OYSTER Big ideas from small particles
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Delft University of Technology
OYSTER
Big ideas from
small particles
Neutron research in brief
OYSTER Why neutron research?
Neutrons are released when atomic
a penetrating look nuclei split. These extremely tiny
particles penetrate deeply into material
into matter exposed to them. By measuring changes
in the neutrons’ speed and direction
when they collide with atoms, we are
able to look inside materials while the
materials themselves remain intact. With
the knowledge thus derived, we gain an
idea of how materials originated and the
processes which play a role. This allows
us to change materials according to our
OYSTER is the project that will make the specifications and give them the best
properties for their function.
research reactor of the Reactor Institute Delft
(RID) considerably broader and more precise How does this neutron research
work now?
in its applicability. With OYSTER, the neutrons The neutrons produced through atomic
generated in the reactor are cooled by a device fission in the research reactor are ”let
containing liquid hydrogen, slowed down and loose” on materials. Around the research
reactor are numerous extremely
made steerable in beams. This makes new and advanced and mostly unique instruments
better measurement techniques possible, even for making measurements. Neutrons
have not only the desirable property
allowing us to monitor the production of materials of penetrating deeply into materials,
and nutrients in real time. they also have the vexing trait of being
difficult to control. They cannot be
steered with electrical or magnetic fields.
Focusing them with lenses also has very
OYSTER offers enormous benefits for little effect. The neutrons simply go
every which way.
international science, health care and
industry. What major improvements will
OYSTER bring?
These are numerous. There is
enormous benefit in being able to
better manipulate neutrons despite their
The RID is setting the pace worldwide with the development physical elusiveness. New measurement
and production of instruments for research using neutrons. possibilities arise and existing methods
These tools are widely used in research centers. Since will be improved a hundredfold.
experimental and fundamental research programs are
possible at the research reactor in Delft, the reactor plays an
indispensable role among major international institutions. After
OYSTER, this position will be strengthened by more research,
greater precision, and greater spin-off benefits for society.
OYSTER’s new capabilities ensure:
n continuation of our edge among top international institutes
n a boost for scientific research at the TU Delft
n a boost for product development in the Netherlands and far
beyond
n development of more effective treatment methods in health
care
n new possibilities for energy generation and storage
The OYSTER project (Optimized Yield – for Science, Technology
& Education – of Radiation) requires an investment of
approximately 20 million euros and will be operational in 2012.
1 OYSTER
RID: Knowledge Center &
The improved reactor
OYSTER Innovator better, faster and more precise Heat production
3 MW
what does it The Reactor Institute Delft is a magnet
for scientists. Rising talent as well as
esteemed scientists are attracted to
measurements Speed
of cold neutrons
500 m/s
deliver? cutting edge research with unique
instruments.
Water function 1: Water slows down fast neutrons Intensity of cold
neutron beam
One of the three neutrons [4] (on page 4) released by nuclear fission must split another uranium
Through OYSTER, major limitations 1 billion neutrons
atom to keep the chain reaction going (the other neutrons are available for experiments). The speed
in the current neutron technology are per s per cm 2
of these fast neutrons is so great (20 million m/s) that almost all neutrons fly off without hitting a
removed. Currently, ”warm” snapshots uranium nucleus. When the reaction takes place in water, the neutrons
are only made at a short distance from collide with the water molecules and are slowed so dramatically
the source because that is the only (to 2000 m/s) that they are able to react with the uranium
place enough neutrons can be captured. nuclei. Without water no chain reaction occurs, and
More neutrons, more power, more speed, and Through OYSTER, scientists will be much the nuclear fission stops. Water pool
fundamentally better results. This is the best way less hindered by these limitations. With The reactor core sits
the five existing and four advanced in a water pool
to describe OYSTER. It is a logical consequence instruments still to be built, the (depth 8 m, volume
of the success and the continuing further measurement capabilities will become 250 m3).
more precise and more versatile. The thickness of
development of the Hoger Onderwijs Reactor that Measurements can be made with both the concrete wall
became operational in 1963. ”warm” and ”cold” neutrons; snapshots varies from 1 to
as well as process-related findings can Circa 10 m about 2.5 m.
be established.
