We present the results of a search for the production of Light elements in (p) over bar p collisions at the Fermilab Tevatron collider. Momentum, time of flight, and dE/dx measurements are used to distinguish nuclei from elementary particles. A production ratio for deuterium to hydrogen is calculated and compared to the primordial value of the big bang model. Some evidence for tritium is found and none for helium isotopes.

This report discusses the following topics on the Soleoidal Detector Collaboration: Summary and overview of the detector; physics and detector requirements; central tracking system; superconducting magnet; calorimetry; muon system; electronics; online computing; offline computing; safety; experimental facilities; installation; test and calibration beam plan; and cost and schedule summary.

The production properties of lambdas (LAMBDA0, LAMBDA0BAR) and cascades (XI-,XI-BAR) in the central region in ppBAR collisions at square-root s = 1.8 TeV at the Fermilab collider are reported. The transverse-momentum spectra of lambdas are measured as a function of multiplicity and the ratios of lambdas to protons (p,pBAR) and to all charged particles are studied as a function of transverse momentum and multiplicity. Moreover the average transverse momentum of cascades and the ratio of cascades to lambdas are presented.

We have studied inclusive photon production from ${\\ensuremath{\\pi}}^{+}p$ interactions at 10.5 GeV/c and found a source of centrally produced direct photons which accounts for (46\\ifmmode\\pm\\else\\textpm\\fi{}9)% of all photons detected with ${{P}_{L}}^{*}$ and ${P}_{T}$ between 0 and 20 MeV/c. The experimental data are found to be in good agreement with a calculation of hadronic inner bremsstrahlung.

With use of the Stanford Linear Accelerator Center hybrid facility 1-m bubble chamber fitted with tantalum plates, a measurement was made of direct unexplained ${e}^{+}{e}^{\ensuremath{-}}$ pair production in 18-GeV/c ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p$ interactions. Limits are set in ${\ensuremath{\pi}}^{+}p$ processes. In ${\ensuremath{\pi}}^{\ensuremath{-}}p$ a signal is observed which cannot be caused by $\ensuremath{\eta}$, $\ensuremath{\omega}$, or $\ensuremath{\rho}$ decay, and for masses $>{m}_{{\ensuremath{\pi}}^{0}}$, $\frac{{e}^{\ifmmode\pm\else\textpm\fi{}}}{{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}}=(0.87\ifmmode\pm\else\textpm\fi{}0.25)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. Some properties of the events are discussed.

Using the Stanford Linear Accelerator Center Hybrid Facility 1-m bubble chamber with tantalum plates, a search was made for single electrons or positrons produced directly in 18-GeV/c ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ interactions. At 90% confidence level (C.L.), $R=\frac{{e}^{\ifmmode\pm\else\textpm\fi{}}}{{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}}<2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. In addition, a limit can be set on charmed particle pair or associated production channels in terms of their semielectronic decay branching ratios, namely, $\ensuremath{\sigma}[{R}_{1}+{R}_{2}]<2.4$ \ensuremath{\mu}b at 90% C.L.

We have measured the Compton electron spectrum coming from photons produced from the decays of ${\ensuremath{\pi}}^{0}$ mesons. The production rate agrees well with that predicted from the Klein-Nishina formula. The agreement, expressed as a ratio $R$ between the predicted and the measured numbers of Compton electrons, is as follows: For Compton-electron energies between 0.1 and 5.0 GeV, $R=1.03\ifmmode\pm\else\textpm\fi{}0.07$; for energies between 0.8 and 5.0 GeV, $R=0.95\ifmmode\pm\else\textpm\fi{}0.14$.

Detailed studies of ..pi../sup +/Ne and ..pi../sup -/Ne interactions at 10.5 GeV/c have been carried out. Multiplicities, correlations, and inclusive momentum and rapidity spectra for ..pi../sup +/, ..pi../sup -/, ..pi../sup 0/, and p are reported. Average multiplicities for K/sup 0/ and ..lambda../sup 0/ production are also determined. Comparisons are made to results from ..pi..p interactions. Relative to ..pi..p collisions, pion production is enhanced in the target-fragmentation region but not in the central or projectile-fragmentation regions. Many of the pion production properties can be understood in terms of a simple kinematical model in which the effective target mass is greater than a nucleon mass. A surprising number of energetic protons are observed (laboratory momentum > or approx. = 1.3 GeV/c). For shower-track multiplicities approx.8, the produced nucleons are found to carry away an average of 40% of the incident momentum, indicating the possible existence of previously unrecognized mechanisms for the efficient momentum transfer to nucleons in particle-nucleus collisions.

Using bubble-chamber data on the reactions ${\ensuremath{\pi}}^{+}d\ensuremath{\rightarrow}{p}_{s}p{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$, ${\ensuremath{\pi}}^{+}d\ensuremath{\rightarrow}{p}_{s}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}n{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ at 7 GeV/c incident $\ensuremath{\pi}$ momentum, $\ensuremath{\pi}\ensuremath{-}\ensuremath{\pi}$ phase shifts are determined for $0.6<M(\ensuremath{\pi}\ensuremath{\pi})<1.5$ GeV/${\mathit{c}}^{2}$. An $I=0$$S$-wave resonance is observed in the ${f}^{0}$ peak region of $M(\ensuremath{\pi}\ensuremath{\pi})$. Constructive $\ensuremath{\rho}\ensuremath{-}\ensuremath{\omega}$ interference is found in the reaction ${\ensuremath{\pi}}^{+}n\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and evidence is presented for some specifically deuteron effects in the data with large spectator-proton momentum.

A partial-wave analysis of the charged three-pion system in the reaction π−p→pπ+π−π− for incident π− momenta from 5 to 25 GeV/c shows the existence of a broad enhancement (∼ 300 MeV) in the JP=2−fπ (S-wave) state in the region of the A3(1650). No other state (J≤4) shows structure in this region. Upper bounds for ρπ and επ decay modes of the A3 are given. The interference of the 2−fπ (S-wave) amplitude with other amplitudes has been observed. The mass variation of the phase of the 2−fπ (S-wave) amplitude measured with respect to the phases of other amplitudes does not show the behavior expected for the relative phase between resonant and nonresonant amplitudes. Results are given on the polarization and momentum-transfer dependence of the A3 and on the A3 production cross section as a function of incident π− momentum.Received 17 July 1972DOI:https://doi.org/10.1103/PhysRevD.7.669©1973 American Physical Society