Transcript PPT

Detecting nuclear contraband
with cosmic ray muons
or
“How to thwart nuclear terrorists
with subatomic particles”
Marcus Hohlmann
High Energy Physics Group, P/SS Dept.
P/SS Freshman Seminar, Sep 19, 2012
Nightmare Scenarios
• Terrorist smuggle highly
enriched uranium (HEU)
or plutonium across
borders and destroy a
city by detonating a
nuclear bomb, or
• Terrorists smuggle
highly radioactive
material into a city and
disperse it with a
conventional explosion
(“dirty bomb”) making
portions of the city
uninhabitable.
T.B. Cochran and M.G. McKinzie, Scientific American, April 2008
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Challenge in Detecting Nuclear Contraband
~ 800 Radiation Portal Monitors (n,) in U.S.
• In 2002, reporters managed to smuggle a
cylinder of depleted uranium shielded in lead
in a suitcase from Vienna to Istanbul via train
and in a cargo container through radiation
monitors into NY harbor. Cargo was flagged for
extra screening, but DU was not sensed.
• In 2003, used route Jakarta – LA, same result!
Sci. Am.,4/2008
6.8 kg DU
• IAEA: During 1993-2006, 275 confirmed incidents with
nuclear material and criminal intent; 14 with HEU, 4 with Pu.
Sci. Am., 4/2008
HEU can be hidden
from conventional
radiation monitoring
because emanating
radiation (,) is easy
to shield in regular
cargo (few mm Pb)
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Scientific American, April 2008
!
A Potential Solution: Muon Tomography - Concept
Muons are subatomic particles that come from cosmic rays and pass through us all the time.
μ
μ
μ-
Detectors locate
muons, giving us an
incoming vector.
Uranium
μ-
Fe
Iron
Small
Scattering
Muons are scattered
less by lower-Z
materials, e.g. iron.
U
Small
Scattering
Large
Scattering
Large
Scattering
Muons are scattered
more by higher-Z
materials, e.g. uranium.
Detectors locate
muons, giving us an
outgoing vector.
4
The location and angle of scattering are reconstructed using the incoming and outgoing vectors.
WIRED magazine article
WIRED online magazine, front-page, July 1, 2010
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
What’s a muon () ?
• Elementary particle
(point particle)
• Carries one elementary charge ±e:
+ and • Very similar to an
electron, but ~200
times more massive
• Unstable ( = 2.2 s):
  e e 
 e e 
• Gets continuously
produced in cosmic
ray air showers
Elementary Particles in the Standard Model of Particle Physics
me = 0.511 MeV/c2
m = 105.658 MeV/c2
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Cosmic Ray Air Showers
Credit: CROP, Creighton U.
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Useful Muon Properties
• Muons produced in the atmosphere by cosmic rays
can easily pass through 8 ft. of solid steel before
being absorbed. Hard to shield against!
• In fact, they are coming through the ceiling and all
the floors and the concrete roof above it and are
entering into our classroom (and you) RIGHT NOW!
• Even though muons do not get absorbed easily, they
DO scatter in the strong electric field of the
nuclei that make up all objects.
• The additional radiation exposure during scans,
e.g. passenger vehicles with people inside, is zero
because muons are natural background radiation.
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Why use cosmic ray muons ?
CR Muons don’t lose much energy due to ionization when passing through matter:
Stopping
power
Muons produced
by cosmic rays
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
How a GEM detector works
±
Ar+
CO2+
Detector volume filled with
Ar/CO2 70:30 gas mixture
eMicro-pattern gas detector (MPGD)
-
1cm
+
300 – 500 V (on each of 3 GEMs)
Florida Tech
triple-GEM
128 el. channels
(400 m pitch)
Anode strips
~ 30 cm
detects an electronic pulse
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Electron Multiplication
• Animation of the avalanche process (electrons are blue, ions are red, the GEM is orange)
• Simulation → keep track of electron and ion drifting and ion losses at the upper GEM electrode
A voltage of  400V is applied between
the two GEM electrodes. The primary
electrons created by the ionizing particle
drift towards the GEM holes where the
high electric field triggers the electron
multiplication process.
M. Titov (Saclay), CERN Detector Seminar, 4/12
Objective: Understanding
the gain in standard GEM
• Single electron-ion pair created
• Ar/CO2 70:30
• ANSYS: model & mesh the GEM
• Magboltz 8.9.6: relevant cross
sections of electron-gas interactions
• Garfield++: simulate e- avalanches
Courtesy: Sven Dildick,
Heinrich Schindler,
Rob Veenhof
• Edrift = 1 kV/cm (above GEM)
• Einduc = 3 kV/cm (below GEM)
• VGEM = 400 V (across GEM)
Developed within the framework
of the RD51 WG4 Software Activities
http://garfieldpp.web.cern.ch/garfieldpp/examples/gemgain
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Full 30cm30cm30cm Prototype
?
Geometry & Mechanical Design (Student Project):
31.1cm
31.7cm
?
Maximizes geometric acceptance
GEM detector
active area
Target plate
All designs by Lenny Grasso; constructed at Fl. Tech
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Muon Tomography Station upstairs
HEP-A Lab
(tour after talk)
Targets
8 GEM Detectors
12,288
readout
channels
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Custom Electronics Development
APV25 Hybrid (128 ch.)
30cm × 30cm
(1536 strips)
HDMI
connector
Panasonic
connector
Diode
protection
Bonded
APV25
chip
Slave card
connector
ADC
in coll.
with
CERN
Sep 19, 2012
12,288 readout channels
(for 8 GEM Detectors)
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Typical 2D Muon “Hit” in GEM det.
pulse
height
(ADC
counts)
X-Strip Cluster
X-Strip Number
pulse
height
(ADC
counts)
gives position measurement in x and y with 100-200 µm precision
Y-Strip Cluster
Strip
Y-Strip Number
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
10 Muon Tracks in Empty Tomography Station
This event display  UG project
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Real Data
1000 Muon Tracks in Empty Tomography Station
This event display  UG project
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Real Data
Scattering Reconstruction
• Simple reconstruction
algorithm using Point
of Closest Approach
(“POCA”) of incoming
and exiting 3-D tracks

