C. Pearson

First Measurement of Proton-Proton Elastic Scattering at RHIC

Abstract The first result of the pp2pp experiment at RHIC on elastic scattering of polarized protons at s =200 GeV is reported here. The exponential slope parameter b of the diffractive peak of the elastic cross section in the t range 0.010⩽|t|⩽0.019 (GeV/c)2 was measured to be b=16.3±1.6(stat.)±0.9(syst.) (GeV/c)−2.

First measurement of A N at s = 200 GeV in polarized proton–proton elastic scattering at RHIC

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

Double spin asymmetries AN N and AS S at sqrt(s) = 200 GeV in polarized proton-proton elastic scattering at RHIC

Abstract We present the first measurements of the double spin asymmetries A N N and A S S at s = 200 xa0GeV , obtained by the PP2PP experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). The data were collected in the four momentum transfer t range 0.01 ⩽ | t | ⩽ 0.03 ( GeV / c ) 2 . The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes ϕ 2 and ϕ 4 at small | t | as well as on the difference Δ σ T between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations.

The First Measurement of the Elastic pp‐scattering Spin Parameters at s = 200 GeV

Elastic scattering of polarized protons in the range of very small momentum transferred was studied for the first time at su2009=u2009200u2009GeV in the experiment pp2pp at RHIC. This article presents the single spin asymmetry AN and the double spin asymmetries ANN and ASS measured in this experiment.

Double spin asymmetries ANN and ASS at s=200GeV in polarized proton–proton elastic scattering at RHIC

Abstract We present the first measurements of the double spin asymmetries A N N and A S S at s = 200 xa0GeV , obtained by the PP2PP experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). The data were collected in the four momentum transfer t range 0.01 ⩽ | t | ⩽ 0.03 ( GeV / c ) 2 . The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes ϕ 2 and ϕ 4 at small | t | as well as on the difference Δ σ T between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations.

Double spin asymmetries ANNANN and ASSASS at s=200 GeV in polarized proton–proton elastic scattering at RHIC

Abstract We present the first measurements of the double spin asymmetries A N N and A S S at s = 200 xa0GeV , obtained by the PP2PP experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). The data were collected in the four momentum transfer t range 0.01 ⩽ | t | ⩽ 0.03 ( GeV / c ) 2 . The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes ϕ 2 and ϕ 4 at small | t | as well as on the difference Δ σ T between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations.

First measurement of AN at in polarized proton–proton elastic scattering at RHIC

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

First measurement of AN at s=200GeV in polarized proton–proton elastic scattering at RHIC

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

Status of the BNL muon (g−2) experiment

The muon (g−2) experiment at Brookhaven has just completed a 3-month run for checkout and initial data-taking. In the first two months beam was taken in a parasitic mode where one out of ten AGS pulses was delivered for commissioning of the beam line, quadrupoles, detectors, and data acquisition system. This was followed by four weeks of dedicated data collection. The main components of the experiment, which include the pion/muon beam line, the superconducting inflector, the superferric storage ring with its pulsed electric quadrupoles and magnetic field measurement system, and the detector system based on lead-scintillating fiber electron calorimeters, have been satisfactorily commissioned. The muon (g−2) precession frequency is clearly seen as a large signal. It is estimaed that over 25×106 decay positrons with energies greater than 1.5 GeV have been detected.