X-Ray Analysis Instrument
Field of the Invention
This invention relates to an X-ray analysis instrument for
carrying out elemental and crystallographic analysis in a
sample.
Background to the Invention
A variety of techniques are established in the art for
analysing both the elemental and structural characteristics
of a material having a crystalline structure. For example,
x-ray diffraction (XRD) relies upon analysis of the pattern
produced by diffraction of x-rays through the closely spaced
lattice of atoms in a crystal to reveal the structural
constituency of the analysed material. Bragg's law allows
the spacing in the crystal lattice to be inferred from the
measured path difference for diffracted x-rays.
X-Ray fluorescence (XRF), by contrast, is a
spectroscopic technique to allow elemental investigation of
a sample without the need for chemical analysis. In XRF,
illumination of a sample with an x-ray beam results in
emission of secondary x-rays having characteristic
wavelengths which are indicative of the elemental
constituency of the sample. In order to permit multi
elemental analysis, the x-ray source for XRF is typically
polychromatic.
Combined XRD/XRF instruments have existed for many
years. A first type of combined XRD/XRF instrument operates
with the sample at atmospheric pressure. A second type of
combined instrument operates in vacuo Each type has
advantages and disadvantages instruments wherein the sample

is analysed in a vacuum tend to provide an enhanced x-ray
analysis particularly though not exclusively for XRF where
the sensitivity to elements having a low atomic number is
increased. On the other hand, the size and physical
arrangement of a non-vacuum instrument is less constrained,
and moreover changing of samples can be carried out more
promptly.
For high quality XRD and a more complete structural
characterisation for mineralogy and phase analysis, it is
desirable to be able to change the measurable angle of
diffraction through a wide range. In a non-vacuum system
this does not present too much difficulty. However in a
vacuum chamber the restricted space limits the opportunity
to improve performance.
Several solutions to the problem of limited space when
analysing a sample in a vacuum chamber using XRD techniques
are proposed in the art.
In XRD-only devices, the x-ray tube and detector may be
rotated with the sample fixed. For combined XRD/XRF devices
however, a single x-ray tube is held in a fixed location
relative to the vacuum chamber and the sample is rotated
whilst the detector is held fixed, the sample is held fixed
whilst the detector is rotated, or, as in US-A-4,263,510,
US-A-5,369,275 and US-A-4,916,720, the sample and detector
are both rotated. The latter arrangement appears to provide
the highest performance in vacuo.
For high quality XRF, however, the distance between the
sample and the tube needs to be small. Unfortunately this
requirement forces a compromise in a combined XRD/XRF
instrument since, as noted, the highest quality XRD
measurements require the sample to be rotatable. This in
turn puts a minimum distance requirement on the location of

the x-ray tube relative to the sample (to avoid collisions
between the two during XRD measurements), so reducing the
maximum performance during XRF measurements.
Commonly assigned US-A-5,406,608 describes a combined
XRD/XRF analyser for analysing samples in vacuo. An x-ray
source is mounted in fixed relation to a vacuum chamber of
the instrument and provides a polychromatic divergent x-ray
beam which illuminates a sample to permit both XRD and XRF
measurements. One or more fixed and/or moveable
fluorescence channels are provided so as to allow selection
of x-rays of a particular wavelength and energy, and to
detect the selected x-ray. A diffraction channel is also
provided which allows selection of a characteristic x-ray
wavelength at the source following diffraction by the
sample. The diffraction channel also has a detection
arrangement. The x-ray diffraction detector is rotatable to
improve XRD measurements. XRF performance is however
optimised by providing multiple fluorescence channels or by
mounting a fluorescence channel (incorporating a detection
arrangement) on a goniometer rotatable about the sample.
Whilst the foregoing arrangement provides a fair
compromise between XRD and XRF performance, it does however
suffer from a number of drawbacks. Firstly, the sample is
fixed relative to the x-ray tube (in other words only the
XRD detector arrangement is rotatable, not the sample) which
limits XRD performance. Secondly, in seeking to avoid
compromising the XRF performance, the arrangement of tube,
sample detectors and vacuum chamber in US-A-5,406,608
restricts the angular range of the XRD detector which in
turn limits the ability to perform more extensive XRD
measurements.

