"Peter, I'm doing an experiment, don't come here! Get out first, get out! ”

Although his experiment was carried out in a metal pipe.

The three types of particles, alpha, beta and gamma, have a penetrating ability from low to high, while the ionization ability is from high to low.

Gamma particles, which have the most penetrating ability, require a very thick lead plate to isolate them completely.

And the alpha particle, which has the weakest penetrating power, basically only needs anything to stop his progress.

This time, Chen Muwu no longer needs to observe the phenomena in the experimental instrument like electron diffraction, so there is no need to put all the equipment used in the experiment into a specially customized special-shaped glass tube like electron diffraction, so he chose a metal tube that is simpler to assemble.

This kind of metal tube must be able to block the alpha particles, so that they are trapped in the tube and cannot penetrate it.

However, the two products produced by this experiment are not as penetrating as the alpha particles.

Whether it is the final product of the substance or the intermediate product of the neutron, the radioactivity of the two particles can be higher than the other.

Even metal pipes have a high chance that they will not be able to isolate them all, and some of them will escape through the metal.

In order to be on the safe side, Chen Muwu also added an additional lead plate to the middle part of the metal pipe to protect the section where neutrons were generated.

In the end, the generated protons were shot into the cloud chamber, and Chen Muwu couldn't add a lead plate even if he wanted to, because there was not only a camera directly above the cloud chamber to take photos to capture the trajectory of the protons, but also a magnetic field near the cloud chamber to ensure that the protons could be deflected smoothly inside.

Both the device that generates the magnetic field and the camera take up a lot of space, and if you add a lead plate to protect it, to be honest, it won't make much of a difference.

Fortunately, the penetration ability of protons is still much lower than that of neutrons, and after two bombardments, as the final product, the energy of protons will not be too high, and Chen Muwu has some luck.

But even if it was a fluke, in addition to the experimental equipment itself and the surrounding shielding devices, he still did a lot of protective measures on himself, wearing special clothes, and inserting a few lead plates in front of important parts.

However, Chen Muwu has protection, but Kapitsa is alone, and he has no armor or magic resistance at all.

In the final analysis, he was too careless, thinking that no one should come to him after the summer vacation, and even if there was an emergency to find him, he should knock on the door first to ask, so he did not post a sentence on the door of the laboratory, "Experimental ground, do not disturb".

Chen Muwu completely forgot that he also had a good friend Kapitsa, so today's incident appeared.

I hope that the amount of neutrons and protons escaping is very small, and it will not affect Kapitsa in any way.

Hearing Chen Muwu's loud shout, Kapitsa first stood in place.

Then he immediately followed the instructions in the words, and walked out of the door step by step.

Chen Muwu closed the baffle containing the polonium-210 lead box so that it no longer emitted alpha particles.

Then he turned off the power to the vacuum pump, the cloud chamber, and the camera, and the whole experiment came to a complete halt.

After doing all this, he walked out of the door in heavy clothes and appeared in front of Capitsa.

"Peter, why are you here?"

"It's not that I've been busy getting married lately, and there are too many things that lead to some stress, so I came back to the Cavendish lab like you, and I want to hide a little bit." Kapitsa jokingly teased Chen Muwu: "Chen, it's already summer vacation, why don't you go back to your home in London, what are you doing in a laboratory?" ”

"Uh......"

Chen Muwu was speechless for a while, he didn't know how to explain to Kapitsa, could it be that he wanted to tell him the truth, saying that he wanted to discover the neutron quietly?

But he couldn't leave Kapitsa to dry for too long, so after a simple thought, Chen Muwu chose to say a nonsense:

"As you can see, I'm experimenting."

Kapitsa, who felt like he was being teased like a child of a few years old, was a little dissatisfied: "Of course I know you're experimenting!" I'm asking you what kind of experiment you're doing, wrapping yourself in three layers inside and three layers outside, like the ancient Egyptian pharaoh Tutankhamun in the newspapers. ”

"I ...... I'm replicating an experiment by Sir Rutherford and Patrick! ”

Chen Muwu finally found a plausible excuse.

