Samstag, 16.11.2019 03:07 Uhr

Large Hadron Collider

Verantwortlicher Autor: Benjamin Lubec Genf, 14.09.2019, 11:46 Uhr
Fachartikel: +++ Special interest +++ Bericht 5116x gelesen

Genf [ENA] The large particle accelerator in Geneva is in full swing. Dr. Jörg Wenninger gives an interview for Benjamin Graf-Lubec and explains what has become important for the scientists at the LHC. After the long winter break, the collision rate was increased and the radiation energy was increased to almost a maximum. But it is not only science that benefits from particle accelerators, because medicine and other scientifi

Graf-Lubec: How did it all start with the LHC? Dr. Wenninger: The ideas date back to the eighties, andin 1984 the first LHC conference tookplace. The main concepts were defined at that time. Construction was approved in the 1990s. Within ten years, the electromagnets were developed and over a total period of 8 years the accelerator was then delivered and installed in the tunnel. Reporter: Who can be thanked for the existence of the LHC? Wenninger: All in all, For me Lyndon Evans is the soul of the LHC. He led the development and construction in the critical period from the mid-1990s to the start.

Graf-Lubec: Who works all the experiments? Wenninger: A total of 2000 scientists at the LHC and about 8000 physicists are working on the data analysis. For each experiment there is a spoke person who is chosen for 2-3 years. The operation and maintenance work is provided by CERN, the physicists come from all over the world. CERN has 22 Member States. These come from Europe. The experiments are independent collaborations and completely international. These are people who are not employed at CERN but are considered users. This is a very interesting psychology, as it is possible for people from twenty countries to bring a stone to the big building without a formal contract.

Graf-Lubec: What has happened so far? Wenninger: So far, we're on 90% power in terms of jet energy, and we still have to fight for 10%. We are already 40% above the target in the collision rate. Thanks to the excellent management, the Higgs boson was discovered as early as 2012. Rate and the property of the particle are currently being analyzed, and more data is needed to better narrow the properties.Count-Lubec: The LHC has been serviced? Wenninger: We had a weak point in the soldering points between electromagnets and had to carry out maintenance. Components were gradually maintained in order to reach the missing 60% of the energy. It took a total of one and a half years.

Graf-Lubec: What are the technical requirements? Wenninger: To increase the energy, we had to fix the vulnerabilities in the soldering between the 1200 magnets. That was almost 12,000 soldering points. Weak soldering could have resulted in an electrical short circuit, which would have resulted in 4 to 6 months of maintenance work. Reporter: Were there any job messages? Wenninger: The initial message was the repairs and limited energy during the first years.

Graf-Lubec: When did they reach the point of no return? Wenninger: It took us six years to reach the target and you can't get there from one moment to the next.Count-Lubec: Is there a command structure? Wenninger: Yes. It is the case that it is not only the management that is discussing. but the ideas are taken into account by everyone. I do the day-to-day commands and my bosses indicate the direction. We have a director who runs the laboratory, but who does not intervene directly and deeply in the management of the LHC, he delegates us the daily management. What exactly is done at what energy intensity is defined by scientific committees in which the physicists of the experiments are represented.

. Graf-Lubec: Do they want to tell the public if it makes sense to invest in the LHC? Wenninger: We are far from the end. There is a relatively consistent model of particles and forces in the LHC that explain the world view. We know that in the universe and what we explain by it is only 5% of the matter and energy that is in space. There is matter that physicists call black matter that does not interact directly with us. On closer examination of the distribution of the galaxy, one realizes that the mass of the particles that is in the stars cannot explain what is happening up there. About 95% of the mass and energy are missing.

Graf-Lubec: What would they tell Albert Einstein if he was still alive? Wenninger: That quantum physics is true after all. He did not believe in quantum mechanics, because quantum theory is not as deterministic as classical physics. Over the last sixty years, it has been proven that the theory is correct. Reporter: Can they call an apparatus similar to the LHC? Wenninger: In the United States there is an accelerator of similar dimensions - that is, a few kilometers. However, the length is only one-fifth of the size of the LHC. However, this accelerator does not have the same scientific objective. There are several 10 000 accelerators in the world, most of which are only a few metres long.

Graf-Lubec: What is the cost of the LHC? Wenninger: The construction cost five billion euros. CERN has a budget of about EUR 800 million. Most of our budget is used to operate the accelerators. I don't have the exact numbers. Reporter: What were they most excited about? Wenninger: We are happy every day when the accelerator is running better. We had the most joy on 10 September 2008, when everything worked on the first beam. But it's never the same again as it was the first time. It's a unique experience to commission a new, more complex and more powerful accelerator. Graf-Lubec: Do you have a personal hero at the LHC? Wenninger: Lyndon Evans.

