J. C. Vander Velde

Production of γ, Λ°, Ks° and Λ° in pp collisions at 102 GeV/c☆

Abstract We have measured cross section for γ , K S °, Λ and Λ production at 102 GeV/ c and find: σ ( γ ) = 170 ± 16 mb ., σ ( K S °) = 4.6 ± 0.5 mb ., σ ( Λ ) = 3.2 ± 0.4 mb ., and σ( Λ ) = 0.23 ± 0.10 mb. Both 〈 n π °〉 and 〈 n Ks °〉 appear to rise linearly with n - while the ratio 〈 n Ks °〉/〈 n π °〉 is approximately independent of n - . The integrated invariant cross section as a function of x as well as d σ /d y and d σ /d p T 2 are presented and compared with other data.

Study of reactions with an identified proton in pp interactions at 69 GeV/c

Abstract The reactions p + p → p + X and p + p → Δ ++ + X at 69 GeV/ c are studied in the Mirabelle bubble chamber at Serpukhov. The distribution of x and missing masses M 2 to the identified proton are shown for different topologies as well as t ′ distributions for different M 2 intervals. The cross section for the single diffractive process is evaluated. Peripheral production of a low-mass Δ ++ π − system is observed.

Antiproton proton annihilations at 1.6-2.2 GeV/c into final states with a K1o meson

Abstract Antiproton proton annihilations into final states containing at least one K1o meson have been studied in a 150 000 picture bubble chamber experiment. The experiment covered six incident antiproton momenta in the range 1.6–2.2 GeV/c. Cross sections at each incident momentum are determined for the more abundantly produced final states, and momentum averaged cross sections are determined for some rarer final states, including K 0 K 0 and K 0 K 0 K + K − . Copious resonance production, including double resonance production, is observed, and percentage contributions of different resonance channels are evaluated. Cross sections and resonance fractions are compared with results of other experiments at antiproton momenta in the range 0.7–3.7 GeV/c.

Predictions and tests of the hypothesis of limiting fragmentation

Abstract It is shown that the hypothesis of limiting fragmentation predicts the way in which the cross sections for production of fast particles in the laboratory should scale with beam energy. The agreement with experiment is investigated for the production of protons and pions in p-p and p-aluminum collisions in the beam momentum range 12 to 70 GeV/c.

Homogeneous Solid State Ionization Detector

A gold-doped silicon crystal was used to measure the most probable energy loss and energyloss distribution of π- mesons at 1.50 Bevç and 2.55 Bev/c. The crystal used was 2 cm in diameter and .25 cm thick. The preparation of the detector is discussed. The results confirm the existence of a density effect in the relations describing the dependence of the most probable energy loss on particle momentum. The energy-loss distribution appears to be broader than the predicted width.

Recent Results from the NAL Bubble Chamber

We present a summary of results obtained during the last few months from the 30‐inch hydrogen bubble chamber at National Accelerator Laboratory.

Rho-omega interference in pp → 4π at 1.6 – 2.2 GeV/c☆

Abstract The π + π − mass spectrum from over 3000 events of the reaction pp→ π + π + π − π − at 1.63–2.20 GeV/ c shows evidence for ρ−ω interference. If we allow for ρ-background interference the evidence is weak in our total data, but is strong when we make a particular cut on the momentum transfer, from the proton or antiproton to the π + π − . A fit to the data with this cut gives a lower limit on the branching ratio ω → π + π − to ω → π + π − π o of 1.9% (95% confidence level).

Search for Ultra High Energy (UHE) γ-ray counterparts of BATSE 3B catalog events

We search for a Ultra High Energy (E>1014 eV) counterpart source to cosmic γ-ray bursts detected with the BATSE detectors. Using the 3B catalog positions, we examine 115 candidate bursts with the CASA-MIA detector for UHE γ-ray emission at or near the time of the observed γ-ray burst. No statistically significant excess of γ-rays is found from any of the candidate event regions. Based upon these results, we calculate the flux limits for UHE emission from these candidate event regions. Typical 95% confidence level flux limits are about 6×10−12 γ  cm−2 sec−1 at a γ-ray detection threshold of 160 TeV.

The Irvine — Michigan — Brookhaven Deep Underground Detector — A Progress Report

We report on the development of an 8000 ton detector designed to study nucleon stability. Design criteria are reviewed and additional physics objectives, within the capabilities of the current detector, are noted.

Properties of Hadrons Produced by Neutrinos in Hydrogen

I will discuss some results on the properties of single and correlated hadrons made in the hadron “jet” via the reaction νp → µ− + jet. We know the direction of the jet to within ± 1° in these events and the vector momenta of the individual charged hadrons are measured to better than a few per cent. Hence we have an excellent method for studying the detailed properties of hadron jets.