G. Von Dardel

Production spectra of π±, K±, p± at large angles in proton-proton collisions in the CERN intersecting storage rings

Abstract Results are given on the inclusive production of charged pions, kaons, and nucleons, in proton-proton collisions at c.m. energies from √ s = 23 to 63 GeV at large angles and for the transverse momentum range 0.1 p T c . The dependence of the production spectra on the collision energy √ s , the transverse momentum p T , and the longitudinal rapidity is discussed.

The Production of Charged Particles with High Transverse Momentum in Proton-Proton Collisions at the CERN ISR

Results are given on the inclusive production of charged pions, kaons and nucleons in high-energy proton-proton collisions in the centre-of-mass rapidity range |ycm| < 1 and for transverse momenta up to 4.8 GeV/c. The dependence of the composition of produced particles on ycm, the total energy s, and transverse momentum pT is discussed.

Production of high transverse momentum particles in p-p-collisions in the central region at the CERN ISR

Abstract The inclusive production al all charged particles of transverse momentum p T between 1.5 and 4.4 GeV/ c at centre of mass angles 90° and 59.4° from p-p-collisions with √ s = 44 and 53 GeV has been measured. No strong energy dependence is observed for these transverse momenta.

The axial field spectrometer at the CERN ISR

Abstract The axial field spectrometer is being exploited in a wide-ranging programme to study pp and p p -collisions which are characterized by a large transverse momentum. A specially shaped magnet together with an “imaging” drift chamber is used for efficient detection and momentum analysis of high multiplicity events at interaction rates of up to 5 × 106 s. Particle identification is accomplished over 1 sr; an uranium/scintillator hadron calorimeter will cover more than 8 sr in 1982 to provide an unbiased energy measurement.

Studies of proton-proton collisions at the CERN ISR with an identified charged hadron of high transverse momentum at 90°: (II) On the distribution of charged particles in the central region

Abstract Results are reported from an investigation of proton-proton collisions at a c.m. energy of 52.6 GeV, in which a charged hadron with large transverse momentum is produced near 90° in the c.m.s. We have studied the momentum and charge correlations between identified high- p T trigger particles and other charged particles in the central region (rapidity | y | p T particles with charge opposite to that of the trigger particle in a small solid angle around the trigger particle. The sum of the momenta of charged particles inside | y | c per GeV/ c increase of the trigger momentum. Opposite in azimuth to the trigger particle we observe close pairs of high- p T particles in both neutral and doubly charged combinations. In this region we see an indication of scaling in the x E variable for trigger momenta exceeding 3 GeV/ c . The distribution of charge is strongly correlated with the charge of the trigger particle. Otherwise the type of trigger particle does not affect strongly the observed event structure, but for trigger momenta above 3 GeV/ c , K − and p triggers are observed to have fewer negative high- p T recoil particles within | y |

Evidence for dominant vector-meson production in inelastic proton-proton collisions at 53 GeV c.m. energy

Abstract The Split Field Magnet facility at the CERN ISR has been used to measure inclusive resonance production in inelastic p-p collisions at a c.m. energy of 53 GeV. The mass spectrum of pairs of oppositely charged hadrons shows a strong correlation, which can be explained as a consequence of dominant vector meson production, accounting for more than 60% of all pions and kaons produced.

Large angle production of stable particles heavier than the proton and a search for quarks at the CERN intersecting storage rings

Abstract Measurements have been performed on production of particles with mass 1.5 GeV/c2 and charge ⩾ 2 3 for θlab = 62.5° and s = 53 GeV . At pT = 0.7 GeV/c the relative rate of production of antideuterons to π− is (5 ± 1) × 10−5. The deuteron to antideuteron ratio is 3.7 ± 1.2. No new stable particle has been amongst 0.7 × 108 charged particles entering our detector.

Large-angle inclusive production of charged pions at the CERN ISR with transverse moment a less than 1.0 GeV/c

Abstract The inclusive production of π ± in proton-proton collisons has been measured for the transverse momentum range 0.15 to 1.0 GeV/ c over an angular range of 29° to 89° in the centre-of-mass system and for centre-of-mass energies √ s = 30.6 and 52.8 GeV. For each energy the invariant cross-section foe fixed transverse momentum was found to increase by about 15% as the centre-of-mass rapidity decreases from 1 to 0, i.e. the “central plateau” has not yet been reached.

Direct measurement of the lifetime of the neutral pion

Abstract The lifetime of the neutral pion (π0) has been directly measured. The lifetime has been found to be τπ0 = (0.897±0.022±0.017) × 10−16 s. The systematic error results from uncertainties in the momentum spectrum of the π0 used for the measurement. This measurement yields a decay width of the π0 of (7.34±0.18±0.11) eV. An axial anomaly calculation, which neglects the finite mass of the π0, predicts a value of 7.87 eV.

Mean life of the neutral pion

High energy neutral mesons( rature of the d ) were produced in platinum foils of 3-60 micron thickness exposed to the 18-Bev internal proton beam of the CERN proton synchrotron, and the production of positrons relative to all heavier particles was measured in a secondary beam of 5-Bev/c. The momentum spectrum of rature of the d /sup o/, which is effective in producing 5Bev/c positrons, is obtained by weighting the rature of the d /sup o/ spectrum with the probability that a positron from a rature of the d /sup o/ has a momentum of 5-Bev/c. The momentum spectra of rature of the d /sup o/ and rature of the d /sup +/ are assumed to be of equal shape and the latter was measured. This effective rature of the d /sup o/ spectrum is narrow and is charactetized by an average momentum of 7.12-Bev/c and a rms momentum of 7.26-Bev/c. The mean life was determined to be (1.05 ction in DDT-C/ 0.18) x 10/sup -16/ sec. (C.E.S.)