In the wake of the departed

Nikolay Kuchinsky 14.11.1946 - 26.02.2025

On 26 February, a senior researcher at the Department of Multiple Hadronic Processes of DLNP Nikolay Kuchinsky passed away unexpectedly.

After having graduated from the Physics Department of the Belarusian State University in 1972, N.A.Kuchinsky was seconded to the Laboratory of Nuclear Problems and since 1975, he has become a full-time employee of this Laboratory. Since 1992, he has been Head of Sector No.1 of the Department of Intermediate Energy Physics of DLNP, in 2003, he was promoted to the rank of senior researcher and since 2019, he has been a senior researcher of Sector No.4 of the Department of Multiple Hadron Processes.

From the first days of his work at DLNP, N.A.Kuchinsky was engaged in the investigation of rare and search for forbidden decays of muons and pions. He was one of the developers of the ARES spectrometer, on which world-leading results were obtained. He developed a unique system for reading information from anode wires of cylindrical proportional chambers. It was the basis of his thesis for the degree of Candidate of Physical and Mathematical Sciences that he successfully defended in 1991.

Since 1990, N.A.Kuchinsky has participated in the research on the muonium-antimuonium oscillations carried out at PSI (Switzerland) that resulted in a four-order reduction of the upper limit of the probability of this forbidden process.

The work with the participation of N.A.Kuchinsky on the development of the PIBETA spectrometer at PSI was awarded the first JINR Prize for 2005. On this spectrometer that has no analogues in the world, unique statistics on pion beta-decay, pion and muon radiative decays that exceeds by more than an order of magnitude all previously accumulated world statistics, was obtained. All this allowed to improve the estimate of the probability of pion beta decay by a factor of six. The obtained result is in good agreement with the predictions of the Standard Model.

Simultaneously with the pion beta-decay dataset, the registration of pion radiative decay events was also carried out. These data allowed us to obtain new improved values of the values of the vector and axial-vector pion form factors F_V and F_А.

For a long time, N.A.Kuchinsky was Head of the PEN-MEG Project of the JINR Topical Plan that included the precision measurement of the π→еν decay and the search for the µ→еγ decay on the accelerator at PSI. For the PEN project, with his participation, a unique beam time-projection chamber (TPC) was developed that improved the quality of typed statistics and consequently, the future result. Nikolay Kuchinsky carried out extensive methodological work to significantly improve the accuracy and loading characteristics of straw tubes.

In addition to these main activities, Nikolay Kuchinsky was actively involved in the development of the D0 muon systems on FNAL and COMPASS at CERN and participated in the g-2 project to measure the anomalous muon magnetic moment at FNAL. Several projects in which N.A.Kuchinsky was the leader or executor were supported by RFBR and BRFFR grants.

N.A.Kuchinsky is the author of more than 180 scientific publications, he was awarded the Silver Medal of the All-Union Exhibition of National Economy, the badge "Veteran of nuclear industry and power engineering" and he was awarded the title "Honorary JINR employee".

We knew Nikolay Kuchinsky as a well-known scientist that made a significant contribution to the development of world science. His departure is a great loss for the Laboratory of Nuclear Problems and the whole JINR, for friends and colleagues in many scientific centres. There is no substitute for Nikolay Kuchinsky in the enormous creative and organizational activity that he carried out and in the gigantic responsibility that he bore on his shoulders.

We express our deepest condolences to his family and relatives.

DLNP Directorate, friends and colleagues