W. R. Ditzler

Evidence for multiple scattering of high energy partons in nuclei

Abstract New experimental information is presented about the effect of a nucleus on partons which have undergone a hard scatter. We have observed clear dijet events from 400 GeV / c p-nucleus interactions and compared them to dijets from pp interactions. Our results show that the angular width of the individual jets is only slightly affected by the presence of the nucleus, but the acoplanarity of the jet pairs is sharply increased.

Beam polarization at the ZGS

Abstract A description is given of a beam polarimeter constructed for use at the Argonne ZGS and later at LAMPF. Details of the absolute calibration of these polarimeters are described. Conclusions for the absolute beam polarization at the ZGS impact a number of past polarized beam experiments, causing normalization changes in some cases of 8–25%. The normalization of some past pp polarization measurements are also affected by these results.

Measurement of KLL and KNN in pd → npp at 500, 650 and 800 MeV

Abstract Measurements of the spin transfer parameters, KNN and KLL, at 500, 650 and 800 MeV are presented for the reaction p d → n pp at 0°. The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction us a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV.

Longitudinal energy flow in hard proton-nucleus collisions at 400 GeV/c

Using the E609 calorimeter system, we have measured longitudinal energy flow in hard pA collisions which yield dijet final states. The mean laboratory energy flow into the nuclear target (backward) region, nlab < 2.83, minus the value for pp collisions is found to vary as A0.33 ± 0.12, and reaches a value of 50±8 GeV for Pb. The observed probability distribution of energy flow indicates that the energy transfer to a heavy nucleus seldom fluctuates to small values. We also find that the A dependence of the dijet production cross section depends sensitively upon the energy flow to the target region.

Jet production from nuclei at 400 GeV/c

Abstract Results are presented from a calorimeter study on the production of jets in large- E T proton-nucleus collisions at 400 GeV/c. Jet-like large- p T events from eight nuclear targets are seen with a special jet trigger. As previously observed, the cross section for such events increases slightly faster than the atomic number, much like in the production of large- p T single hadrons. Data on energy flows and multiplicities suggest that a heavy nucleus does not significantly widen the angular distribution of the beam remmants. In the central region the particle flow in hard nuclear collisions is similar to that in soft nuclear collisions.

Measurement of the single-jet invariant cross section at Fermilab

Abstract In an experiment performed at Fermilab we have studied the production of high pt hadron jets from 400 GeV/c pp interactions. A large solid-angle, towered calorimeter was used to trigger and reconstruct the jet events. We report results for inclusive single-jet production and compare those results with QCD predictions and results obtained at the ISR and the SPS Collider.

Measurement of Δ σ L and C LL = ( L , L ; 0 , 0 ) in proton-proton scattering between 300 and 800 MeV

Measurements are reported of the difference ..delta..sigma/sub L/ between proton-proton total cross sections for parallel and antiparallel spin states and of the parameter C/sub L/L for proton-proton elastic scattering near 90/sup 0/, for thirteen energies between 300 and 800 MeV. The ..delta..sigma/sub L/ results agree well with previous ANL ZGS and SIN data, but disagree with recent results from TRIUMF. Attempts to understand the cause of the discrepancy have been unsuccessful, but possible sources are discussed. The ..delta..sigma/sub L/ and C/sub L/L results have been used with other experimental data to extract quantities which depend only on spin-singlet, coupled spin-triplet, and spin-triplet partial waves. Structure is found in these quantities, which appears to be associated with the resonantlike /sup 1/D/sub 2/ and /sup 3/F/sub 3/ partial waves. Additional similar structure is also found, which may be due either to the /sup 3/P/sub 0/ partial wave or the (/sup 3/P/sub 2/, /sup 3/F/sub 2/) partial-wave pair.

CLL = (L, L; 0, 0) measurements and a structure due to a P partial wave in the pp system☆

Measurements of CLL of pp elastic scattering near θc.m. = 90° at thirteen energies between 300 and 800 MeV are reported. These, together with previous values of CNN, are used to extract values of two quantities, ƒs and ƒt, which contain only spin-singlet and only coupled spin-triplet partial waves, respectively. The ƒs curve, which is not dependent on CLL, exhibits the behavior expected for the previously conjectured 1D2 resonance. The ƒt curve also exhibits a resonance-like behavior, which could be due either to the 3P0 or the 3P2 partial wave.

Measurement of. delta. sigma/sub L/ and C/sub L/L = (L,L; 0,0) in proton-proton scattering between 300 and 800 MeV

Measurements are reported of the difference ..delta..sigma/sub L/ between proton-proton total cross sections for parallel and antiparallel spin states and of the parameter C/sub L/L for proton-proton elastic scattering near 90/sup 0/, for thirteen energies between 300 and 800 MeV. The ..delta..sigma/sub L/ results agree well with previous ANL ZGS and SIN data, but disagree with recent results from TRIUMF. Attempts to understand the cause of the discrepancy have been unsuccessful, but possible sources are discussed. The ..delta..sigma/sub L/ and C/sub L/L results have been used with other experimental data to extract quantities which depend only on spin-singlet, coupled spin-triplet, and spin-triplet partial waves. Structure is found in these quantities, which appears to be associated with the resonantlike /sup 1/D/sub 2/ and /sup 3/F/sub 3/ partial waves. Additional similar structure is also found, which may be due either to the /sup 3/P/sub 0/ partial wave or the (/sup 3/P/sub 2/, /sup 3/F/sub 2/) partial-wave pair.

MEASUREMENT OF DELTA SIGMA-l AND C (L, L) = (L, L : 0, 0) N PROTON PROTON SCATTERING BETWEEN 300-MEV AND 800-MEV

Measurements are reported of the difference ..delta..sigma/sub L/ between proton-proton total cross sections for parallel and antiparallel spin states and of the parameter C/sub L/L for proton-proton elastic scattering near 90/sup 0/, for thirteen energies between 300 and 800 MeV. The ..delta..sigma/sub L/ results agree well with previous ANL ZGS and SIN data, but disagree with recent results from TRIUMF. Attempts to understand the cause of the discrepancy have been unsuccessful, but possible sources are discussed. The ..delta..sigma/sub L/ and C/sub L/L results have been used with other experimental data to extract quantities which depend only on spin-singlet, coupled spin-triplet, and spin-triplet partial waves. Structure is found in these quantities, which appears to be associated with the resonantlike /sup 1/D/sub 2/ and /sup 3/F/sub 3/ partial waves. Additional similar structure is also found, which may be due either to the /sup 3/P/sub 0/ partial wave or the (/sup 3/P/sub 2/, /sup 3/F/sub 2/) partial-wave pair.