Search

We have used the Fermilab 30-in. bubble chamber--hybrid spectrometer to study the rapidities of produced particles'' in the interactions of 200-GeV/{ital c} protons and {pi}{sup +} and {ital K}{sup +} mesons with nuclei of gold, silver, and magnesium. The average rapidity decreases linearly with the number of projectile collisions {nu}{sub {ital p}} (up to {nu}{sub {ital p}}=5) with no {ital A} dependence and little beam dependence. The ratio {ital R} of normalized rapidity distributions for hadron-nucleus to hadron-proton interactions shows a plateau in the central region, and becomes much larger in the target region. However, the increase is significantly less than has been reported in previous experiments. As a function of {nu}{sub {ital p}}, the ratio {ital R} rises linearly in the target region, more gently in the central region, and decreases slowly in the projectile region, in all cases with no {ital A} dependence. Some discrepancies with a previous experiment are observed in the central region. Long-range rapidity correlations are observed in hadron-nucleus events, but not in hadron-proton events. For the former, it is shown that the correlations exist only for those events with multiple projectile collisions, as expected in the multichain dual parton model.

Diffraction dissociation of both the beam and target particles has been observed in 150-GeV/c ..pi../sup -/p interactions in the Fermilab 30-in.-bubble-chamber--proportional-wire-chamber hybrid spectrometer. The dissociations are observed as recoil systems opposite leading particles, the signals of which are separated from background where appropriate by a variant of the Van Hove sector cut, thus allowing the high-mass portion of the spectrum to be observed. Pion dissociation has a cross section of 1758 +- 105 ..mu..b, divided among two-, four-, and six-prong events; some rho/sup 0/ production is seen and comes primarily from the ..pi../sup -/ ..-->.. 2..pi../sup -/..pi../sup +/ channel. The proton dissociation cross section is 1726 +- 100 ..mu..b, again divided among two-, four-, and six-prong events. The final state contains a neutron more frequently than a proton in the two- and six-prong events, a proton more frequently in the four-prong events. Production of ..delta../sup + +/ is observed in the p ..-->.. p..pi../sup +/..pi../sup -/ dissociations.

From a study of 8-GeV/c ..pi../sup -/p interactions, the various two-pion and four-pion decay channels available to the g/sup -/ meson have been investigated. Our results indicate that the dominant 4..pi.. decay modes involve intermediate rho and ..omega.. production without significant A/sub 2/ formation.

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.

We have studied the inclusive production of K/sup asteriskplus-or-minus/(890) and Y/sup asteriskplus-or-minus/(1385) in pp, ..pi../sup +/p, and K/sup +/p interactions at 147 GeV/c. The experiment used the Fermilab 30-inch hydrogen bubble chamber with the hybrid spectrometer system. Results are based on a sample of 1916 observed K/sub S/ and 932 observed ..lambda... Inclusive cross sections are given for K/sup asteriskplus-or-minus/ and Y/sup asteriskplus-or-minus/ production from the three beams, and comparisons are made with experiments at other energies. Feynman-x and transverse-momentum-squared distributions are also calculated. The results suggest that the K/sup asterisk-/ is entirely produced in the central region, while the K/sup asterisk+/ includes a component from beam fragmentation. Comparisons are made with the additive quark model.

We have studied inclusive ${\ensuremath{\rho}}^{0}$ and ${\ensuremath{\Delta}}^{++}$ production in ${\ensuremath{\pi}}^{+}p$ and ${\ensuremath{\pi}}^{\ensuremath{-}}p$ interactions at 15 GeV/c in a region where pion exchange has been found to dominate the resonance production. By using ${\ensuremath{\rho}}^{0}$ production, the off-mass-shell interactions of virtual pions with the target protons have been studied and compared with the same on-shell reactions at comparable energy. No significant differences between on-shell and off-shell reactions have been found in topological-cross-section ratios, inclusive longitudinal- or transverse-momentum distributions, or elastic $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ distributions. The effect of the negative mass squared of the virtual pions has also been studied. Inclusive ${\ensuremath{\Delta}}^{++}$ production has been found to be dominated by pion exchange for $|t|\ensuremath{\lesssim}0.4$ (${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. We have studied the interactions of these off-shell pions with the beam pions as a function of energy. The ratio $\frac{{\ensuremath{\sigma}}_{\mathrm{el}}}{{\ensuremath{\sigma}}_{T}}$ and the average charged-particle multiplicities $〈{n}_{X}〉$ have been examined and compared with those for various hadron-proton reactions. The values of $〈{n}_{X}〉$ have also been studied in terms of a simple model and found to give results consistent with studies at higher energies. We also present longitudinal- and transverse-momentum distributions for produced pions, as well as $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ distributions for $\ensuremath{\pi}\ensuremath{\pi}$ elastic scattering.

