High energy gamma ray production in proton-induced reactions at 104, 145, and 195 MeV

Abstract

Energy spectra and angular distributions have been measured for high energy gamma rays (E~& 20 MeV) from proton-nucleus reactions at 104, 145, and 195 MeV on targets of C, Zn, and Pb. Gamma rays were observed with energies up to 170 MeV. The spectra sho~ed difFerences from the typical exponential shape that is observed in gamma ray production from heavy-ion reactions. The angular distribution of the gamma ray is forward peaked in the laboratory, which is consistent with emission from a moving source. A comparison is made with previous measurements at 72, 140, 168, and 200 MeV. The experimental evidence indicates that first-chance incoherent proton-neutron bremsstrahlung is the main production mechanism.PACS number(s): 25.40. -h

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.…”

“…Our analysis begins with the p+ 208 Pb reaction, which has been intensively studied by different experimental groups and, so, has proper experimental material [1, 6,9]. However, the authors of [1, 9] observed a difference in experimental data from the typical exponential shape of the bremsstrahlung spectrum previously measured by Edington and Rose in [1].…”

“…We emphasize that our new approach is applicable for analysis (i.e., this approach should be able to extract information about radius parameter r R of the proton-nucleus potential) of even conflicting experimental data. So, we chose two experimental data sets [1] and [6,9] at the corresponding incident proton energies of 140 MeV and 145 MeV, and for the chosen angle between directions of the emitted photons and the incident protons which equals 90 • .…”

“…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.…”

“…We start our analysis from the p + 208 Pb reaction, which was intensively studied by different research groups and, thus has more evidence [1, 6,9]. 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].…”