Few-Nucleon Systems: Notes about the Status and Results of Investigations

Radiation technologies have found wide application in power engineering, medicine, biology and other areas of human activities. However, theoretical calculations of nuclear reactions and, correspondingly, the interpretation of experimental results appear model-dependent. The model-independent calculation of the nuclear reaction must take into account the structure of the nuclear ground state, the final-state nucleon interaction and the contribution of meson exchange currents. These calculations can be carried out only with due regard for realistic NN and 3N forces between nucleons and also, with the use of exact methods of solving the many-body problem. In this technique it is expedient to conduct investigations of nuclear reactions as from few-nucleon systems in the energy area of the particles below the meson-producing threshold. The tensor part of NN interaction and 3NF,s generate the lightest nuclei states with nonzero orbital momenta of nucleons. These states in the lightest nuclei is conditioned the properties of inter-nucleonic forces, and therefore, similar effects should be observed unexceptionally in all nuclei. The review papers are generally devoted to three-nucleon systems. In this paper primary attention is given to the investigation of the $^4$He nucleus

Design of deeply cooled ultra-low dissipation amplifier and measuring cell for quantum measurements with a microwave single-photon counter

The requirements and details of designing a measuring cell and low-back-action deeply-cooled amplifier for quantum measurements at 10 mK are discussed. This equipment is a part of a microwave single-photon counter based on a superconducting flux qubit. The high electron mobility transistors (HEMTs) in the amplifier operate in unsaturated microcurrent regime and dissipate only 1 microwatt of dc power per transistor. Simulated amplifier gain is 15 dB at 450 MHz with a high-impedance (~5 kOhm signal source and standard 50-Ohm output.Comment: 10 pages, 7 figures. To be published in Fizika Nizkikh Temperatur (Low Temperature Physics) vol. 50, No.1 (2024