A system of four magnets which is a part of the SPASCHARM experimental setup at the U-70 accelerator facility for the study of spin effects in hadronic interactions is described. An unique magnet ...with the field of 2.4 T and a field uniformity at the level of 10
–4
in a working volume of 60 cm
3
is used to pump up and hold polarization in a polarized proton frozen target. A special wide-aperture magnet is the central part of the spectrometer of the setup based on the drift tubes. For precision steering the beam to the center of the target, two small magnets correctors developed by the Efremov Research Institute of Electrophysical Equipment have been manufactured and introduced into the setup.
First results on
-dependence measurements in inclusive
meson production in
interactions (
, Al, Cu, Sn, and W) are presented at
GeV/
c
. The ratios of the differential cross sections of four of these ...nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable
and transverse momentum
GeV/
c
.
mesons were detected in the decay mode
at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex.
—
The control system for the detectors of the SPASCHARM experimental setup that is being developed at the U-70 accelerator complex (Protvino) is described. The general design concept of the control ...system and an example of application of the EPICS software are considered. The electronic modules of the control system that have been put in operation as of the present are described.
The SPASCHARM experiment is aimed at a systematic study of the nucleon spin structure and the spin dependence of the strong interaction of antimatter and matter with matter at energies up to 45 GeV. ...As part of the first stage of the experiment, the study of the spin properties of hadrons will take place in a beam of negatively charged hadrons on existing beamline 14 at the operating SPASCHARM setup at the U70 facility. At the second stage, the production of polarized beams of protons and antiprotons is envisaged in beamline 24A of the U-70 accelerator facility. A polarized antiproton beam will certainly become a unique beam in the world. It is planned to measure single-spin asymmetries in dozens of reactions, both on hydrogen and on various nuclei. At the SPASCHARM facility, it is also possible to measure the transverse polarization of hyperons and elements of the spin density matrix of vector mesons. The spin structure of the nucleon will be investigated in the study of quarkonium production to determine the contribution of gluons to the proton spin. The presence of two types of polarized beams and eight types of nonpolarized beams (π
±
,
K
±
,
p
,
,
d
,
C
), in combination with a polarized target, expands the range of studies of polarization phenomena and enhances the uniqueness of the project.
A new experiment SPASCHARM for systematic study of polarization phenomena in the inclusive and exclusive hadronic reactions in the energy range of IHEP accelerator U-70 (12–50
GeV) is currently under ...development. The universal experimental setup will detect dozens of various resonances and stable particles produced in collisions of unpolarized beams with the polarized target, and at the next stage, using polarized proton and antiproton beams. At the beginning, the final states consisting of light quarks (
u
,
d
,
s
) will be reconstructed, and later on the charmonium states will be studied. Measurements are planned for a variety of beams:
π
±
,
K
±
,
p
, antiprotons. Hyperon polarization and spin density matrix elements of the vector mesons will be measured along with the single-spin asymmetry (SSA). The 2
π
-acceptance in azimuth, which is extremely useful for reduction of systematic errors in measurements of spin observables, will be implemented in the experiment. The solid angle acceptance of the setup,
Δ
θ
≈
2
5
0
mrad vertically and 350 mrad horizontally in the beam fragmentation region, covers a wide range of kinematic variables
p
T
and
x
F
. This provides the opportunity for separating dependences on these two variables which is usually not possible in the setups with a small solid angle acceptance. Unlike some previous polarization experiments, the SPASCHARM will be able to simultaneously accumulate and record data on the both, charged and neutral particle production.
Polarimeters for the SPASCHARM Experiment Semenov, P. A.; Bogdanov, A. A.; Bukreeva, S. I. ...
International journal of modern physics. Conference series,
2016, Letnik:
40, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
A beam channel of polarized protons and antiprotons produced from decays of
Λ
- and anti-
Λ
-hyperons for the SPASCHARM experiment is to be built at IHEP U-70 accelerator in Protvino, Russia. The ...methods for tagging and measuring polarization of the beam (anti)protons are discussed in this report. The fast on-line beam tagging exploits the correlations between polarization and kinematics of (anti)protons originated from (anti)
Λ
-decays. In the intermediate focus of primary target, decay (anti)protons of different transverse polarizations are spatially dispersed transversely with respect to the beam axis. The tagging system, consisting of fast beam detectors with good spatial resolution, measures the momentum and trajectory of each beam particle, including its position at the intermediate focus, thus allowing instant (on-line) assignment of the transverse polarization value to each (anti)proton. This system is also extremely useful for the beam channel tuning. While being fast and convenient, the polarization tagging fully relies on computing of particle transportation in the beam channel. In order to verify the real beam polarization and operating of the tagging system and beam channel, the independent absolute beam polarimetry is to be used. It is based on measuring the spin asymmetries in elastic scattering of beam (anti)protons in Coulomb-Nuclear Interference (CNI) and diffractive kinematic regions. It is estimated that less than one week of data taking would allow measuring an absolute beam polarization at the statistical accuracy of
∼
4–5%.
A new experiment SPASCHARM devoted to a systematic study of polarization phenomena in hadron-hadron interactions in the energy range 10-70 GeV is under preparation at IHEP (Protvino). The physical ...observables will be single-spin asymmetries, hyperon polarizations and spin-density matrix elements. A universal setup will detect and identify various neutral and charge particles in the full azimuthal angle and a wide polar angle range. A polarized target is used to measure the SSA. The SPASCHARM sub-detectors are being designed and constructed now. The possibility of obtaining a polarized proton beam for the SPASCHARM experiment from Lambda decays is under study.
The results obtained by measuring, at the U-70 accelerator in Protvino, the single-spin asymmetry
A
N
in the reaction
p
+
p
└
→ π
0
+
X
at a beam energy of 50 GeV in the Feynman variable range of ...−0.6 <
x
F
< −0.1 are presented. The asymmetry
A
N
is close to zero at small |
x
F
| and grows in magnitude with |
x
F
|, reaching 6.4% in the region of |
x
F
| > 0.25. The results of these measurements agree with data of the E704 experiment on the asymmetry of
π
0
mesons at the Fermi National Accelerator Laboratory in the region of polarized-beam fragmentation and with the results of measurements in the region of polarized-target fragmentation that were performed in Protvino by using a 40-GeV
π
−
-meson beam and a 70-GeV proton beam.
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