With OYSTER, the neutron source is coupled to a coolant of
liquid hydrogen. At extremely low temperatures (250 degrees The RID is part of an international
below 0 Celsius), the properties of neutrons change in such a network of top institutes that procure OYSTER EXPANSION Neutrons
way that they can more easily be guided and directed. In a box knowledge and instruments in Delft for
More power The 100 million billion
a (production) process is simulated (temperature, pressure, their own research. The RID has been neutrons that are
asked to contribute to the European
movement, mixing). The neutrons are steered crossways The thermal power (heat generated every
neutron institute under development, the second in the reactor
through the box, and we see how the material being studied production) of the reactor
European Spallation Source. For a large core fly off in all
reacts to the treatment – in some cases even when changes will be increased from 2 to
group of (international) companies, the directions. Neutrons
occur quickly. 3 MW. By splitting more
RID is of vital importance in developing are uncharged
uranium per second, 1.5
products for the food industry, particles and
times more neutrons are
microelectronics, steel and plastics therefore cannot be
generated. About 3 grams
What does OYSTER deliver? production, etc.
of uranium are then used steered with
per day. magnets.
The potential is vast. For example, through OYSTER we can see In the health care sector, the Reactor
Institute Delft works with research
in real time:
n how hydrogen is stored in special metallo-organic buffers
hospitals in developing diagnostic
methods and treatments for fighting
n how ultrathin coatings peel from surfaces Beam tubes
cancer and other diseases.
n how foods change their structure through movement, cooling Researchers want to conduct
experiments with neutrons. Six beam Water vapor
or heating. We therefore learn more about curdling and In the energy sector, neutron research
coagulation processes, important for the development of diet tubes (diameter 20 cm) must lead the
leads to better methods of storing
foods. neutrons from the pool to the experiments.
energy with hydrogen and batteries.
n under what circumstances types of steel and plastic attain Neutrons that fly more or less straight into the
their optimal properties beam tubes will reach the experimental setup. All other
n under what circumstances and how the magnetic properties
neutrons fly through the tube wall and are absorbed by the tube
walls, the water and the concrete. Through OYSTER, about one in
of materials change
every million neutrons will reach an experimental setup.
n how dune sand behaves under changing conditions so that
we can make judgments about our sea walls
n how change processes occur in mixtures such as paint Primary cooling circuit Secondary cooling circuit
Water function 2: Water cools the reactor core
RESEARCH REACTOR
All heat released by the nuclear fission is led off through the water in the In a normal nuclear plant, the heat released by nuclear
pool [5]. A pump ensures circulation (288 m3/h) through the pool. The fission is used to generate steam. The steam drives
cooling water is suctioned off via a funnel along all the fuel plates. The turbines which produce electricity.
warm water releases its heat in a heat exchanger [6] and once cooled The goal of the Delft reactor is to generate neutrons
(max. 40 o C), flows back into the pool [7]. The secondary cooling system for conducting scientific experiments.
discharges its heat to the environment [8] through evaporation into the air.
2 OYSTER 3 OYSTER
COLD NEUTRONS New control rods Ventilation shaft OYSTER EXPANSION
Six aluminum tubes filled with boron carbide can be inserted into the reactor Ventilators suck the air out of
The main advantage of ”cold” neutrons is their greater core. If two of these control rods are lowered completely into the core, they
Result of planned expansion
the hall [2] and conduct it via a
tendency to remain in the beam guides; consequently, 100 absorb all free-flying neutrons and thereby stop the nuclear fission. If a filter and a ventilation shaft
times more neutrons reach the experiments than with ”warm” Clean air The total neutron intensity of the modified reactor will be
power outage occurs, the control rods fall into the core by themselves. (height 60 m) outside.
neutrons. A second advantage is that with the greater 100 times greater than that of the current reactor, allowing
Detectors measure the vented
wavelength of ”cold” neutrons, larger structures become larger structures or smaller details in studied materials to
air for the presence of
visible. A third advantage is that the ”cold” neutrons move less become visible than we can currently see. In addition,
radioactive compounds.
quickly through a test material, allowing more precise measurements can be taken 100 times more quickly than
As soon as radioactivity is
measurements. To make cold neutrons, the current reactor is currently the case.
measured, the gastight valves
must be fitted with a neutron cooler [1] which slows the fast,
close off the airflow and the
”warm” (40 o C) neutrons to slower, ”cold” neutrons (-250o C).
reactor is shut down.
The measurements will then take much less time and will yield
more information.
Reactor building
In the airtight steel hall [3]
(diameter 25 m, height 28 m)
a lower air pressure ensures
Reflector elements that no air can leak into the
Beryllium reflectors environment.
