This paper presents the energy dependence of multiplicity and net-electric charge fluctuations in p+p interactions at beam momenta 20, 31, 40, 80, and 158 Ge V /c . Results are corrected for the experimental biases and quantified with the use of cumulants and factorial cumulants. Cumulant ratios are an essential tool in the search for the critical point of strongly interacting matter in heavy ion collisions. Measurements performed in p+p interactions provide a vital baseline estimation in these studies. The measured signals are compared with the string hadronic models Epos1.99 and FTFP-BERT.

Measurements of K_S^0 meson production via its π^+π^- decay mode in inelastic p+p interactions at incident projectile momenta of 31, 40 and 80 GeV/c (√(s_NN)=7.7, 8.8 and 12.3 GeV, respectively) are presented. The data were recorded by the NA61/SHINE spectrometer at the CERN Super Proton Synchrotron. Double-differential distributions were obtained in transverse momentum and rapidity. The mean multiplicities of K_S^0 mesons were determined to be (5.95 ± 0.19 (stat) ± 0.22 (sys)) × 10^-2 at 31 GeV/c, (7.61 ± 0.13 (stat) ± 0.31 (sys)) × 10^-2 at 40 GeV/c and (11.58 ± 0.12 (stat) ± 0.37 (sys)) × 10^-2 at 80 GeV/c. The results on K^0_S production are compared with model calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from other experiments.

Abstract The yields of $$K^0_S$$ K S 0 mesons have been measured in inelastic p+p interactions at incident projectile momenta of 31, 40 and 80 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c ( $$\sqrt{s_{NN}}=7.7, 8.8$$ s NN = 7.7 , 8.8 and 12.3 $$\text {Ge}\hspace{-1.00006pt}\text {V}$$ Ge V , respectively). The data were recorded by the NA61 $$/$$ / SHINE spectrometer at the CERN Super Proton Synchrotron and the $$K^0_S$$ K S 0 mesons identified via their decays into $$\pi ^{+} \pi ^{-}$$ π + π - pairs. Double-differential distributions are presented as function of transverse momentum and rapidity. The mean multiplicities of $$K^0_S$$ K S 0 mesons were determined to be $$(5.95 \pm 0.19 (stat) \pm 0.30 (sys)) \times 10^{-2}$$ ( 5.95 ± 0.19 ( s t a t ) ± 0.30 ( s y s ) ) × 10 - 2 at 31 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c , $$(7.61 \pm 0.13 (stat) \pm 0.43 (sys)) \times 10^{-2}$$ ( 7.61 ± 0.13 ( s t a t ) ± 0.43 ( s y s ) ) × 10 - 2 at 40 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c and $$(11.58 \pm 0.12 (stat) \pm 0.55 (sys)) \times 10^{-2}$$ ( 11.58 ± 0.12 ( s t a t ) ± 0.55 ( s y s ) ) × 10 - 2 at 80 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c . The results on $$K^{0}_{S}$$ K S 0 production are compared with the production of charged kaons in corresponding reactions and with model calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from other experiments.

The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of π ^± , K^± , p and p̅ produced in ^40Ar+^45Sc collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A Ge V /c . The analysis uses the 10 K^± / π ^± ratios as well as of inverse slope parameters of the K^± transverse mass distributions are placed in between those found in inelastic p+p and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.

The yields of K^0_S mesons have been measured in inelastic p+p interactions at incident projectile momenta of 31, 40 and 80 GeV/c ( √(s_NN)=7.7, 8.8 and 12.3 GeV , respectively). The data were recorded by the NA61 / SHINE spectrometer at the CERN Super Proton Synchrotron and the K^0_S mesons identified via their decays into π ^+π ^- pairs. Double-differential distributions are presented as function of transverse momentum and rapidity. The mean multiplicities of K^0_S mesons were determined to be (5.95 ± 0.19 (stat) ± 0.30 (sys)) × 10^-2 at 31 GeV/c , (7.61 ± 0.13 (stat) ± 0.43 (sys)) × 10^-2 at 40 GeV/c and (11.58 ± 0.12 (stat) ± 0.55 (sys)) × 10^-2 at 80 GeV/c . The results on K^0_S production are compared with the production of charged kaons in corresponding reactions and with model calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from other experiments.

