Reborn and become a Great Scientist

Chapter 416 155 Positively Charged Positrons

Chen Muwu had just obtained positive experimental results, and someone raised discordant objections from the side. Of course Rutherford would not be happy.

Even if you are Bohr, so what?

"Niels, are you saying what went wrong in Chen's experiment, or what did I say wrong? Tell me your opinion."

As he spoke, Rutherford's beard drooped.

"Sir, of course Dr. Chen's experiment is not wrong, because all of us are here to watch. I think what is wrong is your previous hypothesis, that is, considering 'neutron' as a consistent particle system of 'proton + electron'.

"I think neutrons should be the same as protons and electrons, which are irreducible 'elementary particles'."

Bohr was not afraid of Rutherford's harshness at all, and directly expressed his true thoughts.

Chadwick took over the topic: "But the experimental data is already clear. The mass of the neutron is 1.0067 units, the sum of the masses of the proton and the electron is 1.0078 units, and the binding energy between the two is about 1 About a megaelectronvolt. Combined with the data just measured by Dr. Chen, the neutron as a bound state of a proton and an electron fits the system, which is completely compatible with existing knowledge."

What Chadwick said makes sense, but his reasoning is entirely based on the complete credibility of the experimental data measured by Chen Muwu.

Chen Muwu did not expect that the current experimental conditions would force him to measure such inaccurate data, which would instead become evidence for Chadwick to refute Bohr.

As everyone knows, Bohr is actually the most correct one.

Historically, it was Bohr who, after Chadwick discovered the neutron, was the first to propose that neutrons should be fundamental particles, rather than protons and electrons, which fit the system.

Rutherford frowned and asked Chen Muwu, the good student who was standing next to him and whom he believed the most at this time: "Chen, what do you think of this?"

Chen Muwu was in a dilemma. He could not directly say that Rutherford's theory was indeed wrong and that only Bohr's conjecture was correct.

Physics is a subject based on experiments. Experiments must be done to explain whose theory is right and whose theory is wrong.

"Uh, Sir, James, and Professor Bohr, I think this matter is like a couple quarreling. Everyone on both sides feels that they are right, otherwise it would be impossible to quarrel.

"How about this? How about I design another experiment and use another method to more accurately measure the true mass of the neutron?"

Chen Muwu feels that sometimes it is not a good thing to invite all the world's top physicists to Stockholm.

His papers were originally intended to be published one after another in his own "Journal of Prince's College".

As a result, in the academic dispute between Bohr, Rutherford and Chadwick, it was Chen Muwu himself who was harmed.

"Have you thought of a new experimental method? What are you going to do?"

Not only Rutherford, but basically everyone present stared at Chen Muwu with doubts, looking forward to what his next answer would be.

"Well, I think it's very simple. You can use gamma rays to bombard the deuteron, decompose the deuteron into a proton and a neutron, and use the conservation of energy during the nuclear reaction to measure the mass of the neutron.

"The binding energy of deuterons is very small. I estimate it is only a few megaelectronvolts. This nuclear reaction is not difficult to operate.

"How about this, Dr. Zhao and Dr. Cockcroft, the two of you are responsible for doing this experiment to measure the precise mass of neutrons?"

Chen Muwu assigned this experimental task.

Now that Neutron has definitely discovered it, he will not continue to do other things personally.

What's more, Chen Muwu has other things to do.

"of course."

"No problem at all."

Zhao Zhongyao and Cockcroft agreed in unison.

The fact that Chen Muwu could hand over this experimental task to them showed his trust in them.

"Chen, what about us?"

Irena also wanted a task next to her. Why didn't her brother-in-law think about her and Frederic's family first in everything? Instead, he gave all the credit to the man who came to Stockholm with him from Cambridge University. What about two colleagues?

"Irena, Frederick, we need to take advantage of Dr. Zhao and Dr. Cockcroft's experiments to write this paper on the discovery of neutrons, and then combine it with the previous discovery of the 85th The papers on element No. 43, which is similar to iodine, and element No. 43, which is similar to manganese, were published together in the Journal of Prince's College.

