dc.description.abstract | Dragoljub K. Jovanović, a world-renowned scientist from Serbia, a
university professor and a corresponding member of the Serbian Academy of
Sciences and Arts, was born on March 7th, 1891 in Paraćin. His father Kosta
Jovanović was a craft sman and his mother Persa, née Dimitrijević, was a
housewife. He attended primary school in Paraćin, secondary in Jagodina,
Kragujevac and Belgrade, where he graduated.
Aft er the graduation in 1910, D. Jovanović enrolled at the Faculty of
Philosophy in Belgrade, the department of chemistry, headed by professor
Sima Lozanić. His fi nal year of studies was interrupted by the Great War. In
November 1915, as a volunteer at an archive, he was interned in the
concentration camp Aschach in Austria where he stayed until the end of the
war in 1918. Upon release from war captivity, he completed his chemical
studies at the beginning of 1919 and began working as a secondary school
chemistry teacher, and then as an assistant at the Faculty of Philosophy in
Belgrade. Th e scholarship from Belgrade University enabled him to travel to
France, in September 1920. In Paris, he continued his education at the then
most prominent institute for research of radium and naturally occurring
radioactive elements. Th e topic of his doctoral dissertation was the isolation
and testing of the secondary “outputs” within the spectrum of chemical
elements of the radioactive thorium family, know at the time as mesothorium-2.
At the same time, he also published his most important research papers in the
world’s leading scientifi c journals which earned him a huge international
reputation. He defended his doctoral thesis on June 3rd, 1925, before a
prominent committee consisting of the double Nobel Prize winner Marie
Curie, the following year’s Nobel Prize winner for physics Jean Baptiste Perrin,
and André-Louis Debierne, a famous chemist of his time, the discoverer of the
element actinium, and Marie Curie’s assistant. At the request of Marie Curie,
he continued his research in Paris until the end of September 1928. During his
stay in Paris, he became a member of the French Physical Society.
Before fi nally returning from Paris in 1927, he was appointed as an
associate professor of physics at the School of Medicine in Belgrade and
director of the Institute of Radiology and Physics at the same school. He
assumed his assigned roles upon his return from Paris in 1928.
Between the two world wars, he used the Institute of Radiology and
Physics as the base for his teaching and scientifi c activities. For a few years aft er
returning to Serbia, he made basic provisions for the Institute. He personally
made apparatuses, modelling them on the equipment form the Institute for Radium Research or using his original ideas. Th e preparatory period enabled
him to continue research work albeit under much more limiting conditions
than those in Paris. Th e focus of his research, in which he included numerous
assistants – teachers from the School of Medicine – now was on the impact of
radioactivity on living organisms for medical purposes. In 1932, she started
teaching physics to medical students when the subject was transferred from the
Faculty of Philosophy at Captain Miša’s Mansion to the School of Medicine. He
was promoted to the rank of full professor in 1939. Th e Second World War led
to an almost complete suspension of university education, and aft er initial
disagreements with the occupying authorities, D. Jovanović found refuge in
Sokobanja where he remained during the war period. Aft er the liberation, on
June 26th, 1945, he went back to teaching physics at the School of Medicine but
soon, on December 25th, 1945 he was appointed professor of physics at the
Faculty of Philosophy (nowadays the Faculty of Natural Sciences) at which, due
to staff shortages, he also taught physics.
He met his wife Mirjana Trbojević (1902–1982), the daughter of the
Belgrade county doctor and the director of the City Polyclinic, at the beginning
of January 1927 and they were married on February 25th, 1929. Th ey had two
sons, born in 1930 and 1933 respectively, both of whom acquired higher
education and accomplished successful scientifi c careers in the USA where
they remained living. Th eir children also have university degrees.
