TABLE OF CONTENTS

Title page    –         –         –         –         –         –         –         –         –

Certification –         –         –         –         –         –         –         –         –

Dedication   –         –         –         –         –         –         –         –         –

Acknowledgement –         –         –         –         –         –         –         –

Table of Content    –         –         –         –         –         –         –         –

CHAPTER ONE 

1.0     Introduction –         –         –         –         –         –         –         –

1.1     Description of Non-dispersive x-ray

fluorescence (NDXFR)    –         –         –         –         –         –

1.2     Overview of Absorptometer      –         –         –         –         –

1.3     Instrumentation of a Non-dispersive x-ray absorptometer  –

CHAPTER TWO

2.0     Working principle of an Energy

Dispersive X-ray fluorescence (EDXRF) spectrometer      –

2.1     Description of EDXRF    –         –         –         –         –         –

2.2     Important component      –         –         –         –         –         –

2.2.1 The X-ray Tube      –         –         –         –         –         –         –

2.2.2 X-ray tube working principle      –         –         –         –         –

2.2.3 Peltier cooled x-ray Detector (PCD)     –         –         –         –

2.2.4 Filters  –         –         –         –         –         –         –         –         –

2.2.5 Collimator     –         –         –         –         –         –         –         –

 2.2.6 Goniometer  –         –         –         –         –         –         –         –

CHAPTER THREE

3.0     Application of Non-disperse X-ray fluorescence     –         –

3.1     Application and working principle of Absorptometer        –

3.2     Computational model of Non-dispersive

X-ray fluorescence           –         –         –         –         –         –

3.3     Experimental setup of Non-dispersive

X-ray fluorescence           –         –         –         –         –         –

3.4 X-ray source of performance considerations

CHAPTER FOUR

4.0 Conclusion       –         –         –         –         –         –         –         –

4.1 Recommendation       –         –         –         –         –         –         –

References

CHAPTER ONE

1.0 INTRODUCTION

1.1     Resorption of Non-Dispersive X-ray Fluourence

X-ray fluorescence (XRF) instruments are used in many industries for elemental identification and quantification for many different purposes.  The available instruments span a wide range of performance, capability and cost between different systems.  The increasing use of XRF has been enabled not only by miniaturized source and detector technology, but also by increased diversity of price, performance and available features at both the high and low ends.  High-performance ED-XRF handheld and benchtop instruments use high performance x-ray sources and SDDs with energy resolution as low as 130eV or count rates as high as 1Mcps, and can feature many different calibration modes, integrated geo-location and camera images and many other features.  Lower cost XRF instruments may use a less capable x-ray source and a Si-PIN detector with 170eV resolution or count rates up to 100kcps.  There has been a rising demand for low-cost XRF systems, especially handheld systems that trade some amount of performance and functionality for lower cost.  Much of the effort in creating reduced-cost systems has been focused on process improvements and business strategies to produce the same instruments more cheaply.  Little effort has been made to develop an XRF system with fewer necessary components, based on a different strategy.  Edge-absorption non-dispersive x-ray fluorescence (EA-NDXRF) may be a strategy for developing a very low-cost XRF system, as it eliminates the need for an energy dispersive detector and digital pulse processor.

For applications where measurement of only a single element is necessary, such as determination of sulfur content in oil, the system can be made cheaper by use of non-dispersive x-ray fluorescence (NDXRF).  In NDXRF, the sample is irradiated by a source, but only the intensity of fluorescent x-rays is measured, not the energy.  A pair of filters is selected to be placed between the sample and a proportional counter.  One filter allows the target element’s fluorescent x-rays and higher energy x-rays through but blocks radiation from lower energy x-rays, and the other blocks the target element’s fluorescent x-rays but passes radiation of higher energy.  Concentration of the target element is determined by taking the difference in intensity between the measurements taken through the two filters and comparing that intensity to known standards.  Multiple methods are employed to achieve this, including filter switching, use of secondary targets, or a pair of balanced proportional counters (Carr-Brion, 1966).  While this technique allows for low-cost instruments, they are limited to measurement of only a single element.

