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Microtron underneath the Vítkov Hill

Microtron underneath the Vítkov Hill

2023-01-17 06:30:13

The Vítkov Hill within the middle of Prague hides a pedestrian tunnel underneath it, along with a number of previous tunnels for trains. However solely few folks know what lies behind utterly inconspicuous spray-painted steel doorways.

Simply outdoors the door, you may see a 22kV transformer station, which provides the required energy for all of the tools inside. It was initially meant for Karlín district.

To the left, you may stroll by slender concrete corridors. These result in a small room with a number of doorways.

Behind the blue door on the left is a warehouse and an enormous concrete lens that was as soon as movable, permitting the tunnel to be closed to extend its resistance to atomic explosion.

The door on the correct really feel significantly extra fascinating due to the pictograms:

The primary slender room behind the door hides a mechanical workshop.

The subsequent room is an digital laboratory:

The penultimate room varieties a sort of crossroad, during which there are two different rooms moreover the doorways by which we entered. One big, armored, one regular. Behind these two tons of lead-filled, hydraulic-operated doorways, is a microtron.

Behind the regular ones on the left is the spectrometer the place the samples are analyzed. On the correct, there a management panel, which has hardly modified since 1981:

(The plaquette with the schema diagram roughly within the center is worthy of observe.)

The grey field within the image on the correct is an electromagnetic wave modulator, like the sort utilized in RADARs. It’s a one-off manufacturing from St. Petersburg, Russia. The ensuing wave is routed by the wave-guide to the final and most necessary room, hidden behind an airlock consisting of a pair of giant lead doorways. These present shielding equal to a few meters of concrete:

That is the place the Microtron MT25 is positioned.

A microtron is a particle accelerator accelerating a gaggle of electrons into variable pace (=power). Microwaves are fed into the crimson cylindrical chamber, the place they work together with the recent voltage-induced crystal of the cavity resonator (?hexaboride?). This offers the electrons within the valence spheres of the crystal preliminary power and pushes them out. The charged particles then make a round motion within the magnetic subject.

(Cavity resonator part. There is a crystal within the crevice within the center. Sorry concerning the blurry picture.)

Electrons are accelerated in teams known as “bunches” alongside round paths, during which they stick as a result of the whole chamber is one giant magnet, affecting their trajectories.

The complete machine is timed and calculated in order that the size of the electron circulation alongside the circle is a a number of of the wavelength of incoming electromagnetic radiation. Because of this, electrons are repeatedly given about 1 MeV of power in every orbit, inflicting them to maneuver to the next orbit with a bigger radius.


This explicit microtron permits to pick out a number of inside diameters of runways and thus additionally output energies scaled by 1MeV steps from 6 MeV to 25 MeV. The bunch of electrons is then sooner or later led out and directed by different magnets to a particular goal.

The outlet channel is principally a sliding pipe that may be positioned on a particular observe. It should be set earlier than switching on the machine, which leads to deciding on the power degree of the bunch.

(CHVÁTIL, David, Miroslav VOGNAR a Pavel KRIST. Mikrotron MT 25 – zdroj tvrdého záření gama [online]. , 1 [cit. 2020-04-01]. Obtainable from:

Curiously, due to the interior design, it’s not doable to manage the electron present underneath 13 MeV as a result of the pipe can’t be shifted to the suitable observe. Change to decrease power states is completed by changing a cavity resonator by one, which produces an power of solely 0.5 MeV. This successfully divides the obtained power ranges of the particles by two.

Electrons are then introduced into electron guides, that are principally pipes with electromagnets connected:

Dipoles, which act as output selectors, mean you can choose a particular electron tube through the use of the identical rule as within the microtron – the charged particle curves its trajectory in an exterior magnetic subject. The extra energetic the particle, the stronger magnets are wanted. On this means, a straight-flying particle might be led into certainly one of a number of tubes.

You possibly can see the electromagnets on the pipes, which our information refers to as “quadruple duplets”. These permit the bunch to be targeted or defocused, from a couple of millimeters to about twelve centimeters. The precept is a bit just like the focusing method utilized in previous CRT TVs.

