75 years of the Dzhelepov Laboratory of Nuclear Problems

The first Dubna accelerator

The Dzhelepov Laboratory of Nuclear Problems is the very first nuclear centre that originated in the place that is currently known to the whole world as Dubna. The fate of this centre was determined on 18 August, 1946, when on the initiative of Academician I.V.Kurchatov, the government of the USSR decided to construct the first large accelerator in the country - a synchrocyclotron aimed at carrying out fundamental research in the field of nuclear physics.

On 14 December, on the day of the 75th anniversary of the launch of the first Dubna accelerator, the employees of the anniversary laboratory, their colleagues from other laboratories and research centres will gather at the Cultural Centre "Mir" for a ceremonial meeting.
In honor of this significant date, we are publishing the already historical memoirs written for our newspaper by Mikhail MESHCHERYAKOV and Venedikt DZHELEPOV, both veterans of the Laboratory.

FROM THE RECOLLECTIONS OF M.G.Meshcheryakov it follows that from the second half of 1944, in the circles of Soviet scientists engaged in research in the field of nuclear physics, a discussion on the possibility of constructing particle accelerators in our country started. Several meetings on this issue were held chaired by Academician I.V.Kurchatov in the Laboratory No.2 of the USSR Academy of Sciences organized by him that later became the Institute of Atomic Energy of the USSR Academy of Sciences (today, the RRC "Kurchatov Institute"). A.I.Alikhanov, V.I.Veksler, K.D.Sinelnikov, I.E.Tamm participated in the meetings, B.A.Nikitin, L.I.Rusinov, D.V.Efremov and M.G.Meshcheryakov that was then in charge of the cyclotron at the Radium Institute of the USSR Academy of Sciences, were invited from Leningrad. As a result of the discussions, it was decided that in order to ensure promising areas of fundamental physical research, it was necessary to construct in the USSR two accelerators with record energies for that time - a proton accelerator with 450-500 MeV with a subsequent increase in energy to 650-700 MeV and an electron accelerator with an energy of at least 250 MeV.

This point of view of physicists formed the basis of a fateful decision for Dubna by the government of the USSR (1946), on the basis of which a swampy area of forest on the right bank of the upper Volga near the settlement of Bolshaya Volga was allocated from the State Fund for the construction of an accelerator and a scientific centre.

Almost two years passed and in 1948, this centre was established. For reasons of secrecy and proximity to the Moscow Sea, it was named the Hydrotechnical Laboratory (HTL) of the Academy of Sciences of the USSR. In fact, it was a branch of Laboratory No.2 that was headed in Moscow by Igor Kurchatov.

Mikhail Meshcheryakov was appointed Director of HTL and Scientific Leader of the accelerator developments and Venedikt Dzhelepov was appointed his Deputy. The design of the accelerator magnet and electrical equipment was carried out under the supervision of Professor D.V.Efremov, an employee of the special design bureau of the Leningrad plant "Elektrosila". Development of the high-frequency system of the accelerator and the powerful high-frequency generator was carried out under the supervision of Corresponding Member of the USSR Academy of Sciences A.L.Mintz.

At the insistence of I.V.Kurchatov, development of the synchrocyclotron was started in Laboratory No.2. An accelerator department was organized there (headed by M.G.Meshcheryakov) whose mission was to design a current prototype of the future synchrocyclotron in the shortest possible time and to test the autophasing principle on it. In December 1947, such a prototype was already in operation and by mid-1948, all the essential features of the synchrocyclotron technique of accelerating protons had been studied on it. The department's employees N.P.Bogachev, E.L.Grigoriev, V.S.Katyshev, A.A.Reut and A.A.Kropin took an active part in this research. From the very beginning, it was assumed that after completing the investigations of the new accelerator prototype, this department would move to the synchrocyclotron construction site and become the core of the future scientific centre. In 1948-1949, N.I.Frolov, Yu.M.Kazarinov, A.G.Vakhromeev, B.I.Zamolodchikov, B.M.Golovin, as well as then-graduate students V.P.Dmitrievsky, A.E.Ignatenko, G.I.Selivanov, L.M.Soroko joined the synchrocyclotron laboratory. This small group laid the foundation for the first scientific staff of Dubna.