Summary of the Invention
Against the foregoing background, it is an object of
the present invention to provide an improved XRD/XRF
analysis instrument for analysis of samples in vacuo.
According to the present invention there is provided an
apparatus for carrying out both x-ray diffraction (XRD) and
x-ray fluorescence (XRF) analysis of a crystalline sample,
comprising, an evacuable chamber; a sample holder located
within the evacuable chamber, for mounting the crystalline
sample so that it may be analysed; an x-ray fluorescence
source mounted within the evacuable chamber, for
illuminating the crystalline sample with x-rays; an XRF
detection arrangement for detecting secondary x-rays emitted
from the surface of the crystalline sample as a result of
illumination by x-rays from the said x-ray fluorescence
source; characterized by an x-ray diffraction source, also
mounted within the evacuable chamber but separate from the
x-ray fluorescence source, for illuminating the crystalline
sample with x-rays; an XRD detection arrangement for
detecting x-rays of a characteristic wavelength which have
been diffracted by the crystalline sample; and a moveable
XRD support assembly, comprising a first part configured to
mount the XRD source for relative movement between the XRD
source and the sample holder, and a second part configured
to mount the XRD detection arrangement for relative movement
between the XRD detection arrangement and the sample holder.
The apparatus in accordance with the invention thus provides
separate x-ray tubes within the vacuum chamber, a first for
illuminating the sample with x-rays for XRF and a second for
illuminating the sample with x-rays for XRD. The XRD tube
and the corresponding XRD detection arrangement are both

mounted for relative movement with respect to the sample.
The apparatus is therefore capable of acquiring XRF data for
complete chemical or elemental analysis while the XRD data
provide the complete structural or phase analysis on the
same sample within the same embodiment under vacuum.
Previous combined XRD and XRF arrangements have either
compromised on accuracy and/or ability to measure low atomic
number elements by having the sample at atmosphere, or have
used a single static x-ray tube in vacuo, for both XRD and
XRF. The latter arrangements result in compromises: either
the range of angles of XRD measurements is limited (for
example, where the XRD detector is moveable as in the
arrangement of US-A-5,406,608, the range of available angles
is between about 25 and 55 degrees), and/or the proximity of
the x-ray source to the sample, for XRF measurements is
limited, since the requirement to rotate the sample forces
the x-ray tube to be backed off from the sample (to prevent
collisions) which limits XRF performance
It is well known by those skilled in the art that
increasing the number of x-ray tubes is difficult in a
vacuum chamber because of the additional cooling
requirements. For accurate XRD measurements, an x-ray source
of lkW or more is recommended; the preferred embodiment is a
1.8kW source operating at 45kV and 40mA. Mounting a powerful
x-ray source within vacuum complicates the problem of
cooling the source as the available surface area through
which heat can be transferred is reduced. It is therefore
desirable to mount as much of the x-ray tube outside the
vacuum chamber as possible to allow heat transfer out of the
tube. However for a combined XRD-XRF instrument, the XRD
detector must be mounted on the same side of the sample as
is the tube, and must be displaced away from the sample.

This displacement is required so that diffracted x-rays have
diverged before reaching the detector so that the detector
can have improved angular resolution. The distance between
the sample and the detector should be maintained under
vacuum and so the sample must be well inside the vacuum
chamber. This then means that a fixed x-ray tube must also
protrude deep inside the vacuum chamber and only one end of
the x-ray tube is accessible from outside the vacuum
chamber, exacerbating the heat transfer problem. This
problem is further compounded if that x-ray tube must be
rotatable within vacuum as there then cannot be any part of
the tube that abuts the housing, and the tube is fully
enclosed within vacuum. Previous combined XRD-XRF
instruments have been restricted either by using the same
fixed x-ray tube for both XRD and XRF, or by using two fixed
x-ray tubes and rotating the sample and the XRD detector
when performing XRD analysis.
Additionally, increasing the number of x-ray sources
requires increased space within the vacuum chamber Space is
at a premium in a vacuum chamber because increasing the size
of the vacuum chamber increases its manufacturing cost and
requires larger capacity, more expensive, vacuum pumps.
Furthermore, as US-A-5,406,608 and other prior art documents
also acknowledge, a single x-ray source minimizes cost.
However, the inventors have realised that, if a second
tube is provided for XRD, which is moveable relative to the
sample and a moveable XRD detection arrangement is provided
as well, a much wider range of diffraction angles can be
measured. Preferred embodiments permit a range of a few
degrees (eg, 7 degrees) up to about 80 degrees to be
measured. At the same time the separate XRD tube and
detection arrangement avoids the need to compromise with