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 highp T jets frompp interactionse + e − annihilations andvp interactions. The effect of subtracting the leading particles and the effect of lowp T diffractive and non diffractive components are investigated.

The Fermilab hybrid 30-in. bubble-chamber spectrometer was exposed to a tagged 147-GeV/c positive beam containing ..pi../sup +/, K/sup +/, and p. A sample of 3003 K/sup +/p, 19 410 pp, and 20 745 ..pi../sup +/p interactions is used to derive sigma/sub n/, , f/sub 2//sup tsc/c, and /D for each beam particle. These values are compared to values obtained at other, mostly lower, beam momenta. The overall dependence of on E/sub a/, the available center-of-mass energy, for these three reactions as well as ..pi../sup -/p and pp interactions has been determined.

In an experiment with the 30-inch Hybrid Spectrometer at Fermilab we have obtained the inclusive and semi-inclusive production cross sections of the ϱ0 meson using a conventional background subtraction technique. Production cross sections for the ϱ0 are derived as a function of the Feynman scaling variablex, and the transverse variablespt2 andEt=(pt2+M2)1/2. The longitudinal distributions are compared with the (1−x) dependence of the proton and meson valence quark structure functions, using various forms of recombination and fragmentation models. The transverse distributions are compared with thermodynamic models. We give density matrix elements for the ϱ0 production from pions in the extreme forward region.

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. Thep t -dependence at low-p t is in agreement with the expectation from geometrical correlation of the valence quarks.

We have done an inclusive study of ϱ0 production in π−p interactions at 15 GeV/c. Evidence for two different production mechanisms, in addition to the known quasi two-body processes, is presented: production of ϱ0's in the central region of rapidity similar to the “pionization” region seen in the inclusive studies of pions; and forward production in the beam dissociation region of rapidity. Cross sections and rapidity distributions for the ϱ0 are given inclusively and by topology, and the results are compared with similar studies at other energies and with other incident particles. Results are also presented for the semi-inclusive reaction π−p → pϱ0 + X− and the exclusive final state pπ−ϱ0.

Results are reported based on a study of π − p interactions at 147 GeV/ c in the FERMILAB 30-inch Proportional Wire Hybrid Bubble Chamber System. We have measured the topological cross sections and separated two-prong elastic and inelastic channels. In addition, we have extracted leading particle cross sections using the increased momentum resolution of the downstream proportional wire chambers. We have compared our results with experiments and predictions of a simple fragmentation hyphothesis.

We present data on inclusive and semi-inclusive ϱ 0 production in 147 GeV/ c π − p interactions. We find a total cross section of 7.3 ± 1.3 mb. Most of this cross section is found in the lower topology events (⩽ 10 prongs), and in the central and forward rapidity regions. The P T 2 dependence of ϱ 0 production, 〈: n > ϱ 0 per event, and the ϱ 0 / π + ratios are also discussed.

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.

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 Fermi's statistical model and by Landau's hydrodynamical model.

An analysis is presented of the production of jets in low-ptπ±p,k+p,pp collisions at 147 GeV/c collected at Fermilab in the rapid cycling hydrogen bubble chamber hybrid spectrometer. It is shown that selected events are more planar than predicted by a cylindrical phase space, but that 3-jet and 4-jet like structures seen in the momentum flows are reasonably reproduced by the cylindrical phase space events subjected to the same mathematical manipulation required to build momentum flows.

A study of charged particle production in 147 GeV/c π − p collisions yields no evidence for an electrically neutral central region or corresponding rapidity plateau. The results do indicate that electric charge and transverse momentum may be locally conserved over small intervals on the rapidity axis. These results support a picture in which the observed hadrons are emitted in clusters whose quantum numbers vary as a function of rapidity and reflect the incident channel quantum numbers at the extremes of the rapidity scale.

