The Maverick Israeli Scientist Who Nearly Discovered the Island of Stability

Tamar Rotem
Tamar Rotem
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Tamar Rotem
Tamar Rotem

Amnon Marinov spent most of 1970 in the Rutherford High Energy Laboratory, near Oxford, England. He holed up there night and day, arriving home at ungodly hours in a nearby town on the banks of the Thames ‏(where he lived with his wife and four children‏). Then, one night, it happened: Marinov became convinced he had discovered a new chemical element for the periodic table: No. 112.

At the time Marinov was a young scientist, around 40 years old, on a sabbatical from the Hebrew University. He was totally immersed in studying the elements of nuclear physics but was also attracted to chemistry. Because he couldn’t decide between them, he found a way to combine the two during that year at Rutherford, and was now convinced he was on the verge of a breakthrough.

Marinov died in December 2011. During his life, he belonged to an exclusive team of nuclear physicists working in a field called superheavy elements research. His activity is not generally known, although the results of his experiments still have a place in current scientific discourse. Many of his students and colleagues, in Israel and worldwide, believe he would have received the Nobel Prize had he continued with his research, and that he did not receive proper recognition.

Marinov was born in 1930 in Jerusalem, grew up during the siege of the city, experienced the 1936 Arab riots, joined the Palmach prestate militia and fought in the 1948 War of Independence. After the war he was among the founders of Kibbutz Tzora ‏(near Beit Shemesh‏), together with his wife, Rachel, a nurse. In the early years, while pursuing university studies, he worked in agriculture on the kibbutz, but eventually moved to Jerusalem.

Marinov was the only one who ever came close, or so he claimed, to discovering the “island of stability” located on the map of the natural elements − one of the most enduring mysteries in nature. An island of stability refers to heavy elements listed in the periodic table that do not disintegrate quickly. The discovery of these regions of stability is likely to complete our knowledge of the substances from which our world is composed, point to new sources of energy, and lead to the deciphering of another piece of the puzzle that is our universe.

Marinov claimed that the mysterious element ‏(No. 112‏) he succeeded in isolating lasted for over a month. In other words, it was a relatively stable element. This gave people reason to believe that Marinov had indeed come close to discovering that island of stability. The entire field received a tremendous boost, and there was buzz about a Nobel. But Marinov, who in 2009 once again reported discovery of a new element, No. 122, did not receive recognition for his discoveries, one reason being his original and unconventional methods, which other scientists couldn’t replicate for various reasons ‏(for example, the use of radioactive material‏), and therefore his findings were not validated.

Despite repeated attempts, and despite finding the isotopes, to this day scientists have not found the specific elements themselves ‏(in other words, atoms with an equal number of protons and a different number of neutrons‏) which dissipated silently. Studies published recently further establish the theoretical models with which Marinov explained the results of his experiments. There is a reasonable basis for assuming that, since the theoretical explanation has been completed, scientists will try to precisely reconstruct his initial experiment, which still exists in the scientific discourse of superheavy elements.

The person who coined the term “island of stability” and sent generations of nuclear physicists in search of it was a chemist named Glenn Theodore Seaborg. Seaborg was an American scientist who worked alongside Robert Oppenheimer on the Manhattan Project in the 1940s. A Nobel laureate in chemistry, Seaborg was an elegant man with a bulbous nose and nerves of steel. Up until the late 1990s, there was no American or international committee on nuclear energy or the nuclear arms race in which he didn’t participate. He achieved his scientific fame for being responsible − alone or at the head of a group of scientists − for the discovery of 10 elements, including plutonium ‏(with which uranium is enriched‏).

Most of the known elements that exist in nature were discovered in the 18th and 19th centuries or even earlier, and a few in the 20th century. In 1869, a young Russian scientist called Dmitri Mendeleev invented the periodic table of elements, thereby making the lives of all those researching the elements easier. The Mendeleev table is a brilliant classification of the chemical elements according to the number of protons in the nucleus of their atoms. Each element, both old and new, whether it is copper, iron or oxygen, has a serial number, which also attests to its mass ‏(although it ignores the mass of the neutrons, for example‏).

The higher its number on the periodic table, the heavier and less stable the element is, with a greater chance of disintegrating. In effect, the elements above No. 83 are atoms that disintegrate spontaneously − in other words, they are radioactive. In scientific language, the instability of an element is reflected in the fact that its half-life ‏(the period of time required for half the atoms to disintegrate and turn into another chemical element‏) is short.

Star of the table

Mendeleev organized the elements into families and groups, according to their chemical characteristics. The 20th century is considered the age of the elements. At first, there were scientists who believed that the role of the table of elements had ended, that there was no more chance of finding additional elements in nature. However, prior to the 1940s, initial groundbreaking experiments were conducted, by Seaborg himself, among others, to create artificial elements.

The exclusive focus of the scientists during that period was on one charismatic and unstable element, No. 92, uranium. Until 1940 it was the heaviest element known to scientists. The more they learned about its characteristics and capabilities, the more it became the unquestioned star of the periodic table. For a long time, they believed it was the last element existing in nature. Thanks to uranium, though, the road was paved to a new and wonderful world of elements.

