Read the Beforeitsnews.com story here. Advertise at Before It's News here.
Profile image
By Bradley J Roth
Contributor profile | More stories
Story Views
Now:
Last hour:
Last 24 hours:
Total:

Patrick Blackett and Pair Production

% of readers think this story is Fact. Add your two cents.



Patrick Blackett.

In Chapter 15 of Intermediate Physics for Medicine and Biology, Russ Hobbie and I describe pair production.

A photon… can produce a particle-antiparticle pair: a negative electron and a positron… Since the rest energy (mec2) of an electron or positron is 0.51 MeV, pair production is energetically impossible for photons below 2mec2 = 1.02 MeV…

Pair production always takes place in the Coulomb field of another particle (usually a nucleus) that recoils to conserve momentum.

I often wonder how surprising or unexpected phenomena are discovered. Pair production was first observed by English physicist Patrick Blackett. Here is part of the entry about Blackett in Asimov’s Biographical Encyclopedia of Science & Technology.

Asimov’s Biographical
Encyclopedia of
Science & Technology.

BLACKETT, Patrick Maynard

English physicist

Born: London, November 18, 1897

Died: London, July 13, 1974

Blackett entered a naval school in 1910, at thirteen, to train as a naval officer. The outbreak of World War I came just in time to make use of him and he was at sea throughout the war, taking part in the Battle of Jutland.

With the war over, however, he resigned from the navy and went to Cambridge, where he studied under Ernest Rutherford and obtained his master’s degree in 1923. In 1933 he became professor of physics at the University of London, moving on to Manchester in 1937.

It was Blackett who first turned to the wholesale use of the Wilson cloud chamber [a box containing moist air which produces a visible track when an ion passes through it, condensing the moisture into tiny droplets]…

In 1935 Blackett showed that gamma rays, on passing through lead, sometimes disappear, giving rise to a positron and an electron. This was the first clear-cut case of the conversion of energy into matter. This confirmed the famous E = mc2 equation of Einstein as precisely as did the more numerous examples, earlier observed, of the conversion of matter to energy (and even more dramatically).

During World War II, Blackett worked on the development of radar and the atomic bomb… After the war, however, he was one of those most vociferously concerned with the dangers of nuclear warfare. In 1948 he was awarded the Nobel Prize in physics for his work with and upon the Wilson cloud chamber.

More detail about the discovery of pair production specifically can be found at the Linda Hall Library website.

In 1929, Paul Dirac had predicted the possibility of antimatter, specifically anti-electrons, or positrons, as they would eventually be called. His prediction was purely a result of his relativistic quantum mechanics, and had no experimental basis, so Blackett (with the help of an Italian vsitor, Giuseppe Occhialini), went looking, again with the help of a modified cloud chamber. Blackett suspected that the newly discovered cosmic rays were particles, and not gamma rays (as Robert Millikan at Caltech maintained). Blackett thought that a cosmic particle traveling very fast might have the energy to strike a nucleus and create an electron-positron pair, as Dirac predicted. They installed a magnet around the cloud chamber, to make the particles curve, and rigged the cloud chamber to a Geiger counter, so that the camera was triggered only when the Geiger counter detected an interaction. As a result, their photographs showed interactions nearly every time. They took thousands, and by 1932, 8 of those showed what appeared to be a new particle with the mass of an electron but curving in the direction of a positively charged particle. They had discovered the positron. But while Blackett, a very careful experimenter, checked and double-checked the results, a young American working for Millikan, Carl Anderson, detected positive electrons in his cloud chamber at Caltech in August of 1932, and he published his results first, in 1933. Anderson’s discovery was purely fortuitous – he did not even know of Dirac’s prediction. But in 1936, Anderson received the Noble Prize in Physics, and Blackett and Occhialini did not, which irritated the British physics community no end, although Blackett never complained or showed any concern. His own Nobel Prize would come in 1948, when he was finally recognized for his break-through work in particle physics.

If you watched last summer’s hit movie Oppenheimer, you might recall a scene where a young Oppenheimer tried to poison his supervisor with a apple injected with cyanide. That supervisor was Patrick Blackett.

The Nobel Prize committee always summarizes a recipient’s contribution in a brief sentence. I’ll end with Blackett’s summary:

“for his development of the Wilson cloud chamber method, and his discoveries therewith in the fields of nuclear physics and cosmic radiation”

The scene from Oppenheimer when Oppie poisons Blackett’s apple.

https://www.youtube.com/watch?v=P8RBHS8zrfk

 

Patrick Blackett—Draw My Life. From the Operational Research Society.

https://www.youtube.com/watch?v=jg5IQ5Hf2G0


Source: http://hobbieroth.blogspot.com/2024/06/patrick-blackett-and-pair-production.html


Before It’s News® is a community of individuals who report on what’s going on around them, from all around the world.

Anyone can join.
Anyone can contribute.
Anyone can become informed about their world.

"United We Stand" Click Here To Create Your Personal Citizen Journalist Account Today, Be Sure To Invite Your Friends.

Lion’s Mane Mushroom Nootropic

Mushrooms are having a moment. One fabulous fungus in particular, lion’s mane, may help improve memory, depression and anxiety symptoms. They are also an excellent source of nutrients that show promise as a therapy for dementia, and other neurodegenerative diseases. If you’re living with anxiety or depression, you may be curious about all the therapy options out there — including the natural ones.Our Lion’s Mane WHOLE MIND Nootropic Blend has been formulated to utilize the potency of Lion’s mane but also include the benefits of four other Highly Beneficial Mushrooms. Synergistically, they work together to Build your health through improving cognitive function and immunity regardless of your age. Our Nootropic not only improves your Cognitive Function and Activates your Immune System, But it benefits growth of Essential Gut Flora, further enhancing your Vitality.



Our Formula includes: Lion’s Mane Mushrooms which Increase Brain Power through nerve growth, lessen anxiety, reduce depression, and improve concentration. Its an excellent adaptogen, promotes sleep and improves immunity.


Shiitake Mushrooms which Fight cancer cells and infectious disease, boost the immune system, promotes brain function, and serves as a source of B vitamins.


Maitake Mushrooms which regulate blood sugar levels of diabetics, reduce hypertension and boosts the immune system.


Reishi Mushrooms which Fight inflammation, liver disease, fatigue, tumor growth and cancer. They Improve skin disorders and soothes digestive problems, stomach ulcers and leaky gut syndrome.


Chaga Mushrooms which have anti-aging effects, boost immune function, improve stamina and athletic performance, even act as a natural aphrodisiac, fighting diabetes and improving liver function.


Try Our Lion’s Mane WHOLE MIND Nootropic Blend 60 Capsules Today. Be 100% Satisfied or Receive a Full Money Back Guarantee. Order Yours Today by Following This Link.

Report abuse

Comments

Your Comments
Question   Razz  Sad   Evil  Exclaim  Smile  Redface  Biggrin  Surprised  Eek   Confused   Cool  LOL   Mad   Twisted  Rolleyes   Wink  Idea  Arrow  Neutral  Cry   Mr. Green

MOST RECENT
Load more ...

SignUp

Login

Newsletter

Email this story
Email this story

If you really want to ban this commenter, please write down the reason:

If you really want to disable all recommended stories, click on OK button. After that, you will be redirect to your options page.