XRF, so that, in preferred embodiments the (separate) XRF
tube can be mounted in fixed, close proximity to the sample
in the sample holder (which may, nonetheless, be journalled
for rotation about a vertical axis).
By having the XRD apparatus in vacuo, the sample can be
isolated from, for example, moisture ingress. This in turn
assists in the analysis of certain industrial compounds such
as cement and its constituents (eg, free lime) which are
very hygroscopic and thus rapidly deteriorate in the
presence of water in moist air.
By having the sample fixed horizontally, powder samples
can be accommodated without spillage Prior art
configurations where the sample holder rotates are either
limited in the types of samples that they can analyse, or
must restrict the sample angle rotation, limiting the
performance of the XRD measurements able to be made. Powder
samples are commonly analysed in the cement industry, for
example.
Preferably the XRD tube and XRD detection arrangement
are each mounted upon separate arms of a single goniometer.
Alternatively, two separate goniometers may be utilised so
that the motions of the XRD source and XRD detector may be
operated independently, though it is preferable that both
motions be controlled by a single controller such as a
computer. The XRD tube is preferably located wholly within
the vacuum chamber so that its angular motion is
unrestricted, and in that case the appropriate power and
cooling facilities may be provided by employing high vacuum
feed-throughs from external of the vacuum chamber into the
interior thereof, with, optionally, flexible conduits within
the chamber so that the XRD tube may move relative to the
chamber.

A significant advantage of such a fully integrated XRD
and XRF apparatus is the synergy of chemical analysis data
to interpret the XRD data for mineral analysis in that the
XRF data is provided as additional input to the XRD
processing system in order to validate and quantify the
corresponding minerals or phases in the same sample. A
single operating system preferably collects the data from
both XRF and XRD modes of the instrument which is then
processed to obtain a complete chemical and mineral
characterization of the polycrystalline material.
Brief Description of the Drawings
The invention may be put into practice in a number of
ways, and a specific embodiment will now be described by way
of example only and with reference to the accompanying
figures in which:
Figure 1 shows a top view of a combined XRD/XRF
apparatus embodying the present invention and including both
XRD and XRF tubes and detectors;
Figure 2 shows a sectional view along a line A-A1 of
Figure 1, further illustrating the arrangement of the XRD
tube and detector;
Figure 3 shows a sectional view along the line B-B' of
Figure 1, further illustrating the arrangement of the XRF
tube and detectors;
Figure 4a shows a sectional view along the line C-C of
Figure 1, illustrating the XRD tube in further detail

together with xts manner of connection with and through the
vacuum housing, and
Figure 4b shows a side view of the arrangement of
Figure 4a.
Detailed Description of a preferred embodiment
Referring first to Figure 1, a schematic top view of a
combined XRD/XRF apparatus 10 is shown. The apparatus 10
includes a vacuum chamber 15 containing XRD components,
labelled generally at 20, and described in further detail
below as well as in connection with Figure 2, and separate
XRF components indicated generally at 30 and described below
in connection with Figure 3.
The XRD components 20, in more detail, comprise an XRD
tube 40 and an XRD detector 50, each of which is mounted
upon a respective arm of an XRD goniometer 60. The
goniometer 60 and the XRD tube 40 and XRD detector 50
mounted upon it are moveable relative to a vertical axis A
(passing into the paper as viewed in Figure 1) in a manner
to be described subsequently. The axis A also defines the
centre of a sample holder 100 which, in use, holds a
crystalline sample (not shown) to be analysed.
Associated with the XRD goniometer 60 are goniometer
drivers 70 which may, for example, be manually or computer
controlled to drive the XRD goniometer 60 to a chosen
angular position. Finally, Figure 1 also illustrates
schematically the location of cooling and power conduits 80,
for providing cooling and electrical power to the XRD tube
40. As may be seen from the plan view of Figure 1, the XRD
tube 40 is physically isolated from the walls of the vacuum

