Simulating Gravity -- Part I: Some Basics

There are many canned programs out there in the marketplace that teachers can download and use to illustrate physics problems or principles, such as projectile motion. But what do the students learn from this? They play games all day long and never realize that the reason that their "characters" move about and jump over canyons along (hopefully) parabolic trajectories is because someone programmed in that detail of the motion into the software. So, let's have the students do that themselves!

Many programming environments are freely (or easily) available in which examples can be built up using first principles learned in the classroom; let the students “see for themselves” the laws of physics in use. For example, spreadsheet programs, like Excel, Numbers, Lotus, etc. (and their variants), make it easy for values of one 'cell' to be computed based upon the numbers input into previous cells. Editing features, like copying formulas from a line of cells into the cells in the line directly below, are easy and ideal for generating iterative calculations.

Let's look at an example...

Consider the motion of a particle undergoing free fall. Make a table, such as shown here. Starting with some "initial conditions" (x,y, etc. at time t=0), compute the values at subsequent times by calculating x, vx, etc. after a time dt, as indicated.















Next, create such a table in Excel (say) and let the program do the work...

An example Excel spreadsheet can be found here ( FreeFall.xls ).

By selecting the horizontal (x) and vertical (y) position numbers you want to plot, one can typically have the program make a grap, and voila!:


Here is a picture of what one would see in Excel:



So, the students not only see the result (hopefully, a parabolic trajectory!), but they see that it's simply the application of some simple relationships that they learned in class and can easily remember -- dv = a dt, dx = v dt, and so forth. One can explain how "dt" needs to be chosen to be small enough to make it a smooth, "continuous" variable, and so forth. (In fact, make dt too large, and see what happens!)

There is so much that can be learned and discussed from this simple exercise; plus, the students will learn a basic skill -- how to use a spreadsheet program to do more than balance a checkbook (do students even do THAT anymore?); a skill that they can use in college and beyond.

Once you get this far, it's a simple matter to extend the concept to a more complicated situation, but one which is still easily performed by the student -- let's try a planetary orbit around the sun! We're actually most of the way to being able to do this calculation using the spreadsheet we developed above. All we need to do is to modify the cells that contain the acceleration -- that is, modify our description of the force acting on the particle (planet, or satellite in this case).

The figure below provides a way of seeing the relationships, and the x and y accelerations can be easily computed from Newton's Universal Law of Gravitation:

Rather than using MKS units (meters, kilograms, seconds), it might be easiest to use units of "astronomical units" (average distance from earth to the sun), solar mass, and years (AU, Msol, yr). In this case, Newton's constant becomes:

G = (2 pi)^2 (AU^3)/(yr^2 Msol) = 39.4784 (AU^3)/(yr^2 Msol)

[It's easiest to see this if you consider purely circular motion of a planet around the sun.]

So, we input these relations into our "cells" that describe particle acceleration, and -- instantly -- the spreadsheet gives a plot of the result (see the file: PlanetOrb.xls ):

To start with, have the particle begin on a circular path. (This is the default condition in the spreadsheet.) How did we guess our initial conditions? By our choice of units they're simply:

• x0 = 1 AU, y0 = 0 AU; vx0 = 0 AU/yr, vy0 = 2 pi AU/yr -- try it out!
  

Next, try the following:

• x0 = 2 AU, y0 = 0 AU; vx0 = 0 AU/yr, vy0 = 1 pi AU/yr -- did you get an ellipse?

How about:

• x0 = -25 AU, y0 = 3 AU; vx0 = 5 AU/yr, vy0 = 0 pi AU/yr -- did you get a hyperbola?

Lastly (for today), can you use the spreadsheet to estimate the escape velocity from the earth's orbit?

ANS: "Launch" a particle from a distance of 1 AU. Start out with a speed of 2 AU/yr, and plot x vs. t. Do you see the particle "turn around"? Gradually try increasing initial speeds until the particle appears to fly off "forever" (always increase x with time). What minimum speed is required to "escape"?
Try:

• x0 = 1 AU, y0 = 0 AU; vx0 = 2 AU/yr, vy0 = 0 AU/yr
• how far does the particle get before it "turns around"?
  
