TX 75237.Permanent address: Los Alamos National Laboratory, Los Alamos, NM 87545. Present address: EGRzG/EM, 130 Robin Hill Rd. , Goleta, CA 93116. for pion energies between 150 and 300 MeV. The energy dependences of the absorption cross sections for energies above 315 MeV for heavy nuclei are unknown.Early models of pion absorption emphasized quasi-
Absolute pp-elastic-differential cross sections were measured at incident energies 492, 576, 642, 728, and 793 MeV from about 30' to 90' c.m. The total uncertainty was determined to be less than 170, made possible by particle counting for beaxn normalization and extensive cross-checks of systematic eQects. These new data are consistent with previous data above 600 MeV but have uncertainties about a factor of 10 smaller. Near 500 MeV these data are consistent with 90' data from TRIUMF, but differ signi6cantly from similar data from PSI; the cause of this discrepancy is discussed.PACS number(s): 25.40.Cm, 25.10.+s 'Present address:
The absolute p-d elastic-scattering differential cross sections were measured at 641.3 and 792.7MeV beam energies over a range of c.m. angles from -35' to -115' and -35' to -140', respectively. The longitudinally polarized (L-type) proton beam produced by the Lamb-shift ion source at LAMPF was used. The beam intensity was measured to high accuracy (-0.1%) by a scintillatorbeam particle-counting system designed and developed prior to the experiment. Typical uncertainties in the absolute cross sections were about 2 -3% total, somewhat larger at back angles. The present results were compared with the existing measurements and the controversy about the previous data at 800 MeV was resolved. The present data can be fit with a relativistic multiple-scattering theory which uses off-mass-shell extrapolations of the nucleon-nucleon amplitudes suggested by the structure of derivative meson-nucleon couplings. Relativistic-impulse-approximation calculations do not fit these data at either energy.
Cross sections have been measured for proton emission following r+ absorption on Li, C, Al, Ni, Sn, Pb, and Q for pion kinetic energies of 50, 100, 150, and 200 MeV by using a large-solid-angle bismuth germanate detector array. An increasing fraction of transitions to states of large missing energy and with particles other than protons is observed as the energy and mass increase. PACS numbers: 25.80.Ls Despite much study [1], pion absorption is still not well understood in detail, even in light nuclei. Most studies of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.