I attempted to seize the precept in key particulars within the animation right here:

The output of the electron information seems like this (center of the picture):

Mainly, a pipe terminated with some materials. On the picture above, it’s a movie with a luminophore layer, which causes it to shine the place electrons move by it. This mild is monitored by a closely shielded digicam positioned above the microtron, which is pointing at this movie by the mirror.

Further filters might be positioned behind the foil. A fabric with a big proton quantity causes electrons to interrupt within the Coulomb subject of filter particles. Some supplies (tungsten, for instance) are calculated to cease electrons utterly by knocking an electron out of the nucleus, making a gap that fills up with one other electron whereas emitting gamma photon emissions. Different supplies, similar to lead or depleted uranium, trigger gamma photons to transform into neutrons (the electron has such power {that a} neutron comes out of the nucleus).

With this straightforward precept, it’s doable to get a stream of electrons, gamma and neutron radiation from one machine.

Electrons are mono-energetic as a result of all others are eradicated after they fall out of synchronization of the accelerated “bunch” in round orbits. Emitted photons have a steady power spectrum.

Right here, the electron ray is directed to a briefly constructed wall of lead bricks, which is used to defend undesirable radiation, aside from a small slender area within the tube which you’ll be able to see in the midst of the wall.

A rotating face with an engine on which the irradiated pattern rotates can be typically used. If we take a look at the top of the second electron information, it seems prefer it leads into the void in entrance of a inexperienced field:

It’s price noting the aluminum-looking tube to the left of the orange pillar. It’s a pipe for pneumatic tube capsules. These are irradiated by a slender crack within the center after which sucked out with a darkish grey hose, which is for the time being disconnected within the picture above. The capsule pipeline goes to the room subsequent door, the place is a spectrograph that measures the spectrum of the irradiated pattern, thus gaining, for instance, details about its composition.

The pneumatic capsule system makes doable detection and evaluation of samples with a really brief half-life (seconds or much less).

To carry the lid, there’s a small crane with a journey observe above the microtron. It’s used for upkeep, substitute of the cavity resonator and so forth. The ingot forming the physique of the microtron is used as a pole attachment of the magnet, which creates a homogeneous magnetic subject. Nevertheless, there are additionally correction coils that modify imperfect round pathways affected by materials inhomogeneities.

The electron is about 1000 occasions lighter than the proton, i.e. the acceleration of electrons is 1000 occasions simpler than acceleration of protons. CERN’s most well-known particle accelerator has 7 TeV for protons. This offers power variations a few billion occasions higher (6 orders of magnitude per tera +1,000 occasions extra per proton) in comparison with the microtron. As our information explains, you may’t use a comparability to a snail and a Formulation One as a result of there’s only some orders of magnitude distinction in pace.

In principle, it might sound that the microtron doesn’t have a lot use when there are devices able to attaining considerably higher power everywhere in the world. Nevertheless, the microtron has an excellent benefit within the big configurability of the bunch, energies and sorts of emitted particles. But in addition in the truth that it achieves small energies that can be utilized, for instance, for chemical adjustments.

From the particle physic follows, that if the particle’s power is lower than 10 MeV, the charged particles are unable to cross the Coulomb barrier, and thus there might be no nuclear response. In different phrases, all adjustments that happen are solely on a chemical foundation, supported by the power of the microtron. Because of this, there is no such thing as a induced exercise within the irradiated object when the irradiation is completed (the pattern isn’t radioactive).

A whole lot of the makes use of are for biologists and meals producers. For instance, the Meals Analysis Institute stated it needed to enhance the fabric of the sausage casings, so they may crack much less. In response to our information, this was really achieved by low-energy irradiation, the place after a number of makes an attempt they had been capable of finding a configuration inflicting networking on the materials degree. On this means, it’s doable to get totally different bodily and chemical behaviors from the identical particles of fabric by reordering its construction.