The synchrocyclotron was launched in record time - 14 December, 1949. It was a historic event - the first accelerator in the USSR and the first in Dubna started operating. At present, this day is considered the birthday of the Laboratory of Nuclear Problems.

At first, deuterons were accelerated to an energy of 280 MeV, alpha particles - to 250 MeV and soon protons - to 480 MeV on the synchrocyclotron. Until 1953, the synchrocyclotron was the largest accelerator in the world.

In 1953, after having increased the diameter of the synchrocyclotron magnet poles to six meters and substantially having reconstructed its high-frequency system, a proton version of the accelerator was put into operation with a proton energy of 680 MeV and a proton beam intensity of about 0.3 µA. At the same time, V.P.Dmitrievsky implemented a new, regenerative technique of extracting particles from the accelerator that allowed him to increase the intensity of the extracted beam by tens of times.

In 1958-1962, under the supervision of B.I.Zamolodchikov research was carried out at the DLNP synchrocyclotron that resulted in a tenfold increase in the intensity of the accelerated internal proton beam of the synchrocyclotron. The beam current at the final radius was 2.4 µA. As a result of the above-mentioned research, the DLNP synchrocyclotron began to operate for a physical experiment for 6-6.5 thousand hours per year. An experimental pavilion was designed, separated from the accelerator by a four-meter wall and covered with a thick one-and-a-half-meter ceiling made of heavy concrete. 14 beams of protons, pions and neutrons of various energies were brought into this hall using a deflecting magnet and collimators. Thanks to the occurrence of beams of polarized protons, positively and negatively charged pions, neutrons and especially beams of muons obtained from the decay of pions in a 15-meter hard-focusing channel of magnetic lenses (headed by B.I.Zamolodchikov and A.A.Kropin), the possibilities for implementing various physical experiments on the synchrocyclotron were significantly expanded. It opened up new horizons for fundamental research in nuclear physics not only for physicists from Dubna, but also for scientists from Moscow, Leningrad, Kharkov and other cities.

Indeed, many pioneering investigations were carried out at the synchrocyclotron under the supervision of M.G.Meshcheryakov and V.P.Dzhelepov that laid the foundations of advanced high-energy elementary particle physics. The leading Soviet scientists took part in the discussion and development of the research programme at this accelerator: I.V.Kurchatov, Ya.B.Zeldovich, I.E.Tamm, N.N.Semenov, L.D.Landau, A.B.Migdal, I.Ya.Pomeranchuk, A.I.Alikhanov, I.I.Gurevich, G.I.Budker, V.I.Goldansky and others.

In 1953, HTL obtained the status of an independent academic institution - the Institute of Nuclear Problems of the USSR Academy of Sciences. In 1956, INP having become a member of JINR was known as the Laboratory of Nuclear Problems. V.P.Dzhelepov was elected Director and he headed DLNP dutifully until 1988. The DLNP synchrocyclotron became the first operating basic facility of JINR.

Employees of the Sector of Professor M.G.Meshcheryakov of DLNP (in the first row in the centre). 1959

ACCORDING TO V.P.Dzhelepov, heroic efforts of the developers of the synchrocyclotron, its commissioning and the beginning of research on it marked the birth of a new field of nuclear physics in our country - high-energy physics. A large group of engineers and scientists of the Laboratory were twice awarded the Stalin Prize, as well as Orders of the Soviet Union for development of the accelerator and implementation of significant physical research.

Thanks to the synchrocyclotron, the Laboratory of Nuclear Problems became the founder of a number of scientific areas at JINR. These are investigations on mu-catalysis, the dynamics of elementary particle and atomic nucleus transformations, rare decays of pions and kaons, the physics of neutrinos and electroweak interactions, nuclear spectroscopy, the production of polarized proton and deuterium targets with a high degree of polarization. The Laboratory of Nuclear Problems was the first in the USSR to use high-energy protons (and other charged particles) for the therapy of malignant tumors. It was the first to produce beams of protons and neutrons with energies of hundreds of MeV for biophysical and radiobiological research in space medicine. The possibility of using high-current isochronous cyclotrons to control subcritical assemblies and to develop on this basis safe nuclear power engineering and facilities for the transmutation of nuclear waste has been considered. The relevance of these investigations only increases with time.

