Figure 1

Feynman diagrams for $\mathit{NN}$ bremsstrahlung: (a) external process, (b) internal process, (c) rescattering process.Reuse & Permissions

Figure 2

(a) Full-target data for mean incident neutron energy $T_{\mathrm{inc}}=225$ MeV and ${\theta }_n={\theta }_p={28}^{°}$, plotted as a function of scattered neutron and proton kinetic energies. (b) Data after subtraction of empty-target and random-coincidence background. The solid curve is the kinematic locus for $T_{\mathrm{inc}}=225$ MeV along which $\mathit{np}$ bremsstrahlung events should fall. The solid circles indicate emitted photon angles of $0^{°}$ and ${180}^{°}$ at low and high nucleon energies, respectively. The lower (upper) portion of the curve between $0^{°}$ and ${180}^{°}$ corresponds to photons emitted on the neutron (proton) side of the beam. The vertical (horizontal) short-dashed line represents the proton (neutron) detection threshold. The long-dashed curves illustrate a kinematic cut as described in the text.Reuse & Permissions

Figure 3

Photon angular distributions in $\mathit{np}$ bremsstrahlung for (a) ${\theta }_p={\theta }_n={12}^{°}$; (b) ${\theta }_p={12}^{°},{\theta }_n={32}^{°}$; (c) ${\theta }_p={\theta }_n={20}^{°}$; (d) ${\theta }_p={20}^{°},{\theta }_n={32}^{°}$; (e) ${\theta }_p={\theta }_n={28}^{°}$; (f) ${\theta }_p={28}^{°},{\theta }_n={32}^{°}$. Negative (positive) angles correspond to photons emitted on the neutron (proton) side of the beam. The data (solid circles) have been summed over the incident neutron energy range 175–275 MeV; the inner error bars are the statistical uncertainties; the outer error bars include systematic uncertainties [16]. The curves are the theoretical predictions of Brown [7, 14] (solid curves) and Timmermans et al. [9] (dashed curves). The blue and red shaded bands represent an average over the detector acceptances of the predictions of Brown [17] and Timmermans et al. [18], respectively, with out-of-plane contributions included. The open circles in (a) are quasifree $\mathit{pn}$ bremstrahlung cross sections at ${\theta }_n=13.5^{°},{\theta }_p={12}^{°}$, and incident energy 190 MeV from the $\mathit{pd}$ bremsstrahlung experiment of Volkerts et al. [6]. The statistical uncertainties are comparable to the size of the symbols.Reuse & Permissions