Search

Experimental results on the production of dimuons by 800-GeV protons incident on a copper target are presented. The results include measurements of both the continuum of dimuons and the dimuon decays of the three lowest-mass $\ensuremath{\Upsilon}$ $S$ states. A description of the apparatus, data acquisition, and analysis techniques is included. A comparison of the results with data taken at lower incident energies indicates a scaling behavior of the continuum dimuon yields.

Single-particle distributions have been measured at the Stanford Linear Accelerator Center for the inclusive processes ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}X$ and ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}X$ at 10.0 and 15.5 GeV/c. The kinematic range for secondary pions was ${p}_{T}=0.15$ GeV/c to 0.9 GeV/c and $x=0 \mathrm{to} 0.5$. The differential cross sections have been assumed to be slowly varying and have been fitted to smooth functions of $x$ and ${p}_{T}$. Cross sections have been obtained for all incoming and outgoing pion charges. The cross sections for the reactions with incident and outgoing pions of like charge are higher than those for unlike charge, but have similar shape. The cross section as a function of the rapidity is plotted together with that of $pp$ inclusive scattering at CERN ISR energies, for the purpose of comparing pion and proton fragmentation.

Cross sections for the inclusive processes $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}X \mathrm{and} \mathrm{pX}$ have been measured at the Stanford Linear Accelerator Center for linearly polarized photons of average energy 10 and 14 GeV. The kinematic range of detected particles was ${P}_{T}=0.15 \mathrm{to} 1.0$ GeV/c, $x=0 \mathrm{to} \ensuremath{-}0.32$ for pions and -0.3 to -0.8 for protons at 10 GeV; the 14-GeV data had measurements at $x=0$ for pions and $x\ensuremath{\approx}\ensuremath{-}0.3$ for protons. The experiment was carried out using collimated coherent bremsstrahlung from a thin diamond radiator and the SLAC 1.6-GeV/c spectrometer. The variation of the cross section, as a function of $x$ and ${P}_{T}$, shows a marked similarity to that observed for pion and proton production from $\mathrm{pp}$ collisions. Our results show little dependence of the pion invariant cross section on either energy or polarization. The $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$ ratio varies from 1.3 at $x=0 \mathrm{to} 1.75$ at $x=\ensuremath{-}0.32$.

Author(s): Hague, J.F.; Rothberg, J.E.; Schenck, A.; Williams, D.L.; Williams, R.W.; Young, K.K.; Crowe, K.M.

The reaction p + Fe ..-->.. ..mu../sup +/ + ..mu../sup -/ + anything has been measursed at an incident momentum of 400 GeV/c. An enhancement of the order of 80 events is observed with M/sub mumu/ = 9.5 GeV at approximately the 4-standard-deviation level.