(a metal that absorbs
almost no neutrons)
must reflect as many
free-flying neutrons as
possible to the fuel
elements.
Neutrons
Beam guides
Uranium
70 cm
OYSTER EXPANSION OYSTER EXPANSION
New reactor configuration Neutron cooler
The new reactor core has nine fuel elements (instead of Right next to the nuclear reactor a
the current 20 elements). reservoir is placed containing liquid
hydrogen (temperature -250 o C).
The neutrons that are released in the
Current fuel plates reactor fly through the cold hydrogen,
Each fuel element (8 x 8 x 60 cm) consists of 19 fuel which slows their speed from 2000 m/s
plates. A fuel plate is an airtight aluminum box to 500 m/s. The reservoir consists of
containing a thin sheet of uranium silicide. The reactor an aluminum tank with inlets and
core contains a total of 4 kg of uranium. outlets leading to a heat exchanger.
Nuclear fission in the fuel plates
Neutrons fly through the aluminum cladding and cause
nuclear fission of the uranium. All isotopes produced by
High-energy radiation Experimental hall
the fission reaction remain in the fuel plate and never
end up in the water. The high-energy radiation is largely
absorbed by the aluminum cladding (the rest by the
Aim of the reactor: neutron research
water). The energy generated is released into the water Uranium nucleus
In the measurement instruments around the research
that flows between the plates (3 mm space between the
reactor, neutrons are directed at a piece of test material.
plates).
The neutrons change speed and direction as they collide
with atoms in the test material. Through the diffraction or
Nuclear fission of uranium scattering of the neutrons measured, we obtain an
Three free
Atoms consist of a cloud of negatively charged particles ”image” of the composition and structure of materials at
neutrons
(electrons) that orbit around a nucleus of positive particles the atomic level which cannot be achieved in any other
(protons) and uncharged particles (neutrons). When a way.
neutron from outside collides with a uranium nucleus and
the atom takes that neutron into its nucleus, the uranium
OYSTER EXPANSION
nucleus splits into two smaller nuclei and three neutrons. Free neutron
The mass of the fission products is smaller than that of the New instruments
fissionable material because the reaction converts some
mass into energy. This energy is released as kinetic energy In addition to the five existing instruments, three new
and high-energy radiation. Fission of one gram of uranium Proton instruments will be built which only work with ”cold”
releases 24.000 kWh of energy. This is equivalent to neutrons. These new instruments will permit measure-
burning 2.500 liters of gasoline. Fission product ments that are currently impossible.
4 OYSTER 5 OYSTER
ROG is an existing instrument that will External radiation Liposome
perform 100 times better with OYSTER. High-energy radiation [1] Liposomes are small, hollow spheres
Apart from layer thicknesses themselves, the destroys tumor cells. External of fat (diameter about 0.01 mm).
Better roughness of layer surfaces will also become
visible.
radiation of a patient has the
major disadvantage that the
radiation also destroys healthy
The wall consists of a double layer of
molecules whose head dissolves in
water and whose tail dissolves in fat
semiconductors In the production of chips, mirrors are used
for directing extreme-UV light. The coatings
cells. (comparable to a soap).
The hollow liposomes are well suited
and artificial hips
to transporting a medicine [2]
on these mirrors are extremely critical: the through the body. The fat sphere
slightest film or residue dramatically reduces Making a liposome with a then works as a packaging which
with ROG
the reflection. This can be examined using the radioactive core keeps the medicine isolated until it
ROG. A capsule of liposomes containing a arrives at a diseased cell. There the
For an artificial hip, the quality of the coating holmium atom, for example, in their package must open so that the
determines whether or not it will be rejected hollow interior, is placed next to the medicine can do its work.
by the body. With ROG the quality of this sort reactor core via a tube [3]. The neutrons
of coating can be determined with extreme make the holmium atom radioactive. The fat
An instrument that promises improved products in numerous precision, and any deterioration can be sphere absorbs almost no neutrons, and the
sectors is the Reflectometer for Surfaces and Interfaces monitored. radioactivity induced in the fat is so short-
Research (ROG). This instrument can look at the thinnest lived that it has already disappeared before
the sphere leaves the reactor.
layers and coatings. ROG measures how neutrons reflect at
a grazing angle of incidence. From this can be deduced how
carbohydrates bind to various materials, how magnetic layers
on tapes and hard drives behave and how coatings adhere to
materials for artificial hips.
