A. Subramanian

Multiplicity of charged particles in 800 GeV p-p interactions

Abstract Results are reported concerning the charged-particle multiplicity distribution obtained in an exposure of the high-resolution hydrogen bubble chamber LEBC to a beam of 800 GeV protons at the Fermilab MPS. This is the first time that such data have been available at this energy. The distribution of the number n ch of charged particles produced in inelastic interactions obeys KNO-scaling. The average multiplicity is 〈 n ch 〉 = 10.26±0.15. For n ch ⩾8 the data can be well fitted to a negative binomial. The difference between the overall experimental multiplicity distribution and that resulting from the latter fit is in agreement with the contribution expected from diffractive processes.

Inclusive Charm Cross-Sections in 800-GeV/c p p Interactions

Abstract We report a measurement of the inclusive D/D production cross section in 800 GeV/ c proton-proton interactions. The experiment used the high resolution bubble chamber LEBC exposed to an 800 GeV/ c proton beam at the Fermilab MPS. We obtain σ( D/ D )=59 −15 +22 μ b (statistical errors), having analysed 25% of the total data sample. Comparison with 400 GeV/ c pp dat a obtained with LEBC at CERN shows a D/D cross section increase by a factor of 1.7 −0.5 +0.7 . This is in good agreement with fusion model calculations.

Observation of a dip-bump structure in differential cross section for pp → nn in the 700–760 MeV/c momentum range

Abstract Based on a sample of about 3500 events, we have measured the total and differential cross sections of p p → n n in the 700–760 MeV/c incident momentum region. It is found that σCE = 10.7 ± 0.2 mb at the average momentum of 730 MeV/c. The differential angular distribution is characterised by a sharp peak and a dip in the forward direction followed by a secondary maximum. The position of the dip corresponds to |t| ≈ mπ2. These results are compared with the predictions of the model of Bryan-Phillips. On the other hand, this dip-bump structure can be well understood on a simple picture involving a π exchange and a constant background (for |t| ≲ 3 mπ2).

Properties of pp annihilations into strange particles at 702 and 757 MeV/c

Abstract p p annihilations, leading to the production of at least one neutral K meson in the final state, have been studied in the incident momentum region of 700–760 MeV/ c . Topological cross sections and cross sections for the various exclusive final states are presented. Detailed analyses of the different final states have been carried out to study the importance of resonance production and of quasi two-body and quasi three-body processes. A detailed study of the K K π system in the four-body final states shows that the F 1 meson is a spurious effect due to systematic biases. In the momentum range investigated, the C = +1 final states are strongly suppressed.

Study of the D(1285) and E(1420) resonances produced in pp annihilations at 700–760 MeV/c

In this paper we have investigated the properties of the D(1285) and E(1420) meson resonances using the five-body annihilation channels pp → KKπππ obtained in a large statistics experiment (28 events/μb). The analysis favours the 1+ spin-parity assignment for the D(1285) meson. The dominant decay mode of the D(1285) into KKπ is found to be δ(970)π. The situation concerning the E(1420) meson remains confused although not inconsistent with previous analyses. Partial cross sections on resonance production are also presented.

Test of scale invariance in pion production at high energies using cosmic ray primary nucleon and sea level Muon intensities

Abstract An analysis made using the ratio of intensities of the cosmic ray nucleons at the top of the atmosphere and muons at sea level indicates the validity of the hypothesis of Feynman regarding scale invariance in particle production in the energy region 50 GeV to 2 × 10 4 GeV.

A study of np annihilations around 0.65 GeV/c

Abstract n p annihilations with ⩾ 3 prongs with an incident antineutron momentum between 0.5 and 0.8 GeV/c are analysed. We present the topological branching ratios and cross sections, the resonance production rates and possible ϱ-ω interference effects.

Studies of\(\bar pp \to \bar nn\) and\(\bar np\) annihilation at incident momenta of 700 and 760 MeV/c

AbstractResults are presented on the charge exchange reaction

General features ofK+d interactions at 70 GeV/c

\bar pp \to \bar nn