Xueba starts with change

Chapter 532 Searching for Heavy Neutrino Experiments
"From the perspective of the complete framework of the three generations of neutrino oscillations, for the theoretical study of neutrino oscillations, we can start with neutrino oscillations in a vacuum..."

When the time came to 8 o'clock in the evening, Chen Zhou was immersed in his own research again.

The basis of neutrino oscillation theory is also the ideal vacuum state.

Neutrinos are produced in the vacuum through the flavor state, and the propagation process is the mass state.

Finally, it is detected by the taste state, and the components in the mixed taste of neutrinos have changed.

This phenomenon of neutrino flavor transfer is neutrino oscillation.

"The taste state of a neutrino is a linear superposition of the mass state of a neutrino, and the specific formula is Vα(x)=α=1∑UaaVa(x)..."

While Chen Zhou's brain was running fast, there were more and more formulas on the draft paper.

Below this formula, Chen Zhou marked three more conditions.

1 is that neutrinos are plane waves with definite energy and momentum, 2 is that neutrinos are relativistic particles, and 3 is that neutrinos travel along a definite axis.

This is because, only under the approximate conditions of the neutrino oscillation experiment in vacuum made by the predecessors, the neutrino oscillation experiment formula deduced, and then talk about the more complicated solar neutrino oscillation experiment, is meaningful.

Theoretical research, at any time, is also from basic to complex.

Combining these three approximate conditions, the pen in Chen Zhou's hand moved quickly on the draft paper.

"...Finally, an expression for the probability of oscillation can be obtained: p(α→β;t)=∑|U*αa||Uβa|+2Re[a≠b∑U*αaUβaUabU*βb exp(-i(Δmab /2p)t)]..."

"Here α, β are the taste state of the neutrino, t is the time evolution of the mass eigenstate, i is the unit vector of the x-axis, U* is the mixing matrix, Δmab is the mass difference of the neutrino, p is the neutrino The chances of a micron surviving..."

After getting the expression of the oscillation probability, Chen Zhou stopped the pen in his hand, and habitually clicked on the draft paper.

Two conditions flashed through my mind.

are the two conditions that neutrino oscillation needs to meet.

1 is that neutrinos must have poor mass.

2 is that the mixing matrix must have non-zero off-diagonal elements, that is, neutrinos must be mixed.

From this we can also confirm the most basic point, neutrinos have mass!
Only when this point is confirmed, the experiment of searching for heavy neutrinos will be meaningful.

Instead of clicking on the draft paper, Chen Zhou tightened his grip on the pen, and began to start with the Erwei neutrino mixing matrix. Combined with the oscillation formula, he theoretically deduced how much the oscillation wavelength needs to be defined to make the oscillation amplitude obvious after all.

With the passage of time, Chen Zhou also obtained the desired theoretical formula.

From this, it can also be determined that in the neutrino oscillation experiment, in order to accurately determine the mass difference and mixing angle of different neutrinos, the experimental settings should choose the appropriate distance for different neutrino oscillation parameters, Maximize the oscillatory term.

After initially finishing the theory of neutrino oscillation in vacuum, Chen Zhou glanced at the time, and it was already past 1 o'clock at night.

After thinking about it, Chen Zhou did not immediately carry out theoretical research on the next one, the neutrino oscillation experiment of the MSW effect of solar neutrinos.

He picked up the draft paper that he had put aside earlier, and started to sort it out again.

For some reason, Chen Zhou always felt that he seemed to have missed something.

It's a pity that Chen Zhou, who combed through it again, still couldn't find what he felt was missing.

The next day, Chen Zhou followed his good living habits.

Get up and run in the morning.

Afterwards, after finishing breakfast, he returned to his room.

Chen Zhou had told Bertolucci yesterday that he needed an independent and quiet space and time.

Therefore, he will not participate in the experimental preparations for CERN.

After he completes his theoretical research, or after he has made initial progress in theoretical research, he will come to work with the researchers to carry out the last major experiment of CERN this year.

Although Bertolucci was somewhat unwilling, he finally agreed to Chen Zhou's request.

Originally, Bertolucci and Mitch Johnstone came back to participate in the experiment under the name of Chen Zhou, so that he could see the powerful strength of CERN, thereby impressing Chen Zhou, and awarded the youngest Nobel Prize in Physics in history. The little thought that the winner joined.

But now, people have their own plans, and they are not so impressive at all.

However, when Bertolucci and Mitch Johnstone discussed, the two also changed their original plan.

