Nuclear interactions of 200 GeV protons in emulsion

Proton-nucleus interactions have been studied in nuclear emulsion exposed to the NAL 200 GeV proton beam. The inelastic mean free path is found to be 35.5 ± 0.8 cm and the average shower particle multiplicity is 12.9 ± 0.2. The angular distribution reveals some characteristics features of proton-nucleus interactions.     

Hadron production in 200 GeV μ-copper and μ-carbon deep inelastic interactions

The measurements of the z and p_T² distribution of hadrons produced in the interactions of 200 GeV muons with copper and carbon nuclei are shown in different x_Bj and virtual photon energy intervals. Effects of the jet scattering are seen at the lowest virtual photon energies while for energies above 70 GeV there is no evidence of these effects. Comparison with a theoretical model indicates that at high jet energies the parton fragmentation distance is greater than the nuclear radius and that the parton absorption cross section is less than 10 mb.     

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.     

Emission of deuterons in the interactions of 9 GeV protons with lead nuclei

The emission of deuterons with energies ranging from 17 to 104 MeV in interactions of 9 GeV protons with lead nuclei has been studied using nuclear emulsion. These deuterons constitute about $\text{1}\text{6}$ of the secondary heavily ionising particles (β < 0.7). Observed features of the emission of the deuterons with energies above 28 MeV can be interpreted in terms of the mechanism proposed by Butler and Pearson.     

An interpretation of high-energy inelastic interactions of pions with heavy emulsion nuclei

An analysis of the basic characteristics of secondary particles created in the interaction of pions with heavy emulsion nuclei at the highest accelarator energies available is presented. Calculations were performed with an intra-nuclear cascade model using the Monte-Carlo method, taking into account the “trailing effect”. Emission of slow particles from the excited residual nucleus was calculated using Weisskopf's evaporation theory. The theoretical results were compared with experimental results at 17.2 and 60 GeV interactions.     

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.     

Missing mass spectra in pp inelastic scattering at total energies of 23 GeV and 31 GeV

Results are reported of measurements of the momentum spectra of protons emitted at small angles in inelastic reactions at the CERN ISR. The data are for total energies $\text{s}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of 23 GeV and 31 GeV. The structure of the peak at low values of the missing mass M (of the system recoiling against the observed proton) is studied. The missing mass distributions have the form (M²)^?B(t) where t is the four-momentum transfer squared. B(t) drops from 0.98±0.06 at t=?0.15 GeV² to 0.20±0.15 at t=?1.65 GeV². The results are compared with a simple triple-Regge formula.     

Evidence for azimuthal correlations in inelastic interactions of56Fe nuclei in emulsion at 2.5A GeV/c

Azimuthal correlations in angles between various types of charged secondary particles from inelastic interactions of relativistic⁵⁶Fe nuclei with the nuclei of nuclear emulsions have been investigated. It is observed that all types of charged secondaries produced are emitted asymmetrically in the azimuthal plane. The degree of azimuthal asymmetry increases with the decrease of impact parameter. We have also observed that particles belonging to different kinematical regions of the nucleus-nucleus interaction (intergroup correlation) have a tendency to be emitted to the opposite sides in the azimuthal plane.     

A search for charmed particles originating from the interactions of 300 GeV/c protons in emulsion nuclei

The associated production of charmed particles by the interactions of 300 GeV/c protons with complex nuclei has been sought using nuclear emulsions. The failure to observe any candidates for this process among some 60,000 interactions investigated implies, provided charmed particles lifetimes are in the range 10^?12 to 10^?14 s, a cross section for their associated production by the interactions of 300 GeV/c protons with nucleons of less than 1.5 microbarns at a 90% confidence level.     

Antiproton-neutron interactions at 100 GeV/c

From an exposure of the 30-inch deuterium filled bubble chamber to a 100 GeV/c antiproton-enriched beam at FNAL, we have calculated the topological cross sections for antiproton-neutron interactions with three or more charged particles in the final state. A comparison of our data with pn data at the same momentum allows us to estimate the annihilation contribution to each multiplicity, and hence calculate the average value, and width, of the annihilation multiplicity distribution. Our results are consistent with those from $\text{p}\text{p}$ data at 100 GeV/c, but depart from the trend of lower-energy $\text{p}\text{p}$ data.     

