On 16 August, scientists completed a 6-week data set as part of the neutrino programme for measuring hadron yields in hadron-nuclear interactions in the NA61/SHINE experiment at European Organization for Nuclear Research (CERN). Statistics were collected for 11 different systems with more than 380 million events. The run was successful, among other things, thanks to JINR employees participating in the experiment. They developed and put into operation a new time-of-flight system for identifying charged particles.

NA61/SHINE is a fixed target experiment at the Super Proton Synchrotron at CERN. In the experiment, scientists study hadron final states arising from the interaction of various particles (from hadrons to lead nuclei) at proton momentum up to 400 GeV/s and 13A—150A GeV/s nuclear momentum. Now, about 135 physicists from 14 countries and 35 institutes are working in the NA61/SHINE experiment. A group of JINR staff members takes an active part in the experiment (Head of the group is Professor A. I. Malakhova, deputies are A. A. Zaitsev and A. V. Dmitriev).

Example of Xe collision event at 150A GeV/c momentum at fixed lanthanum target. Photo by CERN

From 5 July to 16 August, the main areas of the experimental programme were measurements of the interactions of K⁺, π⁺, and p beam hadrons at 60-120 GeV/s momentum at titanium and carbon targets. During the run, scientists managed to collect statistics for 11 different systems with more than 380 million events.

According to the researchers, measurements of hadron yields in hadron-nuclear interactions play a key role in improving calculations for predicting the initial neutrino flux in experiments studying neutrino oscillations in J-PARC and Fermilab.

“Scientists chose values of the energies of the incoming particles, as well as the interacting systems to replicate the conditions for the birth of a neutrino beam in the DUNE experiment, planned at the accelerator complex of the Fermi National Accelerator Laboratory,” Andrey Zaitsev, a senior researcher at the Scientific and Experimental Department of Heavy Ion Physics at the Laboratory of High Energy Physics at JINR, comments on the results of the run. “For example, data on the interaction of kaons with carbon are important for reducing uncertainty in the high-energy tail of the neutrino flux, since neutrinos from kaon decays dominate it. At present, there are no data on the interaction of kaons at the corresponding energies. The titanium data will further allow observing the interactions in the target’s protective case, which will be made of titanium. Proton-carbon data will improve the errors of hadron spectra obtained from 2016 – 2017 data.”

Earlier in 2022, an updated NA61/SHINE facility was put into operation with a maximum data collection frequency of 1.6 kHz instead of 80 Hz. During the first year’s operation of the updated facility, scientists collected more than 180 million proton interactions at 31 GeV/s momentum on a copy of the T2K experiment target (Japan), as well as 56 million events within the strong interactions programme, expanded by the research on the formation of D-mesons in collisions of lead nuclei at 150 GeV/nucleon energy of the projectile nucleus.

JINR staff members developed and created a 1728-channel arm of a time-of-flight system for NA61/SHINE based on multi-gap resistive plate chambers (MRPC), which has operated successfully in the last two runs.

In addition to participating in the runs and developing new equipment of the NA61/SHINE experiment, JINR group staff members analyse data, carry out theoretical research on relativistic nuclear interactions and computer simulation of the experiment.