Abstract The critical point of strongly interacting matter is searched for at the CERN SPS by the NA61/SHINE experiment in central $$^{40}$$ 40 Ar + $$^{45}$$ 45 Sc collisions at 13 A, 19 A, 30 A, 40 A, and 75 A GeV/c. The dependence of the second-order scaled factorial moments of proton multiplicity distributions on the number of subdivisions in transverse momentum space is measured. The intermittency analysis uses statistically independent data sets for every subdivision in transverse and cumulative-transverse momentum variables. The results obtained do not indicate the searched intermittent pattern. An upper limit on the fraction of correlated protons and the intermittency index is obtained based on a comparison with the Power-law Model.

AbstractThe NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $$\pi ^\pm $$ π ± , $$K^\pm $$ K ± , p and $$\bar{p}$$ p ¯ produced in $$^{40}\hbox {Ar+}^{45}\hbox {Sc}$$ 40 Ar+ 45 Sc collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A $$\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c$$ Ge V / c . The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the $$K^\pm $$ K ± /$$\pi ^\pm $$ π ± ratios as well as of inverse slope parameters of the $$K^\pm $$ K ± transverse mass distributions are placed in between those found in inelastic $$p+p$$ p + p and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.

The critical point of strongly interacting matter is searched for at the CERN SPS by the NA61/SHINE experiment in central $^{40}$Ar +$^{45}$Sc collisions at 13$A$, 19$A$, 30$A$, 40$A$, and 75$A$ GeV/$c$. The dependence of the second-order scaled factorial moments of proton multiplicity distributions on the number of subdivisions in transverse momentum space is measured. The intermittency analysis uses statistically independent data sets for every subdivision in transverse and cumulative-transverse momentum variables. The results obtained do not indicate the searched intermittent pattern. An upper limit on the fraction of correlated protons and the intermittency index is obtained based on a comparison with the Power-law Model.

We report on the first production of an antihydrogen beam by charge exchange of 6.1 keV antiprotons with a cloud of positronium in the GBAR experiment at CERN. The antiproton beam was delivered by the AD/ELENA facility. The positronium target was produced from a positron beam itself obtained from an electron linear accelerator. We observe an excess over background indicating antihydrogen production with a significance of 3-4 standard deviations.

Abstract The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $$\pi ^\pm $$ π ± , $$K^\pm $$ K ± , p and $$\bar{p}$$ p ¯ produced in $$^{40}\hbox {Ar+}^{45}\hbox {Sc}$$ 40 Ar+ 45 Sc collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A $$\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c$$ Ge V / c . The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the $$K^\pm $$ K ± / $$\pi ^\pm $$ π ± ratios as well as of inverse slope parameters of the $$K^\pm $$ K ± transverse mass distributions are placed in between those found in inelastic $$p+p$$ p + p and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.

The critical point of strongly interacting matter is searched for at the CERN SPS by the NA61/SHINE experiment in central Ar-40 +Sc-45 collisions at 13A, 19A, 30A, 40A, and 75A GeV/c. The dependence of the second-order scaled factorial moments of proton multiplicity distributions on the number of subdivisions in transverse momentum space is measured. The intermittency analysis uses statistically independent data sets for every subdivision in transverse and cumulative-transverse momentum variables. The results obtained do not indicate the searched intermittent pattern. An upper limit on the fraction of correlated protons and the intermittency index is obtained based on a comparison with the Power-law Model