• next, increase vx0 to 3 AU/yr, 4 AU/yr, etc.; how far now?

• what should the answer be?
  
• ... compare with v_esc = sqrt( 2GM/R)!
  

The above exercises could easily be broken up into about 2 class periods or more, depending upon how far the teacher wants to take this, what questions are answered, etc. But next time we'll take what we've learned and try to analyze a more specific problem.

Coming up: Let's program our computer to calculate a "trip to Mars"!
We can do this!

[Speaking of Mars: what's up with these emails about Mars' closest approach, and being "as big as a full moon," and not happening again for "5000, maybe 17,000 years"?? I see these posts every year (since the real "closest approach" that happened in 2003, and won't happen again until 2020). And the latest one says that Mars will appear as big "as the full moon"! What bunk!]

Helping Teach Teachers Teach Physics

Over the past few years while working with high school teachers at Fermilab, and also watching my kids go through physics classes at their own high schools, I found that too often kids were being taught "which equations to use when", rather than the principles behind those equations. I remember one teacher was having my stepson's class recite three mnemonics that would help them to remember which equation to use when faced with a problem regarding two-body problems where the bodies traveled in a straight line. One equation was for when the two bodies were both initially in motion. One equation was for when one of the bodies was initially at rest. And the third equation was for when the two bodies "stuck together" after the collision. My son was having trouble remembering "which" to use "when".

I tried to teach my son that there was really only one equation that needed remembering -- the momentum before the collision was equal to the momentum after the collision. Then, you just have to modify this statement to illustrate the problem at hand, and solve it algebraically. He liked that approach, but when he tried it on a quiz he got the problem wrong because he didn't "use the right equation; remember the mnemonics!!!" He never really liked physics, and didn't do too well; but then I found out that the teacher was a well-qualified biology teacher who recently was assigned to teach physics, a subject that she had taken, once, many years ago...

This, of course, is a situation found all over the country. Teachers are "teaching" physics because they had a course in it during college, or ... perhaps not. The fact that they are a science or math teacher, or maybe just had a math course, often means that they are qualified to teach physics to high school seniors contemplating college and their future careers. It's true, I believe, that a smart, motivated kid will find ways to learn what he or she wants to learn, but a really qualified teacher showing the excitement of physics and its usefulness in everyday life, especially the true underlying meaning of all of those "problems" kids are asked to solve should not be substituted by rote memorization of frivolous (to the students if not to the teacher) phrases.

Certainly a great part of the blame in all this lies in the fact that teaching for a while now has no longer been seen as a respectable career, and those who are actually good at it and can do well at it are enticed to move on to "more meaningful" work, like making money for a corporation. If a person knows enough physics to really teach it well to high school students, then they know enough to work for a company or lab, where they can receive salaries 2-3 times or more than a teacher's salary, and receive benefits that cannot be found in the teaching sector (including education reimbursement -- remember, teachers need more education to move up the scale!). They may feel motivated right out of college to go ahead and teach "for the better good," but such science teachers quickly burn out as they see their college friends moving quickly ahead (whatever that means) in life.

This is not something that can be changed overnight. Even though the present presidential administration recognizes the need for stronger educational practices, and stronger scientific education in the country, one cannot just lay off all the unqualified teachers and replace them with new "qualified" teachers. Firstly, the teachers we have today -- though some may not know the subject they teach as well as they would like -- still may have many years of experience in the classroom which is vitally important to any successful program and which the "new" teachers won't immediately have. Secondly, there aren't enough "new" teachers who are trained, readily equipped and who have the desire to change their present careers and go into teaching for such an overhaul to happen over night.

