Where did all the anti-matter go? One physicist seeks answers in Homestake

BY WENDY PITLICK, Black Hills Pioneer
http://www.zwire.com/site/news.cfm?newsid=18121130&BRD=1300&PAG=461&dept_id=156925&rfi=8

Yuri Kamyshkov, a physics professor at the University of Tennessee at Knoxville, Tenn., has written a proposal to do anti-matter research in the proposed deep underground science and engineering laboratory at Homestake. The research is the first of its kind to be conducted in the United States, and Kamyshkov will be working in collaboration with several other physicists from the University of Tennessee, Indiana University, North Carolina State University, Maryland, the University of South Dakota, California State University, and the Oak Ridge National Laboratory in Tennessee.

"All anti-matter seems to have disappeared in the universe," Kamyshkov said. "However, we believe that at the very beginning of the universe matter and anti-matter was produced in equal amounts. So the question is where anti-matter disappeared (to). This is a big outstanding problem in physics and cosmology which (has stood) for many years and we are trying to understand how to resolve that."

According to Kamyshkov, in the 1930s physicists discovered that almost every particle in the world has an anti-particle, and each particle that is created has an opposite in equal parts. When matter and anti-matter particles meet they "annihilate" - destroy each other producing neutral photons (particles of light) and neutrinos. But scientists have never been able to find how anti-matter disappeared in the universe leaving us only with matter in the form of planets, stars, galaxies, and galaxy clusters.

In the early days of the universe, Kamyshkov says, matter and anti-matter were converted into each other at varying rates, which produced a non-equilibrium among the particles and anti-particles. This, Kamyshkov said, is called a CP-Violation, which is a violation of symmetry between particles and antiparticles.

"(But) since we observe no anti-matter in the universe anti-matter particles should disappear," Kamyshkov explained. "But since they annihilate with matter particles then the matter particles should also disappear,"

Kamyshkov also said there is striking evidence that in the universe every atom of matter had approximately two billion photons left in the form of microwave background radiation.

"This microwave radiation is a witness of the annihilation which happened between matter and anti-matter," he said. "As a result of this annihilation we are left only with matter and we need to understand how it happened at that time."

In order to discover how this happened, Kamyshkov plans to study neutrons, which on their own do not possess an electric charge and can be easily detected if they convert to an anti-particle.

In order to do this, Kamyshkov said he plans to drop neutrons down one of Homestake's vertical shafts. The neutrons, he said will be allowed to fall down to at least 1 kilometer (3,000 feet). On this long way that will take neutrons only about one second, neutrons will move in a vacuum and have to be shielded against the Earth's magnetic field. Under these conditions with vast number's of neutrons there will be a chance that one neutron will be converted to anti-neutron. This will be immediately detected.

"In the early universe there was a very high temperature," he said. "At this high temperature matter to anti-matter and anti-matter to matter conversion processes could be accelerated and at present low temperatures in the universe they are very rare and need special conditions for observation."

Unlike most experiments, which will be conducted on a horizontal working surface at a specific level of the mine, Kamyshkov said his experiment is unique because he needs a straight vertical shaft that leads down 3,000 feet. That's why Homestake is ideal because its depth and its shafts are readily available for dropping particles into the mine.

While his research will not have any immediate effects beyond satisfying scientific minds and the general public's curiosity about the early workings of the universe, just having that understanding alone could yield some significant effects in the future, Kamyshkov said. "As you know scientific experiments in physics are always very much promoting technology and development of new things," he said. "Let's take one example; X-rays at some point about 100 years ago were the frontier of high-energy physics. Now it is in every clinic, even in underdeveloped countries and we do not think to ask where it came from. There is a very important aspect that the connection between the present-day frontier technology and future benefits to the society is not immediate. You put money into the research and it will not return tomorrow. This situation is like the situation between parents and children. When you pay for your children, you send them to school; you pay a lot of money for them. You never expect that tomorrow they will pay you back and you will get some return. You like to do that. I think the attitude of the general public to physics should be like the attitude of parents to children. We do it for the future."

But before Kamyshkov starts planning his research for the DUSEL he said he must first conduct a feasibility study to determine the best, most cost-effective ways to get it done. Proposed to be done in cooperation with Dongming Mei from the University of South Dakota and other collaborators, Kamyshkov said he is still waiting for the National Science Foundation to approve the nearly $800,000 feasibility study. During the study, Kamyshkov said he will examine such things as whether the Homestake shafts are completely straight and solid, and whether they move when they are jarred. He will also examine the magnetic field that lies underground along the shaft.

"If there is a little bit of iron somewhere in the ground in the shaft area or any other magnetic material that might create a local increase of the earth's magnetic field we need to understand that," he said. "In this experiment we will need to shield that magnetic field of the earth and any magnetic anomaly which might potentially be present."

While Kamyshkov said his experiment can ultimately be conducted anywhere that contains a vertical shaft leading 3,000 feet underground, Homestake is ideal because the infrastructure is already in place. But, like scientists all over the country, he is anxiously awaiting the NSF's decision about the DUSEL site. "If we know for sure that it is Homestake it will help us focus our efforts considerably," he said.