chamber 15 so its motion may be unimpeded The vacuum
chamber 15 itself is, in use, evacuated using standard
pumping equipment which will be familiar to those of
ordinary skill and which is not illustrated in Figure 1.
The separate XRF components 30 comprise, in brief, an
XRF tube 90 which is fixed relative to the sample holder 100
and the vacuum chamber 15, and is located coaxially with the
axis A of the sample holder 100. The XRF components 30 also
include an XRF detector 110 mounted upon an XRF goniometer
120. Instead of a single XRF detector 110 mounted upon an
XRF goniometer 120 so that the detector 110 may be moved, a
plurality of fixed XRF channels may instead be located at
spatially separate places within the vacuum chamber 15, to
allow simultaneous selection and measurement of fluorescence
x-rays from the sample of differing energies. The details
of the XRF detector do not, however, form a part of the
present invention and any suitable known arrangement may be
employed, such as that which is described in detail in
commonly assigned US-A-5,406,608, the contents of which are
incorporated by reference in their entirety.
Figure 2 shows a sectional view along the line A-A' of
Figure 1, illustrating the arrangement of the XRD components
20 in further detail. As described above in connection with
Figure 1, a vertical axis A defines a longitudal axis of the
XRF tube 90 which has a rhodium tipped anode 130 located
adjacent the sample holder 100. The use of rhodium as an x-
ray anode target material is, of course, merely one of a
range of possible target materials, such as copper,
tungsten, molybdenum and gold; the specific target material
of the x-ray anode which is employed determines the energy
distribution of the x-rays emitted from the XRF tube 90.

As may be seen more clearly in Figure 2, the axis of
the sample holder 100 is coterminous with the axis A of the
XRF tube 90
The XRD tube 40 is mounted upon the right hand arm of
the XRD goniometer 60 as viewed in Figure 2. The XRD tube
40 is preferably a monochromatic source of x-rays which
allows a well resolved diffraction pattern to be obtained,
as described below The XRD tube 40 also preferably has a
relatively high power output in order to provide for the
lowest detection limits In the preferred embodiment, the
power output of the XRD tube 40 is 1800 Watts at 45kV and
4 0mA.
The XRD tube 40 has a tube window 220 (see also Figure
4a) which communicates with XRD divergent optics 45 on the
output thereof, to produce a divergent, monochromatic beam
of x-rays that that irradiates the sample in the sample
holder 100.
In use, the right hand goniometer driver 70 actuates
the right hand arm of the XRD goniometer 60 so that the XRD
tube 40 describes arcuate movement about the sample holder
100 wherein a sample is mounted. The general direction of
movement of the XRD tube on the goniometer arm is indicated
by 0D. The angle between the sample (strictly, the crystal
plans within the sample) and the XRD tube defines the
diffraction in accordance with Braggs's Law: nX. = 2dhki Sm0i
where n is an integral number of wavelengths X, 0i is the
angle of diffraction, and dhki is the interplanar distance
dependent upon the Miller indices h, k and 1 of the crystal.
The Bragg Law requirement that 9 and X are matched
necessitates that a range of wavelengths or angle is
available. The wider the range of angles 0 is available,

