The AFIT of Today is the Air Force of Tomorrow.
Muon Concentration and Moderation to
Study Muon Catalyzed Fusion in a
Deuterium Gas Multiwire Proportional
Counter
Dr. Larry Burggraf
Major Greg Van Dyk
Department of Engineering Physics
January 7, 2013
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
Outline
The AFIT of Today is the Air Force of Tomorrow.
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Overview
Muon Scatter
Muon Moderation
Muon Catalyzed Fusion (µCF)
Roadmap
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
2
Overview
The AFIT of Today is the Air Force of Tomorrow.
Combine modeling and experimental measurements to
investigate µCF detection strategy
Areas of Research:
• Muon scatter lens: focus atmospheric muons to increase
muons on target
• Muon moderation: moderate atmospheric muon energies
from 1 GeV to approx 50 MeV incident on deuterium
detector
• Muon catalyzed fusion: detection of low energy muons
and fusion neutrons, for maximization of fusions in a
multi-wire proportional counter
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
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Celestial Plane
Atmospheric Muons
Muon Imaging,
Moderation and
Detection by μCF
Muon Lens
Plastic Coincident 1
Power Supplies
Moderating Material
Time of Flight
Energy Information
Plastic Coincident 2
Digital Data Capture
NaI Energy Detector
Fusion
Products
Fusion
Products
Neutron Detector
(24 PMT, EJ-309 Liquid Scintillator)
Multiwire Proportional Counter
NTS
Muon Scatter Phenomenon
The AFIT of Today is the Air Force of Tomorrow.
• Use characteristic thickness, t, for a given scattering
material to scatter the maximum amount of muons at a
certain angle, σave (Gaussian distribution width), to a
focal point
1
 theta  f ( Z )
13.6
zch
p
2 2

