These are data from Nucl Phys B100(1975) 237-290. Alper et. al. (Brithsh-Scandinavian Collaboration). The abstract reads:

Results are given on the inclusive production of charged pions, kaons, and nucleons in proton-proton collisions at c.m. energies from sqrt(s)=23 to 63 GeV at large angles and for the transverse momentum range 0.1< pt< 4.8 GeV/c. The dependence of the production spectra on the collision energy sqrt(s), the transverse momentum pT, and the longitudinal rapidity is discussed.

Many years ago, I had them scanned in by some scanning service at the lab. The scanner made many errors, and I went over the files pretty thoroughly to catch them all. Substitutions 8->B or 1->l are easy to find, but there may be a few 8->3 and 3->8 left. Feel free to check the files against the original publication! If you find errors, please let me know.

I have them here in various electronic forms,

• The scanned file, after manual cleanup of scanning errors. The other fomats are made by reading and parsing this file.

• As freezer-formatted tables. Column 1 is rapidity y, column 2 is kt=mt-m, derived from pt, and columns 3 and 4 are the invariant cross section and error. Note that the cross sections in the paper are E*dsigma/dp_vector, with units mb/GeV^2/c^3, so I divide this by the total inelastic pp cross section at the appropriate c.m. energy (taken from the Particle Data Booklet, Phys.Rev.D50 (1994), page 1336), to arrive at the invariant cross section.
  

  cm. Energy	pi+	pi-	K+	K-	p	pbar
  23 GeV	click	click	click	click	click	click
  31 GeV	click	click	click	click	click	click
  45 GeV	click	click	click	click	click	click
  53 GeV	click	click	click	click	click	click
  63 GeV	click	click	click	click	- -	- -

• As HBOOK plots, this is the source file alper.hst, or as the postscript generated from this file: pi+-, K+-, p+-.