In this paper we present new data for the reactions π−p→pslow+X− and π−p→πfast− + X+ at 147 GeV/c. This is the first time that experimental information on these two processes has been obtained using the same apparatus at Fermilab energies. The triple-Regge formalism is applied to the differential cross sections dσ/dMx2 of both reactions using all the data at present available in the literature. A good description of the data is obtained when parameters from a triple-Regge fit of the reaction pp → p + X are used, together with the assumption of factorization of the pomeron and the reggeons. The equality of the dσ/dMx2 distributions of the two reactions may be explained in terms of an interesting assumption in the framework of the independent quark model and imposes an additional relation between the triple-Regge terms.

We present in this paper a study of the ..delta../sup + +/(1232) inclusive production for momentum transfer squared to the target proton, vertical-bartvertical-bar < 1 (GeV/c)/sup 2/. We have investigated the production mechanism of the ..delta../sup + +/ by measuring its density matrix elements as a function of t and of the missing mass squared, M/sub X//sup 2/, and by carrying out a triple-Regge analysis. For vertical-bartvertical-bar < 0.4 (GeV/c)/sup 2/, the ..delta../sup + +/ production mechanism is consistent with one-pion exchange. We have also studied the average charged multiplicity recoiling from the ..delta../sup + +/ as a function of M/sub X//sup 2/, for vertical-bartvertical-bar < 0.4 (GeV/c)/sup 2/. The study yields information about the ..pi../sup -/..pi../sup -/ average charged multiplicity.

Four low-mass “diffractive like” reactions π ± p → π ± (p π 0 ) and π ± p → π ± (n π + ) have been studied at 3.9 GeV/ c incident pion momentum. These channels have been studied in the framework of a two-component model and we have proposed a definition of the diffraction dissociation amplitude. The following three features of the data are discussed: (1) an apparent violation of the predictions of isospin invariance for the cross section ratios, (2) the marked anisotropy of the s -channel helicity distributions and (3) the absence of the cross-over effect in the differential cross sections. The predictions of a two-component model previously used to explain the low mass I = 1 2 ( N π) enhancement [1] and s - and t -channel helicity non-conservation [2] are seen to be in agreement with these observations. Predictions are also made for higher energy incident pions and incident K, p, and p projectiles. These predictions are compared with available data including recent results at Fermilab and ISR energies.

The experimentally determined average charged-particle multiplicities, , of the systems, X, produced in the following reactions for 147 GeV/c incident pion momentum are presented as functions of the square of the invariant mass of X, M/sub x//sup 2/, and of *t*: ..pi../sup -/p ..-->.. ..pi../sup -//sub fast/X, ..pi../sup -/p ..-->.. pX, ..pi../sup -/p ..-->.. ..delta../sup + +/X, ..pi../sup -/p ..-->.. (..pi../sup -/..pi../sup +/)/sub rho//sup 0/X, and ..pi../sup -/p ..-->.. ..lambda../sup 0/X. Details of the analysis are discussed. These data can be fit by the expression = A + BlnM/sub X//sup 2/ + C*t* and the coefficients obtained for B are equal within their uncertainties. C is significantly different from zero only for ..pi../sup -/p ..-->.. ..pi../sup -//sub fast/X.

Results from a high-statistics experiment involving an exposure of the SLAC 82-in. hydrogen bubble chamber to a beam of 8-GeV/c ..pi../sup -/ yielding a final state of ..pi../sup -/..pi../sup +/..pi../sup -/p are presented. Copious production of rho, ..delta../sup + +/, and f is found. Considerable quasi-two-body production in which one particle decays to one of the above resonances is also observed. Some double-resonance production involving baryon and meson resonances is also seen. The production properties of rho, ..delta../sup + +/, and f mesons are well described by a double-Regge model.

A recently proposed method of calculating experimental lower bounds, b L , on the root-mean-squared impact parameter of multiparticle processes has been applied to a variety of reactions in π − p interactions at 15 and 147 GeV/ c . The values obtained for b L show a decrease of the root-mean-squared impact parameter with increasing multiplicity at fixed energy and a very slow increase, if any, of b L with energy at fixed multiplicity. Furthermore, the results might indicate that absorption effects in multiparticle production in π − p interactions are not important. The transverse momentum transfer correlation matrices calculated in this paper have a diagonal form in agreement with multiperipheral type models.

