May the One-and-Only Force Be with You


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Gross, Mikenberg and Shoa, in the lab

Once upon a time the universe was a simple place. It was composed of a few particles interacting by means of just one basic force. But being a very hot and extremely energetic universe, it existed for only a few seconds following the Big Bang. As the seconds passed, the energy spread out through the expanding space and the universe cooled, exactly like a cup of tea.
Its primary particles, able to exist only at very high energy levels, continued to multiply and form complex, highly charged relationships. In this way we progressed, more or less, from a simple primeval universe to our more complex cosmos, where we can recline and sip our tea (though it is cooling as well) while perusing at leisure articles on scientific principles.
For most of us, the complex place in which we live is a world filled with visual marvels. But physicists are not content with visible reality; their quest is to get to the root of its forces and to examine whether our visual reality is truly based on the profound-but-lost simplicity of the ancient universe.
An important milestone in their scientific research was the unification of electromagnetic and weak forces into a single, more ancient force, known as the electroweak force. The remaining missing link for proving the existence of the electroweak force is a force-carrying particle named the Higgs boson.
Weizmann Institute scientists at the Nella and Leon Benoziyo Center for High Energy Physics are participating in an international effort to find the Higgs, which is considered responsible for providing mass to all the particles in the universe. The research is being conducted in the largest particle accelerator in the world, known as LEP, at the European Laboratory for Particle Physics (CERN), near Geneva. This accelerator is located in a circular 16.7-mile (27-km) tunnel, excavated 110 yards (100 meters) below the earth's surface.
Weizmann scientists Dr. Daniel Lellouch, Dr. Lorne Levinson, Prof. Eilam Gross, and Prof. Ehud Duchovni, led by Prof. Giora Mikenberg of the Particle Physics Department, Director of the Benoziyo Center, are working in Europe within the framework of scientific cooperation agreements signed between Israel and CERN.
In the accelerator, particles moving in opposite directions create numerous collisions. A highly energized system develops in the vicinity of the collision, similar to the conditions that existed among particles during the first moment following the Big Bang. As a result, the particles of matter are converted into energy. This is an illustration of Einstein's famous equation; E=mc2 describes the equivalence between matter and energy. Subsequently, the energy spreads throughout the space and the system cools (just as happened in the developing universe). The energy is reconverted into particles of matter that undergo the same multistage process until they form the particles capable of existing in our familiar reality.
Scientists monitoring the various stages of this process are learning about the structure of matter and the development of the universe. But herein lies the rub: These energetic particles exist for only fractions of a second. To detect their very existence, it is necessary to identify the tracks they leave behind -- for which purpose scientists construct particle detectors. For example, in order to detect and identify the Higgs, the Institute's scientists, headed by Prof. Mikenberg, developed the thinnest gas-based particle detector in existence. This detector is capable of identifying tracks left by the passage of charged particles at a rate 50 times greater than that achieved by previous detectors. (Most of these detectors are made at the Weizmann Institute, while some are manufactured in Japan in close collaboration with Institute scientists.)
According to Mikenberg, unlocking the mystery of the Higgs depends primarily on its mass. "The heavier it is, the more powerful are the collisions required for its discovery. The current CERN accelerator is capable of producing collisions with an energy of about 200 billion electron volts."
What if the Higgs is too heavy for the current accelerator?
"In that event, the research will continue with a new accelerator now being installed in the circular tunnel, which will create about one billion collisions per second with energies that will, undoubtedly, trap this elusive particle."
The days of the Higgs as a particle-in-theory are numbered. If it ultimately transpires that the mass of the Higgs is close to 100 billion electron volts, it is likely that a supersymmetry will exist between the force-carrying particles and the "worldly" particles of matter.
It may also demonstrate the possibility that at the foundation of the material universe there existed a single, two-dimensional particle: a "superstring" -- the ancestor of all other particles.
The significance of this activity is the opening of a new and exciting hunting season for a swarm of anonymous particles filling key positions in the complex reality of our world. The real prize upon finding them could be the long-sought proof that at the origin of reality there existed a one-and-only basic force of nature, the descendants of which exist today.