In 1940, a Jewish nuclear physicist, Lise Meitner, discovered that the nucleus of the uranium atom would split into small nuclei while emitting neutrons. This nuclear fission was accompanied by a huge release of energy, and later became the basis for the operation of a nuclear reactor. The Nobel for the discovery of nuclear fission went to her boss at their German laboratory, chemist Otto Hahn, when she fled from the Nazis.

On the other side of the ocean, in the same year that nuclear fission was discovered, Seaborg bombarded uranium with heavy hydrogen ‏(deuterium‏) via a particle accelerator, and produced plutonium. It was the first transuranium element discovered and produced in large quantities. Its discovery made possible the manufacture of nuclear weapons, in total secrecy, in U.S. laboratories. The process of producing uranium by bombarding one nucleus with another at terrifying speed inside an accelerator became the standard for the production of the synthetic elements − first the heavy elements, called transuranium, and then those that followed, the superheavy elements.

Despite these developments, in the late 1960s the periodic table had progressed only a few steps beyond the first 100 elements. In those years, chemistry textbooks declared that the table of elements included 106 elements. The 106th element was discovered by Seaborg, and it was considered only proper to name it after its discoverer ‏(Seaborgium, Sg‏). All his achievements and fame didn’t help Seaborg, though: The fact that a still-living scientist had an element named after him was unacceptable to his colleagues, who only calmed down after his death in 1999.

The turning point in the search for the island of stability came in 1969. Seaborg claimed that somewhere out there, waiting to be discovered, were stable elements − real, not theoretical − which don’t decay quickly and have existed since the dawn of time. In effect, he predicted the existence of unknown elements with a very long half-life. He claimed that stability exists in the higher numbers of entries on the periodic table, in the area of an isotope with 114 protons and 184 neutrons, among others. In other words, far beyond unstable elements.

For nuclear physicists Seaborg’s prediction meant that the table of elements had begun to progress toward a new horizon. There was a need for a groundbreaking scientist, an experimental and adventurous physicist, who would embark on this journey to the unknown to discover instability. This journey would theoretically take him beyond the “mountains” of stability ‏(elements with a smaller mass‏) to the middle of the ocean in which elements split and disintegrate constantly.

In 1971, two years after the theory of the island of stability was presented, the scientific world was in uproar when Marinov, who headed a group of European scientists, used techniques of chemical separation to achieve results supporting the possibility of a new element.

Marinov found that a minuscule amount of the new element was chemically identical to mercury − an element that, according to the table of elements, is located in the row above it, in the same column. With this discovery, which was not fully proven at the time, Marinov skipped several steps in the table: from 95 − which was the last element discovered at the time − to 112.

This jump is not negligible. It takes years, sometimes an entire career, to reach those elements. Marinov’s students and colleagues say that these were backbreaking processes of trial and error in calculations and measurements, followed by experiments, and constructed layer upon layer.

That’s why such discoveries commonly led to Nobel Prizes for their discoverers.

The main reason for the excitement in the scientific community at the discovery, which received extensive press coverage, was that Marinov claimed that the new element he had discovered was stable. For the most part the physicists had found isolated atoms, and the life of the new elements created with accelerators was so short − a split second or less − that they dissipated with a murmur and turned into other elements.

Marinov, though, claimed the life of the element he had discovered was much longer: 47 days. According to Prof. Stilian Gelberg, a nuclear physicist who was Marinov’s student and colleague, and Prof. Raymond Moreh, a nuclear physicist from Ben-Gurion University of the Negev, and formerly a senior official at the nuclear reactor in Dimona − Marinov’s discovery indirectly gave the field a tremendous push.

The theory of nuclear physics at the time was that heavy elements could be created only through a collision of heavy atoms at very high energy. And because such a collision can be created only in particle accelerators, research institutes all over the world that wanted to replicate the experiment and discover superheavy elements themselves began to acquire accelerators. Accelerators were built in the United States, Russia and Germany. At the CERN nuclear research center in Switzerland, they began designing accelerators that were larger and stronger than any other.

The Weizmann Institute of Science in Rehovot also built an accelerator at the time, which operated until about a decade ago. Marinov did a significant part of his later work there, work that shed light on the discovery of element 112.

The first accelerators were anemic and far less expensive versions of the familiar particle accelerator at CERN that more recently identified the so-called “God particle.” The originality and brilliance of Marinov’s discovery in 1971, which attracted the attention of the scientific community, actually lay in his indirect and nonstandard use of the accelerator. For example, he used the waste products of the accelerator. He also tested the secondary reaction of a heavy substance called tungsten, which is used to block the particles in the CERN accelerator. Marinov believed that because this substance had already been bombarded with high energy using proton beams, its bombarded nuclei could interact with other nuclei, and this process could lead to the creation of superheavy nuclei in the secondary reaction.

Instances of fraud

He also theorized that, based on its location on the periodic table, element 112 would have chemical properties identical to mercury ‏(No. 80‏). The idea of combining chemistry and nuclear physics − and specifically of using the principles of the chemical similarity between the elements − was not common at the time.

