A.J. Simon

Energy-dependent measurements of the pp elastic analyzing power and narrow dibaryon resonances

Abstract The energy dependence of the pp elastic analyzing power has been measured using an internal target during polarized beam acceleration. The data were obtained in incident-energy steps varying from 4 to 17 MeV over an energy range from 0.5 to 2.0 GeV. The statistical uncertainty of the analyzing power is typically less than 0.01. A narrow structure is observed around 2.17 GeV in the two-proton invariant mass distribution. A possible explanation for the structure with narrow resonances is discussed.

Accurate intensity measurements for proton beams with a 201 MHz structure

A counting system which measures the absolute beam intensity accurately (< 1%) at intermediate energies with a beam microstructure of 201.25 MHz or lower is described in this paper. The number of beam micropulses containing one or more beam particles are counted and time-sequenced coincidences between micropulses correct this number to obtain the actual number of beam particles using formulas based on Poisson statistics. The counting system, both the experimental setup and the correction method, was examined fully with two different beam microstructures. 10 MHz and 201.25 MHz, the two main beam microstructures at LAMPF. Maximum beam intensities, below which the system is accurate within a few tenths of a percent, were determined to be ∼ 0/4 pA and ∼ 0.1 pA average beam currents for the 5 ns and 100 ns beam microstructures, respectively.

Absolute differential cross-section measurements for p + p → π+ + d reaction at 500–800 MeV

Abstract Absolute differential cross sections for the reaction p + p → π + + d were measured at 491.9, 575.5, 641.6, 728.2 and 793.0 MeV. These measurements covered an angular range from 50° to 120° in c.m. except for the 491.9 MeV case, where the angular range was ∼70°–~105° in c.m. The beam intensity was measured by counting the individual beam particles using a scintillator beam-counting system. The typical accuracy for the beam counting was ∼0.1%. The uncertainty in the target length was about half a percent or lower. The overall uncertainty in the differential cross-section measurement was 1.5–2.5%, including the total systematic and statistical uncertainties. The results were compared with the existing data.

Quick polarization analyzer (QPAN)

Abstract A high count rate polarimeter for the measurement and monitoring of the polarization of an intermediate energy neutron beam has been developed. The device, QPAN, consists of a double arm telescope with adjustable copper absorbers. The asymmetry of the protons scattered from the liquid hydrogen (LH2) target is calculated from the count differential between two arms, positioned above and below the beam.

Energy dependence of the analyzing power for the pp → π+d reaction in the energy region 500–800 MeV

Abstract The energy dependence of the analyzing power A y for the pp → π + d reaction was measured during polarized beam acceleration from 500 to 800 MeV, using an internal target inserted into the beam every acceleration cycle. The measurements were made with the pion laboratory angle fixed at 68° and with incident proton energy bins varying from 10 to 30 MeV in width. The statistical accuracy per bin is ΔA y ⋍ 0.06 .