A high-energy electron accelerator is used in the treatment of patients in the so-called intraoperative electron radiotherapy (IOERT). The work aimed to present the results of the validation of a new design of an electron beam applicator for use in IOERT. A novel solution was described along with the design optimization method based on Monte Carlo simulations. In this solution, the applicator consists of two parts. The lower exchangeable part collimates the therapeutic field. Measurements were made based on the International Electrotechnical Commission (IEC) standard recommendations. The measurement described in the standard has been adapted to the specificity of the intraoperative accelerator Source to Skin Distance - of 60 cm and applicators with a circular cross-sectional area. Measurements were performed for nominal beam energies of 6, 10, and 12 MeV and two therapeutic field diameters of 6 and 10 cm. The dose due to stray X-ray radiation in all energies is less than 0.3% and increases for energies from 6 to 12 MeV by 2.9 times from 0.1 for 6MeV to 0.29 for 12 MeV. The average dose due to leakage radiation also shows an increasing trend and is higher for a 6 cm diameter applicator. Validation confirmed the usefulness of the novel applicator design for clinical applications. Thanks to the use of 3D printing, it was possible to make applicators that are transparent, biocompatible and, at the same time, light and form a beam field with therapeutically useful accuracy, and the leakage radiation does not exceed normative recommendations.

AbstractThe yields of $$K^0_S$$ K S 0 mesons have been measured in inelastic p+p interactions at incident projectile momenta of 31, 40 and 80 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c ($$\sqrt{s_{NN}}=7.7, 8.8$$ s NN = 7.7 , 8.8 and 12.3 $$\text {Ge}\hspace{-1.00006pt}\text {V}$$ Ge V , respectively). The data were recorded by the NA61$$/$$ / SHINE spectrometer at the CERN Super Proton Synchrotron and the $$K^0_S$$ K S 0 mesons identified via their decays into $$\pi ^{+} \pi ^{-}$$ π + π - pairs. Double-differential distributions are presented as function of transverse momentum and rapidity. The mean multiplicities of $$K^0_S$$ K S 0 mesons were determined to be $$(5.95 \pm 0.19 (stat) \pm 0.30 (sys)) \times 10^{-2}$$ ( 5.95 ± 0.19 ( s t a t ) ± 0.30 ( s y s ) ) × 10 - 2 at 31 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c , $$(7.61 \pm 0.13 (stat) \pm 0.43 (sys)) \times 10^{-2}$$ ( 7.61 ± 0.13 ( s t a t ) ± 0.43 ( s y s ) ) × 10 - 2 at 40 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c and $$(11.58 \pm 0.12 (stat) \pm 0.55 (sys)) \times 10^{-2}$$ ( 11.58 ± 0.12 ( s t a t ) ± 0.55 ( s y s ) ) × 10 - 2 at 80 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ Ge V / c . The results on $$K^{0}_{S}$$ K S 0 production are compared with the production of charged kaons in corresponding reactions and with model calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from other experiments.

The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $\pi^\pm$, $K^\pm$, $p$ and $\bar{p}$ produced in $^{40}$Ar+$^{45}$Sc collisions at beam momenta of 13$A$, 19$A$, 30$A$, 40$A$, 75$A$ and 150$A$ GeV/$c$. The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the $K^\pm$/$\pi^\pm$ ratios as well as of inverse slope parameters of the $K^\pm$ transverse mass distributions are placed in between those found in inelastic $p$+$p$ and central Pb+Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical (SMES, HRG) or dynamical (EPOS, UrQMD, PHSD, SMASH) models.

The critical point of dense, strongly interacting matter is searched for at the CERN SPS in 40Ar + 45Sc collisions at 150A Ge V /c. The dependence of second-order scaled factorial moments of proton multiplicity distribution on the number of subdivisions of transverse momentum space is measured. The intermittency analysis is performed using both transverse momentum and cumulative transverse momentum. For the first time, statistically independent data sets are used for each subdivision number. The obtained results do not indicate any statistically significant intermittency pattern. An upper limit on the fraction of correlated proton pairs and the power of the correlation function is obtained based on a comparison with the Power-law Model developed for this purpose.