Present teachers, those who are willing to learn and adapt and wish to provide the best education to the students, should be provided special training to better prepare them to teach in the modern physics classroom. There are physicists in this country (one immediately comes to mind) that would truly enjoy spending part of their time for, say, a semester or two, re-teaching high school physics to high school teachers who will potentially need to teach physics. That is, have the scientist show the teachers how THEY would get the points across to students; show them how to use the equipment they find lying around in the back room of the high school science department. Show them how to teach using their own self-made apparatus when the back room doesn't have any equipment lying around! Show the teachers how they, the scientists, approach solving problems (at the high school level). I think the results would be very surprising. Most physicists don't simply recall a mnemonic device that helps them remember which equation to use -- they solve problems like puzzles, starting from basic principles and applying logic. One of the reasons I did so well in physics was that I didn't have to memorize as much as I would have had to in other subjects. (Biology comes to mind...)

Most scientists that I know tell me that there was a teacher or two in their early years that greatly influenced them, their thinking, and their desire to become scientists. If present-day teachers could hear from some of these scientists to learn what sparked them at age 16, then this could be a wealth of information for the teachers to use in their classrooms.

Next time, I'd like to discuss how one can use "everyday" software to use a computer to solve seemingly complicated physics problems using high school physics. I'll ultimately share a problem that I had to work out as a senior in college. How would that possibly be of interest at the high school level? Well, in my college days, computers were main frames that took up entire basements of physics and math buildings, typing out "punch cards" and feeding them into a card reader; I had to use one to solve this problem (actually, part of this problem -- the part I will share next time). Today, kids play video games in THEIR basements on computers that have 100,000 times the power of the one I used in the 1970's. But, while they use the computers as game devices, they don't often realize that they can program the computer themselves to solve problems like calculating trajectories to send a space probe to Mars, or simulating the motion of stars near the center of the galaxy. It's all just Newton's laws, which they learn in high school, and they have all they power they need to "solve the problem -- no mnemonics required!"

Angels and Demons

Even though the movie has been out for a while now, I still receive questions from visitors to Fermilab about our production of antimatter, and whether there is any "validity" in the premise that a "bomb" could be produced using our supply, or the supply that the movie suggests will be generated by the LHC at CERN.

Besides the slight change in the ending (the movie's ending is much better than that in the book!), it was great to see some actual views of CERN and the LHC tunnel in the movie "Angels and Demons". One has to realize that the "control" of the accelerator is not underground nor just outside of the detector, but rather several kilometers away in an above-ground building. And the accelerator operators don't wear lab coats. And... But, the film has enough going for it to make it interesting. What's also interesting, which most people know by now, is that (a) the LHC at CERN will not be used to make antimatter, except as a result of individual particle collisions in the experiments, and (b) even if it were optimized to make antiparticles at an appreciable rate, it would take far too long to get the amount presented in the movie.

Let's make a simple calculation, using the highest antimatter production going on in the world today, the Fermilab Antiproton Source. At Fermilab, beams of protons are accelerated within several stages of accelerators to a final energy of 120 GeV per proton -- that means that each proton is accelerated through a net voltage of 120 Billion volts. The beam of protons is focused and sent into a target made of a Nickel alloy, where the energy of the collisions of the protons with the nuclei of the target is high enough that new particles can be created (E = mc^2). Any particles with a negative charge, and with a momentum of 8.9 GeV/c are collected in a storage ring that is made up of electromagnets and tuned to operate for that particular momentum. Many of those particles, like pions and kaons, etc., will very quickly decay away -- however, stable particles -- like antiprotons -- will remain forever (as far as we know) and can be collected in the ring. In the Fermilab facility, about 20 antiprotons with this particular momentum are collected for every one million (10^6) protons that hit the target.

Now, the facility can produce about 8 trillion (8 x 10^12) protons each with 120 GeV energy every 2.2 seconds to send to the target. That means that 8 x 10^12 x 20/10^6 = 160 x 10^6 antiprotons are produced every 2.2 sec. OR, 0.16 x 10^9 /2.2 s x 3600 s / hr = 26 x 10^10 antiprotons every hour (260 billion/hr).

