Analyzing the effects of neutron polarizabilities in elastic Compton scattering off 3He

Abstract

Motivated by the fact that a polarized 3 He nucleus behaves as an 'effective' neutron target, we examine manifestations of neutron electromagnetic polarizabilities in elastic Compton scattering from the Helium-3 nucleus. We calculate both unpolarized and double-polarization observables using chiral perturbation theory to next-to-leading order (O(e 2 Q)) at energies, ω < ∼ m π , where m π is the pion mass. Our results show that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities.

Signatures of the chiral two-pion exchange electromagnetic currents in theH2andHe3Rozpędzik1, Golak2, Kölling3 et al. 2011Phys. Rev. C313541View full textAdd to dashboardCite

“…ChEFT has also been used to study the electromagnetic properties of the deuteron [3,4] and 3 He [5,6]. One of the fundamental processes observed for the deuteron is the photodisintegration reaction.…”

Active helium target: Neutron scalar polarizability extraction via Compton scattering

“…The proposed experiment to measure the neutron scalar polarizabilities is based on a recent theoretical model stating that the 3 He Compton scattering cross sections are particularly sensitive to these values [1]. The cross sectionsthe probability of an event occurring-will be measured by using an active helium target originally built for use in Lund, Sweden, in conjunction with the Mainzer Microtron and the Crystal Ball (CB) and Two-Armed Photon Spectrometer (TAPS) detectors (Fig.…”

“…+ 3 He ! " (1), which has significant presence above 100 MeV, is the largest contributor, with the 3 He nucleus breaking into two protons and a neutron (2) as the next largest [4].…”

High-accuracy analysis of Compton scattering in chiral effective field theory: Status and future

“…This is now being extended both to higher energies and by including the new single-nucleon amplitudes. For 3 He, the results in a variant without explicit ∆(1232) and for ω ∈ [80; 120] MeV [14] are extended, too. In few-nucleon systems, the Thomson limit as exact low-energy theorem is a result of NN rescattering between photon emission and absorption.…”

“…Around 3 He-4 He- 6 Li may well be the "sweet-spot" between needs and wants of theorists and experimentalists. Neutron values can also be isolated both in quasi-free kinematics and from polarised 3 He, which effectively is a free-neutron target [14].…”