the more information on the crystal structure may be
obtained
Mounted on the left hand arm (as viewed in Figure 2) of
the XRD goniometer 60 is an XRD detector 50 As with the
XRD tube 40, the goniometer driver 70 allows the left hand
XRD goniometer arm to drive the XRD detector 50 in an
arcuate direction 0D about the sample holder 100. The
details of the XRD detector 50 do not form a part of the
present invention as such and the skilled person will
appreciate that any suitable XRD detection arrangement could
be employed. In brief, however, the XRD detector comprises
XRD receiving optics 55 including a monochromator crystal, a
collimator (not shown) and a detector array 65. The
monochromator crystal is positioned at a specific angle
relative to the sample and the diffracted beam, such that a
chosen characteristic wavelength from the XRD source 40 is
selected and passes into the detector. When the apparatus
10 embodying the present invention is operated in combined
XRD/XRF mode (that is, with both XRD and XRF analyses taking
place simultaneously), this crystal isolates fluorescence x-
rays from the XRF tube 90 (which can cause a huge background
in XRD analysis), and also unwanted diffraction peaks, so
that a diffraction pattern of the sample may be obtained by
scanning of the XRD tube 40 and XRD detector 50. It is to
be understood that the monochromator is not an essential
feature of the XRD detector, however For example, the
primary radiation from the XRD tube 40 could be filtered
instead so as to provide a single wavelength beam (e.g., the
Copper K alpha line). In that case the monochromator can be
omitted from the secondary beam particularly where the XRF
tube 90 is not operating simultaneously (so that the

problems of sample fluorescence creating a background during
XRD analysis are avoided).
In one embodiment the XRD tube 40 and XRD detector 50
are independently moveable via the goniometer drivers 70,
but in a preferred embodiment a central controller governs
arcuate movement of both so that a wide range of angles
between the x-ray source from XRD tube 40 and the detection
channel in the detector 50 can be achieved. Importantly,
because the XRD and XRF components 20, 30 are in different
planes (along different axes - see Figure 1), with separate
x-ray tubes for each part of the system, there is
significantly more room for movement of the XRD tube 40 and
XRD detector 50, resulting m a total angle subtended
between the source of x-rays from the XRD tube 40 and the
XRD detector 50 down to around 7 degrees (approximately 3.5
degrees to the horizontal, on each side of the sample), up
to as much as 80 degrees (40 degrees to the horizontal for
the XRD tube 40 and XRD detector 50 respectively)
Photons detected by the XRD detector 50 are counted and
processed by electronic means which is not shown, to provide
a diffractogram.
Turning now to Figure 3, a section along the line B-B'
of Figure 1 is shown. Again the XRF tube 90 is shown along
the longitudinal axis A with the anode 130 shown adjacent to
the sample in the sample holder 100
In use, x-rays from the XRF tube 90 strike the sample
in the sample holder 100 and this causes the emission of
secondary x-rays. The sample holder 100 is itself rotatable
to permit the sample orientation to be altered during
investigation Characteristic energies of fluorescence x-
rays emitted from the sample are separated from the
continuum of x-ray energies by, for example, Bragg

reflection from the surface of a crystal. A static
fluorescence detection channel operable on this basis is
shown on the left hand side of Figure 3. The static
fluorescence detection channel comprises an XRF
monochromator 140, an XRF scintillation detector 150, an XRF
sealed or gas flow detector 160 such as a gas filled
counter, and an XRF Bragg crystal 170.
Fluorescence x-rays from the sample pass into the
monochromator 140 and impinge on the Bragg crystal 170 which
diffracts only one wavelength related to a specific element
at a particular Bragg angle The Bragg crystal 170 thus acts
to monochromate and focus a beam of x-rays of the desired
energy onto the detectors 150, 160. A number of static
fluorescence channels such as that shown in the left hand
side of Figure 3 may be employed to allow simultaneous
selection and measurement of fluorescence x-rays of
differing energies. Such an array of static channels is
particularly useful when the apparatus 10 is set up to
monitor, for example, the specific proportions of known
elements within an industrial process such as the
manufacture of steel or cement.
The use of static fluorescence channels is, however,
typically otherwise inflexible since each channel is
configured to measure only a certainly energy (and hence, to
identify a specific element). To overcome this drawback,
therefore, a sequential fluorescence channel mounted upon an
XRF goniometer 120 may additional or alternatively be
provided and such an arrangement is shown on the right hand
side of Figure 3. The XRF detector 110 of Figure 1 is shown
m more detail as, for example, a scintillation detector 190
and a flow proportional counter (FPC) detector 200. Each is
mounted upon the XRF goniometer 120 along with a collimator

