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 30cm30cm30cm 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
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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