The synchrocyclotron acquired a new lease of life in 1967 when a project was proposed to upgrade it into a phasotron with a spiral magnetic field structure for proton energy of 680 MeV (project "F"). The implementation of project "F" was supervised by V.P.Dzhelepov and V.P.Dmitrievsky and at the final stage - by L.M.Onishchenko. During the reconstruction of the machine, almost all the basic components and systems of the synchrocyclotron were replaced. Of the old accelerator equipment, only the yoke of the main magnet and high-vacuum units remained. Given the enormous dimensions of the basic components (the magnet pole is 6 meters), it was necessary to manufacture complex multi-ton components with jewelry precision (fractions of a millimeter) that required unique mechanical machines, available only in single versions at specialized enterprises in the country. A number of both mechanical and technological issues were also met during the manufacture of two frequency variators that are practically high-speed turbines. The construction of the entire complex of unique equipment for the facility "F" took a total of more than 12 years.

The physical launch of the phasotron was carried out in summer, 1984. Thus, the Dubna synchrocyclotron was reconstructed into a new accelerator - a phasotron with a spiral variation of the magnetic field, increasing with the increase of radius. Protons in it were accelerated to an energy of 680 MeV. At the same time, the maximum current of the internal beam was increased by 4 times, the intensity of the extracted beam - by 20 times. It significantly expanded the range of research at the Laboratory of Nuclear Problems. To successfully carry out this research, additional pavilions were constructed - a low-background laboratory, a pavilion for research on nuclear spectroscopy, a six-cabin complex for the treatment of oncological diseases and a number of others.

The commissioning of the Dubna synchrocyclotron, capable of accelerating particles to register energies at that time and afterwards, its modification and the implementation of unique physical investigations - all this laid a solid foundation for the research programme of the Laboratory of Nuclear Problems of JINR. The achieved and internationally recognized successes of the DLNP employees, the vast accumulated experience - all this inextricably relates to the first Dubna accelerator - the synchrocyclotron.

DLNP SCIENTISTS ARE THE AUTHORS OF 13 scientific discoveries registered in the State Register of the Soviet Union. The results of scientific research of the Laboratory have been awarded more than 100 times by the Joint Institute for Nuclear Research. More than 105 doctoral and more than 360 candidate theses have been defended at DLNP by employees from all JINR Member States. Many of the Laboratory's graduates currently head large staffs of scientists at various institutes and laboratories in Russia and other JINR Member States.

The above-mentioned research areas of the Laboratory of Nuclear Problems, originating from the first Dubna synchrocyclotron, have not only not lost their significance but have become even more in demand. These areas develop all the time, acquiring even greater relevance and determining the current face of the Dzhelepov Laboratory of Nuclear Problems.

In accordance with the long-term development plan of JINR (the "road map"), progress in the field of modern nuclear physics and elementary particle physics can be divided into interrelated areas - research based on increasing accelerator energy, research based on increasing accelerator intensities, increasing the accuracy of non-accelerator research and research in particle astrophysics.

Based on these general areas, DLNP JINR focuses on four main areas. These are investigations of neutrino physics and the research of rare processes in order to verify and to refine modern concepts in the field of particle physics. This is participation in the development of Russian facilities and research on them. In particular, DLNP is going to develop a high-precision compact electromagnetic calorimeter for the NICA/MPD detector. Developments on other detectors are also underway. These are prestigious international partner research programmes at unique accelerator complexes, such as the Tevatron (FNAL), LHC (CERN), FAIR (GSI), ILC and others. And finally, this is current relevant research, in particular, proton therapy and development of a medical accelerator complex.

