics and some familiarity with data analysis languages such as Python and Matlab would be an advantage. Silicon Drift Detectors (SDDs) are commonly used X-ray detectors. They have an active area of about 40 mm 2. Usually it is not necessary to know their response (resolution and efficiency) as a function of spatial impact of the X-ray because this effect is averaged out. However, at CSIRO we are increasingly making use of specialised X-ray optics and we enter situations where different energies are focused on different areas on the SDD. We have already observed a change in response depending on where the X-ray hits the detector. The goal of this project is to use a polycapillary optic that focuses X-ray generated by a conventional X-ray tube to a spot of 100 micrometres diameter to scan the surface of the detector and measure its response to X-rays: efficiency and resolution as a function of place of impact. If time permits one can look at energy dependence as well. The student will use a conventional X-ray tube and has to align it with the polycapillary optic so a 100 micrometre spot size is achieved. The alignment happens with positioning stages that need be programmed by the student. Once the alignment is complete an SDD detector will be set up, so that the X-ray spot is on its active area. The student will then program a scan, read out detector spectra and analyse them for efficiency and resolution. The student will also run a simple Monte Carlo simulation of this setup in order to obtain a better understanding of interactions of X-rays with silicon. The project would cover the following elements: Learning about the operation of X-ray tubes and high-resolution X-ray detectors Setting up, aligning and running experiments to measure X-ray output and energy spectra with a polycapillary optic and a silicon drift detector Prepare a report and presentation about your findings Assist in preparing a paper describing findings in a scientific journal focused on detectors 3
V2. Vacation project Study of XRF Compton Tails to improve the performance of a Toxic Trace Element XRF Detector Supervisor: Dr Yves Van Haarlem (yves.vanhaarlem@csiro.au) Skills required: This introductory project would suit students from a wide range of science backgrounds. General physics and some familiarity with data analysis languages such as Python and Matlab would be an advantage. CSIRO has developed a highly accurate (parts-per-billion level) toxic trace element detector using X-ray fluorescence (XRF). As we become better at detecting low concentrations we are also more sensitive to the effects that cause interference or overlaps. This can be seen as an X-ray fluorescent line of an abundant element in the sample is close to the one we are interested in and the low energy tail of this line can overlap with the signal we want to accurately measure. One effect that causes overlaps is Compton scattering of fluorescent X-rays in the sample before it reaches the detector. The student will use the trace element XRF detector to isolate and study XRF tails caused by Compton scattering in the sample. The student will focus on one chemical element and will prepare samples containing high concentrations (larger than 1000 parts-per-million) of this element, starting with a water matrix going to samples with a high average atomic number (Z). The higher Z, the less Compton scattering is measured as more absorption takes place in the sample. This can be used to separate out the Compton tailing from other processes. The student will irradiate these samples and take X-ray spectra that they will then analyse. The student will also run simulations of these experiments in order to understand and explain the ongoing processes. Learning about the operation of X-ray tubes and high-resolution X-ray detectors Setting up and running experiments to measure X-ray energy spectra Applying Python/Matlab basic skills to analyse the X-ray spectra Using computer modelling techniques to understand and isolate physical processes Prepare a report and presentation about your findings A good project to do if you are interested in H2, H3 4
V3. Vacation project - Characterising X-ray Tube Target PSF to improve X-Ray Imaging Supervisor: Dr Yi Liu (yi.liu@csiro.au) Skills required: This introductory project would suit students from a wide range of science backgrounds. General physics and some familiarity with data analysis languages such as Python and Matlab would be an advantage. In X-ray imaging, it is usually assumed that the X-ray generator is a true point source. However, this is an approximation and a large target spot size can cause blurred images. In reality, the conventional X-ray source can be mathematically modelled as a point spread function (PSF) convoluted with a point source, usually with the PSF taking the form of a 2D Gaussian function. How to determine such PSF of an X-ray tube is crucially important for obtaining high quality X-ray images. There are several micro-focused X-ray sources available commercially, which have very small target size (~1 micron) and these can be regarded as a true point-source. The problems with such micro-focused X-ray sources are they tend to be expensive, hard to maintain, and can break down easily. The goal of this project is to characterise the target PSF of a conventional X-ray tube by setting up experiments, measure various images and analyse the data to work out the PSF. With such a PSF known, it is then possible to correct the smear effect of the non-point source of X-ray image by deconvolution. The student will use a conventional X-ray tube and a flat panel X-ray detector with proper blocking materials at various locations and orientations to acquire various images. Then these images will be analysed very carefully to take care of X-ray scatter on flat panel detector, before working out the 2D PSF of the X-ray tube. Then, scatter correction and source PSF deconvolution will be applied on sample X-ray images to improve the quality of these images. Learning about the operation of X-ray tubes and high-resolution flat panel X-ray detectors Setting up and running experiments to measure X-ray images Learning basic image processing techniques including scatter correction and deconvolution Prepare a report and presentation about your findings 5