Thus, if the facility ran non-stop (present conditions generate an effective "up-time" of about 70% throughout a typical year), for 1 billion years, then roughly 26 x 10^10 /hr x 24 hr/day x 365.24 days/ year x 10^9 (1 billion) years x 0.70 = 1.6 x 10^24 antiprotons would be generated.

Coincidentally, the mass of an antiproton is the same as the mass of a proton: 1.6 x 10^-24 gram. Thus, in a BILLION YEARS of running, we could produce *** 1 gram *** of antimatter!

OK, so the 1/4 gram of antimatter that goes "missing" in the movie would only take 250,000,000 years to generate...

"Yes, but couldn't we upgrade the Fermilab accelerator to do better?"

Indeed, if the targeting stations were upgraded, and we could use the full power of the "Main Injector" accelerator (which operates at 120 GeV/proton), then one could imagine 4 x 10^13 every 1.5 seconds at best -- a rate that would be 40/8 x 2.2/1.5 = 7 times better. THUS, it could generate 1/4 gram in "only" about 36 million years!

The other question often asked is, "Isn't the LHC much higher energy? So couldn't it make antimatter that much faster?"

First of all, the LHC can't ramp up and down in 2.2 seconds or anything close to that. It takes many minutes for the accelerator to reach full energy. So, even if it does have over 50 times the energy of the Fermilab Main Injector (it will contain, ultimately, roughly the same number of particles), it takes about 500 times longer to ramp up and down to its final energy. So, the "rate" that it could produce antiprotons is far less than what would be done at Fermlab's machine.

- - -

It's still cool that antimatter exists at all. And, that most of the antimatter produced and accumulated for scientific use in the world so far has been produced right outside of Chicago...


Aerial view of part of the Fermilab accelerator complex. The "oval"-shaped accelerator at the top is the Main Injector, which typically operates at 120 GeV per proton. The small "triangular" arrangement of buildings near the bottom house equipment for the Antiproton Source, located about 20 feet below the surface.

Thanks, A-a-P groups!

Dr. Syphers,

I would like to use this post to thank you and all of the physicists that took time out to respond to our posts. I would aslo like to thank you for being an inspiration to me and my fellow classmates.

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Hi everyone,

I wanted to thank you for participating in Adopt-a-Physicist. It has been a lot of fun answering your questions and talking physics, astronomy, basketball, and work with all of you. Have a great end-of-the-year, and a great summer.

I have posted past entries on my blog site ( http://SyPhy.com ) and may post some of our discussions there, too, for others to gain insights. Feel free to visit me there.

Thanks again,
-Mike Syphers


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Dr. Syphers,
Thanks for all your help. I learned a lot about the fermilab, tevatron, and particle accelerators in general. I enjoyed talking to you the past couple weeks, and you helped get a better understanding of physics, the higgs particle, and many other things.
Thanks,
Ryan D

Sound's Interesting...

My name is Branden and Im currnetly a senior. My question for you is do you work with sound waves.

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Hi Branden,
I don't actually work with sound waves in my job. I do enjoy using my iPod, though...
Cheers,
-Mike

Growing Up...

Hello Dr. Syphers,
I was wondering if you were raised in a scientific enviornment. Were many of the people around you interested in science, or was there just something about it you liked?
Are there any youtube videos you know of that illustrate the concepts you are interested in?
Ryan D.
PS How do you feel about pluto not being considered a planet anymore?


---

Hi Ryan,

No, I was not raised in a scientific environment. My oldest sister and I were the first in my family to go to college. But our parents were very loving and caring and taught all of us kids (5 in all) that we could be and do anything we wanted if we worked hard at it. And that's what we all did.

Why science? From a very young age, maybe 6 or 7, I would stare at the stars in the sky and wonder what they were and how to get up there and why did they move around and what was the sun and the mooon and ... I really didn't know anyone else who was interested in science until I got into high school and took chemistry and physics. When I saw a physics book and learned that this science could explain the motion of the planets -- 10 years after I first started thinking about it! -- then I was hooked on physics.