Liposome
diameter 0.01 mm
Gamma radiation destroys liposomes
The reactor core gives off not only
neutrons but also gamma radiation.
This gamma radiation can destroy the
structure and the wall of the fat spheres,
releasing the holmium atoms [2] from
OYSTER will give this medical development their packaging. In order to prevent this,
a substantial boost. CNIF allows extremely the fat sphere is now irradiated at a site
pure nuclear medicines or therapeutic far from the reactor core where there is
Better materials to be made. The current generation
of radionuclides contains many inactive Neutrons
little gamma radiation, but also few
neutrons. More neutrons would make the
components. These sometimes have
treatment of
holmium radioactive more quickly.
undesirable chemical properties with adverse Cold source
health effects. Or they needlessly saturate
cancer the tumor being treated, thus reducing the
effectiveness of the radiation.
OYSTER EXPANSION: CNIF
Liposomes
Cold neutron source
with CNIF With CNIF we are able to separate out the
inactive molecules in radionuclides, leaving
The new cold source [4] will
Internal radiation
A liposome containing a
fulfill a double function.
behind a practically pure and extremely First of all, the cold source slows
radioactive atom in its
effective radioactive material. This allows for a hollow interior is injected
down the neutrons so that they
more effective combating of cancer cells and into the body. Within a
collide more frequently with the
With the Cold Neutron Irradiation Facility (CNIF), materials can a reduction in side effects. minute the liposome
holmium atoms.
be made radioactive. This instrument is placed strategically arrives at its destination
Second, the reservoir of liquid
behind the cold source, where it receives many cold neutrons and becomes wedged
The manufacturing of this sort of ”nuclear hydrogen functions as a shield
inside a tumor. The
and little gamma radiation. CNIF thus makes complex structures medicine” must take place in close proximity against gamma radiation. The
radioactive atom briefly
radioactive without destroying them. to treatment centers. The radioisotopes quantity of neutrons reaching the
releases high-energy
are often short-lived and must therefore be liposomes is maximized without
radiation. The radiation
This capability offers useful perspectives for new treatment applied in a treatment within a few hours; destroying the fat sphere with
stops the growth of the
methods for serious forms of cancer. The Reactor Institute Delft otherwise they lose their effectiveness. the damaging gamma radiation.
tumor cells while the
is currently working with research hospitals in the development This allows more effective
High-energy surrounding, healthy cells
of a new generation of radioisotopes. These are, in a manner medicine packages to be
Tumor cells radiation remain unharmed.
produced.
of speaking, nuclear medicines that fight cancer cells very
precisely without damaging healthy tissue.
Tumorcellen
6 OYSTER 7 OYSTER
Texture in storage Scattering through fat OYSTER EXPANSION: SESANS
In the ideal case, the texture When a neutron moves through
in a sealed tub of cheese cheese spread and collides with a Better measurement
Innovative spread is fixed (from the
factory to the consumer) [6],
so that all fat spheres remain
fat sphere, the neutron changes
direction [9]. The path length of
the neutron through the second
With “warm” neutrons, SESANS
can measure 10,000 times faster
food products
than the classical apparatus with a
in place and the cheese magnetic field therefore changes,
projection screen, allowing us to
cannot separate into a fat making the neutron swing less to
see structures 100 times greater
the right than to the left. The final
with SESANS
later and a water layer.
(to 10 micrometers). With long
orientation of the neutron
wavelength “cold” neutrons the
has now changed.
size becomes 20 micrometers;
Polarized neutrons OYSTER also allows a measure-
Using a crystal and a mirror, all the ment to be taken in 1/100th the
neutrons of one speed and orientation time.
are selected [7].
The Spin Echo Small Angle Neutron Scattering facility (SESANS) Fat spheres in water
is a neutron polarizer. This instrument measures the scattering Cheese spread consists of
of the neutrons. The polarized neutrons change direction small spheres of fat and
through collision with atoms in the research material. This water. The size and
scattering angle is measurable through the trick of converting consistency of the fat
it into rotation. This trick allows supersmall scattering angles to spheres determine whether
be measured, shedding light on the larger-scale structure within cheese tastes ”creamy.”
