References - Bogoliubov Laboratory of Theoretical Physics - JINR

forward angles, where vector Ay and tensor Ayy analyzing powers have large values with
two-arm magnetic spectrometer ALPHA[1]. It was demonstrated recently at COSY at
ANKE spectrometer at the initial deuteron energy of 1170 MeV that the vector and tensor
analyzing powers for d − p elastic scattering are also large. d − p elastic scattering at large
angles has been successfully used for deuteron beam polarimetry at RIKEN[2].
The aim of the experiment is to obtain the Ay, Ayy, andAxx analyzing powers in
d − p elastic scattering at large angles at the 270−2000 MeV energy range to study the
possibility to the use this reaction for the efficient polarimetry of deuterons in the wide
energy range.
The analyzing powers data at the energies in a GeV region are necessary for the DSS
project at Nuclotron−M. New facility RIBF at RIKEN will have polarized deuterons at
880 MeV and, therefore, also requires the development of the high energy polarimetry.
The polarimeter was constructed at the Internal
Target Station(ITS) of Nuclotron-M.
A schematic view of the polarimeter is shown
in Fig.1. A detector support to install deuteron
and proton detectors is placed downstream of the
ITS. Each plastic scintillation counters coupled to
a photo-multiplier tube Hamamatsu H7416MOD
is arranged on the left, right, up and down of
the beam axis to allow determination of the spindependent
asymmetry of the reaction. A detector
for quasielastic-pp scattering is used as the monitor
of beam intensity.
Analyzing powers for the d − p elastic scattering
at the energies 880 and 2000 MeV were measured
with this newly-constructed polarimeter in
June 2005.
Figure 1: Schematic view of the detector
setup.
Polarized deuterons were provided by PIS(”polarized ion source”) POLARIS. In the
present experiment the data were taken for unpolarized, ”2-6” and ”3-5” spin modes of
POLARIS which had the following theoretical maximum polarization (pz,pzz)=(0,0),(1/3,1)
and (1/3,-1), respectively. The quantization axis is perpendicular to the beam circulation
plane of Nuclotron. The spin states of POLARIS were changed spill by spill.
The typical beam intensity in Nuclotron ring was 2-3×10 7 deuterons per spill. The
10μm CH2 foil was used as a proton target, while the measurements with carbon target
were made to estimate the background originating from quasifree scattering on carbon.
Prior to the analyzing powers measurement at 880 and 2000 MeV, the beam polarization
measurement was carried out at 270 MeV, where well established data on the analyzing
powers exist [2]-[5].
The beam polarization was determined by using asymmetry of the d−p elastic scattering
yields and known analyzing powers of the reaction at 270 MeV[2,4,5]. Data for several
scattering angles were used in the polarization determination: 75 ◦ , 86.5 ◦ ,95 ◦ , 105 ◦ , 115 ◦ ,
126.3 ◦ , and 135 ◦ . The analyzing powers values Ay, Ayy, Axx and Axz and their errors at
these angles were obtained by the cubic spline interpolation of the data from Refs.[2,4,5].
The values of the tensor pyy and vector py polarizations of the beam for ”2-6” and
”3-5” spin modes of POLARIS obtained at different angles are presented in Fig.2. The
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