To lighten the temper, we had been instructed about an experiment with the getting old of cognac by irradiation, which was finally successful. The bodily precept relies on releasing ester and ketone molecules from the top of chains of complicated molecules that may in any other case must be launched by cosmic radiation, Brownian movement, warmth, and usually the oscillation of molecules. Esters and ketones are stated to make the most effective tastes and are sure on the ends of molecules by weak forces, from the place they fall off on their very own over time. The equal of 20 years of maturation is alleged to take about ninety seconds on microtron. It must be added that on this means it’s not doable to create, for instance, the style of an oak barrel, solely to launch already current style molecules.

Usually, the microtron is used for drugs. Among the many issues that made it to the media was the event of diamond nano-technology, which was additionally developed due to irradiation on the microtron. This know-how permits for instance to render most cancers cell by cell, and even the processes inside cells.

The irradiation of a particular organic gelatine of animal origin was additionally fascinating as a result of they managed to create a stable and biocompatible materials usable as bone substitutes. These replacements, for instance, of titanium clavicle joints, don’t trigger the physique’s immune response.

Additional, our information lists the use for electronics testing and describes the verification of assorted particle detectors, in addition to the radiation resistance of electronics used within the navy or area industries. The lead-brick fence was used to confirm the operate of the delicate detector a fortnight earlier than our go to, and served to cut back radiation to a smaller degree.

For instance, he additionally mentions the power to find out whether or not irradiated supplies have modified, so, for instance, totally different elements of Temelín Nuclear Power Station had been examined right here.

Irradiation of assorted crystals can be frequent, for instance for the Crytur firm, which is alleged to be the one firm outdoors Russia and China able to producing crystals of the required quality, so the Germans approached it concerning the development of a scintillation detector for a newly constructed particle accelerator in Darmstadt.

Moreover, they assist to prototype particular electrode supplies for brand spanking new sorts of batteries as a result of they’ll create totally different chemical or bodily constructions by irradiation that might not be produced by different processes. For instance, irradiation can switch molecules into a particular construction, trigger them to be semi-permeable or to create small holes in them.

That is most likely probably the most fascinating a part of the work for David Chvátil as a result of it’s crucial to hold out interdisciplinary cooperation with chemists and materials physicists. They typically don’t perceive nuclear physics, so it’s crucial to organize tailored options for them and develop numerous inventive procedures.

Nevertheless, the most typical use is the so-called photon activation evaluation. It really works by an electron being knocked out of the nucleus of the goal materials by radiation. This makes the nucleus unstable, and β-decay turns it into a component that’s to the left of it within the periodic desk of components. In doing so, attribute photon radiation is emitted. That is particular to every factor by its power and spectrum. By measuring these photons and their spectrum, it’s doable to search out out precisely what components, and even their isotopes, are current within the materials.

This technique has a really excessive sensitivity for some components – they are often detected with a decision of as much as 1 ppm, i.e. detect one particle in one million of others. In the course of the communist regime within the Czech Republic, the microtron was used on this solution to seek for gold, by measurement of proportion of gold in soil samples.

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Completely different components have to be analyzed for various lengths of time, relying on the fabric, it may be as much as hours. Photon evaluation is fascinating as a result of the workplaces the place it could be carried out are few, not like neutron evaluation, which is extensively practiced on the planet.

Extra lately, the microtron made headlines, for instance, when it was concerned in analyzing Tycho de Brahe’s beard after historians speculated about his poisoning. And likewise when it was used to analyze the bracelet that archaeologists discovered on a prehistoric man.

The function of microtron is principally in analysis and prototyping, not in manufacturing. As soon as a course of is fine-tuned and explored, a radioactive supply similar to Cobalt 60 is often used. These are additionally used for instance for sterilizing all spices and dressing supplies within the European Union, but additionally irradiating furnishings in opposition to worms and so forth.