the research material. A loose distribution of fat
spheres [1] of about 1
micrometer is experienced
Food products are being prepared at ever greater distances
as creamy, while a clump of
from the places where they are consumed. The composition of
spheres [2] larger than 10
foods is also being more precisely tuned to the dietary needs of micrometers is experienced Guide field
western consumers. With SESANS, we can look into the food to as grainy. It is not possible
observe how it is affected by preparation. with a microscope to see the
behavior of fat spheres Inclined
With OYSTER the possibilities are greatly increased because we inside cheese because it is magnetic field Cheese Neutron counter
can observe changes in real time. We can, for example, literally not transparent. But with
watch milk turn into cheese and thus learn to predict what SESANS, it is possible.
the effect of a given treatment on this food will be. Cooling, Opposite fields Seeking maximum polarization Size of spheres
heating, stirring and shaking, centrifuging or ripening. With this The polarized neutrons move through two inclined By increasing the strength of the From the size of the magnetic field, the
knowledge we can also take post-manufacturing effects into Unsteerable neutron Magnetic field planes with opposite magnetic fields. Regardless of magnetic fields, a moment arises when speed of the neutrons and their speed
account. A neutron has no charge and the neutrons’ angle of incidence, the path traveled the scattered neutron has swung of rotation, the difference in path
does not change its direction of in both planes is equally long, thus a neutron swings exactly one time fewer to the right length through the magnetic fields and
movement [3] when it moves just as often to the left as to the right in the two than to the left. When the neutrons therefore the scattering angle of
With OYSTER we can ensure that an ice cream bar tastes even
through a magnetic field. fields. At the end of the measurement device [8], were selectively scattered at that the neutron can be calculated. The
better after it has left the factory. The manufacturer can make
the number of neutrons having the starting angle, SESANS sees a maximum distribution of preferred angles reveals
more intelligent use of the knowledge that the ice cream leaves
orientation is measured (= polarization). If the polarization from the scattered the size of the spheres in the sample,
a cooled space several times during transport, so that when we
neutrons have not collided, all neutrons will still be neutrons having taken on the the distances between the spheres and
consume the ice cream, it is in optimal condition. pointing in the same direction, and the polarization same orientation as the unscattered the wall thickness of a hollow fat
With OYSTER the composition of food can also be changed and is maximal. neutrons. sphere.
adapted for a healthier diet. Food manufacturers are currently
investing in research on whether fat spheres can be replaced by
bubbles containing no fat but only water. Food then becomes
cheaper, because fat is more expensive than water. At the same
time, these ”light” food products will taste good because they NEUTRONS Deriving sphere size from shadow
are perceived as creamy. This is both a commercially interesting pattern
and a healthy development.
RESEMBLE LIGHT Scattering Because light is a wave, light shining
angle through the slit casts a pattern of shadows
SESANS measures the Slit on the screen behind much larger than the
scattering (change in slit. From the distances between the
Neutron
direction) of neutrons ”scattering angle of maximum light
resulting when a neutron intensity,” the size of the slit can be
(for example) collides with calculated. If there are several slits, the
a fat sphere.This scattering wave patterns of the slits intensify (much
Neutron spin is comparable to the light) or dim (less light) one another. The
Because a neutron consists of a positive, a negative and scattering of light through Sphere preferred angles then provide information
a neutral quark, a neutron changes orientation (like a a slit: a neutron behaves distance on the distances between the slits and their
compass needle) [4] in a magnetic field. A neutron also as a particle but also arrangement (ordering). This works just
has an inherent spin, an angular momentum of constant has wave properties, the same with SESANS, except that light
size. When a neutron enters a magnetic field, the just like light. intensity is not measured, but the number
”spinning compass needle” swings (precession) [5] of neutrons (=intensity) that has changed
around the direction of the magnet’s field. direction and therefore orientation.
8 OYSTER 9 OYSTER
OYSTER EXPANSION: NDF
New instrument
Better Porous metallo-organic frameworks are composed
of organic molecules bound together by metal Hydrogen is a promising
solar cells atoms. Hydrogen atoms [1] end up in the open
spaces in the framework. Researchers want to
understand how the hydrogen atoms nestle in
energy storage material for
the future. Hydrogen can be
stored as a gas or liquid in
with these hollow spaces. Specific atoms can stimulate
[2] or block the storage of hydrogen atoms. With
a tank (like liquid propane).
It is also possible to store
POSH 2D-ACAR a microscope we cannot look into a material at
the atomic level. With NDF we can.
hydrogen in solids, such as
metallo-organic materials.