EA-NDXRF is a method that allows for detection of multiple elements in a single scan, while using a reduced number and cost of components, combining the versatility of ED-XRF with the low cost of NDXRF.

The concept of EA-NDXRF relies on use of the absorption edges of the elements in samples.  For instance, a sample with both copper and silver will not have any emission from the silver L band until the excitation energy is over ~4keV, no copper K emission until ~9keV, and no silver K emission until ~25keV.  By measuring the total x-ray intensity as the x-ray source energy is varied, the sample can be identified by the energies at which the intensity increases.

At each absorption edge within a sample, the intensity will more steeply increase.  The location of the rises in intensity identifies the element, and the overall increase gives information about elemental quantity.  While this method may not have as low of detection limits as an EDXRF system, it could still be capable for applications where low limits of detection are not needed.

Non-dispersive x-ray fluorescence (NDXRF) got its start in the 1920’s when Ross and other experimenters discovered that they could isolate an x-ray line for an element by using two filters made of different elements over two detectors. One filter absorbs the elements x-rays, while the other transmits them.

The difference in counts between the two matched detectors with balanced filters is the net intensity and is related to that elements concentration. When combined with earlier work that demonstrated that elements could be measured by measuring total x-ray intensities from some simple samples, a new and powerful method was born. Unfortunately it was almost 50 years later when small microprocessor based analyzers were built in the 1970’s that NDXRF started to make a commercial impact.

1.2     Overview of Absorptometer

The new Absorptometer “C” Data Acquisition System determines oil absorption in compliance with ASTM D 2414 as well as ASTM D 3493 including     new    procedures B and C.
The Absorptometer “C” Data Acquisition System consists of the following major components:

• frequency inverter drive unit with precise torque measurement
• high-precision measuring mixer with special blades
• high-precision burette, variable programmable titration rate for optimum test procedure
• 64-bit software for Windows VISTA, Windows 7 and Windows 8

The measuring principle is the same as with the previous models, but in contrast to these, the instrument and burette do no longer stop automatically, enabling evaluation acc. to the new procedures B and C of ASTM D 2414.
The user-optimized, modern 64-bit software of the Absorptometer “C” offers numerous advantages for daily laboratory use:

• Continuous operation at low cost: Mixer-specific determination of the TLS (torque limit switch) and all other important data
• System normalization as per ASTM with standard reference carbon blacks, including the possibility of normalization with other than standard carbon blacks
• Normalization trends show mixer wear
• Choice between local and remote operation
• Automatic saving of tests in remote operation
• Definition of test lists and test patterns
• Full burette control via PC, incl. variable programmable titration rate for quick titration at the beginning and reduced rates during the significant test phase
• Separate selection of operator and printout language
• Evaluation fully meets ASTM D 2414 incl. new procedures B (end-point at 70 % of maximum torque) and C (end-point at fixed but reduced torque level)
• Calculation of 3^rd order polynomial in the significant part of the torque curve
• Manifold graphics options
• One PC can handle up to 4 instruments with 2 or more interchangeable mixers each

1.3     Intrumentation of Non-Dispersive Absorptometer

This instrument is used for routine non-destructive chemicals analysis of rocks, mineral, sediments and fluids. It works on wavelength-dispersive spectroscopic principles that are similar to an electron microprobe. However, an XRFcannot generally make analysis at the small spot sizes typically use of EPMA work of larger fractions of geological materials. The relative ease of low cost of sample preparation and the stability and ease of use of X-ray spectrometer make this one of the most widely use method for analysis of major trace elements in rocks, minerals and sediment.

The analysis of major and trace element in geological material by XRF is made by the behaviour of atoms when they interact with X-ray radiation. An XRF spectrometer work because it is a scattered. But some is also absorbed within the sample in a manner that depends on its chemistry. The incident x-ray bean is typically produced from a Rh target although W, Mo, Cr and others can also be used, depending on the application.

When this primary beam, illuminates the sample, it is said to be excited. The excited sample in turn emits X-ray along a spectrum of wavelength characteristics of the types of atoms present in the sample.