Production of lowmomentum photons and hadrons at x=0 and associated multiplicities with a charged hadron at x=0 in proton-proton collisions at the CERN ISR

A small magnetic pair spectrometer (fig. 1) has been used to study the production of charged hadrons at theta=90 degress. The analysis of pions, kaons, proton and antiproton production was completed during 1976, and this year the cross sections for deuteron and antideuteron production have been extracted in the range 0.15< pt<0.75 GeV/c at sqrt(s) = 45 and 53 GeV. The antideuteron invariant cross section has a similar dependence on pt, as antiprotons, but with a yield about 1/2000 of the antiprotons. The d/anti-d ratio is about 4.

The spectrometer was used to trigger the 4pi scintillation hodoscope system of Pisa-Stony Brook. Results on the topology of the associated event has been published. One curious effect seen is the increase in the low pt pion associated multiplicities when pt goes to zero.

The analysis is also done where a pair of opposite charge particles were recorded predominately electron pairs from photon conversion in a converter placed in between the two front multwire proportional chambers.

Figure 1