This series of existing and well-known instruments works with Neutron beam Detectors
antimatter. The acronym stands for POSitrons at the Higher Measuring the distances between atoms
education reactor 2-Detector Angular Correlation Annihilation A warm neutron beam is aimed at a crystalline
Radiation. This instrument uses primarily gamma radiation close test material. Two ”choppers” [3] (spinning
Test material
to the reactor core to generate positrons. wheels with holes in them) allow regular
Energy is converted into antimatter that triggers an annihilation pulses of neutrons through (= start time).
reaction in the sample to be studied. This is when a particle
(electron) comes in contact with its antiparticle (positron) The neutrons are reflected by the planes of
and they destroy each other. The energy released from this is the crystal and are absorbed by a number of
measurable. Very small variations in the results consequently detectors [4] (=stop time). From the distance
shed light on the movement of electrons in close proximity to traveled and the time of flight (=stop time
irregularities in the material being examined. plus start time), the wavelength of each
neutron is calculated. The wavelength, the
reflection angle [5] and the intensity of the
This is good news for the solar cell. Performance would be less energy will be lost due to reflection. The
reflection show which distances occur between
much improved if the solar cell were completely black instead behavior of the electrons close to the defects
the crystal planes in the test materials. Special
of predominantly blue. With POSH 2D-ACAR we can look into is therefore of great importance. software can then calculate the entire crystal
ways to make solar cells black by means of ”defects” in the lattice.
crystal lattice. This will also improve the energy efficiency, since
Reflection angle
Detector
Neutron
OYSTER makes new energy techniques
possible. With NDF we can see how and
under what conditions hydrogen is stored in
More metallo-organic materials. These have the
remarkable property of being able to store a
larger volume of hydrogen than a hydrogen
efficient energy tank. NDF shows where the hydrogen stays in
the crystalline structure of the material.
storage NDF is also used in research on energy
Kitchen salt
Measurement of a single crystal of kitchen
salt reveals just one distance [6], so that the
with NDF storage in batteries. Knowledge and
understanding of crystalline structures and
the working of various parts of superbatteries
crystal lattice is immediately known.
are crucial in the development of electric
vehicles and decentralized (mobile!) Lattice surface CHARGING AND
availability of electrical power. DISCHARGING
The Neutron Diffraction Facility (NDF) is playing an important Neutrons reflect strongly off crystalline materials With NDF, the ”empty” crystal lattice of a
role in the development of our future energy supply. NDF is a A signal of a reflection off a single atom is not detected. If the atoms are metallo-organic material is measured first,
new instrument that works with the characteristic wavelength of arranged in a regular way in crystal planes, and if the pathlength difference and thereafter the situation if hydrogen is
”warm” neutrons. By measuring the reflection of the neutrons between the reflections off the different planes is a multiple of the neutron added. The extra distances ”show” where
as a function of the angle it is possible to unravel the structure wavelength, the reflections intensify each other and are measured as an and how the hydrogen atoms are located in
of crystals. intense signal by the detectors. the lattice.
10 OYSTER 11 OYSTER
With OYSTER these possibilities are expanded Positron source Repair of cracks at the atomic level
much further. OYSTER allows us to observe The positron source is Small clusters of copper atoms in the atomic
the faster processes in steel production and shoved close to the lattice of aluminum give aluminum alloys their
Stronger see the appearance and disappearance of
smaller grains. We see in real time what
reactor core via a
beam tube.
mechanical strength. If not all the copper atoms
clump together during manufacturing, the free
copper atoms can act as a filler.
steel
happens in the formation of steel and how
As soon as cracks appear at the atomic
changes affect it.
level, for example in an airplane
This is interesting to steel manufacturers.
with PANDA
wing, free copper atoms [1]
Because steel undergoes extensive processing fill the gaps.
after manufacture, the properties of the
product also change. The ability to predict
these changes allows one to take them into
account in advance. Steel can thus acquire
its optimal properties only after pressing and
treatment in zinc baths and paint lines. And
maintain these properties for years in summer Positrons
The Poly Axis Neutron Depolarization Analysis (PANDA) and winter.
apparatus is a ”neutron aligner.” Every neutron is a little magnet
that can be pointed. The ”aligned neutrons” are sent through Neutrons Magnetic
the research material. The exiting neutrons are measured to Test material fields
see how much they have ”swung.” We are then able to look into vacuum test space A long coil is
materials and see their magnetic structure. wrapped
around the
The composition of steel thus becomes visible: tightly packed Lifetime detector vacuum tube.
grains, some of which are magnetic. The size and composition This coil
of the grains change during solidification, but also afterwards creates the
from rolling and further working. This whole process can be magnetic field
Gamma radiation that guides
simulated in the PANDA. Through a better understanding of the
processes we can optimize production methods. We can make the positrons
to the test
judgments about the steel’s strength and even predict when Tungsten grid
material.
steel will fail. This will allow us to build better bridges and put The positron source consists of a series of
safer crumple zones in cars. tungsten grids close to the reactor core.