We examine the polarization properties exhibited by ${\ensuremath{\rho}}^{0}'\mathrm{s}$ and ${\ensuremath{\omega}}^{0}'\mathrm{s}$ in the reactions ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}+{X}^{0}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\omega}}^{0}+\mathrm{charged}\mathrm{particles}$ at 15 GeV/c. ${\ensuremath{\rho}}^{0}$ production is analyzed in the framework of the triple Regge model. The trajectory coupled to the ${\ensuremath{\pi}}^{\ensuremath{-}}$ ${\ensuremath{\rho}}^{0}$ is $\ensuremath{\alpha}(t)=(\ensuremath{-}0.12\ifmmode\pm\else\textpm\fi{}0.07)+(0.78\ifmmode\pm\else\textpm\fi{}0.21)t$ in good agreement with the $\ensuremath{\pi}$ trajectory. The properties of the system recoiling against the ${\ensuremath{\rho}}^{0}$ (off-shell $``{\ensuremath{\pi}}^{\ensuremath{-}}''p$ reaction) are very similar to those of the final states of on-shell ${\ensuremath{\pi}}^{\ensuremath{-}}p$ reactions at the same center-of-mass energy.

Distributions with respect toz andzR for the fastest and second fastest particles produced in both beam and target hemispheres from 147 GeV/c π− interactions are compared with each other and with the distributions for the fastest and second fastest particles from deepinelastic leptoproduction and Field-Feynman curves. The distributions and curves for the fastest particles are very similar, with the exception of the identified protons. Those for the second fastest are in agreement. Distributions with respect toz′R for the first through fourth fastest particles (excepting the protons) are all similar, suggesting that the shape of the distributions may be determined by the available longitudinal phase space.

A new method of analysis (leading charge model) based on the zone graph technique is used to separate charged particles produced in the target, projectile and central regions of phase space. A significant fraction of the centrally produced particles follow a Bose momentum distribution with temperature of 131 ± 2 MeV.

We report on the interactions of an incident 200 GeV / c beam composed of 33% protons, 16% kaons, and 48% pions on targets of silver and gold mounted in the Fermilab 30″ bubble chamber. Within our limited statistics, we find the total cross sections and average multiplicities to agree with previously published data. We find the KNO scaling distribution curve to be broader for heavy nuclei than for hydrogen. We present the first data for V0 production on gold and silver. We also present, for the first time, evidence for a positive charge excess among the sample of relativistic tracks from interactions on gold and silver. We observe a trend where the positive charge excess increases with target atomic number and with increasing charged particle multiplicity. We find the charge excess to exist among the sample of particles having greater than 2 GeV / c momentum and to persist in the sample with momentum greater than 4 GeV / c.

The results of a study of the reaction π-p→π-π-π+p at 2 147 GeV/c carried out at the Fermilab Proportional Wire 30″ Bubble Chamber Hybrid Spectrometer are reported. More than 92% of the cross-section ((670±41) μb) for this reaction is contained in those for proton and pion diffraction dissociation. The cross-sections for pion diffraction events with three-pion invariant mass in given regions are in agreement with values obtained by extrapolation of fits to data at lower incidentpion momenta. ρ0π- events make an important contribution in the A1 and A2 mass regions, and the data are consistent with contributions from f0π- in the A3 mass region. The cross-section for proton diffraction events is in agreement with a smooth extrapolation of the data at lower momentum.

The inclusive production of the ${\ensuremath{\Delta}}^{++}(1232)$ resonance in ${\ensuremath{\pi}}^{\ensuremath{-}}p$ collisions at 147 GeV/c has been studied. The ${\ensuremath{\Delta}}^{++}$ is found to be produced in comparable amounts in four-, six-, eight-, and ten-prong events. The Feynman-$x$, ${t}^{\ensuremath{'}}$, ${{P}_{T}}^{2}$, and the decay angular distributions of the ${\ensuremath{\Delta}}^{++}$ are found to be consistent with the predictions of a one-pion-exchange model with absorption. Essentially all of the ${\ensuremath{\Delta}}^{++}$ are found to be associated with a ${\ensuremath{\Delta}}^{++}$${\ensuremath{\pi}}^{\ensuremath{-}}$ low-mass enhancement. The ${\ensuremath{\Delta}}^{++}$ cross section is approximately constant from 11 to 205 GeV/c, which could indicate that the ${\ensuremath{\Delta}}^{++}$ is a decay product of a target-fragmentation object. While the one-pion-exchange character of the ${\ensuremath{\Delta}}^{++}$ production and the target-fragmentation character of the ${\ensuremath{\Delta}}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}$ low-mass enhancement can both be described in terms of a Deck-type diagram, a Monte Carlo study indicates that any mechanism that produces particles with limited transverse momentum will yield a ${\ensuremath{\Delta}}^{++}{\ensuremath{\pi}}^{\ensuremath{-}}$ low-mass enhancement.

