^Pj and ^D^ amplitudes. This behavior, already present in the "box diagram/' is clearly due to the opening of inelastic channels. We do not wish to enter the controversy about whether these should be called resonances. ^^In conclusion, we have shown that, using OPE forces and the isobar model, a relativistic unitary theory of N-N scattering and single pion production at intermediate energies can adequately describe the inelastic cross section. To fit the elastic data, however, will require more detailed dynamics. Combining this three-body theory with what is known from one-boson-exchange potentials at lower energies should permit the extension of our understanding of nucleon-nucleon dynamics into this region. In particular, the spin-dependent cross sections around 1 GeV promise to be a very interesting testing groimd for any model.
We have measured inclusive particle production in neutron-nucleus collisions at high energies. Data on positive and negative particles produced in nuclei, ranging in size from Be to Pb, are presented for essentially the full forward hemisphere in the centerof-mass system. Fits of the iovmA a to the invariant production cross section indicate that a changes from ~ 0.85 to ~ 0.55 for laboratory rapidities ranging from 3 to 8. Multiperipheral models which invoke cut contributions to particle production in nuclei predict such behavior.There has recently been renewed interest in the study of hadronic production using nuclear targets. 1 This has largely been fostered by the hope that through an examination of particle production in nuclear matter we can obtain information about the space-time development of hadronic collisions during their nascent stages. The fact that the produced-particle multiplicity at high energies is only a weak function of atomic number has already dispelled any naive notions regarding the presence of intranuclear cascading. Previously available data appeared to favor formulations such as those provided by the energy-flux cascade model and the simple multiperipheral model, 1 both of which predict a moderate increase of multiplicity with increasing atomic number for pion production at central rapidities, and essentially no dependence of multiplicity on nuclear size for larger rapidities (regime of projectile fragmentation). The data we present, although in general agreement with earlier measurements at high energy, clearly demonstrate that multiplicity at large rapidities is a decreasing function of atomic number. Our observations are consequently not consistent with the simplest ideas favored previously for describing production on nuclear targets, but are in accord with expectations from models which admit contributions from exchanges involving several multiperipheral chains.We have performed an experiment to measure charged-particle production in neutron collisions with the following nuclear targets: Be, Al, Cu, Sn, and Pb. The beam was the broad-band, 1-mrad, M3 neutral beam at Fermilab, consisting of neutrons, with minor K L°, n, and y components (at ^>1% level). The neutron momentum spectrum was peaked at about 300 GeV/c, with a full width at half-maximum of ~200 GeV/c. 2 The primary-71
Backward meson production in the reaction n'p-*pn~Tt*Tt~ has been studied with use of a streamer chamber triggered by the detection of a fast forward proton. For cos 0* <-0.98 we find no evidence of A t or A 2 production, and we determine total backward cross-section upper limits (95% confidence) of 0.93 and 0.72 /ib, respectively. At m^ = 1.9 GeV/c 2 we observe a broad enhancement of about 3-standard-deviation significance. Evidence for backward quasi-two-body production is seen in the P°pir~ and f°pn~ channels.We have studied various channels in the reaction -n~p-»piT + TT~Tr~ where the event trigger required a fast forward proton. The data were obtained in the University of Illinois-Argonne National Laboratory streamer chamber exposed to an 8-GeV/c pion bean at the zero-gradient synchrotron. We discuss here 199 pTr + ir m ir m events with cos0* <-0.98, where 0* is the angle between the incident u~ and the outgoing three-pion system in the overall center-of-mass system. Events in this kinematic region are expected to have baryon exchange as the dominant production mechanism. We find no evidence for A 1 or A 2 production. We do observe production of the p° and/ 0 in quasi-two-body reactions.The apparatus, consisting primarily of a streamer chamber 1 and a hodoscope-Cherenkov-count-er system for selecting fast forward protons, is shown schematically in Fig. 1. The usable volume of the streamer chamber is 1.5 mx 1.0 m x 0.6 m. It was placed in a 14.5-kG magnet and photographed in 18° stereo by three cameras. A 3.8-cm-diamX 30.5-cm-long liquid-hydrogen target enclosed in a foam vacuum box was positioned in the chamber so that about 20 cm of entering beam track and 80 cm of outgoing proton track remained visible. 2 The event trigger required a beam interaction and a fast forward proton. A beam interaction, B 0 H 1 B 1 B 2 B 3 B 4 B 59 was defined by counters B 0 and# x at the momentum slit, B 1? B 2 , and# 3 in the region of the last beam line magnets, a 3.2cm-i.d. annular counter B 4 just in front of the target, and B 5 downstream of the streamer cham-7r~Beam
We present the results of a search at Fermilab for the charmed meson, D°(1865), produced in association with a prompt muon by 300-GeV/c neutrons. We observe no significant enhancement in high-mass K ±r n* systems and report, at the 95% confidence level, an upper limit of 200 nb/nucleon for the production of a pair of charmed particles and their subsequent decay into a K 1^ state and a prompt muon.
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