Muon Speed Analysis Clara Woods, Kyler Natividad, Julia Rathmann-Bloch #phobic_penguins

Overview of Experiment ❖ How fast do muons travel? ❖ How accurately can we measure their speed? Top Detector DAQ (Data Acquisition module) 3 Bottom Detectors 7 ft ft 2

Plateauing Why do we plateau detectors? Plateauing detectors is a way of testing if they are functioning correctly as well as finding the perfect setting for optimal use. What we’re looking for is a nice long place where the graph flattens out. As you can see, detector A has an amazing plateau graph, which tells us that it’s working very well. The other three detectors also plateaued, telling us they were legitimate. 3

Background research PS).pptx Journal of Undergraduate Research in Physics University of Minnesota Distribution of Muon energies at sea level WSU Quarknet Using Excel to analyze data 4

Hypothesis Model/testable prediction: Most of the muons will be travelling at the speed of light: c = 3 * 10^8 m/s. We expect a few to have a lower speed. After a preliminary experiment we found data that largely suggests that we will get most of our muons at the speed of light. From our solid angle, we calculated our expected count rate to be about 13.5 per minute. Our original experiment gave us a rough count rate of about per minute. Solid Angle of a Pyramid 5

Analysis Overview 1A68F930 BE 00 3C BD A A68F BD A A68F A 00 3E 00 3C BD A A F50B A A1655 2B F50B A A F50B A A E 00 3A 3A F50B A A F50B A Raw Data from DAQ Quarknet Analysis to get rid of extra information Speed Analysis Final Graphs 6

Analysis 1A68F930 BE 00 3C BD A A68F BD A A68F A 00 3E 00 3C BD A A F50B A A1655 2B F50B A A F50B A A E 00 3A 3A F50B A A F50B A ns timer Timing data for detector A (1.25 ns resolution) B CD GPS data, we are not using this *All used numbers are in hexadecimal Calculations: t = t_topdetector - t_bottom detector v = d/t We set the DAQ to only show us four fold coincidence, meaning that it will ignore an event that does not trigger all four detectors. 7

Preliminary Data Our first day of experiment Three more days of preliminary data to confirm original results Second peak with a negative time difference (the bottom detector is triggering before the top detector) 8

Possible physical explanations for the second peak Lower-energy backsplash from muon interactions Hidden source underneath floor 9

Ultimate solution The resolution is actually 40 ns The time of each event is found by adding a 40ns clock with a 1.25ns clock. The 1.25ns clock loops every 40ns. Our original analysis used the 40ns clock as a 10ns clock. This caused a -30ns offset when a muon is detected as the 1.25ns clock returns to 0. 10

Re-Calibration DetectorABCD Average Delay (ns) Number of Counts NA Error in counts per minute NA Before we had gotten rid of all false signals and could publish final results, we had to make one more change. We had realized that our detectors were giving us different time delays, so we re-calibrated to get rid of those effects. 11

Results Average speed = (stat) +.02(systematic) ft/ns Muon Number vs. Time Difference 12 c =.984 ft/ns

Additional experiments ~30 ns 13

Different edges Falling edge only Average of falling and leading edges Leading edge only 14

Threshold data V Threshold V Threshold We found no difference in precision between different threshold voltages 15

Conclusions ➢ We found muons traveling at an average speed of.968 ft/ns +.009(stat) +.02(systematic) ft/ns ➢ Light travels at a speed of.984 ft/ns ➢ The muons we measured were traveling at 98.4% +.9% the speed of light 16

Extension experiments ➔ Shielding to see better spectrum ➔ Change distance for increased precision ➔ Measure which sky angle produces the fastest muons ➔ Speed as a function of altitude 17

Thank You! #phobic_penguins Any Questions? Many thanks to: Stuart Briber Vicki Johnson Jason Nielson Tanmayi Sai Brendan Wells All our speakers and our fellow interns