Konstantin Petrzhak

Konstantin Antonovich Petrzhak (alternatively Pietrzak; Константи́н Анто́нович Пе́тржак, ; 4 September 1907– 10 October 1998), k.N, was a Soviet and Russian physicist of Polish origin, and a professor of physics at the Saint Petersburg State University.

Konstantin Petrzhak was born in Łuków, Poland in Russian Empire, on 4 September 1907.

Other Russian documented sources noted his birthplace in Dombrovo in Kaliningrad with same birth date.

Konstantin Petrzhak married Galina Ivanovna Mitrofanova (b. 1918), also a radiochemist.

There is very little information known about his early life and started working at the age of 12 (in 1919) as a painter at a glass-making factory in Malaya Vishera in Russia to provide income to his poor family.

In 1928, Petrzhak was sent to attend the trade school, Rabfak, that was affiliated with the Leningrad State University, where he studied painting which remained his lifelong passion.

Later, he used his talent in painting when he covered the plates of ionization chamber with uranium which later led to discovery of spontaneous fission.

He also learned to play the music and was an amateur violinist and guitar player.

Peterzhak went to the Leningrad State University worked with the research group at the university in 1931.

In 1934, Petrzhak found the work at the Khlopin Radium Institute located in the State University in Saint Petersburg (First Radium Institute), which was directed by Igor Kurchatov, a nuclear physicist.

Petrzhak remained associated with the Khlopin Radium Institute for the remainder of his life, and worked under the direction of Vitaly Khlopin and Igor Kurchatov where he eventually defended his thesis at the Ioffe Institute to obtain the Candidate of Sciences, titled: "Study of thorium and samarium radioactivity."

In November 1936, Pertzhak eventually earned his diploma certified under Igor Kurchatov from the Leningrad State University.

In 1939, Kurchatov was assigned research under Georgy Flyorov and Petrzhak to conduct investigation on uranium fission induced by neutrons of different energy levels, following Yakov Frenkel's theory of fission.

Earlier, Flyorov and his assistant Tatiana Nikitinskaya had already made an ionization chamber to detect heavy particles, and were directed to increase the sensitivity of the ionization chamber.

The team created a multilayer ionization chamber to detect decay products originating from the fission of uranium.

The ionization chamber utilized electrodes with a total surface area of about 1000 cm2.

The chamber's 15 plates were covered with uranium oxide with approximate surface density of 10–20 mg/cm2.

The detector compared particle activity to a background level control.

When the source of neutrons was taken away, the detector still found particles.

The team made three ionization chambers to prove that the effect was not an error, including a more sensitive chamber with a surface area of 6000 cm2.

Despite the instrument's high sensitivity, cosmic rays were still a possible source of particle activity.

The team moved to an underground lab in the Dinamo station of Moscow Metro (about 50 m below the earth surface) in an attempt to rule out the effects of cosmic rays.

Receiving credit with Georgy Flyorov, a physicist, for the discovery of spontaneous fission of uranium in 1940, Petrzhak's career in physics was then spent mostly in the former Soviet program of nuclear weapons.

In May 1940, they were confident that they had discovered spontaneous fission.

The certificate of discovery stated, "the new type of radioactivity with mother nucleus decays into two nuclei, that have kinetic energy of about 160 MeV".

Later, the discovery of spontaneous fission was confirmed by Otto Robert Frisch.

In 1940, Petrzhak was recommended for the top team in the Soviet atomic bomb project.

He is rumored to have participated in the said project.

When the Soviet Union entered World War II, Petrzhak was eligible to serve in the Red Army.

Winning the Stalin Prize would exempt him from front line service.

In the early 1940s, the Academy of Sciences of the Soviet Union nominated him for the award, which he did not receive.

Sources disagree on whether Petrzhak volunteered, or was drafted into the army.

Petrzhak served in the military intelligence company of a CIWS regiment first as a junior lieutenant, and later as a senior lieutenant.

On 28 June 1941, he participated in the battle of Karelian Isthmus.

Later, he fought in Volkhov Front.

In March 1942 he was ordered to leave the army and join evacuated Radium Institute scientists in Kazan.

In 1943, Petrzhak studied neutron induced fission of uranium under the supervision of professor Piotr Lukirski.

In 1944, Petrzhak proposed a method to determine the number of neutrons present during a nuclear reaction, based on the number of protons.

He also participated in the development of technology to extract plutonium from irradiated uranium blocks.

Jointly with M. Yakunin, Petrzhak developed methods for the radiochemical determination of plutonium, and found the mean free path of Pu-239 alpha particles.