Why is antimatter difficult to create?

  • I
  • Thread starter LotusTK
  • Start date
  • #1
36
0

Main Question or Discussion Point

Why is antimatter difficult to create?

I know that heavier particles are more difficult to create because you need a high energy collision to give the heavy particle any chance of being created. And i know why antiparticles are difficult to keep in existence and store AFTER they are created, but why are they difficult to create in the first place?

I have seen an exam question asked a few times "why is antimatter difficult to create?" And the mark schemes are useless, and it isn't actually on the syllabus...
 

Answers and Replies

  • #2
34,053
9,912
Matter is hard to create as well. We happen to have matter around us, so you usually don't have to create it. And even if you would have to, it is easier to slow down and capture.
 
  • #3
36
0
But is it not the case that only a small fraction of what we manage create in accelerators is antimatter? Thats what i meant about it being hard to create.
 
  • #4
34,053
9,912
Baryons and antibaryons are always created in pairs, due to baryon number conservation. Mesons don't have a meaningful matter/antimatter assignment, so let's ignore them. That means matter and antimatter are always created in the same amount.
 
  • #5
SteamKing
Staff Emeritus
Science Advisor
Homework Helper
12,798
1,666
The trick is to separate the antimatter from matter and keep it confined. This is what's difficult to do for extended periods of time, and it becomes progressively more dangerous the more antimatter one accumulates. A lot of the matter-antimatter particle pairs which are created in accelerator collisions wind up annihiiating one another shortly after they are created.

https://en.wikipedia.org/wiki/Antimatter
 
  • #6
34,053
9,912
and it becomes progressively more dangerous the more antimatter one accumulates.
If all the labs worldwode could have accumulated and combined the antimatter caught in the last decades, it would be sufficient to cook a few cups of coffee with it. Not that dangerous.
 
  • #7
36
0
I didnt know they were created in equal pairs. I thought that we can "easily" create particles in colliders but was more difficult to make antiparticles come into existence/ be created in colliders.

On the note about danger, i was reading that a 1 kilo annihilation of matter and antimatter gives off more energy than the tsar nuclear bomb! And considering that we apparently need 25 billion pounds to create 1 milligram (IIRC) I dont think we will ever get anywhere close to accumilating enough for it to be any real danger.
 
  • #8
SteamKing
Staff Emeritus
Science Advisor
Homework Helper
12,798
1,666
If all the labs worldwode could have accumulated and combined the antimatter caught in the last decades, it would be sufficient to cook a few cups of coffee with it. Not that dangerous.
Yes, at the quantities they have been able to trap and store so far.

But what happens if the science and technology advance to let labs start to store antimatter in kilogram-sized lots?
 
  • #9
ZapperZ
Staff Emeritus
Science Advisor
Education Advisor
Insights Author
35,538
4,311
Take note that we don't have to go all exotic to create antimatter. In a PET scan, the radioactive substance that is injected into a subject emits positrons. Voila! Antimatter!

The e-p annihilation is the foundation of this diagnostic method.

Zz.
 
  • #10
PAllen
Science Advisor
2019 Award
7,967
1,260
If all the labs worldwode could have accumulated and combined the antimatter caught in the last decades, it would be sufficient to cook a few cups of coffee with it. Not that dangerous.
really? 1 gram would have twice the explosive yield of the Nagasaki atomic bomb.
 
  • #11
34,053
9,912
CERN stores antihydrogen in bunches of ~1000 atoms, a world record. Antiprotons without positrons can be trapped in larger amounts, but that approach is not scalable.

Fermilab produced 2 ng over decades or 360 kJ (adding 2 ng of normal matter) - just antiprotons, enough to bring 1 kg of water to the boiling point.
 
  • #12
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2019 Award
24,031
6,602
The weight of all the antiprotons produced and captured at accelerators is probably around 100 picograms. That's smaller than the average human cell by about an order of magnitude.

Antimatter from potassium-40 decays in the earth';s crust is produced (and annihilated) at about the rate of 10 pounds per day.

In the time it took you to read this, a few dozen particles of antimatter from cosmic rays entered and exited your body.
 
  • #13
1
0
Whoa, Antimatter just sounds cool. :)
 
  • #14
PAllen
Science Advisor
2019 Award
7,967
1,260
...

Antimatter from potassium-40 decays in the earth';s crust is produced (and annihilated) at about the rate of 10 pounds per day.
Interesting. So the earth's crust (very massive, obviously), is being heated to the tune of several hundred standard thermonuclear bombs ( 1 megaton) per day, from potassium 40 decays!
 
  • #15
3,379
942
Whoa, Antimatter just sounds cool. :)
It's not fun at parties though.
 
  • #17
ChrisVer
Gold Member
3,331
438
antimatter was difficult to be created at the very early times of the Universe, the reason is still unknown... Obviously we live in a "matter" world with a low % of antimatter, meaning that for some reason at some point matter was preferentially produced compared to antimatter...This goes around as matter-antimatter asymmetry
 
  • #18
1,484
3,042
Hi @LotusTK, here are two very nice clips from the ALPHA (antimatter) experiment at CERN:


 
Last edited:
  • #19
97
34
Whoa, Antimatter just sounds cool. :)
Thread Necromancer. I would deny you a cookie, but instead will offer you one with a full ounce of antimatter sprinkles on top.

One ounce of antimatter sprinkles will react with one ounce of cookie to produce a 1.2 megaton explosion. The temperature within this explosion will briefly rival those of the interior of the sun. Antimatter is awesome. But it tends to blow it's cool. :)
 
  • #20
1,484
3,042
Not perfectly exactly on topic, sorry, but this recent clip is too cool to not to share here, IMO:

The ALPHA experiment observes light spectrum of antimatter for the first time
 

Related Threads on Why is antimatter difficult to create?

  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
6
Views
813
  • Last Post
Replies
7
Views
7K
Replies
6
Views
2K
  • Last Post
Replies
9
Views
2K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
6
Views
3K
  • Last Post
Replies
4
Views
2K
Replies
32
Views
16K
Top