In 1948, Jovanović was elected a corresponding member of the Serbian
Academy of Sciences at the suggestion of the then corresponding member
Pavle Savić, who continued his radiochemical research, with the explanation
that “he published a series of high-quality works on radioactivity which have the
enduring scientifi c value”. He retired in 1961, as professor of the Faculty of
Natural Sciences, but continued working part-time at the Physics Institute of
the School of Medicine. He was director of the Institute until 1964, and
professor of physics at the School of Medicine until 1967. He passed away on
February 17th, 1970 and was buried at the New Cemetery in Belgrade.
Th e main scientifi c contributions of the D. Jovanović is his research in
the fi eld of natural radioactivity. While working at the Radium Institute in
Paris, he published about twenty articles in the world’s leading scientifi c
journals, mostly in the Comptes rendus de l’Académie des Sciences. Th is included
Jovanović’s feedback on the study of the chemical properties of the elements
from the radioactive thorium family. In his doctoral thesis, he proposed an
original method of isolating the “mesothorium-2” (later identifi ed as the
isotope of actinium 228Ac) in pure form and high concentration, within a fairly
short period of time in order to examine chemical properties, its half-life time
and the radiation emission energy of this short-lived element. Th e main
conclusion was that, due to its chemical properties, mesothorium-2 belongs in group 3b of the periodic table. Jovanovic discovered new lines in the β-ray
spectrum of mesothorium-2 and also that some of the β-rays have so much
energy that they can move at a speed close to the speed of light. Th ose results
have sparked a great deal of interest and, as such, have been used by many other
researchers of β-ray spectroscopy. He also gave an improved method for
determining etalon of radiation. His experience in the chemistry of radioactive
elements was used to isolate the next member of the thorium family,
“radiothorium” (subsequently identifi ed as the isotope of thorium228Th ), which
he later used in biological research, aft er returning to Serbia. Concurrently with
the classic method for determining the absorption coeffi cient of radioactive
radiation in various materials, based on the ionization current, Jovanović
introduced a new, calorimetric method, which additionally contributed to the
clarifi cation of the energy levels of atomic nuclei and the extent of energy
changes in nuclear reactions of naturally occurring radioactive elements.
Summarizing the results of D. Jovanović’s most laborious work, which
matched the highest level of the research and experimental techniques at the
time, it ought to be pointed out that he worked in the years when classic
research methods regarding methodology and the issues of naturally occurring
radioactive elements were coming to their end.
Some thirty years had passed since radioactivity was discovered and
followed by very intense research in this relatively narrow domain of naturally
occurring radioactive elements.
Nevertheless, lots of issues remained to be clarifi ed so Jovanović took it
upon himself to search the unresolved reservoirs of scientifi c knowledge and
amongst them the uncertainty regarding the origin of beta radiation which
baffl ed scientists of his time. It ought to be remembered that those were the
times when, considering the existing level of understanding of radiation, raised
were the questions which later led to breakthroughs in areas regarding the
structure of the atomic nucleus. Answers to those questions were accessible
through the equipment, considered to be fi rst-rate at the time, however
inadequate for dealing with newly generated needs. It took a lot of time, eff ort
and imagination to obtain reliable and scientifi cally based answers which
makes them even more important and valuable. All works of D. Jovanović
published at that time were included in the Handbuch der Experimental-Psychic
Wien-Harms, T. XV, Radioaktivität, edited by K. W. F. Kohlrausch, which is the
best proof of high reputation that he had achieved.
New big advancements in radiochemistry occurred aft er Jovanović
returned to Yugoslavia. He found scarce resource conditions, under which the
progress of physics in the world was quite diffi cult to follow, but he did his best
under the circumstances. While working at the School of Medicine, the world
of radiochemistry witnessed the discovery of neutron from the reaction between beryllium and alpha particles, and the discovery of artificial
radioactivity produced by neutron bombardment. Th is period was marked by
the acquisition, concentration and separation of artificially created
radioisotopes, caused by neutron bombardment, and the development of
applied radiochemistry. At the Institute for Radium, at that time, particularly
prominent researchers were Frederik Joliot-Curie and his wife Irène Joliot-
Curie, whose work, with the participation of Jovanović’s assistant and his
successor in radiochemical research, Pavle Savić, was an introduction to the
discovery of nuclear fi ssion.
