Sulamith Goldhaber

Meson exchange in the reaction K+ + p → K∗ + N∗

The four-particle final states of the K/sup +/-p interaction at 1.96 Bev/ c were investigated. It is found that these states are predominantly produced via the double resonance production K/sup +/ + p yields K/sup */ + N/sup */. The experimental data support a spin-zero meson exchange, presumably a meson( pi ), for small four-momentum transfers. The four particles produced in the reaction are in the isotopic spin T = 1 state and occur in five possible charge combinations. The observed cross sections of these reactions and the branching ratios expected on the assumption that the nucleon and meson( pi ) are always produced in the T = 3/2 state and that the meson (K) and ( pi ) are always produced in the T = 1/2 state are presented. (C.E.S.)

Observation of correlations between vector-meson and baryon-resonance decays☆

Author(s): Goldhaber, Gerson; Brown, John L.; Butterworth, Ian; Goldhaber, Sulamith; Hirata, Allan A.; Kadyk, John A.; Shen, Benjamin C.; Trilling, George H.

The K+p interaction from 864 to 1585 MeV/c; Cross sections and mass distributions☆

Abstract In this paper we present, for five momenta from 864 to 1585 MeV/c, cross sections for stable final states and for resonance production, and an analysis of the KNπ Dalitz plots including the effects of K ∗ (891) − Δ(1236) interference. We see strong interference at all momenta where the K∗ is present, with the relative phase of the K∗N and KΔ amplitudes remaining constant as a function of momentum. We combine our cross-section results with those from other experiments to study the momentum dependence of the partial cross sections in the region of the 1250 MeV/c peak in the total cross section; we find that the total cross-section curve can be represented as the sum of partial cross-section curves, each one smooth and without a peak corresponding to that in the total cross section. Thus this structure is not due to structure in any single partial cross section, but rather to the sharp rises of the single- and double-pion-production channels at widely separated thresholds. This interpretation is at variance with a conventional resonance interpretation of the observed structure in the total cross section.

Properties of negative K-mesons

SummaryAn analysis of interactions of 420 MeV/c K−-mesons incident on a nuclear emulsion stack has been carried out. By following K−-mesons along the track, we obtained information on the interaction of K−-mesons in flight and at rest. The differential scattering cross-section was fitted with diffraction scattering off a black disk with radius 1.32 ·A1/3 fermis in agreement with the total reaction cross-section. A compilation of K−-H elastic scattering and absorption events is presented, giving cross-sections of Σkh (scattering)= (48.4−11+15) mb and (ΣKH (absorption) = (11.4-5+9) mb. The inelastic scattering of K−-mesons in complex nuclei has been found to be only 4% of the absorption cross-section. The average energy losses in K− inelastic scattering events is ~ 50% of the incident K energy, in contrast to a 25% loss for K+ inelastic scattering. In the course of this work we have observed a number of decays in flight. Combining these with earlier data, we obtain a mean life of τκ-=(1.3+0.4-0.3)·10-8s. We have identified some of the secondaries from decays in flight, namely 2 Kπ2, Kμ2, and 1Ke3. From K−-H absorption events we have obtained a Σ−Σ+ mass difference of (13.9±1.8) me and a value of the K- mass of (966.7±2.0) me. From an analysis of the charged pion spectrum obtained from K- interactions at rest, it was possible to calculate the ratio of λ to Σ hyperons produced in the primary interaction. We find that in the primary K− nucleon absorption reaction, Σ-hyperon formation dominates over λ-hyperon formation. An energy and strangeness balance shows that 70% of the K− stars at rest emit a λ-particle. This means that about 60% of the Σ-hyperons that are produced are converted to λ-hyperons inside the nucleus in which they were formed.Riassuntoè stata eseguita l’analisi delle interazioni dei mesoni K− di 420 MeV/c incidenti su un paoco di emulsioni nucleari. Seguendo i mesoni K− lungo la traccia abbiamo ottenuto informazioni sull’interazione dei mesoni K− in volo e a riposo. La sezione d’urto differenziale è stata adattata alla sezione d’urto totale della reazione, con uno scattering per diffrazionè con raggio 1.32 A1/3 fermi in accordo con la sezione d’urto totale della reazione. Si presenta una compilazione di eventi di scattering e di assorbimento K−-H, dando sezioni d’urto di ΣKH (scattering) = (48.4−11+15) mb e ΣHK (assorbimento) = (11.4−5+9 ) mb. Lo scattering inelastico dei mesoni K− in nuclei complessi è stato trovato essere solo il 4% della sezione d’urto di assorbimento. Le perdite medie di energia negli eventi di scattering K− anelastici è ~50% dell’energia dei K incidenti in contrasto con la perdita del 25% per gli scattering K+ anelastici. Nel corso del presente lavoro abbiamo osservato alcuni decadimenti in volo. Combinando questi con dati precedenti otteniamo una vita media Τk− = (1.3−0.3+0.4.10-8 s. Abbiamo identificato alcuni dei secondari dei decadimenti in volo: 2 Kπ2, 2 KΜ2 e 1 Ke3. Dagli eventi di assorbimento K−-H abbiamo ottenuto una differenza di massa Σ--Σ+ di (13.9 ± 1.8) me e per la mass del K− il valore (966.7 ± 2.0) me. Dall’analisi dello spettro dei pioni carichi ottenuto dalle interazioni K− a riposo è stato possibile calcolare il rapporto fra gli iperoni A e Σ prodotti nell’interazione primaria. Troviamo che nella reazione primaria di assorbimento di un K−, la formazione di iperoni Σ prevale sulla formazione di iperoni λ. Il bilancio energetico e della stranezza mostra che il 70 % delle stelle K− a riposo emettono una particella λ. CiÒ significa che circa il 60 % degli iperoni Σ prodotti si convertono in iperoni λ all’mterno del nucleo in cui si formano.

