E. Hafen

Inclusive production of neutral strange particles by 147 GeV/cπ+/K+/p interactions in hydrogen

Results are presented from a study of inclusive neutral strange particle production by a 147 GeV/c tagged π+/K+/p beam in the Fermilab 30-inch hydrogen bubble chamber. The experiment made use of the proportional hybrid spectrometer system. Results are based on 995 KS0, 485 Λ, and 83 Λ found in a sample of 132 000 pictures. Cross sections are given for inclusive production of these particles by each of the three beam particles, and comparisons are made with measurements at other energies. Topological cross sections are also calculated, and KNO multiplicity scaling is investigated. Distributions are presented of invariant cross sections as functions of the Feynman scaling variable x and c.m. rapidity y. The transverse momentum-squared distributions with their fitted slopes are also given. Comparisons are made of the production characteristics for the three beam types.

Cross sections and charged multiplicity distributions for π−p and K−p interactions at 147 GeV/c

Abstract The results presented in this paper were obtained from a 105 000 frame exposure of the FNAL Hybrid Proportional Wire Chamber-30 inch Bubble Chamber System, in a tagged beam of 147 GeV/ c negative particles. Elastic, total and topological cross sections were obtained for both π − p and K − p interactions. Comparisons with other data, taken with various beam particles over large momentum intervals, show good agreement with KNO scaling, and similarity in the scaling behavior of σ n for the different beam particles.

A new method to investigate the nuclear effect in leptonic interactions

Abstract High energy neutrino interactions in a heavy liquid bubble chamber were classified by the presence or absence of dark tracks (stubs) at the interaction vertices. Quark distributions, σ ( x ), were compared in the two groups of data. Those with dark tracks, presumably indicative of an interaction with a deeply bound nucleon, show an enhanced nuclear effect.

Upper limit on the prompt muon flux derived from the LVD underground experiment

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured depth-angular distribution of muon intensities has been used to obtain the normalization factor, A, the power index, gamma, of the primary all-nucleon spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the main parameters which determine the spectrum of cosmic ray muons at the sea level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c<2.0 x 10^-3 (95% C.L.) have been obtained. The upper limit to the prompt muon flux favours the models of charm production based on QGSM and the dual parton model.

The effective-energy dependence of the charged particle's multiplicity in p/π+/K+ interactions on protons at 147 GeV/c

Abstract The energy dependence of the average of the charged multiplicity and its dispersion in π + /K + /p interaction on protons at 147 GeV/ c is found to be the same as in e + e − annihilations if an “effective energy” variable is used instead of the total energy. The effective energy S eff is defined as the invariant mass of all secondaries left after the two leading particles have been removed. Fitting the expression aS eff b to the average charge multiplicity 〈 n ch 〉, we find the power b to be in good agreement with the value of 0.25 predicted by Fermis statistical model and by Landaus hydrodynamical model.

The reactionspp→ppπ+π-,K+p→K+pπ+π−π, π+p→ π+,pπ+π− and π−p →π+π− at 147 GeV/c

We have studied the reactionspp→ppπ+π-,K+p→K+pπ+π−π, π+p→ π+,pπ+π− and π−p →π+π− at 147 GeV/c using the 30-inch Fermilab hybrid system. All four reactions were detected with the same apparatus and analyzed in the same way. The energy dependence of the channel cross section was found to beAp−0.6+B for thepp reaction andAp−1+B for the other three. About 90% of the cross section at 147 GeV/c can be accounted for by either beam or target diffraction. Some of the remaining cross section may come from double Pomeron exchange reactions which we tried to isolate. We have tested the hypothesis of a factorizable Pomeron and our data indicates a violation of this hypothesis. We show that the 3π mass enhancement in the mass region 1.2–1.4 GeV is diffractively produced in the π± beam reactions. Fourprong, four-constraint and six-prong, four-constraint cross sections are reported.

Hadron production inπ+,K+p andpp collisions at 147 GeV/c and properties of jet-like multiparticle systems

The gross features of the data are reviewed and the momentum tensor components, 〈S〉, and 〈T〉 are studied. Evidence for coplanarity effects is observed. A probabilistic method to search for jets is proposed. The jets found by this method are seen to be similar to highpT jets frompp interactionse+e− annihilations andvp interactions. The effect of subtracting the leading particles and the effect of lowpT diffractive and non diffractive components are investigated.

A study of meter size RPCs for large area detectors

Abstract This paper presents new results pertinent to the operation and performance of Resistive Plate Chambers (RPCs) in multi-TeV hadron collider (SSC/LHC) environments. Specifically it is an evaluation of the feasibility of using RPCs for a momentum selectable fast muon trigger, taking into consideration such factors as time resolution, high rate behavior, neutron sensitivity and low noise operation, both intrinsic and induced. New results on chamber lifetime, non-flammable gas operation, and pulsed nitrogen laser activation of RPCs are also discussed.

Approach to scaling in inclusive π+/π− ratios at 147 GeV/c

The ratio of hadronic π+/π− production has been studied in the target fragmentation region of π+p, π−p,K+p andp p collisions at 147 GeV/c beam momentum. The difference between this ratio in the π+p and π−p data is less than at lower energies but still present. No difference exists anymore for the π+/π− ratio at this energy betweenK+p andpp collisions. Exclusion of diffraction dissociation and resonance production does not change the main conclusions. The energy dependence of the ratio for π+p and π−p collisions gives evidence for a universal asymptotic ratio for all beams. Thept-dependence at low-pt is in agreement with the expectation from geometrical correlation of the valence quarks.

Leading particle distributions in 200 GeV/c p+A interactions

Abstract Distributions of the leading positive particle have been measured in collisions of a 200 GeV/ c proton beam with hydrogen, Mg, Ag and Au targets using the FNAL Hybrid Spectrometer. Estimates of the rapidity loss of the projectile have been obtained as a function of the target mass, the multiplicity of negative particles and the number of recoil protons. We obtained a lower limit of the rapidity loss of 2.0±0.2 for central p+Au collisions. The impact parameter dependence of the momenta of the first few leading particles has also been investigated with important implications to estimates of energy densities obtained in central collisions.