Gamma Energy Spectra Due to Neutron Capture

These gamma energy plots were collected by taking 1 MeV neutrons incident on a 50 cm thick, 5 cm radius cylindrical block of Gd. The data files for this simulation is /data/cdms1/schmitz/condor_output/HannahTestStand/data/SiPM/1MeVNeutron1000k_GdCapSpectrum.root.

As a general note, the maximum energy of gamma generated by neutron capture on Gd should be 8.5 MeV (with another peak at 7.9 MeV for a different isotope of Gd). The sum of the initial energies of these gammas should be no more than one of these two values depending on the isotope of Gd on which the capture occurred. This is not consistent with the behavior that has been seen here, indicating that either some other process is going on which is generating gammas, or there is something we're doing wrong with the simulation itself (see future meetings; the former seems to be the case). One final note: all the captured neutrons here are tagged as primaries. There were some neutrons (about 0.2 per primary) that were also occasionally captured, but for clarity I decided to only plot the neutrons which were primaries (i.e. had initial energy 1 MeV) and were captured. This cut ended up not changing the shape of the gamma energy spectrum at all, but just know that it happened.

Figure 1: Gamma Energy, Individual	Figure 2: Gamma Energy, Individual (log)
Figure 3: Gamma Energy Sum