Mass spectrum of proton-proton inelastic interactions from 55 to 400 GeV/c at small momentum transfer

The doubly differential cross section d2sigma/dtdM2 for the reaction p + p → p + X was measured as a function of the four-momentum transfer squared (t), the missing-mass squared (M2), and the total center-of-mass energy squared (s). We covered the region 0.024 < -t < 0.234 (GeV/c)2, 0 < M2 < 0.12 s, and 105 < s < 752 GeV2, by detecting the slow recoil proton at large angles with solid-state detectors. The data were taken on polypropelene [(CH2)/sub n/] and carbon targets, and a subtraction was made to obtain the free-proton cross section. We find that our differential cross section can be simply represented by dsigma (s)/dM2 = [(15 +- 0.5)/s + (2.9 +- 0.1)/ M/sup 3.7tsplus-or-minusts0.1/] mb/GeV2. If the energy-independent part of this result is identified with the inelastic diffractive processes then we obtain sigma/sub diff/ = 3.6 +- 0.4 mb after doubling for p-p symmetry. We also observe no significant increase with s for the inclusive cross section integrated to 0.06s or 0.1s