Measurement of charged particle production from 450 GeV/c protons on beryllium

This paper presents the results on charged particle yields and production ratios as measured by the NA56/SPY experiment for 450 GeV/c proton interactions on beryllium targets. The data cover a secondary momentum range from 7 GeV/c to 135 GeV/c and values up to 600 MeV/c. An experimental accuracy on the measured yields in the range from 5% to 10%, depending on the beam momentum, and around 3% for the particle production ratios has been achieved. These measurements are relevant for a precise evaluation of fluxes and composition of neutrino beams at accelerators. Results on the target thickness and shape dependence are also reported. Inclusive invariant cross sections in the forward direction have been derived. Received: 12 January 1999 / Published online: 8 September 1999     

Direct photon production from pions and protons at 200 GeV/c

Direct photon production has been studied by an experiment performed with the NA3 spectrometer at CERN, using incident negative and positive beams at 200 GeV/c interacting with an isoscalar Carbon target. Two different triggers have been used; one of them requires the photon conversion. The experiment is sensitive to direct photons produced with 3.0≦P _T ≦6 GeV/c and center-of-mass rapidity ?0.4≦y ^*≦1.2. Inclusive cross sections are given for incident π^± and protons, and compared with second order QCD predictions; finally an estimation of the gluon structure function of the nucleon is given.     

Channeling of 1.1 GeV/c protons and pions

Channeling effects have been observed for 1.1 GeV/c protons and pions transmitted through a 1 mm thick germanium single crystal.     

Large-angle production of charged pions by 3-12.9?GeV/c protons on beryllium, aluminium and lead targets

Measurements of the double-differential π^± production cross-section in the range of momentum 100 MeV/c≤p< 800 MeV/c and angle 0.35 rad ≤θ<  2.15 rad in proton–beryllium, proton–aluminium and proton–lead collisions are presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12.9 GeV/c hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections d²σ/dpdθ at six incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c, 8.9 GeV/c (Be only), 12 GeV/c and 12.9 GeV/c (Al only)) and compared to previously available data.     

Large-angle production of charged pions by 3?GeV/c–12?GeV/c protons on carbon, copper and tin targets

A measurement of the double-differential π^± production cross-section in proton–carbon, proton–copper and proton–tin collisions in the range of pion momentum 100 MeV/c≤p<800 MeV/c and angle 0.35 rad≤θ<2.15 rad is presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12 GeV/c hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was done using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results are shown for the double-differential cross-sections d²σ/dpdθ at four incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c and 12 GeV/c). PACS 13.75.Cs; 13.85.Ni     

Nuclear mass number dependence of inclusive pion production by pions and protons at 4.3GeV/c

The inclusive production of π⁺ for 0.4≤p_T<1.0 GeV/c in pion-nucleus and proton-nucleus collisions at 4.3 GeV/c was measured. A strong A-dependence of the cross sections at high p_T is observed to be persistent in the low energy region. The ratio of the cross sections for proton-nucleus and pion-nucleus collisions is also observed to be compatible with the quark-parton picture, for p_T>0.6 GeV/c.     

Nuclear interactions of 21 GeV/c protons and 50 GeV/c negative pions in emulsions exposed in a strong magnetic field

Incoherent nuclear interactions of 21 GeV/c protons and 50 GeV/cπ ^?-mesons in emulsions exposed in a strong (180 kG) magnetic field have been investigated. The following topics are covered: the multiplicity of various types of charges secondaries, general features of one-particle rapidity and transverse momentum distributions, energy partitions among secondaries, characteristics of the leading particles and relativistic recoil protons, correlation relations. The experimental data are compared with predictions of current models of nuclear production.     

Coherent production of particles by 67 GeV/c protons on emulsion nuclei

Coherent reactions were observed among one-, three- and may be five-prong interactions of 37 GeV/c protons in nuclear emulsion. Their cross sections were estimated and compared with other data on coherent production in emulsion.     

