A.A. Vorobyov

Experimental investigation of the muon catalyzed dd-fusion

Abstract Using an ionization chamber as a sensitive target of deuterium at 91.6 atm pressure the following parameters of the muon catalyzed dd-fusion have been measured at room temperature: the molecule formation rate Λddμ0=(2.76±0.08) × 102s−; the muon sticking coefficient ω dd , 3 He =0.126±0.004 ; the ratio of the yields R= Y( d+d → 3 He+n ) Y( d+d → 3 H+p ) =1.3±0.04 ; and the muon transfer rate Λ d 0 , 4 He =(3.2±0.3)×10 8 s −1 . The presented rates Λddμ0 and Λd0,4He are normalization to the liquid hydrogen density.

A METHOD FOR STUDIES OF SMALL-ANGLE HADRON-PROTON ELASTIC SCATTERING IN THE COULOMB INTERFERENCE REGION

Abstract A hydrogen-filled ionization chamber used as a target and as a detector of the recoil protons was proposed to be applied for studies of small-angle hadron-proton elastic scattering. The analysis of signals from the chamber electrodes and delay times of the signals made it possible to determine the energy and the emission angle of the recoils, as well as to separate the target volume inside the volume of the chamber. The protons were detected in the energy range 1.0–4.0 MeV, with the energy resolution fwhm = 40 keV. The method can be used in a wide range of incident particle momenta at beam intensities of 104–105 particles/s.

A precision measurement of nuclear muon capture on 3He

In this article we report the results of an experiment performed in 1993 at PSI. The goal was to determine the absolute rate of nuclear muon capture by3He. In the experiment we used a new technique recently developed at Gatchina. As a preliminary result from this experiment we obtainedλc=(1496±3(stat)-3(syst)) s−1.

Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling g P

The rate of nuclear muon capture by the proton has been measured using a new technique based on a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas, which is key to avoiding uncertainties from muonic molecule formation. The capture rate from the hyperfine singlet ground state of the microp atom was obtained from the difference between the micro(-) disappearance rate in hydrogen and the world average for the micro(+) decay rate, yielding Lambda(S)=725.0+/-17.4 s(-1), from which the induced pseudoscalar coupling of the nucleon, g(P)(q(2)=-0.88m(2)(micro))=7.3+/-1.1, is extracted.

SMALL ANGLE pp SCATTERING AT ENERGIES FROM 650 TO 1000 MeV

Received 14 June 1982 (Revised 19 November 1982) Absolute differential cross sections for pp elastic scattering have been measured at kinetic energies of 648, 746, 795, 843, 892, 942 and 992 MeV and for momentum transfer 0.006 < Itl < 0.040 (GeV/c) 2. Both scattered and recoil protons were detected in coincidence. The slope parameters of the diffraction cone and the contribution of the spin-spin amplitudes to forward elastic pp scattering were determined.

Elastic pp-scattering in the coulomb interference region in the momentum range 1.1 to 1.7 GeV/c

Abstract Differential cross-sections for pp elastic scattering in the transfer momentum range 2 x 10−3 ⩽ |t| ⩽ x8 10−3 (GeV/c)2 were studied with a hydrogen filled ionization chamber which was used as a target and as a detector of the recoiled protons. The measurements have been done at Plab. = 1.11 GeV/c, 1.28 GeV/c, 1.34 GeV/c, 1.40 GeV/c and 1.70 GeV/c. The real part of the spin independent forward scattering amplitude has been determined, the results being in agreement with the dispersion relation calculations.

Differential cross sections and analyzing powers for small angle neutron-proton elastic scattering between 378 and 1135 MeV

Abstract We have measured absolute differential cross sections and analyzing powers for neutron-proton elastic scattering for momentum transfer 0.01 t | c ) 2 at several energies between 378 and 1135 MeV. The ionization chamber IKAR filled with methane was used as both a gas target and recoil detector. For the analyzing-power measurements the scattered neutron was detected in scintillation counters in coincidence with the recoil proton detected in IKAR. Special care was taken to ensure a precise absolute normalization of the cross sections, with overall systematic uncertainties of 4–7%.

Experimental survey of the sticking problem in muon catalyzed dt fusion

The “sticking” process dtμ → αμ + n, which constitutes the most severe limit to the number of fusions which a muon can catalyze, is reviewed. Many attempts were made to determine by calculations and measurements the probability for initial stickingωs0 (immediately after dtμ fusion) and for final stickingωs (after the αμ came to rest). Previous results based on neutron disappearance rates and on the observation of αμ-X-rays were controversial and also in some disagreement with theory. New data are reported from PSI on direct observation of final sticking, using a setup with the St. Petersburg ionization chamber. These data mark a significant improvement in reliability and may clarify questions concerning previous discrepancies. The new results isωs∼(0.56±0.04)%, lower than the theory predictionωs=(0.65±0.03)%, at medium density.

Experimental apparatus for the study of small angle neutron-proton elastic scattering at intermediate energies

Abstract An experimental setup for measurements of absolute differential cross sections and analyzing powers in small angle elastic np scattering is described. The main part of the apparatus consists of a multielectrode ionization chamber IKAR filled with methane, serving as both a gas target and a recoil detector. The apparatus was used in measurements with a polarized neutron beam from the Saturne synchrotron (Saclay, France) in the energy range from 378 to 1135 MeV.

Elastic pd and p4He scattering at intermediate energies

Abstract The differential cross sections for elastic p 4 He and pd small angle scattering were measured at energies 991, 890, 793 and 695 MeV, using incident proton beams of the LNPI synchrocyclotron. The systematic error in absolute normalization of the cross section is ± 2%. Both the recoil particles and the forward protons were detected in this experiment. The total cross section and diffraction-cone slope parameter for p 4 He scattering have been extracted from the experimental data. The results of the measurements are compared to a calculation based on diffraction multiple-scattering theory in which nucleon-nucleon amplitudes obtained from a phase-shift analysis were used. It is shown that the slope of the calculated differential cross sections systematically exceeds the slope of the experimental cross sections in p 4 He scattering, unlike pd scattering. It is noted that one of the possible reasons for the observed discrepancy can be an admixture of multiquark bag in the 4 He nucleus.