J.D. Cossairt

Analyzing power in inclusive π+ and π− production at high xF with a 200 GeV polarized proton beam☆

The analyzing power in inclusive charged pion production has been measured using the 200 GeV Fermilab polarized proton beam. A striking dependence in x(F) is observed in which A(N) increases from 0 to 0.42 with increasing x(F) for the pi+ data and decreases from 0 to -0.38 with increasing x(F) for pi- data. The kinematic range covered is 0.2 less-than-or-equal-to x(F) less-than-or-equal-to 0.9 and 0.2 less-than-or-equal-to p(T) 2.0 GeV/c. In a simple model our data indicate that at large x(F) the transverse spin of the proton is correlated with that of its quark constituents.

Large-xF spin asymmetry inπ0 production by 200-GeV polarized protons

The spin asymmetryAN for inclusive π0 production by 200-GeV transversely-polarized protons on a liquid hydrogen target has been measured at Fermilab over a wide range ofxF, with 0.5<pT<2 GeV/c. AtxF>0.3, the asymmetry rises with increasingxF and reaches a value ofAN=0.15±0.03 in the region 0.6<xF<0.8. This result provides new input regarding the question of the internal spin structure of transversely-polarized protons.

The design and performance of the FNAL high-energy polarized beam facility

We describe a new polarized-proton and -antiproton beam with 185-GeV/c momentum in the Fermilab MP beam line which is currently operational. The design uses the parity-conserving decay of lambda and antilambda hyperons to produce polarized protons and antiprotons, respectively. A beam-transport system minimizes depolarization effects and uses a set of 12 dipole magnets that rotate the beam-particle spin direction. A beam-tagging system determines the momentum and polarization of individual beam particles, allowing a selection of particles in definite intervals at momentum and polarization. We measured polarization of the beam by using two types of polarimeters, which verified the determination of polarization by a beam-particle tagging system. Two of these processes are the inverse-Primakoff effect and the Coulomb-nuclear interference (CNI) in elastic proton-proton scattering. Another experiment measured the {pi}{sup 0} production asymmetry of large-x{sub F} values; this process may now be used as an on-line beam polarimeter. 9 refs., 9 figs.

Measurement of single spin asymmetry in η-meson production in p↑p and p̄↑p interactions in the beam fragmentation region at 200 GeV/c

We present experimental results on measuring a single spin asymmetry in η-meson production in the interaction of transversely polarized protons and antiprotons at plab = 200 GeV/c with a proton target in the region 0.2 < xF < 0.7 for p↑p, 0.3 < xF < 0.7 for p↑p and 0.7 < pT < 2.0 GeV/c. A comparison of single spin asymmetries in π- and η-meson production is made.

Radiation measurements in a labyrinth penetration at a high-energy proton accelerator

The efficient design of access penetrations at high-energy proton accelerators is desirable for both economic and personnel protection reasons. This paper reports on a series of measurements made in a personnel access labyrinth which viewed an A1 target bombarded by 400-GeV protons from the Fermilab Tevatron. Measurements of absorbed dose in the labyrinth using tissue-equivalent ion chambers were consistent with theoretical predictions of both the relative attenuation through the penetration and the absolute magnitude near the target. The multisphere technique was used to determine the neutron energy spectrum in one section of the labyrinth. A recombination chamber was used to measure the quality factor of the radiation field in two sections of the labyrinth. Good agreement with the quality factor deduced from the multisphere result was obtained at the same measurement location.

Absorbed dose measurements at an 800 GeV proton accelerator; Comparison with Monte Carlo calculations

Shielding design at high energy proton accelerators is often done using Monte Carlo computer simulations. This report compares such predictions with measurements made at proton energies up to 800 GeV. Agreement of the measurements with the calculations is quite good (within 20%) at small radial distances from the beam axis (R < 0.5 m) while even for a thick soil shield (R ⋍ 5 m) the agreement is acceptable for radiation protection purposes (typically within a factor of two). The scaling with energy of these calculations is found to be in good agreement with a recently published analysis based on the Moyer shielding model. These results are an indication that present techniques of shielding calculations can be extended to those required for higher energy proton accelerators.

Analyzing-power measurements of Coulomb-nuclear interference with the polarized-proton and -antiproton beams at 185 GeV/c

Abstract The analyzing power AN of proton-proton, proton-hydrocarbon, and antiproton-hydrocarbon, scattering in the Coulomb-nuclear interference region has been measured using thhe 185 GeV/c Fermilab polarized-proton and -antiproton beams. The results are found to be consistent with theoretical predictions within statistical uncertainties.

A study of the transport of high energy muons through a soil shield at the tevatron

Abstract The transport of high energy muons in a soil shield was studied by making fluence distribution measurements at three different locations following a 600 m thick earth shield. The incident muon beam had a broad momentum spectrum with a mean of about 500 GeV/c. The results are compared with Monte Carlo calculations of muon transport. Agreement between calculations and measurements is generally excellent when the muon beam was incident directly on the earth shield. In another series of measurements, the muons were magnetically deflected downward before impinging on the shield. This greatly reduced the muon fluence at distant locations and somewhat worsened the agreement between the model calculations and the observations, most likely by increasing the relative importance of sources of muons not included in the model. Still, peak values in muon fluence distributions are adequately described by the calculations.

A study of the production and transport of muons through shielding at the Tevatron

Abstract The fluence distributions of muons were measured at a number of locations downstream of three different target stations in the fixed-target experimental areas of the Fermilab Tevatron. These were compared with Monte-Carlo calculations of muon production by 800 GeV protons and their transport through shielding materials and regions of magnetic fields. Agreement between the measured and calculated fluence is quite satisfactory at distances between 167 and 3000 m from the primary production targets. The calculations are therefore a trustworthy tool for predicting muon fluence distributions.

Single‐spin asymmetries and invariant cross sections of the high transverse‐momentum inclusive π0 production in 200 GeV/c pp and p̄p interactions

The π0 inclusive and semi‐inclusive, single‐spin asymmetries have been measured using transversely‐polarized, 200‐GeV/c proton and antiproton beams colliding with an unpolarized hydrogen target. The measured asymmetries are consistent with a value of zero within the error bars for the kinematic regions, −0.15<xF<+0.15 and 1<pT<4.5 GeV/c. These data indicate that the higher‐twist contribution in QCD to the single‐spin asymmetry in inclusive π0 production may not be as large as was previously expected. Additional evidence for such a conclusion comes from the measurement of a semi‐inclusive π0‐charged particle asymmetry, where the associated charged particles are detected opposite to the π0 azimuthal direction. This experiment also has a high‐statistics measurement of the inclusive π0 cross sections for pp and pp collisions at 200 GeV/c.