Honours Project H1 3D Printed X-Ray Fluorescence Analyser Supervisor: Dr Joel O Dwyer (joel.odwyer@csiro.au) Skills required: This project would suit a student with physics or engineering background and an interest in 3D modelling. Experience with Matlab would be an advantage. CSIRO s On-line Analysis group develops systems that measure the elemental composition of ores fed into mineral processing plants. These systems use the X-ray fluorescence (XRF) method to measure the variety and amount of key chemical elements in the stream of material flowing through the plant. This information is gathered in real-time and fed back to the plant operators, enabling them to optimise the plant conditions based on the chemical composition of the material being processed. This Honours project s aim is to develop a prototype 3D-printed XRF analyser. The student will first learn the physics of XRF and how instrument design and material properties affect the quality of a measured X-ray spectrum. The student will also learn about Monte Carlo simulation, and the basics of 3D modelling and printing. This knowledge will be applied to develop a design for an XRF instrument that will be manufactured with CSIRO s in-house 3D printer. The student will then build the XRF instrument in the laboratory. A series of experiments will be conducted and the XRF spectra of several mineral samples prepared by the student will be collected with the apparatus. The performance of the instrument will be assessed and suggestions made on ways to improve the instrument design. Learning about the physics of XRF and how this can be used to analyse the elemental composition of minerals Using computer modelling to design a simple benchtop XRF instrument Using a 3D printer to build the mechanical structure of the XRF analyser in the laboratory Assembling the analyser and learning how to setup and operate an X-ray tube and X-ray detector Measuring the XRF spectra of mineral samples with the analyser Simple spectral analysis and peak fitting 6
Honours Project H2 High Accuracy Measurements of Heavy Elements using XRF Supervisors: Brianna Ganly (brianna.ganly@csiro.au) and Dr Yves Van Haarlem Skills required: This project would suit students from a wide range of science backgrounds. Physics and some familiarity with data analysis languages such as Python and Matlab would be an advantage. This is a follow up project to work already conducted in CSIRO and published: Measurement of relative line intensities for L-shell X-rays from selected elements between Z=68 (Er) and Z=79 (Au) (X-Ray Spectrometry (2016) vol. 45, pp233-243). As technology improves, highly accurate X-ray fluorescence (XRF) experiments have discovered profound discrepancies between theoretically calculated and measured relative X-ray fluorescent line intensities. This causes errors when we use these theoretical calculated lines to fit XRF spectra in order to establish elemental concentrations. In order to avoid this, we need to have a better knowledge of the correct X-ray line shapes and intensities. To begin with, the student will conduct a literature study about recent studies of X-ray peak intensities and shapes. The student will then use a CSIRO XRF analyser to collect high statistics data XRF measurements of heavy elements. This in collaboration with project H3. The student will analyse the data using some programming. A comparison will be made using the theoretical and measured data. Learning about the operation of X-ray tubes and high-resolution X-ray detectors Setting up and running experiments to measure X-ray energy spectra, this can involve some programming Analyse X-ray spectra with high accuracy Assist in preparation of a paper for publication 7
Honours project H3 High accuracy measurements of light elements using XRF Supervisors: Dr Yves Van Haarlem (yves.vanhaarlem@csiro.au) Skills required: This project would suit a student with a physics or mathematics background. Some experience with data analysis with Python (or Matlab) would be an advantage. This is a follow up project to work already conducted in CSIRO and published: Measurement of relative line intensities for L-shell X-rays from selected elements between Z=68 (Er) and Z=79 (Au) (X-Ray Spectrometry (2016) vol. 45, pp233-243). As technology improves, highly accurate X-ray fluorescence (XRF) experiments have discovered profound discrepancies between theoretically calculated and measured relative X-ray fluorescent line intensities. This causes errors when we use these theoretical calculated lines to fit XRF spectra in order to establish elemental concentrations. In order to avoid this, we need to have a better knowledge of the correct line shapes and intensities. To begin with, the student will conduct a literature study about recent studies of X-ray peak intensities and shapes. The student will then use a CSIRO XRF analyser to collect high statistics data XRF measurements of light elements. This in collaboration with project H2. The student will analyse the data using some programming. A comparison will be made using the theoretical and measured data. Learning about the operation of X-ray tubes and high-resolution X-ray detectors Setting up and running experiments to measure X-ray energy spectra, this can involve some programming Analyse X-ray spectra with very high accuracy Assist in preparation of a paper for Publication 8
Honours project H4 X-Ray Spectroscopy with Consumer-Grade Imaging Sensors Supervisor: Dr Rhys Preston (rhys.preston@csiro.au) Skills required: This project would suit a student with a physics or engineering background and an interest in radiation detection. Some programming experience would be an advantage. Semiconductor-based X-ray detectors are widely used in X-ray fluorescence (XRF) analysis, a valuable technique for material characterisation. Detection is based on recording the ionisation produced in the depletion volume of a diode. Unfortunately, it is difficult to produce a single detector that has both good energy resolution and a large sensitive volume. Technologies that combine these properties (such as Silicon Drift Detectors) tend to be highly specialised; requiring cooling and costing upwards of $10,000. An alternative approach is to combine the outputs from a large array of tiny individual detectors. Such a device already exists: the CMOS active pixel sensors (APS) found in our phones and digital cameras. These integrate millions of diodes and their amplifiers on a single chip, providing low-noise charge measurement at room temperature. Adapting these imaging sensors for X-ray measurement dramatically lowers the potential size and cost of an XRF analyser, allowing the technique to be utilised in new applications. In this project the student will investigate the use of CMOS imaging sensors for high-resolution X-ray spectroscopy. An imaging module will be modified for X-ray detection, through removal of the optics. The student will use the module to measure X-rays from various sources. They will develop algorithms to extract spectroscopic information from the acquired image/video data, and characterise its performance as an X-ray detector. The student will also have the opportunity to use Monte-Carlo code (EGSnrc) to simulate the detector response, comparing the model with the experimental data. The project will involve the following activities: Health and Safety Induction safe use of X-rays and general laboratory safety Learn to operate an X-ray tube and high-resolution X-ray detector Set up experiments to measure various X-ray spectra with imaging module Write software to acquire and process image data (cluster analysis, peak fitting etc.) Set up Monte Carlo simulation (EGSnrc) of imaging sensor and analyse results Assist in preparation of a paper for publication 9