As it is known, current neutrino physics opens up prospects for studying issues that are essential for understanding such natural phenomena as the origin and mass of neutrinos, hierarchy and mixing, combined parity violation, sources of cosmic radiation, others. Studying the properties of these particles and processes involving them is a traditional area of JINR, laid down in the Bruno Pontecorvo Laboratory of Nuclear Problems. Extensive research in the field of neutrino physics is a relevant part of the Laboratory's current activities and its basic distinguishing feature.

The investigation of double beta decay processes is one of the top priorities of DLNP. This research is carried out within the framework of the NEMO, GERDA-MAJORANA and Super-NEMO projects. Record limits on the effective mass of neutrinos m_ν<0,04-0,11 eV will be achieved. Observations of neutrino oscillations indicate that this particle has mass and lepton number is not conserved. DLNP takes part in the search for neutrino oscillations by registering tau neutrinos in a muon neutrino beam (the OPERA project), as well as in a project to study unknown neutrino mixing parameters - the Daya Bay reactor neutrino experiment. The GEMMA spectrometer (installed at the Kalinin NPP) is used to carry out experiments to measure the neutrino magnetic moment. The unique parameters of this facility allow us to expect record sensitivity.

The precision research of rare decays of muons and pions, traditional for DLNP, will allow testing the Standard Model and its universality. Thus, an experiment to search for the decay of a muon into an electron and a photon, in which the law of conservation of lepton number is violated will be carried out in DLNP. Measurements of combined parity (CP) violation currently impose significant restrictions on the description of CP violation within the Standard Model. Future research plans of DLNP in this area are related to experiments in Protvino and CERN. DLNP takes part in the investigation of ultra-high-energy cosmic rays, experiments on the direct and indirect search for the so-called dark matter. Direct observation of dark matter particles in a ground-based detector would be an event of great significance for particle physics and cosmology.

DESIGNING AND DEVELOPING current multi-purpose detector systems, as well as their operation is a traditional area of activity of the Laboratory, dating back to the first physical facilities that operated at the synchrocyclotron. At present, one of the relevant plans of DLNP is participation in the development of such Russian facilities as the multifunctional detector MPD for implementing research at the NICA accelerator complex. DLNP employees work on the development of a compact electromagnetic calorimeter for the NICA/MPD detector. Development of the general project, design, photodetectors and electronics has already started.

Within the framework of a broad international partnership, DLNP takes part in long-term worldwide programmes in various scientific centres. Thus, in experiments with the CDF and D0 detectors at the Tevatron colliding beam accelerator (FNAL), DLNP employees have already obtained physical results of fundamental significance. The experience gained in these experiments is extremely important for participation in experiments at the Large Hadron Collider (LHC). DLNP's main expectations in the field of fundamental high energy concern the ATLAS experiment at the LHC (CERN) that is aimed at precision measurement of proton interaction products at a record energy of 14 TeV.

Currently, DLNP scientists are actively involved in development of an accelerator and detectors for the FAIR project in Darmstadt, an international accelerator complex of a new generation. The immediate plans include development of a muon system for the PANDA experiment. DLNP employees take part in experiments to test antiproton polarization techniques that is the basis for developing a project to carry out research in the field of spin physics at FAIR.

Research on an accelerator and detectors is carried out in DLNP within the framework of the International Linear Collider (ILC) project that will allow carrying out and supplementing the unique research started at the LHC.

Proton therapy and further development of hadron therapy techniques and facilities, development and construction of detectors and instruments for both nanostructure and research of new materials, as well as for security systems and medical equipment are traditionally significant areas of applied research for DLNP. For example, the project "Treatment of tumors using proton beams" is implemented in three stages. The first stage is development of conformal tumor treatment at the DLNP phasotron, personnel training and certification of the proton therapy technique for use in the Russian Federation. The second stage is the design and construction of specialized accelerators for proton and ion therapy that is currently implemented jointly with the Belgian company IBA. The third stage is scheduled to transfer proton therapy technologies and equipment to medical centres under construction in Russia that will be able to have a throughput of up to 1000 patients per year each.

With reporting by the weekly "Dubna", No. 50 of 18 December, 2009