This out-of-the-box thinking led to the assumption that Marinov would receive a Nobel Prize. However, it was this original thinking that made it difficult for scientists to repeat and validate his experiments. Marinov’s problem, in that experiment, was that the tungsten from the accelerator was an active radioactive substance that was dangerous to use. In the 1970s, safety consciousness was not as important as in recent times. During those years, other research groups that attempted to improve on his experiment ‏(instead of replicating it precisely‏) were unable to achieve the same results as Marinov’s group. And in the 1980s nobody wanted to repeat the experiment because of the risk. So, in effect, although Marinov repeated and improved the experiment, and published his findings, the original research was abandoned, putting an end to the chance that it would be formally recognized.

The passionate interest in the field led to stiff competition among scientists and research institutes. Those who discovered new elements found mainly a few unstable elements, and it turned out that the field required a tremendous amount of work. In 1998, a group of scientists announced that it had succeeded in creating element No. 114, but the isotope differed from the one that Seaborg had referred to.

The stiff competition also gave rise to instances of fraud. The most famous of these cases involved research at the prestigious Lawrence Berkeley National Laboratory in California, which in 2001 was forced to retract its dramatic announcement of two years earlier about the discovery of elements Nos. 116 and 118. This was after it transpired that Victor Ninov, one of the most famous scientists in the field, had forged the results.

Because Marinov’s experiment was not recognized or recreated, element No. 112 did not receive recognition for many years. It was only in 2009 − despite strong opposition from Marinov, who together with other scientists appealed the decision − that an international scientific committee decided that recognition for finding No. 112 would go to a German group called GSI. This in spite of the fact that they had found a different, short-lived isotope, one with fewer neutrons and less stable than the one Marinov claimed to have discovered. The element was named copernicium ‏(Cn‏).

Despite his bitter disappointment, Marinov wasn’t discouraged. In 2009 he published in a scientific journal that he had also discovered element No. 122. This was, once again, a major jump in the periodic table. The last known element before it was No. 118 ‏(which turned out to be a forgery, as mentioned‏). Marinov and his team claimed that No. 122 exists in nature and is not synthetic, and that it was discovered in a solution of thorium, a natural radioactive metal.

“We assumed that if such an element exists in nature, it could be together with thorium in very small quantities,” Marinov explained in Haaretz at the time. “That’s why we took a solution of thorium and used a mass separator to measure the precise mass of this atom. We found that in every 10 to the power of 12 atoms of thorium, there is one atom of this element. This is the heaviest element discovered until now.” Some scientists soon began to have doubts. They claimed that the proofs of discovery were not sufficiently grounded, and that there was no possibility that such a heavy element could exist in nature.

During his years of work − and he worked to his dying day − Prof. Marinov accumulated both fans and opponents. The prolonged failure to recognize his discovery of No. 112, and the increasing doubts about his work and unconventional methods, did not dishearten him. Although other scientists were unable to repeat and validate his experiments, only a few months ago a group of scientists from Germany, Russia and Switzerland published an article saying that theoretically it was possible.

The objections of his opponents failed to undermine Marinov’s status as an internationally renowned scientist, a member of an exclusive community of nuclear physicists leading the study of superheavy elements. His supporters believe that the opposition to Marinov is partly a matter of internal politics. They say the fact that he went against the tide and questioned the discoveries by means of accelerators, preferring simpler methods ‏(such as chemical separation‏), is likely to have a negative effect on the huge budget for accelerators.

Prof. Moreh says that the importance of the discovery of superheavy elements can be understood only in the context of the strategic elements ‏(such as plutonium‏) and the development of alternative energies.

Uranium marked the undeciphered superheavy elements as having the potential for the discovery of new energy, which may some day release the world from its dependence on fossil fuels that pollute the environment and are running out, and thus enhanced their reputation. Moreh believes this is why the study of the superheavy elements became one of the most important scientific fronts at the end of the 20th century, and countries allocated huge budgets for its development. In his opinion, until the new millennium it was the most prestigious front of nuclear physics. At the start of the 21st century, the focus − and the prestige − moved from discovery of those elements to another field, particle physics, which made great advancements ‏(the Higgs boson, most famously‏). But the riddles of the superheavy elements are still awaiting a solution, and a new discovery could restore them to center stage.

Plutonium, says Prof. Gelberg, was also discovered inadvertently, and without any attempt to try to understand its use in advance. What motivates scientists to research and try to make new discoveries? Why are they seeking more elements in nature? And why does the island of stability tempt them as though it were inhabited by those mythological sirens singing to sailors on the high seas? For exactly the same reason that mankind has always been attracted to reach the moon, conquer Mount Everest or discover new countries: the very fact that they are there.

The accelerator at the Weizmann Institute. Marinov continued his work there in later years.Credit: Niv Singer
Amnon Marinov. In the 1980s scientists were afraid to repeat his groundbreaking experiments, due to their dangerous nature.
Marinov with his wife, Rachel. Long nights were spent in the laboratory at Rutherford.