"The first draft of this paper has been written by you."

"Nothing to say!"

The new task given to them by Chen Muwu not only did not make Mr. and Mrs. Curie feel unhappy, but instead made them very interested.

In the entire experiment of discovering neutrons, except for Frederick's calculation of the masses before and after the nuclear reaction of iodine-like elements, everything else was done by Chen Muwu alone.

Now he asked the two of them to write a paper together, obviously wanting everyone to put their names on the final published paper.

After Zhao Zhongyao, Cockcroft, Irena and Frederick each received their tasks and left, Chen Muwu continued to entertain several guests from afar.

While picking up the cloud chamber photographic films on the table, he said politely to everyone: "I estimate that it will take some time for the experimental results from Dr. Zhao and Dr. Cockcroft to come out.

"I don't think we need to stay in the laboratory waiting for the results. Why not go outside and have a cup of tea first."

Although both Bohr and Rutherford wanted to know the exact mass of the neutron measured experimentally as soon as possible, who was right and who was wrong in their opinions.

But Chen Muwu's words are also very reasonable. This experiment conducted by Zhao Zhongyao and Cockcroft cannot produce results in a few hours. If it is faster, it can be one or two days, if it is slower, it is possible in three to five days.

Bohr thought that when Chen Muwu was talking about going out for a cup of tea, it should be the kind of British afternoon tea where hot black tea is added to cold milk.

But he didn't expect that what Chen Muwu served was exquisite porcelain from China, and the tea he brewed was crystal clear green tea.

What surprised him even more was that Rutherford, Chadwick and Kapitsa had no objection at all and drank green tea without milk or sugar with relish.

"Chen, no matter how much the Royal Academy of Sciences in Sweden does not want to award the Nobel Prize in Physics to you again, I think it is a certainty that you will win another Nobel Prize in Physics this time.

"Whether it is a cyclotron or the discovery of neutrons, two people can win at least two Nobel Prizes in Physics if these two achievements are combined. But if you do it all by yourself in a short period of time, you can only win two Nobel Prizes." I can get one. I feel a little loss for you." After searching for the neutron for more than ten years, Chen Muwu discovered it. Rutherford was in a good mood. He thought of Sweden and naturally thought of it. Nobel Prize.

Kapitsa also echoed: "I think this time not only the Nobel Prize in Physics, but also the Nobel Prize in Chemistry should be awarded to Chen Cai.

“When the isotope of hydrogen was discovered before, there were already calls on the market to award the chemistry prize to Chen, but the Swedish jury pretended not to listen.

"Now Chen has discovered two isotopes of hydrogen, and he has also discovered two new elements that chemists who only test ores will never discover in their lifetime.

"I think it would be really rude of the Royal Swedish Academy of Sciences to pretend to be dead again this time."

After taking a sip of green tea, Bohr felt that it still had a unique flavor without adding milk or sugar and said with a smile: "I hope they will award these two awards to Chen Muwu in the same year, so as to create a new story."

Chen Muwu, who was praised by everyone, was drinking tea while frowning and staring at the cloud chamber photographic films in his hand.

What are recorded on these negatives are the particle trajectories of the collision of neutrons with hydrogen, deuterium and helium nuclei after alpha particles bombard the boron crystal.

Because seeds are used for bombardment, there is no layer of paraffin behind the boron crystal to slow down the neutrons. Instead, the neutrons are directly incident into the cloud chamber after they come out of the boron crystal.

Chen Muwu pretended to frown. In fact, he had already found what he was looking for.

The reason why he did this was to attract other people's attention.

As soon as he dozed off, someone gave him a pillow. Kapitsa noticed these strange things: "Chen, what's wrong? Did you have some conflict with the Swedish Nobel Prize jury? Why did you mention the Nobel Prize? Does it make you so depressed?”