A study of the inclusive production of ${K}_{S}^{0}$, $\ensuremath{\Lambda}$, and $\overline{\ensuremath{\Lambda}}$ in ${\ensuremath{\pi}}^{\ensuremath{-}}p$ interactions at 15 GeV / c is presented. Inclusive cross sections for single neutral strange particles and neutral-strange-particle pairs are given. Longitudinal- and transverse-momentum distributions of the produced particles are presented. The average charged multiplicities of the systems recoiling against the $\ensuremath{\Lambda}$ and the ${K}_{S}^{0}$ are compared and the results analyzed in the framework of a simple model. The $\ensuremath{\Lambda}$ polarization is found to be in good agreement with $\ensuremath{\Lambda}$ production from other strangeness-nonannihilating processes. Production of $\ensuremath{\Lambda}'\mathrm{s}$ in the target fragmentation region is studied in the framework of the triple-Regge-pole-exchange model. The cross section for inclusive ${K}^{*+}(890)$ production has been measured as 195 \ifmmode\pm\else\textpm\fi{} 35 \ensuremath{\mu}b, and the ${\ensuremath{\Sigma}}^{+}(1385)$ inclusive cross section has been found to be 174 \ifmmode\pm\else\textpm\fi{} 25 \ensuremath{\mu}b. The ${K}^{*+}(890)$ and ${\ensuremath{\Sigma}}^{+}(1385)$ differential cross sections as functions of rapidity and transverse momentum are presented and discussed.

We have searched for the production of long-lived R-..delta../sup + +/ hadrons, which contain a gluino in addition to three up quarks, in pp, ..pi../sup +/p, and K/sup +/p interactions at 147 GeV/c. For R-..delta../sup + +/'s of lifetime greater than 10/sup -9/ sec, and laboratory momentum greater than 2 GeV/c, we place 90%-confidence-level upper limits of 6.1 ..mu..b in pp collisions, 4.4 ..mu..b in ..pi../sup +/p, and 29 ..mu..b in K/sup +/p.

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.

We have used the Fermilab 30-in. bubble-chamber hybrid spectrometer to study multiparticle production in the interactions of 200-GeV/c protons and ..pi../sup +/ and K/sup +/ mesons with nuclei of gold, silver, and magnesium. We find that the multiplicities of produced particles and negative particles increase linearly with the number of projectile collisions, with no beam or target dependence. The number of secondary collisions in the nucleus increases significantly less rapidly with the number of projectile collisions than has been reported by a streamer chamber experiment. The properties of secondary collisions suggest that they arise from rescattering of recoil nucleons rather than intranuclear cascade of produced particles. Dispersions of multiplicity distributions at fixed impact parameter are in better agreement with a model of independent sources than with Koba-Nielsen-Olesen scaling.

We have studied a sample of events taken in the SLAC 82″ chamber and measured by PEPR. These events contain an identified proton with momentum less than 1 GeV/c. We have isolated the produced ρ0 and ω in these events and have been able to classify them as to production mechanism. We find that these vector mesons are mainly decay products of diffractively produced mesons.

This report describes a wafer-scale design for an infrared focal place processor (FPP) to operate in a space environment. The functions of a generic focal plane processor are described, followed by a detailed discussion of a design to be implemented in RVLSI wafer-scale technology for a space-based application. A prototype of this processor (PFPP) will actually be fabricated in rad-hard silicon-on-insulator 3-micrometers technology. Finally, the question of reliability is explored, and a philosophy of fault tolerance is presented which will lead to a reasonable probability of success over a five-year lifetime. Keywords include: Focal plane processor, Infrared detector, Wafer-scale integration, VLSI, Time-dependant Fault tolerance, and Image processors.