The HEPD history, along with the whole PNPI history, started within the precincts of the Leningrad Physical-Technical
Institute (LPTI, *Our alma mater*) long before the official birthday of B.P.Konstantinov Petersburg Nuclear Physics Institute (PNPI).
In the middle of 50s, there were two small laboratories at LPTI whose
activities were directed towards the experimental research with particle accelerators. Those were the Cyclotron laboratory headed by Prof.
D.G.AIkhazov
(see article)
and the Roentgen and gamma rays laboratory headed by Prof. A.P.Komar. The experimental basis of
the laboratories was modest - a small cyclotron for acceleration of heavy ions with the energy up to 3 MeV per nucleon and a
100 MeV electron synchrocyclotron.
Around these facilities, there was a group of young physicists eager to work on the problems
of nuclear and high energy physics arising at that time. This small community was actively replenished with new members,
mostly graduates from the Nuclear Physics Faculty of the Leningrad Polytechnic Institute, also headed by Prof.
A.P.Komar.
Both the leaders and the students were unexperienced in investigations in the nuclear physics field, had poor technical
equipment, and, in addition, were isolated from the world community, the situation tipical for Russian institutes of that time. To some extent, this was compensated by enthusiasm
and youth of the community. On the other hand, the conditions turned out to be favourable for development of self-dependency
and inventiveness of the young physicists and engineers since it was necessary to invent practically everything - from physical
apparatus to power supplies, amplifiers, amplitude analyzers etc. And not only to invent, but to produce everything by themselves.
The next stage was the decision to organize at Gatchina a branch-institute of the LPTI, specially oriented on nuclear physics,
and the decision to construct there a proton
synchrocyclotron
(SC) )
with the record for this type of accelerators energy of
1000 MeV. The SC project was worked out at the Efremov institute with participation of LPTI engineers. The SC construction started in 1959. At the end of 1967 the trial start of the accelerator
took place, and full exploitation began from April of 1970.
In order to organize the research work at the SC, the High Energy Physics Laboratory (renamed later as High Energy Physics Division, HEPD) was created in 1963 on the basis of the
Roentgen and gamma rays laboratory (the first 15 members of this laboratory were officially transferred to HEPD on Juny 10, 1963).
A.P.Komar has become the first leader of HEPD, he directed the laboratory until 1971.
In 1971 Alexey A. Vorobyov
was elected Head of the Laboratory of High Energy Physics.
From that time, the preparations for the experiments at the synchrocyclotron began.
Various equipment was elaborated: magnetic spectrometers, scintillation hodoscopes, a mass-separator, a hydrogen bubble chamber,
a heavy-liquid diffusion chamber, a polarized proton target.
It should be mentioned that the SC proved to be a very useful accelerator, especially for nuclear studies. The 1000 MeV energy of the
protons was optimal for the nuclear structure studies (the ideal region for applying the Glauber-Sitenko theory for quantitative
description of the nuclear reactions). The small energy spread of the beam (0.3 MeV), the good duty factor (30%), the high enough
intensity (1 micro A) make this accelerator valuable even in the up-to-date nuclear studies. For example, the program of production and
investigation of the nuclei far from the nuclear stability region (IRIS project), which already has given many important results, still has very interesting continuations, especially in the study of neutron-rich nuclei.
The elementary particle physics has the feature of saturation with appearance of new accelerators of higher energy or of higher intensity.
Of course, our SC is not an exclusion from this principle. Nevertheless, during these years many important results were obtained,
especially in the field of the pion-proton and proton-proton interactions. A series of experiments on muon catalyzed nuclear
fusion reactions was successfully carried out in the muon channel of the SC. The muon beam is also effectively used for studies of
magnetic properties of various materials with the muon spin-rotation method.
The 1000 MeV proton beam also proved to be effective for neuro-surgical operations.
The proton therapeutics method
worked out at PNPI jointly with Central Research Institute of Roentgenology and Radiology
(RRCRST)
of the Ministry of Public Health is being successfully used already for more than 30 years treating the most complicated brain diseases. About 1394
patients had been treated during this period.
(see video film)
Besides the PNPI staff, physicists from
many other institutes of our country participated in the SC experiments, as well as scientists from USA, France, Germany, Denmark, Sweden, Japan, Italy.
From the very beginning of the HEPD activity, we were guided by two main principles: maximum use of our own accelerator and active
collaboration with other nuclear centres. Such combination of the "outside" and the "inside" programs proved to be quite effective.
Participation in the "outside" program keeps the laboratory constantly at the front line of the fundamental research. On the other hand,
the "inside" program, interesting by itself, nourishes the "outside" one. Just in the SC experiments, the qualified specialists were grown
up and the experimental methods were developed, which later formed the basis of our participation in the international experiments.
The starting point of the
international collaboration was in 1967, when the bilateral collaboration agreement between LPTI and the Niels
Bohr Institute (Denmark) was signed and the first joint experiments (a-spectroscopy) were carried out. Then a similar agreement was
signed with CERN in 1967. In 1973 an intensive program on nuclear structure studies was started in collaboration with the Saclay
laboratory (France). Within this program, the joint experiments were accomplished first at Gatchina and continued later at Saclay after construction of the
SATURN accelerator there.
A decisive step on our way to the world's high energy physics community were the WA9 and NA8 experiments carried out at CERN in
1978-1981. These experiments studied small angle scattering of hadrons with the recoil detector
IKAR worked out at HEPD.
After the successful experiments at CERN, the geography and the scale of our international collaborations permanently widened.
At present, HEPD participates in 16 international projects carrying out in the leading world scientific centres: CERN, FNAL (USA),
PSI (Switzerland), BNL (USA), DESY (Germany), Darmstadt (Germany), Julich (Germany), Saclay (France). And as a rule, our
participation means a serious contribution both to creation of the experimental setups and to the ideology of the experiments.
Sometimes this contribution
was a decisive one such as in the studies of hyperon rare decays at FNAL (E715 and E761 experiments), in the studies of the muon
catalyzed nuclear fusion at PSI, or in the studies of exotic nuclei scattering in Darmstadt.
Since 2016, the group A.A. Vorobyova is preparing an experiment at the MAMI accelerator in Mainz (Germany) to study small-angle electron-proton scattering by the method
of detecting recoil protons. The goal of the experiment is to accurately measure the proton radius and solve the existing “proton radius riddle” associated with the observed
difference in the radius value extracted from data with electrons and muons in experiments on electron-proton and muon-proton scattering, as well as from hydrogen
and mesoatom spectra . A joint similar experiment on the CERN muon beam is also currently under discussion.
Now we are entering the era of "industrial" physics, when the cost of an experiment at colliders goes to hundreds millions of dollars.
Effective participation in such experiments is possible only if one has a powerful technology basis able to produce the
experimental equipment on a large scale. Fortunately, such a base has been created at HEPD during the years of its activity, and now we are trying to
enforce it further. This enabled us to
participate
actively in many collider experiments: L3 (CERN), PHENIX (BNL), DO (FNAL), HERMES (DESY),
ATLAS (CERN), CMS (CERN), ALICE (CERN), LHCb (CERN).
Thus, the foundations for a stable development of HEPD in the future.
Currently, the results obtained in collider experiments form the basis of modern fundamental knowledge of particle physics and fundamental interactions.
The most significant research achievement at the Large Hadron Collider (LHC) is currently the discovery in 2012 of the Standard Model,
the CMS and ATLAS Higgs boson experiment, which is a quantum of the electroweak vacuum field.
The Department of High Energy Physics today is a mature and friendly team consisting
of 162 employees (including 13 doctors and 46 candidates of science).
Alexey A. Vorobyov.