Since Chen Zhou himself is very concerned about the research of this experiment of searching for heavy neutrinos, then respect his own wishes and cooperate with him in the arrangement of the experiment.

It is also a feasible way to let Chen Zhou know the powerful strength of CERN in terms of the specific content of the experiment.

Maybe, with the support of such an outstanding physicist doing theoretical research, they can also have some unexpected gains?
Chen Zhou, who returned to the room, quickly entered the state.

Although he only slept for a little over 4 hours last night, Chen Zhou felt that his mental state was still very full.

How should I put it, some people may really be suitable for scientific research.

As soon as he got involved, it immediately became different.

Not to mention drowsiness and dozing off, there is absolutely no chance of distraction.

"Under the condition of two generations of neutrinos, when an electron flavor neutrino Ve is produced in matter, there is Ve=cosφV1+sinφV2..."

"After reaching the region A≈Ar, r is the distance from the center of the sun to the location, neutrinos become half Ve, half Vμ..."

"This state is similar to the 45° mixing situation in vacuum, and the oscillations are greatly enhanced!"

"When neutrinos propagate to the surface of matter, it becomes V2=cosφVμ+sinφVe..."

"This situation is true for many oscillation processes that occur in the resonance region. The strengthening of oscillations in matter is called the MSW effect."

Chen Zhou, who started to sort out the MSW effect of solar neutrinos, became extremely active in his thinking.

In fact, the MSW effect plays an important role in the process of solar neutrino oscillation.

From the core of the sun to the surface of the sun, the density of the sun decreases gradually, and within the range of less than 0.9 radii, it can be regarded as an approximate exponential decrease.

With the research on the MSW effect of solar neutrinos, the draft paper in front of Chen Zhou gradually became thicker.

Time is passing, but Chen Zhou's research on neutrino oscillation is gradually deepening.

A week passed quickly.

There were also two piles of draft paper on Chen Zhou's desk.

However, these scratch papers are not all the content of neutrino-related research.

There are also studies on the minimal model program in mathematics, and research on particle detectors in chemistry and materials science.

Although Chen Zhou's research focus at this time is on CERN's heavy neutrino search experiment.

However, he will naturally not keep the research directions and research topics that have been determined for a long time, and just put them on hold.

You know, if you put it down for a day, there may be nothing.

However, once the time exceeds a limit, it is difficult to pick up the things that were put down.

Therefore, in order to maintain the efficiency of my own research, I also adjusted the atmosphere of neutrino research by the way.

Chen Zhou is also conducting research on the program of extremely small models and materials for particle detectors.

During the week of Chen Zhou's explosive liver research, Zhang Yifan also successfully "settled" in that laboratory.

The only thing that may make Zhang Yifan feel embarrassed is the Ph.D. in the Department of Chemistry who hopes to use Chen Zhou's name to improve the reputation of the laboratory.

After mistaking Zhang Yifan for Chen Zhou at the beginning, he didn't even show his face.

But fortunately, in the name of "independent" use rights, Zhang Yifan successfully led his classmates to start the material science experiment of the particle detector.

Of course, although the Ph.D. from the Department of Chemistry didn't show up, he arranged for people to follow him.

I'm afraid that this group of "kids" who haven't grown all their hair will break the expensive equipment in his laboratory.

Zhang Yifan also told Chen Zhou about this matter.

What Chen Zhou meant was that he would solve it.

But Zhang Yifan said that there is no need for Chen Zhou to worry about this kind of thing, the reason why he said this is just to let Chen Zhou know what to do.

They can solve this matter themselves, but if they can't, just pretend they didn't see it.

Furthermore, Chen Zhou himself would not conduct experiments in the laboratory, so what effect would it have if he said so?

The most essential problem is that they conduct related experiments in this laboratory.

Therefore, the solution to this matter is still on them.

When he heard Zhang Yifan's words, Chen Zhou's mouth showed a smile unconsciously.

Sure enough, this old tablemate is still reliable!
As soon as Chen Zhou's week-long theoretical research was over, Mitch Johnstone called.

For nothing else, just ask Chen Zhou if he will go to CERN's collider laboratory tomorrow.

Chen Zhou looked at his phone dumbfounded. He never expected that someone could remember the time better than himself.

Of course, Chen Zhou didn't intend to continue his research.

After glancing at the place where the nib stayed, he answered Mitch Johnstone very readily.

Starting tomorrow, officially enter the collider laboratory of CERN, and start to participate in this experiment of searching for heavy neutrinos.

The next day, after the morning run, Chen Zhou quickly finished his breakfast.

Then, together with Cross, came to the collider laboratory.