a
• Treat as single scatter
• Scattering angle:
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons


b
MT Image Reconstruction
Top View
W
Pb
U
Sn
Fe
Point-of-closest-approach reconstruction
for incoming & exiting track
(performed by UG and grad students)
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
MT Image Reconstruction
Sn
Side views
Fe
U
Pb
Point-of-closest-approach reconstruction
for incoming & exiting track
Pb
W
W
U
Sn
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Fe
Uranium Shielded w/ Bronze
40 mm XY slices descending in Z by 5 mm per frame
Tin-bronze shielding
(83% Cu, 7% Sn, 7% Pb, 3% Zn)
with X0 = 1.29 cm & 1.7 cm walls
.
DU
1.7cm
•
•
•
•
Mixed track selection
187,731 reconstructed tracks
NNP cut = 10
2 mm x 2 mm x 40 mm voxels
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
With Lead Shielding
Lead box with 3.4mm thick walls
Tantalum
Lead
Tungsten
inside
Tin
Uranium
Iron
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Muon Tomogram
40 mm XY slices descending in Z by 5 mm per frame
The shielded targets are clearly
visible in the reconstruction
Lead
Tantalum
Tin
•
•
•
•
Uranium
Tungsten
Iron
Combinatoric track selection
292,555 reconstructed tracks
NNP cut = 5
2 mm x 2 mm x 40 mm voxels
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Past UG Research Students
• Georgia Karagiorgi, Ph.D. (HEP), MIT, 2010; now Research
Scientist, Nevis Labs, Columbia U. *
• Julian Spring, Ph.D. cand. (HEP), Boston U.
• Nick Leioatts, Ph.D. cand. (Biophysics), Rochester U. *
• Jen Helsby, Ph.D. cand. (Astrophysics), U. Chicago
• Patrick Ford, Ph.D. stud. (EE), Texas Tech
• Mike Abercrombie, Ph.D. stud. (physics), Wash. U., St. Louis
• Xenia Fave, Ph.D. stud. (medical physics), U. Texas
• Richie Hoch, software engineer, General Dynamics Corp.
• Ben Locke, software engineer, Harris Corp. *
• Will Bittner, software engineer, IBM Linux Research Center
• Jeremy Janney, Navy officer (nuclear submarines)
and many others…
* started during freshman year
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Northrop-Grumman Science Champions
Ben Locke receiving award
from NG officials
(April 2011)
Also got to present his
research to
members of Congress
(“Posters on the Hill”)
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Current UG Research Students
•
•
•
•
•
•
•
•
•
•
•
•
•
Kim Day, Grid Monitoring & Muon Tomography Analysis *
Liz Esposito, GEM Detector Testing
Johanna-Laina Fischer, Cluster Computing & Grid, Web *
Eric Hansen, Muon Tomography Hardware *
Michael Kane, Cluster Computing & Grid *
Swapnil Kumar, MT Upgrade Mechanics
Erik Maki, 3D Visualization of Muon Tomography Data *
Ankit Mohapatra, Gaseous Detector Simulations
Mike Phipps, Muon Tomography Analysis
Jessie Twigger, GEM Detector Construction & Test *
Kimberly Walton, Altium printed circuit board Design for GEM Readout
Jake Wortman, Muon Tomography Hardware *
Christian Zelenka, Muon Tomography Analysis & Operations
* started during freshman year
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Interested ?
• My group is always hiring good UG
students – even freshmen!
• Come “ask and you shall research”:
– Talk to me after this presentation or any time
during my office hours
• TR4-5, W11-12, in Rm. 343 (go through my lab 341)
– Send email: [email protected]
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons

See us at…
http://research.fit.edu/hep_labA/
θFIT
Thank you !
Sep 19, 2012
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
28
Tour of my lab
• For those interested, I will guide a
brief tour of my research lab NOW !
• Feel free to talk to the research students
in the lab afterwards
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
BACKUP MATERIAL
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons
Simulation: “FIT” Scenario
“FIT” is
made of
2 cm thick
uranium
blocks
M. Hohlmann - Detecting nuclear contraband with cosmic ray muons