"Peter, it's not about the Nobel Prize. After winning it once, I have become very open-minded about whether I can win it again.

"——Of course, this doesn't mean that I don't like winning the Nobel Prize. After all, the real bonus and the medal made of pure gold are still very tempting.

"What makes me frown is actually something else."

As he spoke, Chen Muwu put a certain photographic film in his hand on the coffee table surrounded by everyone.

He stretched out his index finger and pointed at a track on the film and asked, "Come and take a look at this track here. Is it strange?

"Looking at its deflection direction in the magnetic field, it should be a positively charged particle.

"Comparing its trajectory with hydrogen, deuterium and helium nuclei, we found that it does not belong to any of the above three nuclei.

"When I look at its trajectory, I always feel that it should be the trajectory of an electron. Then the question arises. This electron seems to be positively charged."

Last summer at the Cavendish Laboratory, Chen Muwu also discovered the existence of positrons in his own experiment to discover neutrons.

As for where do positrons come from?

Of course, the nuclear reaction between the alpha particles and the boron-10 in the boron crystal produces nitrogen-13 and releases a neutron.

Nitrogen-13 is not a stable isotope of nitrogen and has a half-life of less than ten minutes.

Nitrogen-13 undergoes positive beta decay, releasing a positron, and then becomes stable carbon-13.

α+B→n+N.

N→β＋C.

At that time, in the Cavendish Laboratory, there was a paraffin block behind the boron crystal that proved to be bombarded with protons by neutrons. Positrons could still penetrate from the paraffin block and enter the cloud chamber.

Now in Stockholm, the paraffin block behind the boron crystal has disappeared, so the positrons entering the cloud chamber through positive beta decay from nitrogen-13 will be more unimpeded.

It's just that when the cloud chamber photos were used to calculate the mass of neutrons, everyone's attention was focused on this new gadget, neutrons, and no one noticed this positively charged electron trajectory.

After Chen Muwu pointed to the trajectory of the photographic film and brought it up, the shock brought by this positively charged electron to the physicists present was no less than the shock brought by the electron that had just been confirmed to be discovered.

Especially Bohr, when he heard about positively charged electrons from Chen Muwu, he immediately remembered a past event.

It was still in Copenhagen in 1924. Chen Muwu was invited by himself to leave Cambridge University and visit the Institute of Theoretical Physics for a period of time.

At that time, Chen Muwu and Pauli not only raised their fists in Copenhagen, but also made a bet on whether the positively charged electron predicted in Chen's equation existed or not.

Bohr remembered that the bet between Chen Muwu and Pauli was ten pounds.

Some time ago, Pauli told himself triumphantly that the two of them had doubled their bet eight hundred times, from ten pounds to eight thousand pounds.

At that time, I also advised Pauli and told him not to take this risk.

But Pauli felt that Chen Muwu would definitely lose, so he turned a deaf ear to his advice and did not take it to heart at all.

Unexpectedly, just how long had passed before Chen Muwu found the positively charged positron!

seeing is believing.

Bohr leaned forward and wanted to witness the trajectory of this positron from the photographic film.

As for Chen Muwu, he had already started to pick up a ruler and pen and paper to measure and calculate the relevant data of the particles corresponding to this trajectory.

This step of his operation cannot be said to be superfluous, it can only be said to be rigorous.

But whether it was Rutherford, Chadwick or Kapitsa, they all didn't need to wait for Chen Muwu's calculation results. They could all see that this was an electron, but it was an electron with a positive charge.

I originally thought that Chen Muwu's discovery of neutrons was already an incredible achievement.

Unexpectedly, he not only discovered neutrons, but also brought out positrons.

I just mentioned that there are cyclotrons and neutrons, and the Nobel Prize jury should award the Nobel Prize to Chen Muwu again.

Now it seems that if Chen Muwu's name is not on next year's award list, Rutherford has already made plans to go to the Royal Swedish Academy of Sciences to find someone.

(End of this chapter)