Pion absorption in tritium at intermediate energies

Abstract

The angular distribution of nucleons from a kinematically complete measurement of pions absorbed in H on nucleon pairs with isospin T =0 and T = 1 at incident pion energies of 119, 206, and 300 MeV are presented. The T =0 data are quite similar to pion absorption data in deuterium. The integrated absorption cross sections scale within errors with the number of isoscaler neutron-proton pairs. The T =1 cross sections, which correspond to absorption on dineutrons, are an order of magnitude smaller. The angular distributions for isovector absorption show a significant asymmetry, indicating interference effects between amplitudes with or without b isobars in the intermediate states. The existence of a significant three-nucleon absorption component is established. The integrated absorption cross sections for processes involving two and three nucleons were determined. The neutron and proton momentum probability densities in H were determined from the spectator recoil resulting from quasifree twonucleon pion absorption.PACS number(s): 25.80.Ls, 25.10.+s

Pion absorption inHe4above the delta resonance

“…For energies at and below the A, all measurements on sHe [1,2,8) and H [9] are consistent with Ng --1. 5 The apparent absence of any enhancement of QDA in He is puzzling, since the average pn pair separation in this nucleus is half that of the deuteron.…”

pd↔π+treaction around theΔresonance

“…[58]) and π + t → pd (Ref. [59]) have been included. The data at 450 and 500 MeV were taken from Ref.…”

Positive pion absorption on3Heusing modern trinucleon wave functions

“…Cross sections for positive and negative pion absorption on tritium were obtained in Ref. [17]. Overall, this gives a good wealth of data to determine absorption on different nucleon pairs with different isospins in a simple nuclear environment.…”