Inclusive protonlike production cross sections from 0.757 GeV/nucleon La+La collisions.

Abstract

Large discrepancies have existed, factor of \ensuremath{\sim}2.5 (\ensuremath{\sim}5\ensuremath{\sigma}), between a variety of cascade-type theoretical models and published experimental results for the inclusive protonlike production corss sections at the 20\ifmmode^\circ\else\textdegree\fi{} polar laboratory angle for relativistic La + La collisions. In view of this discrepancy the present work was undertaken to check the experimental cross sections for 0.76 GeV/nucleon La + La collisions using a small-acceptance magnetic spectrometer. The 20\ifmmode^\circ\else\textdegree\fi{} cross sections were determined by measuring the appropriate range of polar laboratory angles and momenta which, when transformed into the projectile frame, produce the cross sections at 20\ifmmode^\circ\else\textdegree\fi{}. Cross sections have been determined from 30\ifmmode^\circ\else\textdegree\fi{} to 75\ifmmode^\circ\else\textdegree\fi{} for protons and light nuclei with rigidities from 0.5 to 2.0 GeV/c in the laboratory frame. Cross sections were also deduced at 15\ifmmode^\circ\else\textdegree\fi{} and 20\ifmmode^\circ\else\textdegree\fi{} in the projectile frame for nucleon momenta from 0.9 to 1.5GeV/c. The original experimental results for the larger polar laboratory angles (40\ifmmode^\circ\else\textdegree\fi{} and 60\ifmmode^\circ\else\textdegree\fi{}) were confirmed; however, the 20\ifmmode^\circ\else\textdegree\fi{} cross sections disagree by a factor of about 1.5 (\ensuremath{\sim}2\ensuremath{\sigma}). At large polar laboratory angles (40\ifmmode^\circ\else\textdegree\fi{}-70\ifmmode^\circ\else\textdegree\fi{}) the model calculations disagrees in the low-momentum range with the present data by a factor of 1.5 (\ensuremath{\sim}3\ensuremath{\sigma}). The discrepancy at small polar angles (15\ifmmode^\circ\else\textdegree\fi{} and 20\ifmmode^\circ\else\textdegree\fi{}) has been significantly reduced from the original factor of 2.5 down to a value of 1.2 (\ensuremath{\sim}3\ensuremath{\sigma}).