The Czech Republic is the one post-Soviet nation to construct its personal microtron, due to Professor Čestmír Šimáně. Here’s a translation from Czech wikipedia:

After learning on the grammar college in Opava-Kateřinky and on the third Grammar College in Brno, he graduated from the Technical College of Dr. Edvard Beneš in Brno. After the warfare he labored as an assistant on the College of Science of Masaryk University. In 1947 he succeeded in making use of for a scholarship to check in France. There he studied for 2 years on the Collège de France underneath the management of Professor Frédéric Joliot-Curie. He labored, amongst different issues, in a scientific group coping with cyclotrons and likewise on the accelerator in Ivry. In Paris, he had the chance to attend lectures by the most effective scientists of the time, similar to Louis de Broglie.

After coming back from France, he grew to become the primary worker of the Institute for Atomic Physics. He constructed a laboratory of nuclear physics in Hostivař, Prague. In 1954 he was director of the Institute of Physics of the Czechoslovak Academy of Sciences after which the primary director of the Institute of Nuclear Physics in Řež, which he has quite a lot of credit score for constructing. In 1964 he started to lecture on the College of Nuclear Sciences and Physics engineering of the Czech Technical College in Prague, and from 1967 to 1972 he was dean there. He labored at this college for a complete of forty years.

From 1961 to 1964 he was director of the Technical Provide and Nuclear Supplies Division of the Worldwide Atomic Power Fee in Vienna. At the moment, he additionally labored as an interpreter within the negotiations of Russian and American scientists. In 1956 he grew to become a long-time member of the Scientific Board of the Joint Institute for Nuclear Analysis (SÚJV) in Dubna close to Moscow, the place he served as deputy director from 1973 to 1977.

Professor Šimáně was one of many completely key individuals who was behind the delivery of all nuclear analysis within the Czech Republic. In response to the story of our information, it was he who realized throughout his time in Dubna, that the microtron was the perfect kind of accelerator for the then Czecho-Slovak Republic. Because of him, a design was created in our nation and subsequently the development of the microtron was realized.

This required the blast furnace to cease in Vítkovice and pour iron ingot specifically for the microtron, which was then machined in Pilsen Skoda to the specified form. All different tools besides a couple of items was then made instantly within the premises underneath Vítkov.

The Czech microtron, not like the Russian ones, is within the form of a roughly three-ton pot with a one-ton lid on it. The Russians then use a design the place the lid is detachable from above and beneath. To today, they are saying, there are disputes about which design is best. Ours does not bend as a lot from beneath when an working vacuum of 10^-4 pascal is produced within the microtron.

In response to the story of our information, traditionally there was a Russian and Swedish department of growth. The Swedes used an electron gun to inject electrons, which is why their microtrons had been very costly. The electron gun itself, for power ranges in mega-electron-volts (MeV), might value greater than the remainder of the microtron. In distinction, the Russians developed a way with a cavity resonator, the place the crystal prices a couple of {dollars}.

There are usually few microtrons left on the planet. Within the west, there are virtually no microtrons of the classical kind. Most microtrons of the Swedish kind have been transformed right into a so-called racetrack, which might attain increased power ranges. Racetrack is a mixture with a linear accelerator, the place the microtron appears to be reduce in two, and linear accelerators are inserted between them. It’s usually estimated that there are only some dozen, possibly solely a few dozen nonetheless working microtrons on the planet.

(Obrázek pochází z wikipedie:

Right this moment, linear accelerators are principally used as an alternative of microtrons. For comparability, it’s estimated, that there are about fifteen thousand of them on the planet. Simply in Prague, there may be a minimum of ten. The overwhelming majority is utilized in drugs, particularly in oncology facilities. Linear accelerators are manufactured by about two or three firms on the planet, docs have expertise with them, and they’re principally as user-friendly as doable. You possibly can simply press a couple of buttons and it really works as anticipated.

Mainly, all microtrons of the unique kind are of Russian origin as a result of the Soviet Union outfitted the RVHP (Comecon) countries with them. Microtrons remained, for instance, in East Germany, Poland, Hungary, Romania, Bulgaria and Ukraine. The Vietnamese and Mongols additionally received their very own microtrons. There may be additionally a microtron in a hospital in Moscow, on the Institute of Nuclear Joint Institute for Nuclear Research in Dubna, one is alleged to be someplace in Siberia and one in Canada.

