L. Marshall Libby

ELASTIC SCATTERING OF 2.7 GeV/c ANTIPROTONS ON PROTONS.

The differential elastic scattering cross section for 2.7 GeVc antiprotons on protons has been studied using film from the 20″ BNL hydrogen bubble chamber. The diffraction pattern based on a total sample of 7300 events shows a sharp forward maximum, a first diffraction minimum, and a second maximum. The forward diffraction peak is fitted by (dσdt)elastic =[325 ± 6 mb(GeVc)2] exp[−13.3 ± 0.2(GeVc)−2t and the total elastic cross section is found to be 25.6 ± 0.6 mb. The first and second diffraction peaks are fitted by the optical model formula for a “black” disc. dσdt∼ [j1(2k R sin 12θ)]2 (1 + acos θ)2 where R = 1.2 fm and a = −5.

K−p elastic scattering at 2.24 GeV/c

Abstract The differential elastic scattering cross section for 2.24 GeV/c K−p collisions has been measured in film from the Brookhaven 20″ bubble chamber. The total elastic cross section is found to be 6.2 ± 0.7 mb. The exponential dependence on square of the momentum t in (GeV/c)2 is fitted by ( d σ d Ω elastic = (12.4 ± 1.0 mb/sr) exp (7.81 ± 0.25)t . A A fit to a black disc model requires a radius of 0.95 ± 0.05 fm.

Two meson final states in interactions of 2.7 GeV/c p p

Abstract The cross sections for π+π−, K+K−, and K 0 K0 final states from 2.7 GeV/c p p interactions are: 28±9 γb, 3+6−3 γb, and

Pi-rho mass spectrum in π−p interactions at 6.7 GeV/c; Spin-parity analyses for A(1200) and for A(1300)

Abstract The rho-pion mass spectrum for negative, positive and zero charge has been evaluated in 6.7 GeV/ c π − proton interactions. The enhancement at 1100 MeV is present but is not strongly produced. The A(1300) is produced at a level of 40% above background. Spin-parity as determined by analysis of events in the negative charge state is consistent with 2 + , but other assignments, for example 1 + or 2 − , cannot be excluded. Spin-parity analyses separately on events in the upper and lower halves of the A(1300) peak give identical results. The A(1200) is produced at a level of 30% above background. Spin-parity analysis prefers exclusion of 0 − and 2 + .

Evidence of the hard core in multi-GeV K±p elastic scattering☆

Abstract It is shown that K − p and K + p elastic scattering from 2–20 GeV/ c laboratory beam momentum can be fitted by a single imaginary Yukawa potential term together with a hard core as the potential function in the Dirac equation. A fit cannot be obtained this way unless a hard core is used. Thus three parameters have been found to reproduce elastic scattering over this entire range.

New melting law at high pressures

Abstract A new melting law at high pressures relating the change in molar volume to the change in molar entropy upon melting, of the form C+ In (V L m −V S m )=α(S L m −S 8 m ) , is shown to fit the data presently available.

Evidence for narrow 3π effects near 960 MeV in K − P interaction at 4.6 and 5.0 GeV/c☆

Abstract In an investigation of the final states K − π − π + π O p and K − π − π + π + n produced in K − p interactions at 4.6 and 5.0 GeV/ c we have observed narrow enhancements near 960 MeV in both the π + π − π O and π + π + π − distributions. These structures are strongly associated with the Δ(1236). Also, there is evidence for a possible ϱπ decay for these effects.