L. B. Golovanov

Studying of hypernuclei with nuclotron beams

A spectrometer is created to study relativistic hypernuclei produced with beams of accelerated nuclei from the Nuclotron facility (Dubna, JINR). Test runs have been carried out and the conclusion is drawn that the properties of the facility meet the requirements of the task of searching for unknown and studying poorly known neutron-rich hypernuclei.

A THREE-CELL LIQUID HYDROGEN TARGET FOR AN EXTENDED FOCAL PLANE POLARIMETER

Abstract This article describes the design and working principle of a three-cell liquid hydrogen target produced for the high-energy deuteron polarimeter HYPOM. This target uses liquid helium as a cooling agent. After a general description of the apparatus, tests and operating modes are thoroughly explained. In particular the air controlled self-regulation of helium flow in the cryostat to stabilize the liquid hydrogen level is presented. The main feature of this target is the simplicity of the design as well as its safeness towards any incident. Results of cooling down, filling up of the target and stabilization regime were processed during one experiment of physics at synchrotron Saturne II.

Investigation of the deuteron spin structure at short nucleon-nucleon distances in the reaction of polarized-deuteron fragmentation to cumulative pions

Experimental results on the vector (Ay) and tensor (Ayy) analyzing powers in the fragmentation of 5- and 9-GeV/c polarized deuterons to high-momentum pions in the kinematical region corresponding to pion production on a strongly correlated nucleon pair (cumulative meson production) are presented. The angular and momentum dependences of Ayy are not described by calculations performed in the impulse approximation by using standard deuteron wave functions. An explanation for our data should be sought on the basis of models that treat the deuteron at short distances (deuteron-core region) as a multiquark state—for example, a 6q cluster, whose high orbital angular momentum (D wave) leads to the observed strong dependence of the reaction tensor analyzing power A(

Relativistic hypernuclei at Dubna

\vec d

First measurement of the cross-section ratioR dp(0) in charge-exchange (np) reactions on H2/D2 at 0o andT n = 1 GeV Dubna “Delta-Sigma experiment”

, π)X on the pion transverse momentum.

New Data on Ayy in Deuteron Inclusive Breakup at Large Transverse Momenta and Relativistic Description of the Deuteron at Short Distances

At the Laboratory of High Energies (JINR, Dubna) a unique approach was elaborated with hypernuclei produced by the excitation of the beam nuclei and their decays observed at a distance of tens of cm behind the production target. While the very first experiments were carried out in the Synchrophasotron beams, more extensive hypernuclei research programme is planned for the Nuclotron accelerator and the new spectrometer created by the authors. At the time of the conference the first test run in the Nuclotron beam was in progress. Investigation of hydrogen hypernuclei isotopes is in the first line of the experimental research plans. Namely, lifetimes and production cross sections of Λ 4 H and Λ 3 H will be measured. Search for Λ 6 H is also among the tasks.

A new target for the HYPOM polarimeter with plane LH2 cells

The first results of the measurement of 0o of the cross-section ratioRdp=0.50±0.02 in charge-exchange (np) reaction on H2/D2 targets at the neutron beam kinetic energie 1.0 GeV are presented. As a result the value of the ratio of non spin-flip to spin-flip contribution innp→pn charge-exchange at 0ornp→pn/nf/fl=0.33±0.03 was obtained.

Measurements of T20 in backward elastic dp scattering at deuteron momenta 3.5–6 GeV/c

Preliminary data on the tensor analyzing power A yy in breakup of 9 GeV/c deuterons on hydrogen and carbon nuclei at secondary proton transverse momenta up to ~ 900 MeV/c are presented. The results suggest that a deuteron structure function at short distances can depend on more than one independent variable unlike an ordinary wave function.

Measurement of tensor polarization of deuterons from 3He → d + p breakup at internal momenta up to 0.4 GeV/c

Abstract We present a new liquid hydrogen target working as a secondary target for an extended polarimeter. The specificity of this target is that the inner cell has a parallelepipedic shape. The dimensions along the beam and along the focal plane are maximized, for a small vertical extension, using a much smaller volume of liquid hydrogen, as compared to standard cylindrical cells.

The ratio Rdp of the quasielastic nd → p(nn) to the elastic np → pn charge-exchange-process yields at the proton emitting angle θp,lab = 0° over 0.55–2.0 GeV neutron beam energy region. Experimental results

Polarization phenomena in backward elastic dp scattering were studied with a view to reconstructing the deuteron wave‐function components. Experimental data disagree with predictions based on the impulse approximation which suggests that the wave function may have more than two components. (AIP)