Because of the small variety of items, there aren’t any firms that present business help for microtrons, so if somebody operates it, they must do all the pieces by themselves. You possibly can say that the folks across the microtron have to grasp all the pieces to the final screw and wire, they usually must manufacture a lot of the elements by themselves. This requires folks with a mixture of information so broad that they’ll deal with all the pieces from particle to materials physics, engineering and electronics. Mechanical and digital workshops within the first two rooms, the place college students from a number of colleges take part in upkeep and growth, are additionally used for this goal.

Curiously, in nearly all international locations of the previous RVHP (Comecon), aside from Ukraine, microtrons are not used because of complexity. For instance, Poles, Hungarians, Romanians, and Bulgarians have gave up microtrons, and Vietnamese and Mongols use them solely in a simplified mode.

Along with Russia, the Czech Republic is without doubt one of the few international locations that has adequate specialists for its personal analysis and additional enchancment of microtron know-how and the ensuing benefits (photon activation evaluation) over high-energy accelerators.

It appears to me to be a outstanding hint of Professor Šimáně, who, like Kolben, has raised our small republic to equal to world powers, relating to nuclear know-how.

In fact, we had a number of questions, listed below are a few of the remaining ones that I’ve not been in a position to dissolve into the remainder of the article;

How a lot does an hour of irradiation prices roughly

The microtron is alleged to have 4 totally different accounting modes:

  • For college students, it’s free as a part of numerous dissertations and so forth.
  • For folks from the FJFI (College of Nuclear Sciences and Bodily Engineering) it prices a low value within the order of a whole bunch of Czech crowns (~low tens of €/$), the place they pay just for water and electrical energy.
  • Different scientific institutes within the nation pay about two thousand per hour (~80€, 93$).
  • Lastly, business firms pay about 4 thousand (~160€, 190$).

Laptop management

The microtron isn’t straightforward to manage with a pc as a result of the management principle isn’t totally described by a couple of equations. Work is at present underway to switch the management to Tecomat PLCs.

In response to David Chvátil, he’s at present the one one in Central Europe who can manually begin, management with use of analog-electronic devices, and calibrate the microtron by hand. It’s anticipated that even after the pc management is put in place, the operation will nonetheless happen in semi-automatic mode, just like the take-off of the plane. The operator will first begin and calibrate the machine manually, and solely after reaching the working parameters will move the management to the pc, which can preserve the operation.

Enormous thanks belong to our information, Ing. David Chvátil from the Institute of Nuclear Physics of the Czech Academy of Sciences. His information and rationalization expertise are completely wonderful. He answered all our inquiries to the final element in a complicated technical means, however on the similar time in such a means that everybody understood.

I’ve to say, I wasn’t the one one who was excited concerning the tour, and I would not be afraid to name it epic. Personally, it gave me so many stimuli and issues to consider that even months later, I nonetheless take into consideration the physics across the microtron. The keenness even went to date that I puzzled if I would wish to profile myself on this course sooner or later, and possibly go to remotely examine some sort of related subject.

What impressed me probably the most is the whole configurability of the entire machine. Completely all the pieces might be arrange and modified, from the most important nonsense to the very major capabilities. The folks across the microtron know completely what they’re doing at a degree that I can solely dream of. They can use Microtron in 1000’s of various methods, and play on it like you may play a musical instrument.

Once I was on the tour, I spotted fairly clearly that that is how science is meant to be accomplished and the way a brand new era of scholars ought to be taught. Do not give them costly toys purchased someplace overseas, however allow them to construct a fancy machine from scratch. The community impact creates an enormous profit for the entire republic, which causes these folks, and the folks round them, to turn out to be specialists, who then unfold their experience amongst others.

I received to the microtron by a colleague, whom I really useful an tour to the LVR-15 nuclear reactor in Řež, the place I went with a couple of brmlab guys. You possibly can examine it right here: LVR-15 research reactor near Prague.

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