Detecting Nuclei with MoNA at the NSCL

1. Detecting Nuclei with MoNA at the NSCL Brandon Le, Guthrie Gintzler, Julia Phelps & Rose Nguyen Physics of Atomic Nuclei 2010 Day 1 Day 2 To familiarize ourselves with the Modular Neutron Array (MoNA), we began our experiments by using the oscilloscope to detect the various sources of background radiation, such as cosmic rays (Figure 1). Once we got used to the equipment and its functions, a sample of Californium-52 was placed in known locations next to MoNA and measured with a meter stick in order to calibrate our oscilloscope. A graph of the time delay (Figure 2) between the signal received (between the two bars versus the actual position of the bar was created based on the calibrations (Figure 3). The sample was then placed in an unknown position to test if our graph was accurate in determining the location of the source. Our prediction was that the source was 0.699 m away from the left side. The actual result was 0.807 m. Using the software SpecTl to measure center of gravity [COG] (left), graph produced by information obtained from SpecTl (center) and a screenshot of the SpecTl program (right) SpecTl was used to find sources of radiation in a very similar but more detailed way than when we used the oscilloscope. SpecTl is a software program that gathers thousands of columns of data from MoNA, which is then converted into usable information. We began collecting data from the radiation emitted by a sample of Californium-52. The software then processed the data into graphs, which we analyzed. After interpreting our data, we predicted that the mystery source of radiation was 0.727 m away from the left side of MoNA. The sample was actually 0.735 m. Fig. 1 Practicing using the oscilloscope Day 3 Our concluding experiment involved finding the angular distribution of muons detected by MoNA. Muons are cosmic background radiation, found in the cosmic rays that are always being detected by MoNA. Graduate students collected data overnight, which we then loaded onto SpecTl. We calculated which values corresponded to the angular direction of the muons, and then we found the number of hits each angle got. Finally, we used this data to construct two curves describing the distribution of these hits, shown in the graph (Figure 4). Fig. 3 Graph used to determine source position Fig. 4 Graph of angular distribution of muons The Modular Neutron Array (MoNA) Fig. 2 Reading on the oscilloscope