Science on ice

The travels of a young scientist to the South Pole - and back

Some people feel lucky when the temperature - in the summer - rises to 40 degrees below zero. Those people live under the sun which shines non-stop. These are the scientists who work at the International Research Station in the South Pole, in Antarctica. Dr. Hagar Landsman (Fels), from the Department of Particle Physics and Astrophysics at the Weizmann Institute of Science, is one of these scientists.

Dr. Landsman is a member of the international IceCube research team, named after a unique telescope that tracks particles called neutrinos, and not, as is customary, light particles. Although they are very common, neutrino particles are very difficult to detect: they are almost massless, have no electrical charge, and hardly interact with ordinary matter. The only way to distinguish their existence is through signs left after those rare interactions.

In recent years, a lot of information has been accumulated about these elusive particles - such as, for example, the fact that they can change their type while passing through space - but the hidden is still more than the visible. One of the unsolved mysteries concerns the origin of extremely energetic neutrino particles, which are involved in the cosmic phenomenon known as gamma ray bursts. Observing the neutrinos emitted in these bursts may help scientists understand their origin and how they are created. In addition, the scientists believe that the neutrinos are related to mysterious cosmic rays, and may provide clues to explain strange phenomena that characterize these rays. The neutrino particles may even shed light on the dark sides of the universe - for example, dark matter. "Since the dawn of history, people have used light particles - photons - to observe the universe," says Dr. Landsman. "The IceCube telescope uses neutrino particles for astronomical research, giving us an exciting new perspective on the universe."

Dr. Landesman has been a partner of the IceCube team for eight years, since she received her third degree from the Technion in Haifa, as part of her post-doctoral research at the University of Wisconsin. Its main job is to calibrate and test the telescope's 5,000 detectors, making sure they are working properly.

The IceCube, whose construction was completed only last year, consists of a huge array of detectors, with a volume of one cubic kilometer, which are buried at a depth of two and a half kilometers under the Antarctic ice. At this depth, total darkness prevails, so it is possible to notice rare flashes of light, which occur only in those few cases where neutrino particles come into contact with the ice. At these depths the ice is as clear and transparent as glass, and the flashes of light can travel hundreds of meters and be picked up by the IceCube detector.

Each detector - which is the size of a basketball - is tested and calibrated for several months, since after being buried in the depths of the ice there is no way to repair or move it, yet it must function properly for the next decade. Dr. Landsman performs the final tests and adjustments at the South Pole - shortly before the detector is buried in its place.

Her trips last about four weeks: three of them on the site itself, and the trips last for a week. Unexpected extreme weather conditions may even extend the duration of the trip by several days. When she arrived at the Pole, Dr. Landesman works around the clock - not only because the sun shines all day, but also because she feels the need to make the best use of the short time she is there. "The entire team at the South Pole station, which numbers about 150 scientists, engineers and technical support personnel - works like this. Getting people there involves a very high cost, so only really essential people are allowed to get to the station. Most of the maintenance work - from cleaning the toilets to washing the dishes - is done by all of us."

Most of Dr. Landsman's work is done outdoors. Staying at an altitude of 2,800 meters above sea level can cause altitude sickness, and the extreme dryness is an even bigger problem than the cold. These conditions slow down the pace of work. "In case you forgot a screwdriver, you will waste two precious hours to go back to get it," she says. There is no heating inside the station, to save electricity, and the showers are limited to two minutes, twice a week. "You can get used to anything," says Dr. Landesman. From time to time, the hard work is stopped for recreation - such as, for example, the traditional race around the world that takes place at Christmas, during which the crew members circle the pole, accompanied by snow sleds designed by the station's engineers especially for the occasion.

Dr. Landsman's last trip was to a much closer destination - Italy. At the Weizmann Institute she belongs to the group of Prof. Ehud Duchovni, Prof. Elam Gross and Prof. Amos Barskin, in the Department of Particle Physics and Astrophysics. She is a member of the institute's team participating in the XENON project, whose goal is to try to find evidence of the existence of dark matter particles using a detector located in the depths of the earth at the Gran Sasso National Laboratory in Italy. The team is currently building a new detector, which contains a ton of liquid xenon. Dr. Landesman is involved in both the data analysis and the design of the new device.

On top of that, she is a partner in the planning and development of another neutrino project in the South Pole. The project, known as ARA, is expected to cover an area of ​​100 square kilometers, with detectors located one kilometer apart. These new detectors detect radio waves - and not light waves - so they can be placed closer to the ground, at a depth of only 200 meters. Dr. Landesman describes the ARA as a huge net, designed to catch particularly oily fish - neutrino particles with high energies.

Hagar Landsman (Fels) is married to Adi, also a member of the IceCube team. Since he is involved in the administrative aspects of the project, his business trips take him to Wisconsin - not the South Pole. He is satisfied with the fact that the project, which cost about 300 million dollars, was completed on time, and with a slightly lower budget than what was allocated to him. The couple has two children, a son and a daughter, who probably don't understand exactly what their mother is doing so far from home. "When she was younger, my daughter told everyone who asked her that her mother was going to Antarctica to feed neutrinos to the penguins."