Decades have passed, yet this mystery continues to puzzle scientists.
In an underground laboratory shielded by a rocky mountain, highly radioactive material lies within a container of liquid gallium, emitting particles known as neutrinos that break gallium down into germanium atoms.
The goal is to solve a mystery that has persisted for five decades in the field of physics: The Gallium Anomaly.
Experts from the Los Alamos National Laboratory in the United States state that the gallium anomaly can be described as follows: Measurements of the rate at which neutrinos capture electric charge on gallium from strong radioactive sources have yielded lower than expected results. The enigma of this anomaly has remained unresolved for many years.
A researcher in the Gallex experiment, conducted in the 1990s at the Gran Sasso National Laboratory in Italy, holds a device known as a scintillation counter used to detect germanium atoms. (Photo: Tommaso Guicciardini/INFN/ScienceSource).
Three decades ago, in an earlier version of the current experiment (taking place in the Caucasus Mountains), scientists first discovered a deficit of expected germanium atoms that remains unexplained to this day.
“I think this is one of the most intriguing anomalies in neutrino physics we have today,” says Ben Jones, a neutrino physicist at the University of Texas, Arlington, USA.
For many years, physicists have been studying neutrinos in deep underground experiments at the Baksan Neutrino Observatory in the Caucasus Mountains of Russia. To date, this anomaly remains unresolved, with no signs of a solution on the horizon.
The Unique Characteristics of Gallium
According to the Royal Society of Chemistry, gallium possesses many strange, unusual, and unique traits.
Firstly, although it is solid at room temperature (around 22 degrees Celsius), this silvery-white metal is soft enough to be cut with a knife.
Additionally, it has a low melting point. If you hold a piece of gallium, it will literally melt from the warmth of your hand. Then, if you set it down, it will solidify. Scientists note that gallium has the widest range of existence in a liquid state among metals. Due to this characteristic, gallium is one of the few metals that can replace mercury in thermometers because its melting temperature is close to room temperature.
Another oddity is that this metal contracts when it melts, quite similar to water. As a result, solid gallium floats on its liquid, a property shared only by a few other elements, such as bismuth and antimony. The reason for this peculiar melting behavior has been a point of contention and speculation in the scientific community for about 50 years.
Even with such a low melting point, gallium’s boiling point remains relatively high at 2,204 degrees Celsius—giving it one of the largest ratios between melting and boiling points of any element on Earth.
At low temperatures, gallium is a brittle, glass-like solid that fractures in a shell-like manner (not along natural cleavage planes).
Not only do the visible external features pose a challenge, but gallium also confounds scientists by exhibiting anomalies in the laboratory.
99.999% pure gallium crystals grown in a laboratory. (Image source: Foobar/Creative Commons).
In nature, gallium is never found in its free elemental form and cannot be found in significant quantities in any mineral. Instead, it exists in trace amounts in various compounds, including zinc ore and bauxite.
Most commercial gallium is extracted as a byproduct of aluminum and zinc production, according to Chemicool. The largest gallium producers are Australia, Russia, France, and Germany, according to Live Science.
Chemistry Explained states that about 95% of the world’s gallium consumption is in the electronics industry.
Gallium is used to produce gallium arsenide (GaAs), a compound utilized in microwave and infrared circuits, semiconductors, and blue and violet LEDs. Gallium arsenide can generate direct laser light from electricity and is used in solar panels, including those on NASA’s Mars Exploration Rover.
The compound gallium nitride (GaN) is used as a semiconductor in Blu-ray technology, mobile phones, and pressure sensors for touch switches.
Gallium was once used in nuclear bombs to stabilize crystal structures. Scientists used gallium alloys for the plutonium cores of nuclear weapons to stabilize the allotropes of plutonium.
Gallium is a chemical element with the atomic number 31 and symbol Ga on the periodic table. It belongs to the boron group (group 13) and is in period 4. This metal was discovered in 1875 by the French chemist Paul Emile Lecoq de Boisbaudran, who observed its primary spectral lines while examining materials extracted from a zinc mixture. Shortly after, he isolated the metal and studied its properties, which matched the characteristics predicted by the Russian chemist Dmitry Ivanovich Mendeleyev a few years earlier for eka-aluminum, an undiscovered element at that time located between aluminum and indium in his periodic table. |