"Old crocodile and Patrick's experiment? What is that? The one that bombarded the nitrogen nucleus with an alpha particle and then got the proton? ”

"That's right!"

They all use alpha particles to bombard other elements fixed on the target, and they also shoot a new kind of particle from the nucleus.

Except that the products of the experiments are different, the two experiments should be about the same, right?

He simply switched from nitrogen to lighter, but also fixed, boron.

Nitrogen ranked seventh in ordinal number on the periodic table was replaced by boron, which ranked fifth, and the difference between the two is not too much!

Chen Muwu feels that his doubts are more reasonable, which is called drawing inferences from one case and has a strong spirit of scientific exploration!

The more he thought about it, the more he felt that his explanation was seamless, so the confidence in his heart became more and more sufficient, and the tone in which he spoke to Kapitsa became stronger and stronger.

This startled Kapitsa, who had just startled Chen Muwu.

If you do experiments, you will do experiments, why are you yelling loudly?

Chen Muwu continued to make up the "ins and outs" of why he was doing the experiment: he was idle and bored today, and suddenly remembered that he had once watched the cloud chamber photographic negatives with Blackett, and discovered a new isotope and discovered artificial nuclear transmutation.

Why do alpha particles bombard nitrogen nuclei to produce protons, but bombardment of other nuclei does not?

Is it because the previous experiment was not done well, so the protons were not detected, or did the protons not come out at all?

So he's idle and bored today and wants to redo this experiment.

As a result, the experimental bench had just been set up, and before he could start the experimental device, Kapitsa suddenly pushed open the door of his laboratory.

This remark frightened Kapitsa into a daze, he really believed Chen Muwu's nonsense, and felt that what he said was very reasonable.

Dr. Chen is right, why can't other elements bombard protons?

How did he know that it was because the bombardment was actually a neutron.

Rutherford first experimented with bombarding nitrogen with alpha particles, adding a layer of aluminum foil to the nitrogen gas, which was just thick enough to block the weakest penetrating alpha particles.

In this way, the alpha particles originally emitted from the particle source cannot penetrate the aluminum foil, and if the alpha particles can produce new particles after bombarding the nitrogen nucleus, they will pass through the aluminum foil and hit the phosphor screen placed behind the aluminum foil, so that the light spots of the particles will stay on the phosphor screen for a short time.

However, the only thing that can make the phosphor screen shine is charged particles, such as alpha particles and protons, so Rutherford added a layer of aluminum foil that can block alpha particles behind the nitrogen gas at the beginning, in order to prevent the alpha particles emitted from the radioactive source from misleading the experimental phenomenon.

However, when experiments are carried out with other elements lighter than nitrogen, even if it is the same experimental setup, a new kind of particle can be bombarded, neutrons, which can also penetrate a thin layer of aluminum foil.

But the crux of the matter is that because the neutron is not charged, even if it passes through the aluminum foil, it cannot leave a spot of light on the phosphor screen, which makes Rutherford, who was doing experiments at that time, not know that he has discovered the neutron in his heart, so that he will be trying to find this thing for the next ten years.

And because he didn't leave an opinion on the phosphor screen, Rutherford asked Blackett to repeat his experiment of atomic bombardment with alpha particles, using only nitrogen and not trying anything else.

Of course, even if Blackett Alpha particles bombard lithium-beryllium-boron and produce neutrons, the neutrons will not leave a trail in the cloud chamber.

However, when Chadwick discovered the neutron, he also used the cloud chamber.

Although neutrons do not have a trajectory in the chamber, they can collide with other particles in the chamber, leaving a corresponding collision trajectory.

Chadwick used the protons and other nucleus recoil trajectories recorded in the cloud chamber to calculate the relative atomic mass of this mysterious particle, which is similar to the neutron properties in Rutherford's previous predictions, so he published a paper in a journal saying that neutrons may exist.

Rutherford had the opportunity to discover neutrons a long time ago, but because of a small phosphor screen that would not be displayed when encountering neutral particles, he missed the neutron at that time.

