Figure
2 -- The Car Collision Analogy -- The two cars collide and disappear
into a ball of energy and turn into a book and a chair. As the book's
and the chair's energy drain away, they turn into a ruler and a
pencil.GLUON AND QUARK COLLISIONS AND DECAY
by Lauren Weinstein
My research focuses on gluons and quarks, two of the smallest pieces of matter known to exist. Gluons and quarks cannot be see by the human eye, not only because they are microscopic, but also because they are always paired up with another gluon or quark by an inseparable bond. It is therefore impossible to study their properties as individual units. The only way to prove their existence is through indirect, empirical experimentation.
|
OBJECT |
Mass(Kilograms) |
|
Cantaloupe |
1.0 |
|
Frisbee |
0.00175 |
|
Thumbtack |
0.000439 |
|
Hydrogen Atom |
0.00000000000000000000000000167 |
|
Quark |
0.000000000000000000000000000557 |
|
Electron |
0.00000000000000000000000000000091 |
|
Gluon |
0 |
One method of separating gluons and quarks into their singular states is through a high-speed collision process. In my research, the collision takes place between electrons and positrons (the particle equivalent to an electron but with a positive charge). In order to deduce information about gluons and quarks created in the collision, a researcher must place together several different observations in a seemingly logical order, as though fitting together the pieces of an intricate and detailed puzzle. I use the results of the electron-positron collisions to determine a ratio -- the number of charged particles created from gluons in the collision to the number of charged particles produced from quarks in the collision.
The collision takes place in an enormous machine that accelerates electrons and positrons in a circular path with a circumference of approximately 1/2 mile. Once the electron and positron have reached a speed that is only slightly less than the speed of light, the beams of electrons and positrons are aimed at one another, forcing a multitude of collisions to occur.
We can attempt to draw an analogy between the electron-positron collision and a car collision. The impact of one car colliding with another will create a few dents, a broken window and a cracked headlight. The basic form of the cars, however, will still be discernible after the crash. If, on the other hand, the cars are to behave as subatomic particles in a particle accelerator, they will travel towards each other at such high speeds that a collision of enormous intensity will cause the complete transformation of both cars into gigantic amounts of energy. The ball of energy is so intense that it converts itself into new objects that have no relation to the original cars, such as refrigerators, ovens and stereos.
The newly produced objects, which travel through the air at extremely high speeds, contain vast amounts of energy. As they continue to travel down the road, they repeatedly transform from one object to another. The refrigerator, for instance, converts into a book and a desk, and the oven changes into a chair and a desk. Because, according to the laws of physics, energy must be conserved, the total energy that exists when then is only a refrigerator and an oven must be equal to the total energy that exists when there are books, chairs and desks. Since there are now four objects (a book, a chair and two desks) instead of the original two (the refrigerator and the oven), each object has less energy because the same total amount of energy is being distributed over more objects. As the conversion from one object to another continues, and more items are produced, the energy for each individual body decreases because the total energy is spread over a greater number of objects. This transformation from one object to another happens several times until there is no longer enough energy for it to change forms anymore. Just a fraction of a second after the initial car collision, all that remains of the two cars are bunches of low-energy pencils, rulers and erasers.
Figure
2 -- The Car Collision Analogy -- The two cars collide and disappear
into a ball of energy and turn into a book and a chair. As the book's
and the chair's energy drain away, they turn into a ruler and a
pencil.
Depending on the initial energy of the two cars, different kinds of objects may emerge from the impact of the collision. At one energy level, the aforementioned refrigerators, ovens and stereos may be produced. If the cars collide at a higher initial energy, however, we may find lamps, television sets and microwaves flying down the road. In most cases, when a collision at a particular energy level occurs, the cars will turn into the same objects, such as refrigerators and ovens. In a minority of the collisions at that same energy level, however, it is possible for other background systems to be produced, creating objects other than those found in the set group, such as toasters and computers. When this occurs, it is necessary for researchers to recognize and to separate out the toasters and computers from their data sample to ensure that they are observing the characteristics of only the refrigerators and ovens.
A glimpse at Einstein's famous equation, E=mc2 (energy = mass times the speed-of-light2) reminds us that energy and mass are proportional to one another. This equation helps to explain what happens in the particle accelerator immediately following the electron/positron collision. The enormous amount of energy produced in the collision must, by the law of energy conservation, be conserved in any possible form. As Einstein's equation states, the collision energy can even be converted into mass energy, and thereby form completely new and unrelated particles.
Figure
3 -- The Physics phenomenon. An electron and a positron collide and
turn into a photon. The photon quickly changes into an up quark and
an anti-up quark. The two quarks eventually lose their enegry and
transform into two other particles, a pion and a muon.
In the car collision analogy, it is the final, low-energy objects that I tabulate in my research. In effect, I am simply finding the ratio of the number of pencils, rulers and erasers that are created from the initial refrigerator to the number that are produced from an initial microwave. As mentioned above, the refrigerator system is created from cars at a lower energy than the cars that created the initial microwave system. Using particle physics terminology, I am making a comparison between the number of charged units of matter produced from gluons (the refrigerator) to the number of charged units of matter created by quarks (the oven). In order to ensure that I am looking at only particles produced from gluons and quarks, I must subtract any background events (the toasters and computers) that may be contaminating my experiment. After all background events are taken out of the data sample, I then find the ratio of interest.
I have determined the ratio between the number of charged particles from gluons to quarks to be approximately 1. 04. The fact that the ratio is close to 1 shows a significant relationship between how gluons and quarks interact with one another. Many other experiments have also searched for and found a ratio from gluons to quarks. These other experiments, however, were carried out at much higher energies than my experiment. By comparing our value with those of other experiments performed at higher energies, we can determine if the ratio is dependent on energy. One such experiment, LEP, which examined gluons and quarks created at almost three and a half times the energy at which my experiment was carried out, observed a ratio as large as 1. 27. Because my ratio differs from that of LEP's, and several other experiments, by such an extraordinary amount, we can conclude that the gluon to quark multiplicity ratio is energy dependent.