Correlations associated with small angle protons produced in proton-proton collisions at 31 GeV total energy

High energy inelastic protons with $\text{x = 2 p}{}_{\mathrm{<mtext>L</mtext>}}\text{/s}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{> 0.99}$ observed in 15.3/15.3 GeV proton-proton collisions at the CERN ISR are accompanied by particles whose angular distribution is confined to a narrow cone in the opposite direction. In constrast, lower energy protons (0.72 < x < 0.84) are accompanied in addition, by particles emitted at larger angles. The ratio of the associated charged multiplicities is approximately 0.4.     

Measurement of coherent elastic and inelastic deuteron-proton scattering at s = 2800 GeV2

Data on coherent elastic and inelastic deuteron-proton scattering are presented. The measurements were made at the CERN ISR with a single arm spectrometer, at s = 2800 GeV² and momentum transfer squared (?t) in the range 0.15 to 0.42 GeV².The data are compared with elastic and inelastic diffractive proton-proton scattering data taken with the same apparatus at the same s and t values. The t dependence of the elastic dp → dp differential cross section is compared to simple predictions based on Glauber theory. The differential cross sections for pp → pX and dp → dX are also compared for M_X² → 280 GeV², where M_X denotes the mass of system X recoiling against the measured proton and deuteron.     

Photon production in 69 GeV pp interactions

We present results on 728 photon conversions into electron pairs observed in the hydrogen bubble chamber MIRABELLE. The average number of π° per inelastic pp collision is found to be 2.57 ± 0.13 and this number increases with the number n of charged particles up to n=12. The comparison of our invariant cross section F(x, p⊥, s) for the reaction pp → γ X with higher energy results shows that scaling behaviour is probably reached at 70 GeV.     

Total cross section for neutrino charged current interactions at 3 GeV and 9 GeV

Average total cross sections are given for neutrino charged current interactions at neutrino energies of 2.87 GeV and 9.05 GeV. The ratios $\text{〈σ〉}\text{〈E〉}\text{are}\text{0.69 ± 0.05}\text{and}\text{0.61 ± 0.06}$ in units of 10^?38 cm²/GeV nucleon, respectively The errors include both statistical and systematic uncertainties.     

Inelastic hadron-nucleus interactions at 20 and 37 GeV/c

The experiment studies charged particle production for π^?, K^?, and $\text{p}$ interactions on nuclei at 20 and 37 GeV/c at the CERN SPS. A non-magnetic detector, consisting of CsI(Tl) scintillation and lucite ?erenkov counters, distinguishes between fast particles, mainly pions, and slow particles, mainly nucleons, with a cut at velocity β ≈ 0.7. Angular distributions, multiplicity distributions and correlations of slow and fast particles were analysed. It is shown that the measurement of the correlations can provide a critical test for different theoretical models of the hadron-nucleus interaction. At the energies studied so far a systematic deviation from KNO scaling is observed. This gives further support to the “standard picture” of the hadron-nucleus interaction and it contrasts with predictions of the coherent-tube model. The regularity observed for the angular distribution of fast secondaries as a function of the number of slow particles can only be explained by combining features predicted by different models.     

Upper limits for charm production in 150 GeV p-Be interactions

A search has been made for the hadronic production of charmed baryons and mesons with a large aperture forward magnetic spectrometer using 150 GeV protons originating from the CERN-SPS. A prompt electron trigger was used as a signature for charm. Upper limits at 90% confidence level have been obtained for the production of $\text{Λ}{}_{\mathrm{<mtext>c</mtext>}}{}^{\mathrm{+}}\text{D}{}^0\text{,}\text{D}{}^0\text{D}{}^{\mathrm{+}}\text{and D}{}^{\mathrm{?}}\text{: σ(Λ}{}_{\mathrm{<mtext>c</mtext>}}\text{) ? 8 μ}\text{b}\text{, σ(}\text{D}{}^0\text{) ? 64 μ}\text{b}\text{, σ(}\text{D}{}^0\text{) < 37 μ}\text{b}\text{, σ(}\text{D}{}^{\mathrm{+}}\text{) ? 51 μ}\text{b and}\text{σ(}\text{D}{}^{\mathrm{?}}\text{) ? 49 μ}\text{b}$ per nucleon, assuming linear A dependence. Systematic errors due to uncertainties in branching ratios and to model dependence of the acceptance calculation are discussed.     

A study of trimuon events in 280 GeV muon interactions

In 280 GeV μ⁺ iron interactions the inelastic production of muon pairs has been observed in excess of QED processes. For energies greater than 20 GeV deposited in the target calorimeter the interactions are found to be mainly hadronic. Cross sections are presented for this process in the mass range 1?2.5 GeV/c² and in the kinematic regions covered by the apparatus acceptance. The data are in good agreement with a photon-gluon fusion model for charmed particle production.