Gamma radiation from the core produces
positrons and electrons in the tungsten. An
Energy detector
electrical field leads the positrons into the
magnetic field.
OYSTER EXPANSION: POSH-PALS Recipe for aluminum
More positrons What is the right manufacturing
method? At what temperature and
A cadmium hood [2] absorbs the for how long should aluminum be
neutrons that originate from the core. heated? How much copper should
This releases extra gamma radiation be added? Or does another metal
From the data provided, the size of the
that is converted in the tungsten grids work better? With positrons these
hollow spaces in a structure can be deduced. Free Positron
into extra positrons, making the positron questions can be answered.
Potential fractures then become visible at a copper atom beam
Self-healing
beam seven times more powerful.
very early stage. The instrument can also be
used in the development of ”smart” materials.
aluminum When free copper atoms are added to
aluminum, they fill up the beginning of
Positron and electron disappear
A positively charged positron is repelled by
Lifetime of positrons
With the new PALS apparatus, the
with POSH-PALS hairline cracks. In theory, this leads to ”self-
healing” aluminum: as soon as a fracture
the positive atomic nuclei. After the positron
has been shot into the test material and
lifetime of positrons in defects can
be measured. The larger the
begins, copper atoms repair the damage. slowed down, it then seeks places where defect, the longer it takes for a
atoms are missing. This can be a gap of a + positron to meet an electron and
This continues until the copper atoms are
single atom [3] but also the beginning of a + annihilate. With extra detectors
used up.
crack. that can precisely measure the
With POSH-PALS this process can be followed
annihilation radiation, it can be
in real time so that the optimal composition
Finally the positron annihilates [4] with one discovered which atoms play a role
and lifespan of this self-healing aluminum can of the electrons present around the defect. in the repair.
Positrons Higher Education Reactor – Positron Annihilation be determined. This causes both particles to disappear and PALS measurements of self-healing
Lifetime Spectrometry: this new instrument shoots antimatter two photons (annihilation radiation [5]) are aluminum will show how many and
into a sample to see how long it takes before it meets and released. The existing ACAR-measurement how quickly free copper atoms [6]
destroys its negative counterpart. The larger the spaces in a device gives information about the energy reach and fill the open spaces in
structure, the longer it will take for this to happen. levels of the electrons in the test material. aluminum.
12 OYSTER 13 OYSTER
Determining chemical Detector OYSTER EXPANSION: SNM
composition
The chemical composition Directing neutrons
The of objects is interesting to
figure out - for example,
to determine whether the
With neutrons the composition
of an object can be determined
lie detector pigment of a painting was
really made 300 years ago.
without destroying it.
To analyze a specific piece it is
necessary to aim the neutrons
SNM It is possible to scrape a small
piece of paint off the canvas to
analyze it chemically, but this
precisely. This is possible with
cold neutrons because they are
damages the painting slightly. steerable with hollow glass
fibers.
The Scanning Neutron Microscope (SNM) requires a ”cold” Neutron beam
neutron beam. Via hollow glass fibers the SNM focuses neutrons
at a point on the material to be examined. Some neutrons are
absorbed there. The energy released manifests itself as flashes
of light. These can be measured. The analysis reveals the Analysis with neutrons
details of the composition of the material in the focal point: in When a neutron beam [1] is
theory, all elements in the periodic system can be made visible directed at a painting, some
in this way. pigment atoms take a neutron
into their nucleus and send out
This new measuring instrument will make entirely new a very short flash of light [2]
applications of neutron research possible. ”Authentication
Non-destructive research (high-energy radiation).
The main advantage of analysis with The painting does not change
research” in the world of art and cultural heritage is a promising
neutrons is that it causes no damage to detectably as a result of the
field. With SNM, pigments in paintings can be analyzed to
the test material, allowing the entire analysis because the neutrons
determine whether they came from the master’s palette or surface of a painting to be analyzed only hit one out of every 100
from an art forger of a later period. The same holds true for the millimeter by millimeter. billion pigment atoms.
composition of bronze, glass and pottery.