I'm not all that familiar with the YouTube site, though I go there when other people give me links. There's one video I saw recently about one of the particle detectors we use here at Fermilab:
http://www.youtube.com/watch?v=qPIbjQ_JRk4
Here's one I found that talks about particle accelerators; it looks pretty good, and shows pictures of Fermilab:
http://www.youtube.com/watch?v=M_jIcDOkTAY

Hope that's helpful.

Oh, and feel sorry for little Pluto...

Cheers,
-Mike

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Hi again, Ryan:

CERN is a laboratory on the border of Switzerland and France, near Geneva. I has been the long-time (friendly) rival to Fermilab. For 25 years, Fermilab has held the record for particle energies, with our proton beams in the Tevatron accelerator. In a year or so, CERN's new accelerator -- the LHC -- will be several times stronger (about 5-7 times). It's a very similar machine as the Tevatron, only bigger.

When we collide particles in the Tevatron (or LHC for that matter), we observe all of the bi-products of the collisions. There are certain statistical chances -- that can be calculated from theory -- as to what should happen and how often. The data is taken and analyzed to see if the theories we have match up with what we observe. The energy from the particle collisions creates new particles, many of which have not been created since the Big Bang! So, they are very rare events, and we hope that we can find evidence for a new particle -- the Higgs particle -- that is the missing link. The theories we have today predict that it should exist and if it does we expect to see it a few times if we take enough data.

I'm content working at Fermilab; I enjoy the midwest, and Chicago is a wonderful city. I do wish the SSC had not been canceled, however, as it was a major set-back for our country to stop such an important project.

Thanks,
-Mike

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Fermilab

hello! my name is Grace. I noticed your forum avatar (profile picture?) it's an interesting symbol and i don't think i've seen it before. what does the symbol mean. what does it represent?

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Hi Grace!

The avatar is actually the official logo of the laboratory where I work -- Fermi National Accelerator Laboratory. It actually does have a story. The laboratory houses the world's most powerful particle accelerator, or "atom smasher." This machine guides charged particles (protons and antiprotons) around in a circular path, and eventually smashes them into each other to see what happens. The accelerator has about 1000 very powerful electromagnets in it. Some of the electromagnets (about 780 of them) are used simply to steer the beam in its circular path. The other large magnets (about 220 of them) are used to keep the beam of particles "focused" around this path.

I've attached a figure to look at now. The picture shows three different kinds of electromagnets used in accelerators. The first one on the left has four "poles", and is represented by the four curved lines in the avatar. The second one has two poles (up and down) -- the magnetic field lines go from bottom (North pole) to top (South pole) inside the hole in the center. The two horizontal lines in the avatar represent this "dipole" design.



Anyway, Fermilab was the first lab whose accelerator was made out of a combination of dipole-style magnets and quadrupole-style magnets. So that is why it this logo was chosen for the laboratory.

You can visit the Fermilab web site at: http://www.fnal.gov where the logo is used quite a lot!

Thanks,

- - -

I just picked you for my physicist for our project and I was interested to hear how you liked working at Fermilab

-----

Hi,
I enjoy working there very much. It is a very exciting place to be, with people from all over the world coming together to study the physical world. You can get a lot of information about the lab at our web page: http://www.fnal.gov . As you might notice, it has a lot of interesting architecture, wildlife, cool "toys" to play with, and great people. It's really a nice life, I'd have to say.

Thanks for your question!

Career Choices...

Hello Dr. Syphers,
Was there a time when you didn't want to be a physicist as your career or have you always had that being your primary interest?

~Amanda


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Hi Amanda,

I think I became interested in science at a very young age -- probably around 6 or 7 years old. It was during the 1960's, and the "space race" was on. I became very interested in the stars and planets, and started learning to recognize constellations, etc., and looking at Jupiter's moons through binoculars, and stuff like that. I didn't even know what physics was until I was a Junior in high school -- but when I saw the book I saw the chapter on "Gravity" and I was hooked!! And I've been studying, practicing, and teaching physics ever since.

