Suppression of Soft Nuclear Bremsstrahlung in Proton-Nucleus Collisions

Abstract

Photon energy spectra up to the kinematic limit have been measured in 190 MeV proton reactions with light and heavy nuclei to investigate the influence of the multiple-scattering process on the photon production. Relative to the predictions of models based on a quasifree production mechanism, a strong suppression of bremsstrahlung is observed in the low-energy region of the photon spectrum. We attribute this effect to the interference of photon amplitudes due to multiple scattering of nucleons in the nuclear medium.

New approach to determine proton-nucleus interactions from experimental bremsstrahlung data

“…The authors of [6,9] clearly observed the hump-shaped plateau in the experimental spectrum which is different from the typical exponential shape of the bremsstrahlung spectra previously measured by Edington and Rose in [1]. The further careful measurements of the bremsstrahlung emission in the proton nucleus scattering were done by the TAPS collaboration [11] and results confirmed the clear presence of such a plateau in the spectra. A supposition to explain such behavior of the spectra is to consider the internal dynamic motion of nucleons and collisions between them.…”

“…In Fig. 7 we add our calculations of the bremsstrahlung spectra for p + 58 Ni (a) and p + 107 Ag (b) at E p = 190 MeV in comparison with experimental data [11] which are normalized on the geometrical cross section σ r = 1.44 πA 2/3 fm 2 with A the target mass number (see Fig. 1 in [11] for the data and text in that paper for details).…”

“…6 we present the results of our calculations of the bremsstrahlung spectra for p data (see Figs. 2 and 3 in [11]). In Fig.…”

“…For higher photon energies, we obtain the hump-shaped spectrum which can be explained by the essential role in the emission of interactions between the scattering proton and momenta of nucleons of the nucleus (i.e., noncoherent processes). The careful measurements of the bremsstrahlung emission in the proton nucleus scattering were done by the TAPS collaboration [11] and we must include them in our analysis. In Fig.…”

“…The cross sections of the emitted photons have been measured for a long time (see Refs. [1][2][3][4][5][6][7][8][9][10][11]), and different theoretical models and approaches were developed to estimate the emitted photons (for example, see [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]). In particular, the spectra of the emitted photons are dependent on dynamics of the scattering of the proton off the nucleus, which is determined by interactions between the proton and nucleus.…”