Graf-Lubec: What setting do you have to haveat the LHC to move forward? Wenninger: For the first time, I'm fascinated by work and wouldn't trade it for anything. I work in the evening and at night and at weekends. From time to time, however, it is also good to switch off. Graf-Lubec: What did their parents do? Wenninger: My father was also a physicist. Graf-Lubec: What networks do they have to communicate?

Wenninger: We have our own technical network, but it is demarcated to the outside world. There is only one interface for authorized persons that is protected by an IT division. In the event of breakdowns, people can diagnose from home on the network. On weekends, only two people are in the LHC control room to get the LHC running.Count-Lubec: What will be possible with the LHC in the future? Wenninger: The LHC is only needed for research. A larger FCC accelerator is planned. The infrastructure for cancer cure, for example, is expensive. Certain accelerators should be made smaller, more compact and cheaper.

Graf-Lubec: Do you use apps? Wenninger: There are websites that allow you to track the LHC. This is possible from any web browser. This goes to LHC_page_1. I also use this from home. Count-Lubec: What does a normal working day look like? Wenninger: Basically, if nothing important, it starts at eight o'clock and ends between five and nine o'clock in the evening. Half are mostly used to analyze data and operations and discuss improvements with colleagues, and the other half of the time when I'm not working administratively is there to work on ideas about what to do in the future. Graf-Lubec: Have you seen everything from the LHC?

Wenninger: Most of it is extremely monotonousbecause the same components are repeated. I've seen all the different zones. Graf-Lubec: How does a process at the LHC work? Wenninger: The accelerators at CERN function like a kind of chain. We use magnetic fields to keep the particles on a circular orbit. The magnetic fields cannot be operated from zero to one hundred, similar to the gear shift of a car. Almost everyone has an input and output energy. The beam, when it has reached the maximum energy, is passed into the subsequent accelerator. The protons pass over four pre-accelerators before the LHC.

The process starts with the fact that we use the magnetic fields in the LHC to use the energy for the introduction of the beam. Then we fill the LHC with the number of particles we need for the day. This takes about 30 minutes. Then we increase the magnetic field to accelerate the particles. This takes about 20 minutes. After that, we focus the beam more strongly and bring it down to as small a point as possible of the exponent. We have special magnets to prevent the particles from colliding.

Only when everything is ready do we switch off the magnets, the particles collide and start the experiments. Graf-Lubec: How do they differentiate the particles? Wenninger: When we are in normal operation, 40 million collisions occur per second. Of these, the experiments can write down about 1000. So out of 40 000 collisions, only one is taken. Then the data are analyzed for weeks to years. All physicists naturally hope to see a new particle and, for example, to make black matter visible. The particles are differentiated on the basis of theories. Either you look blind, or you search by model. You try to deduct as much of the data as possible and to exclude nothing important. This requires a lot of prior knowledge and good intuition.

Graf-Lubec: How much do physicists cling to string theory? Wenninger: It's like religion. Some believe in it and some do not. Graf-Lubec: Does the LHC stand out only by its size?Wenninger: All accelerators have a different goal. Some accelerators are there for solid state physics and produce extremely intense X-rays. General physics is the samefor all acceleratorsn.V however, the accelerators differ in many subtleties.Count-Lubec: Do they have any advice for younger generations? Wenninger: You're not always lucky enough to do what you can and can live on. I wish everyone to do what is fun and what you are interested in.

Graf-Lubec: The FCC is in the pipeline? Wenninger: At the moment, the FCC is still a paper study. We're designing and I spend about 10 percent of my time planning. Ata meeting of the particle physicist communities of Europe in 2013, CERN was asked to examine the development of such an accelerator. The results of the study should be published in 2019, then one should have a clearer picture for the FCC. What matters is what is transposed from the LHC to the FCC. Reporter: Would they invest in the FCC? Wenninger: At the moment it is too early. Technically, many aspects still need to be clarified. Graf-Lubec: Is it possible to create a completely new theory using the LHC?

Wenninger: The Higgs particle adds a theory. In theory, that is, there was no building block. Everything else stood coherently together. That is, at the moment you have a closed theory that works with the smaller energies. There are hardly any deviations. There are many predictions and the physicists are looking for deviations, which can be found in the physics of the missing 95% of the universe. However, we do not have a clear indication to complete this theory.

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