The Budker Institute of Nuclear Physics (BINP) is one of the major centres of advanced study of nuclear physics in Russia. It is located in the Siberian town Akademgorodok, on Academician Lavrentiev Avenue. The institute was founded by Gersh Budker in 1959. Following his death in 1977, the institute was renamed in honour of Academician Budker.Despite its name, the centre was not involved either with military atomic science or nuclear reactors— instead, its concentration was on high-energy physics (particularly plasma physics) and particle physics. In 1961 the institute began building VEP-1, the first particle accelerator in the Soviet Union which collided two beams of particles, just a few months after the ADA collider became operational at the Frascati National Laboratories in Italy in February 1961. The BINP now employs over 3000 people, and hosts several research groups and facilities.
Since 1986, a collaboration between the Boreskov Institute of Catalysis (BIC) and the Budker Institute of Nuclear Physics (BINP) has been producing silica aerogel blocks for Cherenkov detectors. Novosibirsk-manufactured aerogel has been employed in several experiments, including KEDR and SND (BINP, Russia), DIRAC and LHCb (CERN, Switzerland), AMS-02 (ISS), and CLAS12 (Jefferson Lab, USA). This work describes key advances in the production technology of large-scale aerogel radiators used in Ring-Imaging CHerenkov (RICH) detectors. Annealing is one of the key stages in the production of highly transparent aerogel in Novosibirsk. This process was studied in detail and optimized to improve the yield of aerogel tiles suitable for RICH detectors. The optical and mechanical properties of the largest silica aerogel samples produced in Novosibirsk using the new annealing procedure are presented.
Linear accelerator of the injector of the synchrotron radiation facility SKIF (SRF SKIF) was assembled in Koltsovo in the end 2024. It is the beginning part of the accelerator complex where the electron beam is formed. After the acceleration up to the energy of 200 MeV the beam is transported to the booster synchrotron. The linear accelerator (linac) consists of the electron source based on the radiofrequency (RF) gun, the bunching channel with the bunching preaccelerator and five regular accelerating structures. Three 50 MW klystrons with the operating frequency of 2856 MHz feed the accelerating structures. Two of the klystrons were developed and manufactured at the Budker Institute of Nuclear Physics of Siberian Branch of Russian Academy of Sciences (BINP SB RAS) in house, while the remaining one was purchased. During the linac operation, maximum values of the RF power in waveguides were achieved. The transverse dynamics of the bunched electron beam was tuned in a single-bunch mode. Using the mechanical waveguide phase shifters, the accelerating field phases were chosen, which provided the required beam energy. Achieved parameters of the linac beam allowed us to proceed to the work with the linac–booster transport channel and the booster synchrotron itself. The article describes the linac launching process together with its current operation status and the achieved beam parameters.
Recently, the KM3NeT experiment reported the detection of a neutrino with exceptionally high energy E = 220 PeV, whose origin remains unclear. The corresponding value of the neutrino flux is in tension with the results of other high-energy neutrino experiments. In this study, we discuss the possibility that this neutrino is cosmogenic, i.e., produced by ultra-high energy cosmic rays during their propagation through the intergalactic medium. We adopt the ultra-high energy cosmic rays flux models derived by the Telescope Array experiment, which features a predominantly light mass composition. We show that the predictions of the cosmogenic neutrino flux in these models are consistent with the measurements of the KM3NeT-only and with that of the “global neutrino observatory” at approximately 2σ level. Notably, this result is achieved in a minimal version of the ultra-high energy cosmic rays flux models, that assume one source population with a standard cosmological evolution. We also estimate the corresponding cosmogenic gamma-ray flux and show that it is consistent with Fermi-LAT Isotropic Diffuse Gamma-Ray Background measurements and ultra-high energy gamma-ray limits; the improvement of the latter can probe these predictions in future.
Abstract In the recent years, argon-based experiments looking for Dark Matter in the Universe have explored the non-standard scenario in which Dark Matter is made by low-mass Weakly Interacting Massive Particles, of mass in the range of 1–10 GeV instead of the canonical hundreds of GeV. Detecting such particles is challenging, as their expected signatures are nuclear recoils with energies below 10 keV, observable solely via ionization. This necessitates a precise understanding of the detector response in this energy regime, which remains incomplete for argon. To address this, the ReD experiment was developed within the framework of the DarkSide-20k Collaboration to produce and characterize few-keV nuclear recoils. A compact dual-phase argon Time Projection Chamber (TPC) was irradiated with neutrons from a $$^{252}$$ 252 Cf source, to produce Ar recoils in the energy range of interest via (n,n’) elastic scattering. A downstream spectrometer composed of 18 plastic scintillators detected the neutrons scattered off Ar nuclei, enabling recoil energy reconstruction via two-body kinematics. The ionization yield $$Q_{y}$$ Q y of argon, defined as the number of electrons produced per unit energy deposit, was measured in a model-independent way between 2 and 10 keV. These measurements extend direct experimental coverage well below the previous limit of approximately 7 keV. The results are consistent with existing data above 7 keV, while they indicate a higher $$Q_{y}$$ Q y at lower energies.
We calculate the three-loop master integrals contributing to the three-loop five-point amplitude on the special Coulomb branch of 𝒩=4 SYM theory. For the genuine pentagon integrals, we follow the approach of Ref. [JHEP 12 (2025) 107], which includes a regularization preserving dual conformal invariance (DCI). As a new ingredient, we introduce a simple method, allowing to factor out the dependence on the DCI cross ratios from the contribution of each region. The remaining integrals are then essentially simplified by taking successive limits of vanishing external invariants. For 3 out of 82 regions contributing to the most complicated integral ℐ_5^(3) we were not able to perform the integration even after these simplifications. For these three regions, we perform the integration-by-parts (IBP) reduction in parametric representation and evaluate the resulting locally finite integrals using HyperInt.
