The measurements of spin-independent part of np→pn forward scattering at energies Tn = 0.55 ÷ 2.0 GeV
Seminars
VBLHEP Special Seminar
A.M.Baldin Relativistic nuclear physics and polarization phenomena #768
Date and Time: Wednesday, 6 June 2018, at 11:00 AM
Venue: Big Conference Hall (bld.215), the Veksler and Baldin Laboratory of High Energy Physics
Seminar topic: «The measurements of spin-independent part of np→pn forward scattering at energies Tn = 0.55 ÷ 2.0 GeV» (“Delta-Sigma” experiment)
Speaker: R.A. Shindin
Abstract:
According to the Pauli principle in the quasi-elastic nd→p(nn) reaction with proton scattering to the zero angle (at small momentum transfer qnn=Pn‒Pp) two neutrons in the recoil can form only S-wave state with full spin Snn = 0, therefore during the charge-exchange of bound (deuteron) proton into the neutron its spin reverses also (Pomeranchuk-Chew hypothesis). Within the impulse approximation this process is determined by the spin-dependent amplitudes of elastic np→pn scattering. The measurement of the differential cross-sections of quasi-elastic nd→p(nn) and elastic np→pn reactions and determination of the Rdp-ratio between them allows to extract the spin observables in experiments with unpolarized particles.
Similar experiments were carried out at energies T < 1 GeV at laboratories LAMPF, LRL, UCRL, Harwell and so on. In the period 2002-07 using the accelerator complex Nuclotron LHE LINR was obtained new values of Rdp-ratio in the interval from 0.5 to 2 GeV. Experimental data was compared with the prediction of phase shift analysis (PSA) and good agreement was observed. Main results of performed work that the spin-dependent and spin-independent parts of the differential cross section for the charge-exchange reaction np→pn in the energy range Tn = 0.5 ÷ 2.0 GeV and proton scattering to the zero angle are about 85% and 15% respectively.
(Following the materials of the Candidate’s thesis)