Other things I was interested in during my teens, and briefly considered studying for a career, were drafting, architecture, and journalism. But science was always there, calling me back...

Thanks for your question!

- - -
Right now we are learning about wavelengths and frequencies for light and sound. We are applying it to mirrors and reflection and refraction.

We understand that you work for Fermilab. What does your job entail?

- - -
Hi,

I'm an accelerator scientist at the lab. I work on the design, operation, and troubleshooting of large particle accelerators. I've been in the business for a while now, so I do quite a bit of administrative work (meetings, writing reports, etc.), but I'm still able to work on real science once in a while, too! I probably do more calculations and computer work than hands-on experimentation, but I always try to do a little of each.

Are there more specific things you'd like to know about my job?

Thanks for your question,
-Mike

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Dear Dr. Syphers,

Hello, my name is Myles F. Thank you for participating in the adopt a physicist program. My group looks forward to talking with you and researching you for furhter information. I guess the best question to start off with is, how and when did you fall in love with physics?

Thank You,

Myles F.


-------
Hi Myles, et al.:

I became very interested in science at a young age -- probably around 6 or 7. I was fascinated by the stars and planets (the Apollo space program was going on around then) and read everything I could about them. My parents bought me a small (and cheap!) telescope back then, and I used it all the time to look at the moon, jupiter, etc. I learned all the constellations visible to me, and the names of the brightest stars, and so forth. So, that's really when it all started.

I took biology as a freshman in high school, and chemistry as a sophomore. The next science class to take was something called "physics," though I didn't know what that was. When I saw the book and saw that one of the chapters was called "Gravity and Planetary Motion," then I REALLY got interested in physics. I took two years of physics in high school and never looked back.

- - -


Hello,
Our group is making a powerpoint on you. I was wondering if you have anything in particular you think we should add into our powerpoint. So far we are putting in backround information about your life and education. We also have slides about the SSC and the Fermilab. Do you suggest we talk about the Higgs particle? (missing link)
Thanks,
Ryan

- - -

Thanks for all of the help. We really appreciate it. It sounds like you have a fun job and you enjoy what you are doing. Also we are celtics fans so we are quite jealous you got to go to that game!

We were wondering if you knew that you wanted to work with physics when you were a senior in High School like us? And what traits are required in a person that wants to go into your field?

- - -


Hi,

Yes, I pretty much knew. I was interested mostly in astrophysics, and started out in college pursuing that area, which combined my early childhood interests in astronomy with what I had learned in my physics classes in high school. I later switched to a straight physics major because at that time there weren't that many jobs in astronomy/astrophysics; there are many more these days. (And, there are astronomers and astrophysicists at Fermilab, so I get to study that stuff after all, whenever I want! Sweet!)

I think the main traits are inquisitiveness, persistence, and some natural talent in logic and mathematics is certainly VERY helpful! I also think that the best scientists are people who are very well rounded -- they play sports, play instruments, sing, dance, travel, read novels, write blogs, climb mountains, etc. (OK, maybe not ALL of that stuff, but you get the drift). The more things you do and experience, the better you can think about the details of the world. My best advice, I think, for young students is just to find yourself, have fun and do meaningful things that make you happy. The rest will follow...

-Mike

- - -
Hello Mr. Michael Syphers

I am excited to find out about your life and more about physics. Thank you for allowing us to adopt you.

Dan T.

- - -

Hello,
I was reading on the internet about the particle accelerator called Cern. How does that compare to the fermilab you work at? And also, what type of results are you hoping for when you have a full on collision between particles?
Thanks,
Ryan D

- - -

I look forward to learning all about your career as a physicist and I hope you will be able to help us with our physics project. Thank you for participating and letting us adopt you as our physicist.

Chris Z

- - -


How long have you specialized in "accelerator physics"?

- - -

Hi,

I've been working in the accerator field for 29 years. I got my PhD (some may say, that's when you become a "real" scientist) 22 years ago.

