M. Yu. Liburg

Observation of significant spin effects in hard collisions at 40 GeV/c

Abstract A single-spin asymmetry in the inclusive π 0 production at small x F was measured. In the experiment 40 GeV/c π − mesons were incident on transversely polarized protons and deutrons. An asymmetry of (40–50)% has been revealed in the hard scattering region.

Polarization in the reaction π−p → π0n at 40 GeV/c

Abstract The paper presents results on measuring the polarization in the reaction π − p→ π 0 n at 40 GeV/ c in the 4-momentum transfer range 0 t |⩽2 (GeV/ c ) 2 . The results based on the statistics of about 2.2 million recorded events made it possible to observe a noticeable value and complex structure in the polarization behaviour up to | t |⩽2 (GeV/ c ) 2 .

Frozen spin polarised deuteron target 60 cm3 in volume

A frozen spin polarised deuteron target cooled by a dilution refrigerator is described. Fully deuterated ethanediol and propanediol synthesised with a Cr(V) complex are used as the target materials. The following results are obtained: the maximum polarisation is 0.4, the maximum spin-lattice relaxation time is up to approximately 1500 h at 20 mK and 0.53 T.

Polarization in charge exchange reaction π−+p→π0+n at 40 GeV/c for the 4-momentum transfer range 0<|t|<2 (GeV/c)2

The results on measuring polarization in charge exchange reaction π−+p→π0+n at 40 GeV/c are presented for the 4-momentum transfer range from 0 up to 2 (GeV/c)2. At |t|≦0.4 (GeV/c)2 the polarization has a positive sign. In the “crossover” region of π± elastic scattering a possible minimum in the polarization behaviour has been seen for the first time. the polarization is zero within the statistical accuracy near this point. In the “deep” region of the charge-exchange differential cross-section the polarization has a negative sign. The presented data are not in agreement with the modern theoretical models.

Measurements of energy behaviour of spin-dependentnp—observables over 1.2–3.7 GeV energy region Dubna “Delta-Sigma” Experiment

New accurate data on the neutron-proton spin-dependent total cross section difference ΔσL(np) at the neutron beam kinetic energies 1.4, 1.7, 1.9 and 2.0 GeV are presented. A number of physical and methodical results on investigation of an elasticnp→pn charge exchange process over a few GeV region are also presented. Measurements were carried out at the Synchrophasotron and Nuclotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research.

Polarization parameters in the reactions π−p↑→ηn and π−p↑→η′n at 40 GeV/c

The polarization parameter in the reactions π−p→ηn and π−p→η′n at 40 GeV/c with −t ranging from 0 to 2.6 (GeV/c)2 and 1.0 (GeV/c)2, respectively, was measured in experiments using a propanediol polarized target. Only gamma particles from the neutral meson decay were detected. The polarization parameter of the first reaction turns out to be negative in a widet interval (0.05<−t<1.6 (GeV/c)2) and probably changes its sign at larger values oft. The average value of the polarization parameter of the second reaction is equal to −17±8)% in the region 0.05<−t<0.5 (GeV/c)2.

Energy dependence of the spin-spin correlation parameter CNN at 50° and 90° c.m. for pp-elastic scattering in the energy range 0.69–0.95 GeV

Abstract The spin-spin correlation parameter C NN at 50° and 90° c.m. for elastic pp-scattering has been obtained in the energy range 0.69–0.95 GeV. It was found that the parameter C NN (90°) shows resonance-like structure at energies near 700 MeV. Its energy dependence does not agree with Hoshizakis phase-shift analysis predictions. C NN (50°) agrees well with these predictions and does not show any structure within the accuracy of the measurements.

Continuous adsorption pumping

A new scheme for an adsorption pump is proposed. The vacuum pump is designed to operate with respect to a rigidly determined four-stroke closed cycle which consists of two isotherms and two isosteres. It is shown that routine information about the thermodynamic properties of the adsorbent is required for detailed calculation of the operating characteristics of the continuous adsorption pump (CAP). Some design peculiarities, such as a small difference in the temperatures of the adsorption and desorption processes, the adsorbent positioning and the method of adsorbent heating, together are expected to provide a pumping capacity for a CAP which is comparable to that of a Roots pump.

Search for azimuthal asymmetry of π0‐meson production in beam fragmentation region on polarized protons and deuterons

The inclusive production of {pi}{sup 0}s in the interaction of unpolarized {pi}{sup {minus}}, {ital k}{sup {minus}}, and antiproton beams with polarized proton and deuteron targets has been studied at IHEP. The absolute value of the asymmetry for {pi}{sup 0} production in the polarized proton and deuteron targets is between zero and fiften percent for large {ital x}={ital P}*/{ital P}*{sub max} and small {ital P}{sub {ital t}} and independent on the quark flavor. Results are presented and compared with theoretical calculations. (AIP)

Measurement of the spin asymmetry of cumulative proton production at 90° in the reaction πd↑→px at 40 GeV by using a polaraized deuterium target

Spin asymmetry of the protons emitted in the (85–95)°L.S. angular region in the π+d↑→p+x reaction was measured using a deuteron frozen‐spin target and a 40 GeV/c pion beam. The experimental results for (0.3–0.7) GeV/c momenta of the protons asre discussed and compared with the predictions of some models of cumulative particle production.