After arriving at the laboratory, Chen Zhou glanced at Cross, who was holding back, and couldn't help laughing: "If you want to ask anything, just ask."

Cross heard the words and quickly asked: "How is it? The results of theoretical research? Have you solved the problem of neutrino oscillation? Can you find heavy neutrinos?"

Although he knew what the other party was going to ask, when the other party really asked these questions, Chen Zhou still said angrily: "Do you really think I am a god? If you say it is solved, it will be solved?"

Cross scratched his head embarrassingly: "The last time you solved the problem of the glue ball experiment, didn't you just solve it..."

Chen Zhou was speechless for a moment. Although he really wanted to refute, he felt that there was nothing wrong with what the other party said.

After a pause, Chen Zhou said leisurely: "There is still a long way to go before the solution is reached, but there are still some preliminary research results, which can be verified through this experiment."

Hearing Chen Zhou's words, Croston's eyes lit up, and he said excitedly: "I knew you wouldn't return empty-handed. Next, let them see what a genius is!"

Chen Zhou said helplessly: "That's not how you go home empty-handed..."

But Cross didn't mind and said: "Anyway, you just need to understand what I mean. This is a new idiom I learned, and I can use it in China in the future."

Chen Zhou shook his head. This guy has really put his heart into learning Chinese recently. He is afraid that he will go to Huaguo when the time comes, because communication will delay the progress of the experiment.

For this point, Chen Zhou still has to give Cross a thumbs up.

After a pause, Chen Zhou added casually: "That's not to let them see what a genius is. It should be said that it's time to show real skills."

When Cross heard the words, he was slightly taken aback. He turned his head and glanced at Chen Zhou. He always felt as if he had heard this word somewhere before, but he couldn't remember it.

At present, most high-energy physics experimental cooperation groups in various countries in the world use long-baseline experimental methods to measure and calculate neutrino oscillations, and at the same time search for corresponding neutrino particles.

For long-baseline neutrino oscillation experiments, a high-energy proton accelerator generates an intense beam of muon neutrinos, and a near-point detector is installed at the exit.

Thereafter, at a distance L from the neutrino outflow port, a large-scale far-point detector is installed.

The structures and detection methods of the two detectors are the same.

Taking the neutrino interaction measured by the near-point detector as a standard, and then comparing it with the neutrino interaction measured by the far-point detector, it is possible to determine whether there is neutrino oscillation, and to know the neutrino oscillation model.

However, because the mass of neutrinos is very small, the probability of oscillation is very low, so L has to be thousands of kilometers away to have a certain sensitivity.

For example, the distance between Japan's K2K and the Super-Kamiokande detector is 250 kilometers, and the distance between the Fermi National Accelerator Laboratory and the MINOS experimental detector in the United States is 730 kilometers.

Therefore, this experimental method is called the long baseline neutrino oscillation experiment.

Also because of sensitivity issues and various factors of long-distance experiments, those "beautiful mistakes" will appear.

And this time, the neutrino oscillation experiment for searching for heavy neutrinos is conducted by CERN in Geneva, through the detection devices ICARUS and OPERA located underground in Italy.

The distance between the two is about 730 kilometers.

Like the laboratories in Japan and the United States, the long-baseline neutrino oscillation experiments conducted at CERN are only a few hundred kilometers away due to the distance between the far-point detector and the near-point detector.

It is shorter than the thousands of kilometers required by theory, so the accuracy and sensitivity of the experiment are relatively low.

But this is an objective experimental condition that cannot be changed temporarily.

Interestingly, when Chen Zhou asked Mitch Johnstone about it.

Mitch Johnstone immediately stated that they planned to cooperate with another laboratory to build a new apolate detector, so as to meet the theoretical requirements.

Upon hearing this, Chen Zhou glanced at Mitch Johnstone with a slightly strange expression.

Anyway, whether it will be built or not has nothing to do with him. Is there any need to explain it in such a hurry?
I have not delved into this issue, nor have I intended to listen in detail to Mitch Johnstone's prepared remarks.

Chen Zhou then began to return to the experiment itself, and began to discuss the experiment with Mitch Johnstone.

His preliminary results in theoretical research must have the cooperation of CERN.

Otherwise, this is just words on white paper after all.

However, what Chen Zhou didn't expect was that.

After listening to his description and reading the research paper.

Mitch Johnstone said with bright eyes: "You wait, I'll go to Dr. Bertolucci right away!"

　Thanks to book friend Yan Hongxue for the 100 starting coins!
　　
　
(End of this chapter)