The neutron emission in projectile fragmentation at relativistic energies was studied with the Large-Area-Neutron-Detector LAND coupled to the ALADIN forward spectrometer at the GSI Schwerionen-Synchrotron (SIS). Stable 124Sn and radioactive 107Sn and 124La beams with an incident energy of 600 MeV/nucleon were used to explore the N/Z dependence of the identified neutron source. A cluster-recognition algorithm is applied for identifying individual particles within the hit distributions registered with LAND. The obtained momentum distributions are extrapolated over the full phase space occupied by the neutrons from the projectile-spectator source. The mean multiplicities of spectator neutrons reach values of up to about 11 and depend strongly on the isotopic composition of the projectile. An effective source temperature of T \approx 2-5 MeV, monotonically increasing with decreasing impact parameter, is deduced from the transverse momentum distributions. For the interpretation of the data, calculations with the statistical multifragmentation model were performed. The variety of excited projectile spectators assumed to decay statistically is represented by an ensemble of excited sources with parameters determined previously from the fragment production observed in the same experiments. The obtained agreement is very satisfactory for more peripheral collisions where, according to the model, neutrons are mainly emitted during the secondary decays of excited fragments. The neutron multiplicity in more central collisions is underestimated, indicating that other sources besides the modeled statistical breakup contribute to the observed neutron yield. The choice made for the symmetry-term coefficient of the liquid-drop description of produced fragments has a weak effect on the predicted neutron multiplicities.

Introduction: The shape of the energy spectrum is an essential component of any electron beam Monte Carlo model. Due to specialized equipment and the long measurement time for the direct methods for determining the energy spectrum, attractive alternatives are backward spectrum reconstructions from the measured data. One such approach is solving the first-degree Fredholm integral equation with appropriate regularization. It makes it possible to calculate the depth distribution as the sum of the distributions from monoenergetic beams. This study aims to determine the optimal value of the regularization parameter for the problem of determining the spectrum of the electron beam produced by a mobile accelerator used during intraoperative radiotherapy. Material and methods: The Geant4 package was used to generate the distributions of deep doses for monoenergetic beams for two models with different degrees of complexity, i.e. simple (theoretical) and full (for the mobile accelerator). The dose distributions for four different shapes of energy spectrum (for each model) were obtained similarly. They were established as the reference data for further calculations. The Dual Annealing optimization method was used to obtain the reconstructed spectrum. The multiple optimizations that differ by the regularization parameter (ranging from 0 to 1) were performed. For each reconstruction, similarity indicators of the energy spectrum and the dose distribution to the referenced data were calculated to determine the optimal regularization parameters. Results: Optimal regularization parameters determined by similarity indicators for the spectrum and the dose distribution differ for geometry models considered in the study. The regularization parameter for the simple geometry ranged from 0.03 to 0.05, while for full geometry, they were from 0.05 to 0.06. The results for conventional linear accelerators found in the literature range from 0.5 to 1.1. Conclusion: The Dual Annealing optimization method can be effectively used to solve the Fredholm equation with Tikhonov regularization to reconstruct an electron beam's energy spectrum. The regularization parameter value depends on the beam-forming system. Its value for the mobile accelerator considered in the study ranges from 0.05 to 0.06, depending on the nominal beam energy value.

This paper reports measurements of two-pion femtoscopic correlations in Be+Be collisions at a beam momentum of 150 A GeV/c (energy available in the center-of-mass system for nucleon pair √(s_NN) = 16.84 GeV) by the NA61/SHINE experiment at the CERN SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent α is approximately constant as a function of m_T , and far from both the Gaussian case of α = 2 or the conjectured value at the critical endpoint, α = 0.5 . The radius scale parameter R shows a slight decrease in m_T , which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter λ as a function of m_T was observed, similar to previous NA44 S + Pb results (obtained with a Gaussian approximation, but unlike RHIC results).

This paper presents multiplicity measurements of charged hadrons produced in 120 GeV/$c$ proton-carbon interactions. The measurements were made using data collected at the NA61/SHINE experiment during two different data-taking periods, with increased phase space coverage in the second configuration due to the addition of new subdetectors. Particle identification via $dE/dx$ was employed to obtain double-differential production multiplicities of $\pi^+$, $\pi^-$, $p$, $\bar{p}$, $K^+$ and $K^-$. These measurements are presented as a function of laboratory momentum in intervals of laboratory polar angle covering the range from 0 to 450 mrad. They provide crucial inputs for current and future long-baseline neutrino experiments, where they are used to estimate the initial neutrino flux.