Cosmic ray muons are produced when high energy particles interact with nuclei in Earth's atmosphere. Muons make up the majority of charged particles that reach sea level and are the only particles (apart from neutrinos) that can penetrate to significant depths underground. The muon flux underground decreases approximately exponentially as a function of depth. We use a cosmic ray detector developed by the QuarkNet Program at Fermi National Laboratory to map the topography of the mountain above an abandoned Pennsylvania Turnpike tunnel by analyzing muon flux at different rock overburdens. Cosmic ray muons have been used in this capacity before to search for hidden chambers in pyramids and for mapping volcanoes. This study provides a unique field experience to learn about particle physics and particle detectors, which could be of interest to students and teachers in physics.

1.
K. A.
Olive
 et al., “
Cosmic ray section of particle data group
,”
Chin. Phys. C.
38
,
090001
(
2014
).
2.
Claus
Grupen
,
Astroparticle Physics
(
Springer
,
Berlin/Heidelberg, Germany
,
2005
).
3.
The Super Cryogenic Dark Matter Search (SCDMS) collaboration website can be found at <http://cdms.berkeley.edu/experiment.html>.
4.
E. P.
George
, “
Cosmic rays measure overburden of tunnel
,”
Commonw. Eng.
1955
,
455
457
(
1955
).
5.
Ch. J.
Rhodes
, “
Muon tomography: Looking inside dangerous places
,”
Sci. Prog.
98
(
3
),
291
299
(
2015
).
6.
Hiroyuki K. M.
Tanaka
, “
Muographic mapping of the subsurface density structures in Miura, Boso and Izu peninsulas, Japan
,”
Sci Rep.
5
,
8305
8315
(
2015
).
7.
L. W.
Alvarez
 et al., “
Search for hidden chambers in the pyramids
,”
Science
167
,
832
839
(
1970
).
8.
More information on Rays Hill tunnel can be found at <https://en.wikipedia.org/wiki/Rays_Hill_Tunnel>.
9.
L. N.
Bogdanova
,
M. G.
Gavrilov
,
V. N.
Kornoukhov
, and
A. S.
Starostin
, “
Cosmic muon flux at shallow depths underground
,”
Phys. At. Nucl.
69(8)
,
1293
1298
(
2006
).
10.
R. A.
Soluk
and
ALTA Collaboration
, “
Educational cosmic ray arrays
,”
AIP Conf. Proc.
828
,
271
276
(
2006
).
11.
R.
Guntera
,
G.
Spiczak
, and
J.
Madsen
, “
Cosmic collaboration in an undergraduate astrophysics laboratory
,”
Am. J. Phys.
78
,
1035
1047
(
2010
).
12.
B.
Brau
,
C.
May
,
R.
Ormond
, and
J.
Essick
, “
Determining the muon mass in an instructional laboratory
,”
Am. J. Phys.
78
,
64
70
(
2010
).
13.
Th.
Coana
,
T.
Liub
, and
J.
Ye
, “
A compact apparatus for muon lifetime measurement and time dilation demonstration in the undergraduate laboratory
,”
Am. J. Phys.
74
,
161
164
(
2006
).
14.
D. P.
Jackson
and
M. T.
Welker
, “
Measuring and modeling cosmic ray showers with an MBL system: An undergraduate project
,”
Am. J. Phys.
69
,
896
900
(
2001
).
15.
N.
Easwar
and
D. A.
MacIntire
, “
Study of the effect of relativistic time dilation on cosmic ray muon flux An undergraduate modern physics experiment
,”
Am. J. Phys.
59
,
589
592
(
1991
).
16.
S.
Hansen
 et al., “
Low-cost data acquisition card for school-network cosmic ray detectors
,”
IEEE Trans. Nucl. Sci.
51
(
3
),
926
930
(
2004
); website for quarknet cosmic ray detector activities: <http://quarknet.fnal.gov/>.
17.
Abaz
Kryemadhi
and
Kyler
Chrestay
, “
Gamma ray spectroscopy with a silicon photomultiplier and a LYSO crystal
,”
Am. J. Phys.
83
,
378
381
(
2015
).
18.
S.
Agostinelli
 et al., “
Geant4 a simulation toolkit
,”
NIM. A
506
(
3
),
250
303
(
2003
).
19.
Private Communication with <www.sens-tech.com>.
20.
G. F.
Knoll
,
Radiation Detection and Measurement
, 4th ed. (
Wiley
,
New York, NY
,
2010
).
21.
A. I.
Barbouti
and
B. C.
Rastin
, “
A study of the absolute intensity of muons at sea level and under various thicknesses of absorber
,”
J. Phys. G: Nucl. Phys.
9
,
1577
1595
(
1983
).
22.
The actual topography data was obtained from <http://www.geocontext.org/publ/2010/04/profiler/en/>.
23.
V. A.
Kudryavtsev
, “
Muon simulation codes MUSIC and MUSUN for underground physics
,”
Comput. Phys. Commun.
180
,
339
346
(
2009
);
V. A.
Kudryavtsev
,
E. V.
Korolkova
, and
N. J. C.
Spooner
, “
Narrow muon bundles from muon pair production in rock
,”
Phys. Lett. B
471
,
251
256
(
1999
);
P.
Antonioli
,
C.
Ghetti
,
E. V.
Korolkova
,
V. A.
Kudryavtsev
, and
G.
Sartorelli
, “
A three-dimensional code for muon propagation through the rock: MUSIC
,”
Astropart. Phys.
7
,
357
268
(
1997
).
24.
G.
Cowan
, “
A survey of unfolding methods for particle physics
,”
Conf. Proc.
C0203181
,
248
257
(
2002
).
25.
W.
Ulmer
and
W.
Kaissl
, “
The inverse problem of a Gaussian convolution and its application to the finite size of the measurement chambers/detectors in photon and proton dosimetry
,”
Phys. Med. Biol.
48
,
707
727
(
2003
).
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.