Thanks for your question,
-Mike
- - -

Hi Dan,

Fermilab may not be the highest energy accelerator lab when the LHC turns on, but it will still have a very important role in high energy physics for many years to come. We are constantly looking at new ways to improve our operation here, and studying new accelerators that we could build that could be complementary to the LHC, using different particles (electrons for instance, rather than protons), and performing studies with more intense beams, not just more energetic beams. So there will be lots to do for a long time.

Cheers,
-Mike

CERN and the LHC

hello sir, i am a junior and I was wondering if you have ever visited the particle accelerator at CERN, and if you have how does it compare to any other particle accelerator you've seen. Also do you know if Fremi-Lab have any anti-matter? From what I know anti-matter is a result of a particle accelerator experiment.

---------

Hi,

Yes, I have visited CERN and seen their particle accelerators. The LHC at CERN is about 5 times bigger than our biggest accelerator here in the U.S., at Fermilab where I work. It is the largest machine in the world, and when it turns on and runs full steam, it will become the highest energy accelerator. Right now, that honor belongs to the Tevatron at my lab. The LHC is indeed a very impressive sight.

As for your second question, yes Fermilab has lots of antimatter, though "lots" is a relative word. The LHC at CERN will collide protons heading one direction with protons heading in the other direction. These protons travel in side-by-side pipes, and then are brought together at "collision points." In the Tevatron, we collide protons with "antiprotons" going in opposite directions within a single pipe. So for this to work, we need to constantly be making antiprotons every day, all day long. We have the biggest anti-matter factory in the world!

We can make about 300 billion antiprotons every hour of operation. We accelerate protons to a high energy, and then steer them into a target. A lot of debris gets generated from the energy of the collision. For every million protons that hit our target, about 20 antiprotons come out and get collected. We repeat this process over and over until we get enough to collide with the protons in our big accelerator.

But like I said, even though we make lots of anti-matter, it's really not that much. Suppose we run our machines 150 hours a week, and 40 weeks during the year. Then, we'd make 1.8 x 10^15 antiprotons each year. A big number, eh? But an antiproton weighs the same as a proton, which is only 1.7x10^-27 kg. So, in a year we only make a couple of nanograms of antimatter at most; in a good year! In one billion years of constant running we'd make two grams of antimatter...

Fun to think about though!

Thanks for your questions!
-Mike

The Higgs!

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

- - -
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


- - -

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

- - -

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

- - -
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

- - -

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

- - -
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

SSC

hello, my name is denisse. im a senior ... and i have a question for you, how did you feel about the cancellation of the ssc project?


Hi Denisse,

It was a very hard thing to go through. It was going to be the largest machine built by mankind, and it was a very exciting project to work on. The government had spent over $2 Billion when it came to a close. (It was going to cost about $9B total.) My family and I moved from Chicago to Texas to work on it, and we lived there for almost 5 years. So, it was hard for us to suddenly be out of a job and looking for work again. It also meant to me that the U.S. wasn't as interested in science as it once was, which was sad, too. Luckily, I think this has all been changing the other way in recent years...

Thanks for your question!

-Mike


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so what exactly was the SSC project? was it a way to conserve energy or what? and who came up with the idea of that project?

-Denisse


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Hi Denisse,

The SSC was the "Superconducting Super Collider." It was going to be a very large particle accelerator, or "atom smasher." It was to be a circular machine, about 53 miles in circumference(!), in which protons would be accelerated to very high energies in opposite directions, and then collided head-on into each other. The energy of these collisions would be converted into new particles -- particles that had not been created like this since the time of the Big Bang -- and then we could study them. This accelerator would have been more than 20 times as powerful as the Tevatron accelerator that we run at Fermilab today.

We build these machines so that we can study the most fundamental questions, like: What is the universe made of? What forces are involved, and how do they work? Scientists first made particle accelerators back in the 1920's, and they have been getting more and more powerful ever since. The Tevatron at Fermilab was built in 1983, and the SSC was thought up by a group of U.S. scientists back in the early 1980's, soon after that. We finally began to build the SSC in 1988. However, it was canceled in 1993.

-Mike