Freddy Binon

Scattering of negative pions on carbon

Abstract Data are presented on elastic and inelastic differential cross sections as well as on total cross sections for negative pions on carbon in the energy range 120 MeV to 280 MeV.

Scattering of Negative Pions on Helium

Abstract Differential cross sections for negative pion scattering on 4 He have been measured at five pion kinetic energies between 110 and 260 MeV in the angular range from 5° to 180°. Total cross sections have also been measured at eleven energies between 67 and 285 MeV. The differential cross sections have been fitted with a phenomenological expression for the nuclear scattering amplitude. Conventional phase shifts have been reconstructed starting from the parameters of the fits.

Coulomb-nuclear interference in π−-12C elastic scattering

Abstract The π − - 12 C elatic differential cross sections have beenmeasured at three kinetic energies around the ( 3 2 , 3 2 ) pion-nucleon resonance, namely 120, 180 and 260 MeV, in the small-angle region [ t ≤ 18 000 (MeV/ c ) 2 ] where the interference between Coulomb and nuclear amplitudes is most pronounced. An expression for the relative phase between Coulomb and nuclear amplitudes has been derived which takes into account a variation linear in t of the nuclear phase. Using this formula, the real part of the forward nuclear amplitude has been deduced from the data at each energy. The results are in good agreement with the predictions of pion-nucleus forward dispersion relations. The nuclear phase seems to vary significantly at 260 MeV.Abstract The π−-12C elatic differential cross sections have beenmeasured at three kinetic energies around the ( 3 2 , 3 2 ) pion-nucleon resonance, namely 120, 180 and 260 MeV, in the small-angle region [t ≤ 18 000 (MeV/c)2] where the interference between Coulomb and nuclear amplitudes is most pronounced. An expression for the relative phase between Coulomb and nuclear amplitudes has been derived which takes into account a variation linear in t of the nuclear phase. Using this formula, the real part of the forward nuclear amplitude has been deduced from the data at each energy. The results are in good agreement with the predictions of pion-nucleus forward dispersion relations. The nuclear phase seems to vary significantly at 260 MeV.

J/ψ production by 24 GeV/c protons

Abstract We report measurements at the CERN PS of the production cross section of J/ψ(3.1) by 24 GeV protons on hydrogen, carbon, and tungsten.

Low pressure multiwire proportional chambers with high time resolution for strongly ionizing particles

Abstract Multiwire proportional chambers have been tested in the range of pressures from 3 to 30 mm Hg of isobutane, pentane and heptane. With 5.5 MeV α particles, a time resolution of 2.5 nsec was obtained at 100% efficiency.

Accurate time measurements with plastic scintillation counters

Abstract A plastic scintillation counter, with a useful areaof 24×25 cm 2 and a resolution of 290 ps (fwhm) for determining the time of impact of a minimum ionizing particle, is described. The resolution may be brought down to 100 ps with smaller counters. Lower time spreads are obtained with more ionizing particles.

A high resolution liquid radiator differential Čerenkov counter

Abstract A liquid-differential Cerenkov counter built to separate protons from kaons between 2 GeV/c and 9.5 GeV/c or kaons from pions up to 5 GeV/c is described. This counter has a 20 cm diameter useful cross-area. It can accept a ±7% momentum bite around its nominal setting. A resolution Δβ β better than 3% is achieved in the vicinity of β = 1.

High-pT two-body correlations and single-particle inclusive hadron spectra in 24 GeV proton-nucleus collisions

SummaryResults are presented on inclusive spectra of π±, K+- and p+- produced in 24 GeV p12C collisions near θc.m. = 90° in the transverse-momentum range 0.49<pT< 2.55 GeV/c; correlations between particles of opposite charges, emitted in opposite directions at θc.m.= ±90° in the range 0.16≤pT≤2.15 GeV/c have been measured through a biasfree experimental method. The correlations as a function of pT orM, the invariant mass of the particle pair, do not show any significant resonance structure. In the K+K+ case the magnitude of the correlation coefficient is six times larger than in the θ+K- one. Such a ratio relevant to strangeness correlation between particles with opposite pc.m. was not observed before.RiassuntoSi presentano i risultati sugli spettri inclusivi di π+-,K+- e p+- prodotti in collisioni p12C a 24 GeV vicino a θc.m. = 90° nell’intervallo dell’impulso trasversale 0.49<pT< < 2.55 GeV/c; si sono misurate le correlazioni fra particelle con cariche opposte emesse in direzioni opposte a μc.m. = ±90° nell’intervallo 0.16 <pT< 2.15 GeV/o con un metodo sperimentale privo di errori sistematici. Le correlazioni in funzione di pT oM, la massa invariante della coppia di particelle, non mostrano alcuna struttura di risonanza significativa. Nel caso di K+K- il valore del coefficiente di correlazione è sei volte maggiore di quello nel caso di θ+K-. Questo rapporto relativo alla correla zione di stranezza fra particelle con p(c.m.) opposto non era stato osservato prima.РезюмеПриводятся результа ты для инклюзивных спектров π±, К±и р+обра зованных при соударениях прот онов с энергией 24 ГэВ12С , вблизи θщm=90° в области поперечных импульсов 0.49 < рT< 2.55 ГэВ/с. Бы ли измерены корреляции между частицами разн оименных зарядов, исп ущенных в противоположных нап равлениях при θим= ±90° области 0.16≤ pт≤2.15 ГэВ/с. Корреляции, как функция рt или М, инвариантной массы пары частиц, не обнаруживают какой-л ибо существенной резона нсной структуры. В слу чае К+К- величина коэффициен та корреляции в шесть раз больше, чем в случае π+К-. Такое отн ошение, относящееся к корреляции страннос ти между частицами с противоположным рnцм, ранее не наблюдалось.