His experience from the Institute of Radium helped Jovanović, upon his
return to Belgrade, continue to follow the progress of physics in the world,
publish his scientifi c papers, and open new research areas, despite his busy
teaching engagements and the working environment which he had to provide
for mostly personally. It is necessary to mention his pioneering work, conducted
in collaboration with his associated from the School of Medicine, on the impact
of radiation on living organisms; Jovanović prepared radioactive sources with
measured activities while, aft erwards, his medical associates studied changes
that occurred in tissues following their exposure to radiation for a certain
period of time. Th ese works were of great importance for the development of
the then little- known methodology of use of radioactive preparations in the
treatment of malignant diseases, practised at the School of Medicine. Jovanović
also made a signifi cant contribution to the study of natural radioactivity in
groundwater, testing waters in spa hospitals throughout Yugoslavia in situ, with
a homemade terrestrial radiation detector. In some water sources in Sokobanja
Spa, Jovanović detected high levels of radon concentration, the second largest
in Europe, which contributed greatly to the popularity of spa and the
development of spa tourism and earned him great admiration and respect of
the municipal leaders and the local population.
While working at the Institute of Physics of the School of Medicine, he
also published papers on intramolecular interactions of alpha radiation and
protons in metal hydride, scintillation in crystal hydrates during hydration, the
Hall eff ect in thin metal foils, etc. As an enthusiast and a science lover, following
the progress of physics in the world in which he could not directly participate
at the time, he wrote lots of publications of a scientifi cally popular and
informative character.
Aft er the Second World War, he founded the Board of the Society of
Mathematicians, Physicists and Astronomers of the SR of Serbia and was its
long-term member. Th e society published Vesnik, one of the rare periodicals
which published scientifi c papers of young authors at the time. As a researcher
and a pedagogue focused on medical applications of physics, he initiated
seminars in medical physics, held every two years and attended by representatives from physical institutes of medical, veterinary, pharmaceutical
and dental faculties from all over Yugoslavia. At the 1966 Sarajevo Seminar, he
was elected president for life of the Coordinating Committee of Medical
Physicists.
Teaching contributions of D. Jovanović in Serbia are immeasurable.
According to the data published in the Archives of the School of Medicine 1920–
2010, since 1937, when fi rst Belgrade doctors graduated, until 1968 when D.
Jovanović stopped teaching physics, 10.729 students graduated from the School
of Medicine, which means that as many students passed the exam before him.
Students from related faculties – pharmacy, veterinary and dentistry – should
also be added to the number, as well as students of physics between 1945 and
1961. The fact that many failed the first time ought to be taken into
consideration, too. As a physics teacher, he is credited with writing textbooks;
10 were published before the Second World War and 8 aft er the war. In the
post-war period they, being rare few textbooks on the subject written in the
Serbian language, played the key role in the education of generations of
physicists at the parent faculty and non-parent ones. Th e 1967 Serbian
translation of the book Th e Character of Physical Law by the Nobel Prize winner
Feynman should also be mentioned.
His teaching enthusiasm, particular temperament and wit, made him
very popular with students, which was obvious at each encounter with them.
His scientifi c and educational achievements were honoured, and he
received many public awards for them: the Order of St. Sava, 3rd Class (before
the Second World War), the 7th of July Award for lifetime achievements in 1961,
the Order of the Republic with the Silver Wreath in 1965, the Marie Curie
Medallion in 1967 on the 100th anniversary of her birth. Posthumously he was
awarded the Charter of the Society of Mathematicians, Physicists and
Astronomers of Serbia in 1978. In 1970, the Institute of Physics of the School
of Medicine was named aft er him. Th e towns of Paraćin and Sokobanja each
got one street named aft er him, too. | sr |