Charm production nearby threshold in pA-interactions at 70 GeV

The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP, Protvino) are presented. Interactions of the 70 GeV proton beam with C, Si and Pb targets were studied to detect decays of charmed $D^0$, $\overline D^0$, $D^+$, $D^-$ mesons and $\Lambda _c^+$ baryon near their production threshold. Measurements of lifetimes and masses are shown a good agreement with PDG data. The inclusive cross sections of charm production and their A-dependencies were obtained. The yields of these particles are compared with the theoretical predictions and the data of other experiments. The measured cross section of the total open charm production ($\sigma _{\mathrm {tot}}(c\overline c)$ = 7.1 $\pm$ 2.3(stat) $\pm$1.4(syst) $\mu$b/nucleon) at the collision c.m. energy $\sqrt {s}$ = 11.8 GeV is well above the QCD model predictions. The contributions of different species of charmed particles to the total cross section of the open charm production in proton-nucleus interactions vary with energy.Comment: 4 pages, 6 pages, 38th International Conference on High Energy Physics 3-10 August 2016, Chicago, US

Clinical and laboratory evaluation of workers metallurgical production dental diseases prevention effectiveness

Показано, что проведение комплексной профилактики стоматологических заболеваний у работников металлургического производства снижает величину колебаний pH ротовой жидкости в отдельных пробах в 2 раза, нормализует процент подвижных ядер буккального эпителия (53 %) и отношение амплитуд колебаний плазмолем и ядер (Апл/Ая 1,79). Кроме того, спектроколориметрически показано, что при этом улучшаются функциональные реакции микрокапиллярного русла на жевательную нагрузку и улучшается барьерная защита десен (снижается проницаемость для красителя раствора Шиллера-Писарева).Показано, що проведення комплексної профілактики стоматологічних захворювань у працівників металургійного виробництва знижує величину коливань pH ротової рідини в окремих пробах в 2 рази, нормалізує відсоток рухливих ядер буккального епітелію (53 %) і відношення амплітуд коливань плазмолем і ядер (Апл/Ая 1,79). Крім того, спектроколориметрично показано, що при цьому покращуються функціональні реакції мікрокапілярного русла на жувальне навантаження і бар'єрний захист ясен (знижується проникність їх для фарбника розчину Шилера-Писарєва).Metallurgical industry occupies a leading position by level of occupational morbidity of workers, which requires the development of effective comprehensive prevention programs, including dental diseases. The aim of the work was to evaluate the influence of the developed complex prevention of major dental diseases metallurgical industry workers on the biophysical parameters of oral liquid, microcapillary bed gums and inflammatory processes in it. Materials and methods. Workers of metallurgical plant (29 persons), in addition to basic therapy, received several times a year, specially designed preventive complex. Was evaluated parameters of oral liquid, buccal epithelium cells, microcapillary bed gums and inflammation in it. Results. Conclusions. Conducted integrated prevention of stomatological diseases among workers of metallurgical production reduces the value in oral liquid of pH oscillations in individual samples in 2 times, normalizes the percentage of mobile nuclei of buccal epithelium (53%) and the ratio of the amplitudes of oscillations plazmolem and nuclei (Apl / An 1.79) improves functional microcapillary reaction of gum to chewing load and barrier protection

Azimuthal Anisotropy of Photon and Charged Particle Emission in Pb+Pb Collisions at 158 A GeV/c

The azimuthal distributions of photons and charged particles with respect to the event plane are investigated as a function of centrality in Pb + Pb collisions at 158 A GeV/c in the WA98 experiment at the CERN SPS. The anisotropy of the azimuthal distributions is characterized using a Fourier analysis. For both the photon and charged particle distributions the first two Fourier coefficients are observed to decrease with increasing centrality. The observed anisotropies of the photon distributions compare well with the expectations from the charged particle measurements for all centralities.Comment: 8 pages and 6 figures. The manuscript has undergone a major revision. The unwanted correlations were enhanced in the random subdivision method used in the earlier version. The present version uses the more established method of division into subevents separated in rapidity to minimise short range correlations. The observed results for charged particles are in agreement with results from the other experiments. The observed anisotropy in photons is explained using flow results of pions and the correlations arising due to the decay of the neutral pion

Interferometry of Direct Photons in Central 280Pb+208Pb Collisions at 158A GeV

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158 AGeV. The invariant interferometric radii were extracted for 100<K_T<300 MeV/c and compared to radii extracted from charged pion correlations. The yield of soft direct photons, K_T<300 MeV/c, was extracted from the correlation strength and compared to theoretical calculations.Comment: 5 pages, 4 figure

Suppression of High-p_T Neutral Pion Production in Central Pb+Pb Collisions at sqrt{s_NN} = 17.3 GeV Relative to p+C and p+Pb Collisions

Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at sqrt{s_NN} = 17.4 GeV at mid-rapidity 2.3 < eta_lab < 3.0 over the range 0.7< p_T < 3.5 GeV/c. The spectra are compared to pi0 spectra measured in Pb+Pb collisions at sqrt{s_NN} = 17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N_part < 300) the yield of pi0's with p_T > 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N_coll), while for central Pb+Pb collisions with N_part > 350 the pi0 yield is suppressed.Comment: 5 pages, 4 figure

Pion Freeze-Out Time in Pb+Pb Collisions at 158 A GeV/c Studied via pi-/pi+ and K-/K+ Ratios

The effect of the final state Coulomb interaction on particles produced in Pb+Pb collisions at 158 A GeV/c has been investigated in the WA98 experiment through the study of the pi-/pi+ and K-/K+ ratios measured as a function of transverse mass. While the ratio for kaons shows no significant transverse mass dependence, the pi-/pi+ ratio is enhanced at small transverse mass values with an enhancement that increases with centrality. A silicon pad detector located near the target is used to estimate the contribution of hyperon decays to the pi-/pi+ ratio. The comparison of results with predictions of the RQMD model in which the Coulomb interaction has been incorporated allows to place constraints on the time of the pion freeze-out.Comment: 9 pages, 12 figure

Search for DCC in 158A GeV Pb+Pb Collisions

A detailed analysis of the phase space distributions of charged particles and photons have been carried out using two independent methods. The results indicate the presence of nonstatistical fluctuations in localized regions of phase space.Comment: Talk at the PANIC99 Conference, June 9-16, 199

Systematics of Inclusive Photon Production in 158 AGeV Pb Induced Reactions on Ni, Nb, and Pb Targets

The multiplicity of inclusive photons has been measured on an event-by-event basis for 158 AGeV Pb induced reactions on Ni, Nb, and Pb targets. The systematics of the pseudorapidity densities at midrapidity (rho_max) and the width of the pseudorapidity distributions have been studied for varying centralities for these collisions. A power law fit to the photon yield as a function of the number of participating nucleons gives a value of 1.13+-0.03 for the exponent. The mean transverse momentum, , of photons determined from the ratio of the measured electromagnetic transverse energy and photon multiplicity, remains almost constant with increasing rho_max. Results are compared with model predictions.Comment: 16 pages including 4 figure