The k+ p interaction from 864 to 1585 mev/c - angular distributions for inelastic scattering

Abstract We present angular distributions for production and decay of the quasi- two-body final states KΔ(1236) and K ∗ (891)p produced in K + p interactions at 864, 969, 1207, 1367 and 1585 MeV/ c . The analysis of these distributionsleads to the following conclusions: (a) KΔ(1236) production near threshold is largely via P-waves and is, except for coupling constants, fairly well approximated at all momenta by the predictions of the Stodolsky-Sakurai ϱ-exchange model; (b) K ∗ (891)p production appears dominated by vector exchange down to threshold, and no evidence of significant relative increase in pseudoscalar exchange contribution at low energy is seen; (c) study of the partial-wave structure of KΔ(1236) production shows no evidence of resonant behavior at the total cross-section peak near 1200 MeV/ c .

Example of an Antiproton-Nucleon Annihilation

The existence of antiprotons has recently been demonstrated at the Berkeley Bevatron by a counter experiment. The antiprotons were found among the momentum-analyzed (1190 Mev/c) negative particles emitted by a copper target bombarded by 6.2-Bev protons. Concurrently with the counter experiment, stacks of nuclear emulsions were exposed in the beam adjusted to 1090 Mev/c negative particles in an experiment designed to observe the properties of antiprotons when coming to rest. This required a 132 g/cm2 copper absorber to slow down the antiprotons sufficiently to stop them in the emulsion stack. Only one antiproton was found in stacks in which seven were expected, assuming a geometric interaction cross section for antiprotons in copper. It has now been found that the cross section in copper is about twice geometric, which explains this low yield.

THE A1 AND K(1320) PHENOMENA -- KINEMATIC ENHANCEMENTS OR MESONS?

In this article we discuss the similarity, down to some very fine details, between the well-known A 1 phenomenon and the more recently discovered K** (1320) phenomenon. We wish to point out that this similarity is truly remarkable and can hardly be coincidental.

The Antiproton-Nucleon Annihilation Process (AntiprotonCollaboration Experiment)

In the exposure to a 7 0 0-MeV/c negative particle beam, 35 antiproton stars have been found. Of these antiprotons, 21 annihilate in flight and three give large-angle scatters ( {Theta} > 15 , T{sub P-} > 50 Mev), while 14 annihilate at rest. From the interactions in flight we obtain the total c r o s s section for antiproton interaction

The lifetime of the τ-meson

SummaryStacks of nuclear emulsions were exposed to the positive K-mesosn beam at two different distances from the target of the Berkeley Bevatron (proper time of flight + slowing-down time: 1.8· 10-9 s and 1.3·10-8 s respectively). The mean lifetime of τ-meson determined from these exposures is (1.0-03+07)·10-8 s.

Interactions and decay of positive K-particles in flight

Author(s): Goldhaber, Gerson; Goldhaber, Sulamith; Iloff, Edwin L.; Lannutti, Joseph E.; Webb, Francis H.; Widgoff, M.; Pevsner, A.; Ritson, D.