210. The XRF goniometer 120 is based upon a 9-20 rotation
wherein a fluorescence spectrum with multiple wavelengths is
collimated by a primary collimator in front of a flat
crystal monochromator. The crystal diffracts only one
wavelength pertaining to one specific element of interest at
a given angle. This diffracted wavelength is then further
collimated by a secondary collimator in front of the
detector The crystal is positioned at an angle 9 and the
detector is located at an angle 20 by means of an optical
encoder mechanism. As the crystal is rotated, that is, as
the angle 0 is changed, different wavelengths are diffracted
at different angles and are identified by the detector
moving in synchronisation at an angle of 20. In this manner,
a complete spectrum may be obtained. By contrast a fixed XRF
channel is designed for one specific wavelength in a static
measurement. In other words, the XRF goniometer 120 acts as
a sequential system wherein one wavelength at a time is
measured during a scan. The monochromator or fixed XRF
channel is on the other hand pre-aligned with a fixed
crystal and fixed detector positions to pick up one specific
wavelength. Preferred embodiments of the present invention
allow for both an XRF goniometer 120 for flexible,
sequential XRF measurements along with a plurality of fixed
XRF channels for specific measurement/detection of a finite
range of known elements (as well, of course, as the separate
XRD components 20).
Turning finally to Figure 4a, a section along the line
C-C of Figure 1 is shown, though not to scale. Figure 4a
shows a partial side and cutaway section of the XRD tube 40
along with associated cooling and power connections As is
apparent from Figure 1 and the foregoing description, the

XRD tube 40 is mechanically and thermally isolated from the
vacuum chamber 15 (unlike the XRF tube 90 which is suspended
from the top of it). By isolating the XRD tube 40 from the
vacuum chamber 15, the former is capable of movement
relative to the latter. The isolation of the XRD tube 40
from the vacuum chamber 15 also prevents thermal conduction,
that is, prevents the vacuum chamber 15 from acting as a
heat sink for the XRD tube 40 As such, however, it is
desirable alternatively to cool the XRD tube 40. It is also
necessary to supply power at relatively high voltages to the
XRD tube 40 and the arrangement of Figure 4a suggests one
embodiment for doing this. As seen in Figure 4a, and also
in Figure 4b which is a close up plan view of the XRD tube
40 as first shown in Figure 1, a high vacuum connection 230
to the XRD tube 40 is provided at an end thereof. A high
voltage cable 240 extends transversely from this high vacuum
connection 230 from the XRD tube 40 towards the vacuum
chamber wall. The high vacuum connection and the cable as
it extends from that are potted using an electrically
insulating material such as an epoxy resin which may be
doped with thermal conductor to assist with the cooling of
the x-ray tube 40.
An insulating stand off or flange 260 within the wall
of the vacuum chamber 15 provides electrical isolation
between the inside of the vacuum chamber 15 and atmosphere
whilst at the same time providing a vacuum tight seal. On
the atmosphere side of the vacuum chamber 15, a second high
voltage connection 270 to an external power supply (not
shown) is provided.
Finally, water cooling to the x-ray tube is effected by
a water cooling inlet 280 and a water cooling outlet 290.
Both inlet and outlet are formed of pipes or conduits which

are at least partly flexible to allow movement of the XRD
tube 40 relative to the vacuum chamber 15. Although not
shown in Figures 4a or 4b, vacuum tight feed throughs or
flanges are also provided in the walls of the vacuum chamber
15 to allow connection of an external water supply.
Although one specific embodiment of the present
invention has been described for illustrative purposes only,
the skilled person will understand that various
modifications may be contemplated without departing from the
scope of the invention which is defined in the accompanying
claims.

