Alexandre Petukhov (1952

Abstract

We are saddened to announce the passing of our colleague and friend Sasha Petukhov on Monday 3 April 2023.

Graduated from the Faculty of Physics of the Leningrad (Petersburg) State University, Sasha started working at the Saint-Petersburg Institute of Nuclear Physics, Gatchina (Russia). He quickly became the leader of a group and received a prestigious State award for a young researcher. All his former colleagues well remember interesting seminars with absolutely exact scientific content, but at the same time with memorable artistic comparisons and even with small stories from his life.

Fig. 1.

Sasha enjoying a dinner at Münich when he was contributing to the development of polarised ³He spin filters within the frame of the NSF-JRA EU project [5]. © ILL – Serge Claisse.

After this brilliant start of his career, Sasha came a few times to ILL and successfully measured in 1996 the spin rotation without parity conservation in Lanthanum on D3 [3]. This was one of the very first experiments performed with a ³He spin filter developed by Francis Tasset.

Francis and one of us immediately realised that he was a brilliant physicist and a very good experimenter, and that they should try to find a position for him at ILL. Sasha came back to carry out another experiment on D3 and then obtained a physicist position shared between the Nuclear and Particle Physics and the Neutron Optics groups in 2001.

During the two following decades, with always humility and kindness, he actively participated in the development of many optical components for polarised beams at the ILL [1] but also through EU projects (Figure 1). He first designed magnetostatic cavities for maintaining the ³He polarisation: a detector including polarisation analysis installed on the diffractometer D3 and a series of boxes for transporting spin filter cells or adding a spin polariser/analyser integrating a ³He spin flipper on an instrument. These boxes were called MagicBox because the field homogeneity was slightly better than the calculated one in the first constructed box. He also helped us build a neutron RF adiabatic flipper with 99.9% efficiency down to 0.42 Å.

He then contributed a lot to the evolution of PASTIS: an insert for polarisation analysis studies on a thermal inelastic spectrometer. He helped one of us to perform the calculations and optimised the design. The latest version allows to perform polarisation analysis for any direction of the magnetic field at the sample position with a ³He neutron spin polariser, a ³He spin flipper and a ³He wide-angle neutron spin analyser [4]. An extended version for time-of-flight spectrometers is also in construction. Last but not least, he co-proposed a new concept of broad-band solid-state polariser [7] and participated actively to the construction of the first one for PF1B. Today, following Sasha’s design, a new analyser is being built for the reflectometer D17.

In parallel, he contributed significantly to the discovery of quantum gravitational states of the neutron [6], to precision measurements of the weak interaction in neutron decay and neutron-nucleus interaction [8], to the discovery of asymmetries in the emission of ternary particles in nuclear fission and to the development of very sensitive diffraction enhanced particle-physics experiments [2]. The measurement of the neutron electric dipole moment via spin rotation in a non-centrosymmetric crystal with the Cryopad was a great venture we cannot forget.

Sasha was both creative and pragmatic. He was also shy, but always smiling. He was a hard worker, used to present seminars in a great artistic style and solved mathematical problems in the traffic jams between Voreppe and ILL. When Sasha was testing a new device, he often said: “I am satisfied with 99.9% polarisation. I can do better. But we have to leave some margin for future generations”.

We were very fortunate to have met and worked with him. It is with great sorrow that we say goodbye to a friend who will be greatly missed. He is survived by his wife Katia and their children Anastasia and Kouzma.

David Jullien, Eddy Lelièvre-Berna and Valery Nesvizhevsky

Institut Laue-Langevin, Grenoble (France)

References

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Alexandre Petukhov (1952–2023)

Abstract

References