48 research outputs found
Measurement of the analyzing power of proton-carbon elastic scattering in the CNI region at RHIC
The single transverse spin asymmetry, A_N, of the p-carbon elastic scattering
process in the Coulomb Nuclear Interference (CNI) region was measured using an
ultra thin carbon target and polarized proton beam in the Relativistic Heavy
Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). In 2004, data were
collected to calibrate the p-carbon process at two RHIC energies (24 GeV, 100
GeV). A_N was obtained as a function of momentum transfer -t. The results were
fit with theoretical models which allow us to assess the contribution from a
hadronic spin flip amplitude.Comment: Contribution to the proceedings of the 16th International Spin
Physics Symposium, spin2004 (Trieste
Search for the Cryptoexotic Member of the Baryon Antidecuplet 1/2+ in the Reactions pi- p --> pi- p and pi- p --> K L
The main goal of this proposal is the search for a narrow cryptoexotic
nucleon resonance by scanning of the pi- p system invariant mass in the region
(1610-1770) MeV with the detection of pi- p and K Lambda decays. The scan is
supposed to be done by the variation of the incident pi- momentum and its
measurement with the accuracy of up to +-0.1% (better than 1 MeV in terms of
the invariant mass in the whole energy range) with a set of proportional
chambers located in the first focus of the magnetooptical channel. High
sensitivity of the method to the resonance under search is shown. The secondary
particles scattered from a liquid hydrogen target are detected by sets of the
wire drift chambers equipped with modern electronics. The time scale of the
project is about 3 years. The budget estimate including manpower, the apparatus
and operation cost, is about 40 million rubles. The beam time required is (4-6)
two week runs on "high" (10 GeV/c) flattop of the ITEP proton synchrotron.Comment: 16 pages, 10 figures. v2: an acknowledge adde
Backward asymmetry measurements in the elastic pion-proton scattering at resonance energies
The asymmetry parameter P was measured for the elastic pion-proton scattering
in the very backward angular region of theta_cm ~ 150-170^o at several pion
beam energies in the invariant mass range containing most of the pion-proton
resonances.
The general goal of the experimental program was to provide new data for
partial wave analyses in order to resolve their uncertainties in the baryon
resonance region to allow the unambiguous baryon spectrum reconstructions.
Until recently the parameter P was not measured in the examined domain that
might be explained by the extremely low cross section. At the same time the
predictions of various partial wave analyses are far from agreement in some
kinematic areas and specifically those areas were chosen for the measurements
where the disagreement is most pronouncing.
The experiment was performed at the ITEP U-10 proton synchrotron, Moscow, by
the ITEP-PNPI collaboration in the latest 5 years.Comment: 6 pages, 5 figures. to be submitted to the European Physical Journa
Influence of spin-rotation measurements on partial-wave analyses of elastic pion-nucleon scattering
Recent measurements of spin-rotation parameters in elastic
scattering are in marked disagreement with predictions of the
Carnegie-MellonBerkeley and Karlsruhe-Helsinki analyses. Using the method of
Barrelet, we show how this discrepancy can be removed. We then show how this
Barrelet transformation alters the partial-wave amplitudes. The effect of
unitarity and analyticity constraints is also considered.Comment: 9 pages, 4 figures. Postscript figures also available from
ftp://clsaid.phys.vt.edu/pub/said/pin/barrele
Double Spin Asymmetries A_NN and A_SS at sqrt{s}=200 GeV in Polarized Proton-Proton Elastic Scattering at RHIC
We present the first measurements of the double spin asymmetries A_NN and
A_SS at sqrt{s}=200 GeV, 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 phi_2 and phi_4 at small t
as well as on the difference Delta(sigma_T) between the total cross sections
for transversely polarized protons with antiparallel or parallel spin
orientations.Comment: 13 pages with 3 figures. Final version accepted by Phys. Lett.