Hide and Go Seek with MoNA: Finding Neutrons and Muons

1. Trina keeps spirits high while hanging out in front of the beam source. Modular Neutron Array (MoNA) Kate finds the time and charge data on the oscilloscope. Brian analyzes the data using Microsoft Excel. Hide and Go Seek with MoNA: Finding Neutrons and Muons Day 1: Finding a Neutron Source with an Oscilloscope Day 2: Finding a Neutron Source with SpecTcl Day 3: Detecting Muons from Cosmic Rays with SpecTcl Overview: Using an oscilloscope, we collected time and charge data for 5-7 neutron scattering events from a californium-252 source, which was placed at various locations along the MoNA bar. By finding the average values for the left and right times, graphs were constructed showing a relationship between time differences and position. Overview: The Day 1 experiment with placing a californium-252 source at several positions along a MoNA bar was repeated. Data analysis was completed with the software package SpecTcl, allowing us to look at 20,000+ neutron scattering events rather than a handful. SpecTcl took time and energy data from the left and right photomultipliers on bar B1 and created plots of the differences. Overview: This experiment required the overnight collection of data using all MoNA bars in order to detect the energy deposited by muons produced from cosmic rays. The goal of the experiment was to determine the speed of a muon through examining data from one of the 9 layers (16 bars) of MoNA. SpecTrl was used in order to analyze the data. SpecTrl Images showing data for muon scattering occuring in the 16 bars of Layer E. Left: histogram of position change between bar 15 and bar 0. Right: histogram of time change between bar 15 and bar 0. Oscilloscope image showing one neutron scattering event at one position. The yellow peak is the left bar signal and the blue peak is the right bar signal. SpecTrl Image showing data for 20,000+ neutron scattering events in bar B1 at one position. Integration of peaks provided mean values. Results: The 5 events were analyzed to calibrate our data collection. The final set of measurements were made to determine the location of the source. The value of Tdiff was -4.18 ns and the energy value was -0.21 MeV. The location of the source was determined to be 0.71 m from the left end of the bar. The actual location was 0.70 m from the left end. The results earned “STAR” recognition. Reflection: We have gained a “hands-on” appreciation for how MoNA provides energy and time data. Results: Data was recorded from three known locations for calibration. The unknown location yielded these values: Tdiff = -2.766 ns and Qdiff = 0.110MeV. The results indicated the location of the source to be 1.28 m from the left end of the bar when we used the fit from the Tdiff graph. The correct location was 1.264 m form the left end of the bar. Reflection: Increasing the number of events analyzed reduces the error in our measurement even though we were not as close to the real value. Results: We first found the average flight time for all the muon events using a Tdiff spectrum by integrating the largest peak. We assumed an average flight path of 150 cm corresponding to the muons traveling straight down from bar 15 to bar 0. Next, we applied a gate to select the time data for only those muons traveling ~180 cm. This resulted in a muon velocity that is only 1.27% away from the accepted muon velocity. Reflection: MoNA was able to help us easily calculate the speed of a particle such as the muon with good accuracy. Research Team: Trina Cannon, Highland Park High School, Dallas, TX Brian Knoop, St. Henry Catholic School, Nashiville, TN Kate Markiewicz, Boston Latin School, Boston, MA