We claim
1 An apparatus (10) for carrying out both x-ray diffraction
(XRD) and x-ray fluorescence (XRF) analysis of a
crystalline sample, comprising
an evacuable chamber(15),
a sample holder (100) located within the evacuable
chamber, for mounting the crystalline sample so that it
may be analysed,
an x-ray fluorescence source (90) mounted within the
evacuable chamber, for illuminating the crystalline
sample with x-rays,
an XRF detection arrangement (110) for detecting
secondary x-rays emitted from the surface of the
crystalline sample as a result of illumination by x-rays
from the said x-ray fluorescence source,
characterized by
an x-ray diffraction source (40), also mounted within the
evacuable chamber but separate from the x-ray
fluorescence source, for illuminating the crystalline
sample with x-rays,
an XRD detection arrangement (50) for detecting x-rays of
a characteristic wavelength which have been diffracted by
the crystalline sample, and

a moveable XRD support assembly (60) , comprising a first
part configured to mount the XRD source for relative
movement between the XRD source and the sample holder,
and a second part configured to mount the XRD detection
arrangement for relative movement between the XRD
detection arrangement and the sample holder
2 The apparatus as claimed in claim 1, wherein the first
part of the moveable support assembly is configured to
mount the XRD tube for rotatable movement through a
plurality of angular positions relative to the sample
holder, and wherein the second part of the moveable
support assembly is configured to mount the XRD detector
for rotatable movement through a plurality of angular
positions relative to the sample holder
3 The apparatus as claimed in claim 2, wherein the moveable
support assembly comprises a goniometer(60), the first
part of the moveable support assembly including a first
arm of the goniometer and the second part of the moveable
support assembly including a second arm of the
goniometer
4 The apparatus as claimed in claim 3, further comprising
goniometer actuating means (70) for actuating each of the
first and second goniometer arms so as to control arcuate
movement of the XRD tube and XRD detection arrangement,
respectively, about the sample holder, between first and
second end stop positions
5 The apparatus as claimed in claim 4, wherein the sample
holder defines a horizontal plane within the evacuable
chamber, wherein the first and second end stop positions

of the XRD detection arrangement subtend angles of
approximately 3 degrees and 40 degrees to that horizontal
plane respectively, and wherein the first and second end
stop positions of the XRD tube subtend angles of
approximately 3 degrees and 40 degrees to that horizontal
plane respectively
6 The apparatus as claimed in any preceding claims, wherein
the XRF tube is mounted in a fixed position relative to
the sample holder and the vacuum chamber
7 The apparatus as claimed in claim 6, wherein the XRF tube
has a longitudinal axis which intersects the sample
holder
8 The apparatus as claimed in any preceding claims, wherein
the sample holder is rotatable about an axis
9 The apparatus as claimed in any preceding claims, wherein
the XRF detection arrangement is mounted upon a moveable
XRF support assembly (12 0)
10 The apparatus as claimed in any preceding claims, wherein
the XRD tube is housed wholly within the vacuum chamber
11 The apparatus as claimed in claim 10, further comprising
a cooling channel (280,290) coupled from externally of
the vacuum chamber to the XRD tube so as to supply
cooling thereto, and a power connection (80) also coupled
from externally of the vacuum chamber to the XRD tube for
supplying power thereto
12 The apparatus as claimed in claim 11, wherein each of the
cooling channel and the power connection is flexible

along at least a part thereof so as to maintain power and
cooling to the XRD tube as it moves relative to the
vacuum chamber in use
13 The apparatus as claimed in any preceding claims, wherein
the XRD tube is arranged to generate a monochromatic x-
ray beam whereas the XRF tube is arranged to generate a
polychromatic x-ray beam

(54) Title X-RAY ANALYSIS INSTRUMENT
(57) Abstract An apparatus for carrying out both x-ray diffraction (XRD) and x-ray fluorescence (XRF) analysis of a crystalline
sample A sample holder is located within an evacuable chamber An x-ray fluorescence source and separate x-ray diffraction
source are mounted within the evacuable chamber An XRF detection arrangement is also provided, for detecting secondary x-rays
emitted from the surface of the crystalline sample as a result of illumination by x-rays from the said x-ray fluorescence source An
XRD detection arrangement is then provided for detecting x-rays of a characteristic wavelength which have been diffracted by the
crystalline sample A moveable XRD support assembly is provided, comprising a first part configured to mount the XRD source
for relative movement between the XRD source and the sample holder, and a second part configured to mount the XRD detection
arrangement for relative movement between the XRD detection arrangement and the sample holder.