Measurement of the production of charged pions by protons on a tantalum target

A measurement of the double-differential cross-section for the production of charged pions in proton–tantalum collisions emitted at large angles from the incoming beam direction is presented. The data were taken in 2002 with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12 GeV/c hitting a tantalum target with a thickness of 5% of a nuclear interaction length. The angular and momentum range covered by the experiment (100 MeV/c ≤p< 800 MeV/c and 0.35 rad ≤θ< 2.15 rad) is of particular importance for the design of a neutrino factory. The produced particles were detected using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. Track recognition, momentum determination and particle identification were all performed based on the measurements made with the TPC. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results are shown for the double-differential cross-sections d²σ/dpdθ at four incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c and 12 GeV/c). In addition, the pion yields within the acceptance of typical neutrino factory designs are shown as a function of beam momentum. The measurement of these yields within a single experiment eliminates most systematic errors in the comparison between rates at different beam momenta and between positive and negative pion production. PACS 13.75.Cs; 13.85.Ni     

Channeling of protons,pions and deuterons in the GeV region

Strong directional effects have been observed when 1.15 and 1.35 GeV/c protons, π⁺ and π^?, and deuterons penetrate through germanium crystals. Transmission, wide-angle scattering, and an attempt to do blocking distributions are obtained from experiments using position-sensitive drift chambers. Corresponding measurements of energy loss in germanium crystals are also presented. These experimental results are compared to theory for energy loss, and satisfactory agreement is obtained.     

The photoproduction of neutral pions from protons between 0.7 GeV and 1.7 GeV

Measurements of differential cross sections for pi-zero photoproduction from protons have been made at angles between 60° and 140° c.m. in the photon energy range 0.7 GeV to 1.7 GeV. The data are compared with the rits provided by three recent partial-wave analyses of pion photoproduction and some significant discrepancies observed.     

ψψ production and limits on beauty meson production from 400 GeV/c protons

From a study of multimuon events obtained in a high luminosity proton-platinum experiment at 400 GeV/c, we find 5 ± 4ψψ events, which correspond to a production cross section σ(ψψ = 27 ± 10 pb. The observed production is compared to the ψψ events previously found in the same apparatus from incoming π^?; a comparison with QCD predictions is performed, giving a good agreement with expectations from gluon-gluon fusion. Finally, using like-sign dimuon, trimuon and quadrimuon events, we give model-dependent upper limits on beauty meson production: 2 nb/nucleon for central models, 20 nb/nucleon for diffractive production.     

Angular distributions of channeled pions and protons up to 250 GeV/c

Channeling phenomena are observed for positive particles of momentum up to 250 GeV/c in a germanium crystal. The polar angular distributions of the channeled particles are compared with theoretical predictions based on a diffusion model. The results indicate that at high particle energy there may be additional mechanisms besides those operative at low energy leading to dechanneling of the particles. In spite of this, channeling effects are observed for particles incident at up to several times the critical angle, in contrast with the results from low energy channeling. Statistical equilibrium in the azimuthal angular distribution has also been observed at all measured beam momenta to about twice the calculated channeling critical angle. The breakdown of statistical equilibrium for the 2 cm crystal used occurs at an incident angle 2–3 times smaller than predicted theoretically.     

Inclusive production of charged pions in p+p collisions at 158 GeV/c beam momentum

New results on the production of charged pions in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. Pions are identified by energy loss measurement in a large TPC tracking system which covers a major fraction of the production phase space. Inclusive invariant cross sections are given on a grid of nearly 300 bins per charge over intervals from 0 to 2 GeV/c in transverse momentum and from 0 to 0.85 in Feynman x. The results are compared to existing data in overlapping energy ranges. Arrival of the final proofs: 8 December 2005     

Thermal emission of pions in antiproton-proton annihilation at 12 GeV/c

Using data of \(\bar pp\) annihilation at 12 GeV/c we have found that centrally-emitted pions follow a thermal energy spectrum with an inclusive temperature of 111±2 MeV, the same as has been found for pions produced in πp collisions at 16 GeV/c. An analysis of individual high-multiplicity events to search for fluctuations in the temperature parameter on an event-byevent basis has been made, using two different methods. We obtained the value 0.18±0.02 for the relative dispersion of the temperature fluctuations.     

Elastic backward scattering of negative pions on protons at 25 and 38 GeV/c

The backward elastic scattering reaction π^?p → pπ^? at momenta 25 and 38 GeV/c have been measured using a magnetic spectrometer with hybrid chambers. The experimental data on the dependence of the cross section dσ/du on the momentum transfer u as well as the energy dependence dσ/du at u = 0 are given.