But in the end, it was Chadwick in the Cavendish lab who discovered the neutron, is this considered "the paper airplane of my childhood, and now it finally flies back into my hands"?

Chen Muwu doesn't need to replicate Chadwick's steps when he discovered the neutron, let the bombarded neutrons bombard protons and other nuclei to calculate the mass of the neutron.

Again, as long as he can bombard the protons in the paraffin wax with neutrons, he can prove that his experiment is a perfect success.

Because he didn't need to write a paper for his experiment, he just wanted to discover the neutron in advance, so that he could have food in his pocket and not panic.

It felt as if he had disturbed Chen Muwu's experiment, and Kapitsa was a little embarrassed.

"Well, Chen, I'm really sorry, I didn't know you were doing an experiment, didn't delay you? Then you go on, I'll come back when you're free. ”

Then he turned and was about to leave.

"Since you're here, don't leave, fortunately, my experiment didn't go to a critical juncture, I just assembled the instrument, and now it's paused. - When are you getting married? ”

When he first entered the door, Kapitsa seemed to mention that he was about to get married, and Chen Muwu secretly hid in the laboratory and didn't help him.

"The date had just been set, at the end of September, just a few days before the start of school in October. Otherwise, everyone is on summer vacation, and it is not appropriate to call them all back for a wedding in the heat of summer. ”

Chen Muwu, who heard Kapitsa's answer, nodded, feeling that this arrangement was very reasonable......

Wrong!

"Peter, shouldn't you go back to your home country and get married in Leegrad? Listening to the meaning of your words, why does it seem like you are going to have a wedding in Cambridge? ”

Chen Muwu just casually said the doubts in his heart, but he didn't expect that his question would overshadow the expression on Kapitsa's face.

"Chen, you know how inconvenient it is for me to go out to England and come back to customs since the severance of diplomatic relations between Britain and my homeland.

"Besides, there are no relatives or friends in my house."

"I'm sorry, I'm sorry, Peter, I forgot about it."

Capitsa was able to leave Sulian to study at Cambridge University because of the major changes in his family, including relatives and first wife and children, who were either infected with the Spanish flu or other diseases.

In order to help this young man with a high talent in physics come out of his depressed state of mind, Su Lian's physics education first went to Professor Fei, and then helped Kapitsa contact with the opportunity to come to Cavendish Laboratory for exchange.

And because of his cleverness, Kapitsa has changed himself from a student who went to exchange and visit to a physicist rooted here.

"Won't there be any relatives in the country?"

"My mother will come with Professor Yofy, and then after the Solvay meeting is over, she will go back with Prof. Jofy."

"Why don't you stay in England longer?"

"I guess even if I want to stay, I won't be able to stay for long."

Kapitsa smiled wryly and gave Chen Muwu a "you know" look.

Yes, Gamow's imagination of Kapitsa taking a passport to study abroad openly was not approved, and he could only use his brains to think of crooked ways.

It is estimated that Kapitsa's mother can come to the UK to attend her son's wedding, which is already a great face-saving for Kapitsa.

"Well, if my aunt comes to England, she can live in my house in London first, and let the two old people live together, which can be regarded as a companion."

"I'm afraid that this won't be done, one of them speaks Chinese and the other speaks Russian, and they don't understand the language.

"I'm planning to buy a house in Cambridge recently and put down roots, but I haven't done it yet. Don't talk about this, Chen, among you, is there anything you need to pay attention to when getting married? ”

Chen Muwu wanted to tell Kapitsa about the marriage trouble in China at first, and before the wedding, several groomsmen played tricks on the groom.

But he didn't know if the current marriage process was like this, so he still said the most conservative, enlarging dates, peanuts, longan and lotus seeds on the marriage bed, implying early birth of a noble son.

"This is good, this is good, when I have a child, I must ask you to be their godfather, after all, you are my best friend."

"But why don't you let me be the best man when you get married?"

"You're too handsome, I can't let you overshadow me on your wedding day."

Kapitsa said matter-of-factly.

(End of chapter)