Muon Speed Analysis
Clara Woods, Kyler Natividad,
#phobic_penguins
Julia
Rathmann-Bloch
Overview of Experiment
❖ How fast do muons
travel?
Top Detector
❖ How accurately can we
measure their speed?
7 ft + 0.14 ft
DAQ (Data
Acquisition module)
3 Bottom
Detectors
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
Using Excel to analyze data
WSU Quarknet
Distribution of Muon energies at sea level
Journal of Undergraduate Research in Physics
University of Minnesota
http://sites.psu.edu/georgecoba/wp-content/uploads/sites/3300/2013/04/Muon-Speed-and-Lifetime.pdf
http://hep.physics.wayne.edu/web/quarknet/summer/2011/WSUQuarknetSummer2011/studentpresentations/session1/Muon%20Speed%20Study%20(G
PS).pptx
http://www.jurp.org/2012/MS138.pdf
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
10 + 3 per minute.
Solid Angle of a Pyramid
http://arxiv.org/abs/1205.1396
5
Analysis Overview
1A68F930
1A68F931
1A68F931
277A1655
277A1655
277A1655
277A1655
277A1656
BE 00 3C 00 00 00 00 00 198BD108 193048.022 170714 A 12 0 +0072
00 00 00 00 22 00 24 00 198BD108 193048.022 170714 A 12 0 +0072
00 3A 00 3E 00 3C 00 39 198BD108 193048.022 170714 A 12 0 +0072
80 00 00 00 26 00 00 00 26F50B48 193057.014 170714 A 12 0 +0040
2B 00 28 00 00 00 29 00 26F50B48 193057.014 170714 A 12 0 +0040
00 00 00 00 00 36 00 00 26F50B48 193057.014 170714 A 12 0 +0040
00 3E 00 3A 3A 00 00 00 26F50B48 193057.014 170714 A 12 0 +0040
00 00 00 00 00 27 00 22 26F50B48 193057.014 170714 A 12 0 +0040
Raw Data from DAQ
Quarknet Analysis to get
rid of extra information
6
Final Graphs
Speed Analysis
Analysis
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.
Calculations:
𝞓t = t_topdetector - t_bottom detector
v = d/𝞓t
Timing data for detector A (1.25 ns resolution)
GPS data, we are not using this
40 ns timer
B
C
D
1A68F930 BE 00 3C 00 00 00 00 00 198BD108 193048.022 170714 A 12 0 +0072
1A68F931 00 00 00 00 22 00 24 00 198BD108 193048.022 170714 A 12 0 +0072
1A68F931 00 3A 00 3E 00 3C 00 39 198BD108 193048.022 170714 A 12 0 +0072
277A1655 80 00 00 00 26 00 00 00 26F50B48 193057.014 170714 A 12 0 +0040
277A1655 2B 00 28 00 00 00 29 00 26F50B48 193057.014 170714 A 12 0 +0040
277A1655 00 00 00 00 00 36 00 00 26F50B48 193057.014 170714 A 12 0 +0040
277A1655 00 3E 00 3A 3A 00 00 00 26F50B48 193057.014 170714 A 12 0 +0040
277A1656 00 00 00 00 00 27 00 22 26F50B48 193057.014 170714 A 12 0 +0040
*All used numbers are in hexadecimal
7
Preliminary Data
Second peak with a negative
time difference (the bottom
detector is triggering before the
top detector)
Our first day of experiment
Three more days of preliminary data to confirm original results
8
Possible physical explanations
for the second peak
Lower-energy backsplash
from muon interactions
Hidden source underneath floor
9
The resolution is actually 40 ns
Ultimate solution
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
Detector
A
B
C
D
Average
Delay (ns)
0
2.5
.2
3.3
Number of
Counts
NA
58831
612320
93670
Error in
counts per
minute
NA
2.42
.69
1.82
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
Muon Number vs. Time Difference
c = .984 ft/ns
Average speed = 0.968 + 0.009(stat) + .02(systematic) ft/ns
12
Additional experiments
~30 ns
13
Different edges
Falling edge only
Average of falling and
leading edges
14
Leading edge only
Threshold data
15
0.400 V Threshold
0.350 V Threshold
We found no difference in precision between
different threshold voltages
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!
Many thanks to:
Stuart Briber
Vicki Johnson
Jason Nielson
Tanmayi Sai
Brendan Wells
#phobic_penguins
All our speakers and
our fellow interns
Any Questions?