References - Bogoliubov Laboratory of Theoretical Physics - JINR

2. Delta-Sigma Experimental Set-up. Transmission measurements over 1.2 - 3.7
GeV of the energy dependence of ΔσL(np) andΔσT (np) have been proposed [1] and
started in Dubna in collaboration with the groups from FSU, France and U.S. To speed
up the proposed measurements the main part of the set-up elements was provided by the
project collaborators. A large (140cm 3 ) Argonne-Saclay polarized proton target (PPT)
[3, 4] was reconstructed, shipped to Dubna, installed at the neutron beam line and tested.
The new polarized neutron beam lines [5, 6] with suitable parameters were prepared,
tuned, and tested by the JINR LHE specialists. The set of neutron detectors with corresponding
electronics (Saclay, Kurchatov Institute and JINR LHE), data acquisition
system (JINR LHE), deuteron beam line polarimeters (PINP, Gatchina and JINR LHE),
and other equipment needed were also prepared, tuned, and tested. The set-up for the
transmission measurements is fully functional but some parts of it needed to be upgraded.
More comprehensive description of the Delta-Sigma set-up for transmission measurements
elements is given in [7 - 8, 11].
The magnetic spectrometer with two sets of multiwire proportional chambers [9 - 10,
11] for detecting protons from np → pn elastic and nd → p(nn) quasi-elastic chargeexchange
processes at θp,Lab =0 ◦ , was installed and tested at the free neutron-beam line
of the JINR VBLHE Nuclotron facility. The spectrometer is a part of the DeltaæSigma
setup.
3. Main Results Obtained under the Project.
Measurements of the −ΔσL(np) energy dependence
were made using the L - polarized deuteron beam from
the JINR LHE Synchrophasotron and the Dubna L -
polarized proton target. Three data taking runs (1995,
1997 and 2001) were carried out for the ΔσL(np) measurementswithanadequateintensityupto5×
10 9
particles/cycle of polarized deuteros. An enough detailed
data set at 10 energy points for the −ΔσL(np)
energy behavior over 1.2 æ 3.7 GeV was obtained [7
- 8]. See also fig.1.
The measurements of the −ΔσL(np) energy dependence
were in the main completed. The Dubna group
of the participants of this investigation has gained
wide experience in carrying out transmission measurements
and is ready to measure the ΔσT (np) spindependent
observable. The detectors for transmission
measurement, electronics and data acquisition system
are also ready.
In the last years, the significant efforts were made
to test and tune the magnetic spectrometer equipment
and there were provided the possibilities for
Figure 1: Energy dependence of the
−ΔσL(np): •, �, � JINR results [7
-8];(�) PSI;(♦) LAMPF;(○) Saturne
II; (solid curves 1, 2, and 3)
FA85, SP99, and SP03 ED GW/VPI
PSA solutions, respectively; (dotted
curve) meson-exchange model; (dashed
curve) contribution from nonperturbative
QCD interaction induced by instantons
[7, 8].
Aookk(np), Aoonn(np) andRdp measurements using prepared magnetic spectrometer. A
number of data taking runs were successfully carried out using an intense quasimonochromatic
unpolarized neutron beam and liquid H2 , liquid D2 , C, CH2 and CD2 targets,
placed in the neutron beam line instead of the PPT. Measurements of the ratio Rdp of the
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