Friday, May 8, 2009

The Higgs!

What is the Higgs Boson and why is it so important?

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Hi,

There is a description of the world -- the "Standard Model" -- which says that the universe is composed of a variety of particles. Objects are made of molecules, molecules of atoms, atoms of protons, neutrons and electrons. Protons and neutrons are made of quarks. There are other particles much like electrons, too -- muons and "tau" particles, and there are tiny little neutral particles -- "neutrinos" -- which we are still learning a lot about these days. When the Standard Model was put together a few decades ago, not all of these particles were known about, but since that time all of the particles mentioned above have been detected, measured, documented, etc. However, the Standard Model has one more particle -- named after Prof. Higgs who proposed that it exists -- which has not been observed yet. It is a particle that would tie the model together in such a way that it would explain why all the other particles have the masses that they do.

If Prof. Higgs is correct and this particle exists, it should be very rare to see. It has to be "made" in the laboratory, and the LHC accelerator being constructed in Europe should be able to make it easily. It might also be being made in our Tevatron accelerator here in Illinois -- we keep sifting through all of our data to see if there are any signs of it. So far, we know where it isn't -- but there's still a chance we'll find it here before the accelerator in Europe turns on.

Thanks for your question!
-Mike


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What work have you been doing in the attempt to find the Higgs Boson? What hobbies do you like to do when your not in work? Also, what do like most about your job?

Thanks,
NHS

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Hi,

I see three questions here...

(A)
The creation of a Higgs Boson is a very rare event in our accelerators (if it exists at all). To find it, we need to generate trillions of particle collisions and sift through the data. The work that I do on this front is to help to improve the operation of the accelerators in order to provide more collisions per week. In this way we can have some hope of finding the Higgs in a shorter period of time, hopefully before the LHC accelerator comes on line in Europe next year.

Imagine a group of particles (protons) moving in one direction and another group of particles (antiprotons) moving toward them in the other direction. Each group of particles can be rather "diffuse" (remember, these are REALLY SMALL objects!), and so mostly the two groups pass right through each other without anything happen. In our case, each group has about 3-10 Trillion particles. BUT, only about 2-3 of them will actually collide! Since they go around in a circle, they'll all get another chance to collide the next time around. The particles just circulate and the groups pass through each other and eventually many of them end up colliding.

The point is, to increase the chances of collisions we can (1) increase the number of particles going in each direction within the ring, and (2) make the size of the particle groups smaller -- squeeze them together more tightly so that they occupy less space and have more probability of hitting the oncoming particles. These are the kind of things that I work on. I also work on optimizing the entire accelerator complex in order to make more antimatter (antiprotons) for the collisions and use them efficiently.


(B)
I enjoy bicycling, photography, tennis, hiking, and basketball (I was at the double-overtime game yesterday where the Bulls beat the Celtics!).


(C)
I think what I like most about my job is the freedom I have to work on very interesting projects, with the most sophisticated of equipment located within a park-like setting, and with some of the smartest people in the world. (Look around our lab's web site: http://www.fnal.gov .) It is so interesting and so much fun -- and they pay me to do it!!

Cheers,
-Mike


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Thank you,
I have been looking through others' posts and have noticed the Higgs Boson come up many times. Could you please explain what this is and how you are involved with it?
-Dan T

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Hi Dan,

The "Standard Model" of particle physics says that matter is made up mostly of quarks and leptons. Combinations of quarks make protons and neutrons, for example. Gluons are particles that interact with quarks to hold everything together. Other particles, like W and Z bosons (sorry about the funny names; most of this came about in the 60's...) interact with the protons and neutrons to make atomic nuclei. Leptons are light-weight particles, like electrons, though there are others, like muons, taus, and neutrinos. Electrons are bound to nuclei by their mutual interactions with photons (light particles, or electromagnetic field particles). While this can explain how everyday matter is composed, there are many combinations of particle interactions that can be generated, measured, etc., which maybe don't happen every day, but they can be created in the lab -- through particle collisions. The particles we accelerate to near the speed of light have enormous energies (for small particles) and when they collide that energy can be converted into mass (E=mc^2), and that's how all these other particles get formed. They may have been around early in the universe, but not so common now. But, we can make them in our collisions.

Anyway, this "Standard Model" has one last element -- predicted by a Prof. Higgs -- which is a particle that interacts with all particles, and is responsible for giving them the mass that they have. That is, the Higgs boson is required to explain why the different quarks and leptons have the masses that they have. It is the last particle of the model that hasn't been observed yet. And who knows, maybe it doesn't exist! Maybe our "model" is wrong! That's what science is all about, and why it's so exciting. Maybe there's something else to discover, which could take us in a whole new direction in our basic understanding, and which could lead to all new discoveries, adventures, and perhaps new innovations. (My iPod is getting kinda old...)

I'm involved in increasing the number of collisions we make in our accelerator so that we have a better chance of finding the Higgs (if it exists) in a shorter amount of time. If things go very well, we should have enough data in the 2-3 years to say whether there is a Higgs particle or not. By that time, CERN's LHC machine should be operating and then THEY'll be able to say for certain very quickly. The race is on!


Cheers,
-Mike

- - -
Dr. Syphers,
You were saying that you are involved in increasing the chances of creating a Higgs particle. How do you do this? Hopefully you will be able to beat CERN in proving the exsistence of the Higgs Particle!
From,
Ryan D

- - -
Hi Ryan,

Imagine a group of particles (protons) moving in one direction and another group of particles (antiprotons) moving toward them in the other direction. Each group of particles can be rather "diffuse" (remember, these are REALLY SMALL objects!), and so mostly the two groups pass right through each other without anything happen. In our case, each group has about 3-10 Trillion particles. BUT, only about 2-3 of them will actually collide! Since they go around in a circle, they'll all get another chance to collide the next time around. The particles just circulate and the groups pass through each other and eventually many of them end up colliding.

The point is, to increase the chances of collisions we can (1) increase the number of particles going in each direction within the ring, and (2) make the size of the particle groups smaller -- squeeze them together more tightly so that they occupy less space and have more probability of hitting the oncoming particles. These are the kind of things that I work on. I also work on optimizing the entire accelerator complex in order to make more antimatter (antiprotons) for the collisions and use them efficiently.

The more collisions we can make per day (per year, etc.), then the more data we'll have to look through to try to find evidence of the Higgs particle.

Thanks for your question,
-Mike

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Dr. Syphers,
Thats really intersting. So your saying that there are groups of protons and anitprotons that are always traveling in the Tevatron? I was looking at pictures of the fermilab and the tevatron and it appeared to have 2 circles. Are there two particle accelerators, or is one circle something else?
Thanks,
Ryan D

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Hi Ryan,
There are indeed two circles. It might be hard to see in the photograph, but one circle is actually twice as large as the other. The smaller circle is an "injector" accelerator that pre-boosts the energy of the particles before they are sent into the largest accelerator (the Tevatron).
-Mike

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Dr. Syphers,
In our powerpoint we had a couple slides about the Higgs boson. I was looking online and it seems to me that if the higgs particle exsists it would explain the mass of the W and Z bosons. Is this true? or does the higgs particle explain something else?
thanks,
Ryan D

- - -

Yes, the Higgs particle is part of the puzzle that could explain the masses of all the particles in the model -- quarks, leptons, and particularly the W and Z bosons.
-Mike

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