  t  
 t 
t
1  0.105ln 
  0.0035  ln 
  
X0 
 X0 
  X 0   

where
f (Z )  1 
X0 
0.24
Z  Z  1
716.4 A
 287 
pZ  Z  1 ln 

 Z 
Average scattering angle
increases with material thickness
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Muon Scatter Distribution
The AFIT of Today is the Air Force of Tomorrow.
• Scattering produces a radial Gaussian distribution
• As σave increases the distribution broadens and the
scattering efficiency decreases
• Scattering can be enhanced if the scattering material is
angled towards focal point near vertical
Vertical thickness was held constant and optimized for 4° scattering.
Inclined from left to right: 2 ° (almost vertical), 90 °(flat).
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Muon Scatter Elements
The AFIT of Today is the Air Force of Tomorrow.
• Assume θ1= θ2 yields the optimal form where the vertical
thickness, t, is optimized for θ1 scattering
• Functional form: y=he-αx where h is the total height and α
varies from 0 (flat) to 1 (vertical)
y
Incident Muon
y
x, f ( x)
Incident Muon
Outer
Surface
Incident Muon
h
θ 1 θ2
Focal
Point
(0,0)
1, f '( x)
t
θ1
Inner
Surface
x
Focal
Point
(0,0)
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x
7
Muon Lens: Continuous Design
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The AFIT of Today is the Air Force of Tomorrow.
GEANT4 Monte Carlo simulations
1 GeV muons
Angle of incidence 0° and 0°-10°
Varied α from 0.0001 to 0.9
Varied h from 500-1500 cm
Higher α’s yielded higher scattering efficiency at
discrete points but lower radial footprint decreases
total scattering efficiency
• Incident angles of 0°-10° favor a lower α
• Results: ~400% increase in flux on 1 cm2 target
with uniform 0° incident muons, ~50% increase of
flux of θ = 0°-10° (cos2θ ) incident muons
Air University: The Intellectual and Leadership Center of the Air Force
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Muon Lens: Discrete Design
The AFIT of Today is the Air Force of Tomorrow.
• Discrete scattering elements shaped to
bring normal (θ=0) muons of energy 1 GeV
to same focus on average.
• Increase scattering efficiency as radial
distance increases
Incident Muons
• Larger footprint
• Larger length of scattering element.
T
• Balance with the decreased scattering
efficiency inherent as the scattering angle
increases
• Increasing T enhances scattering efficiency
• GEANT4 simulations within next month
Optimized design to be built and tested: March 2013
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
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Muon Moderation
The AFIT of Today is the Air Force of Tomorrow.
• GEANT4 simulation using 1 GeV muons at 0° incidence
• (1) Roof with 5.08 cm thick gypsum
• (2) Steel I-beam with the two horizontal supports each
0.635 cm thick
• (3) Second floor with 10.16 cm thick concrete
• (4) Steel I-beam with the two horizontal supports each
0.9525 cm thick
• (5) First floor with 19.05 cm thick concrete
• (6) Experimental setup with moderation and detectors—
Muon lens to be modeled for final analytical design
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
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Muon Moderation
The AFIT of Today is the Air Force of Tomorrow.
• Optimized moderation amount of 130 cm aluminum
• 1 moderated muon stopping in deuterium gas every 80
minutes without incorporating muon lens
• Experimental setup to use time of flight data and NaI(Tl)
energy detector to optimize the amount of aluminum
moderation
Optimal moderation experiment complete: April 2013
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
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Muon Catalyzed Fusion
The AFIT of Today is the Air Force of Tomorrow.
• Muon replaces electron in hydrogen isotope (energies
less than 10 keV)
• Distance between two mesic hydrogens closer then two
electronic hydrogens (10-11 cm vs. 10-8 cm)
• Fusion rate 3 orders of magnitude higher
• Enhanced neutron emission coincident with muon
detection
• Goal: increase fusions per muon by enhanced stripping
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
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Muon Catalyzed Fusion
The AFIT of Today is the Air Force of Tomorrow.
• Fusions per muon
decreased when
fusion products with
lower fusion cross
sections scavenges
the muon ending the
µCF cycle
• Muon can be released
through collisions
induced by movement
in an electric field
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
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Muon Catalyzed Fusion
The AFIT of Today is the Air Force of Tomorrow.
• Multi-wire proportional counter with radial electric field optimal due to
little interaction with walls
• Total radial movement must happen on the order of the muon
lifetime, 2.2 µs
+
+
Cathode
Anode
D
-
+
3He+
µ-
+
3Heµ
µCF
µ
+
+
Exterior Wall
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
14
Roadmap
The AFIT of Today is the Air Force of Tomorrow.
• Muon Scatter
• Optimal lens design: February 1, 2013
• GEANT4 model: February 15, 2013
• Build and test: March 15, 2013
• Muon Moderation
• Test: April 15, 2013
• Muon Catalyzed Fusion
• COMSOL modeling of fields in multiwire proportional
counter: February 15, 2013
• Muons incorporated into ICEPIC: March 1, 2014
• Neutron detector and electronics arrive: March 1, 2013
• Pressurized deuterium tank test: June 1, 2013
• Multi-wire proportional counter test: August 1, 2013
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
15
Conclusion
The AFIT of Today is the Air Force of Tomorrow.
•
•
•
•
•
Overview
Muon Scatter
Muon Moderation
Muon Catalyzed Fusion (µCF)
Roadmap
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
16
Acknowledgments
The AFIT of Today is the Air Force of Tomorrow.
• Detector Donations: DTRA Team Site, Kirtland AFB
• Muon Modeling: Dr Takis Papoulius, Wayne State
University
• Moderation Metal: Wright-Patterson AFB Gun range and
AFIT Modeling and Fabrication Shop
• GEANT Modeling assistance: Dr Abby Bickley and Dr
Justin Clinton
• Detection Electronics Consultation: Maj Benjamin
Kowash
• Research Funding: Dr John Lugisland, AFOSR
• Questions?
Air University: The Intellectual and Leadership Center of the Air Force
Aim High…Fly - Fight - Win
17