Another area of research concerns the organic breakdown of
contaminants. It is known that certain organisms (vegetation,
bacteria) feed on chemical contaminants. With SNM we can
examine how, why and under what conditions organic tissue Glass fibers Focal point Gamma radiation
takes up chemical elements and what happens to them The neutrons are led through a bundle of cross-section 0,2 mm
subsequently. This also opens up new pathways for medical hollow glass fibers (fiber diameter a few
research, such as research into the absorption of contaminated micrometers) to a focal point on the test
compounds by the liver and their effects. material. It is impossible to steer warm
neutrons with glass fibers.
A germanium crystal as a detector
The gamma radiation is absorbed by a
germanium crystal [3] (diameter 10 cm).
Each chemical element emits a different
color of gamma radiation. The relationship
between the gamma colors and the
elements is known. Germanium can detect
very precisely the differences in color and
intensity of gamma radiation.
The germanium crystal converts the
gamma radiation into electrical signals
which are measured.
Liquid nitrogen
The germanium crystal is cooled with
liquid nitrogen [4] (-196 o C) to ensure that Neutron
only electrical pulses occur as a result of beam
the gamma radiation absorbed.
14 OYSTER 15 OYSTER
Inter-
nationalization
Neutron research has yielded many benefits to modern life. ISIS, Oxford, England &
International particle research, such as that conducted in Delft
since 1963, has contributed to more effective health care,
ILL, Grenoble, France
better materials and more precise control of (production)
The largest pulsed neutron source in the
processes. Through these benefits, our quality of life has
world is located in England, while France has
improved considerably.
the most powerful research reactor in the
world. The two enormous research complexes
host the world’s top scientists in the field of
Within the international particle research community, neutron research.
Delft has come to play a unique and indispensable role.
ISIS commissions instruments, developed and
built for this institute, from the RID. ILL also
makes use of Delft knowledge and ideas.
RID, Delft
The RID complements ISIS through its goals
In the Netherlands, the Reactor Institute Delft (RID) is the
and capabilities. In Delft, fundamental and
academic center for radiation-related research and education.
experimental research is conducted that
The RID is a partner with national and international academic
would not be suitable for ISIS and ILL. On the
institutions and contributes to fundamental research in a variety
career ladder, RID serves as a portal for ISIS
of fields. Through a combination of expertise, the reactor
and ILL.
itself, the right instruments and a low-threshold accessibility,
the RID is also the contact point of businesses seeking
innovative applications to enhance the efficiency, safety, and
innovativeness of products. The RID employs 150 people. NRG, Petten
Our country has two research reactors. The
reactor of the European Commission in Petten
European Spallation Source is operated by the Nuclear Research and
consultancy Group (NRG). With the reactor’s
Europe has so far enjoyed a head start on the rest of the world
high power and high radiation levels, the
when it comes to neutron research, with ISIS and ILL as trump
primary research there is materials research
cards. But the United States and Japan are on the verge of
into radiation damage, in which materials are
completing neutron sources that will be stronger than ISIS.
tested for application in high radiation fields.
Petten is also a supplier of radioisotopes
The European neutron community is preparing to build a pulsed
for the medical industry and operates on a
neutron source that will surpass all existing sources by a factor
commercial basis.
of ten: the European Spallation Source. Combining knowledge
and expertise on a European scale makes it possible to maintain
The research reactor of the RID is oriented
our leading position in the world.
towards scientific research, the uses of
radiation to develop better functional
The Netherlands has been asked to contribute to this project
materials and compounds. Delft also develops
via the RID. The Netherlands will therefore, through the RID,
new applications and optimal production
play an important role in the development of this European
methods for medical radioisotopes. Delft thus
research facility.
supplies knowledge that can be applied in
Petten.
16 OYSTERTU Delft
Reactor Instituut Delft
Delft University of Technology
P.O. Box 5042 - 2600 GA Delft
Mekelweg 15 - 2629 JB Delft
T +31 015 27 86744
F +31 015 27 86422
I www.rid.tudelft.nl
Colofon
Coördination & text Zuid-West 3 Communicatie
Translation Roberta Hardy
© Illustrations & text Verdult - Kennis in Beeld, www.kennisinbeeld.nl
© Design cover Verdult - Kennis in Beeld
Graphic lay out Chris Cras Reclame
Production date Februari 2009You can also read
