Transcript Calvin Howell

Applications and Interdisciplinary
Research at TUNL
1. Homeland Security
Faculty: M.W. Ahmed, H.R. Weller and Y. Wu; C.R. Howell and W. Tornow
Facility: HIGS
Funding: DHS/DNDO-ARI [2 grants: (1) polarized fission and (2) NRF]
2. National Nuclear Security
Faculty: G. Mitchell; C.R. Howell and W. Tornow
Facility: DANCE at LANSCE, TUNL tandem lab and HIGS
Funding: DOE/NNSA [3 grants: (1) neutron-induced reactions and (2) NRF]
3. Energy
Faculty: M.W. Ahmed and H.R. Weller
Facility: TUNL tandem lab
Funding: Tri Alpha Energies, Inc.
4. Interdisciplinary
Faculty: C.R. Howell; T.B. Clegg and H.J. Karwowski
Facility: TUNL tandem lab
Funding: DOE/BER
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Photonuclear Reaction Measurements
at HIGS
Photonuclear Measurements on Actinides
• To measure data for photon-induced nuclear reactions that are important for
development of technologies for remote remote analysis of materials and
interrogation of cargo using g-ray beams and for advancing understanding of
the structure of heavy nuclei.
• To educate the next generation of nuclear physicists in research areas and
techniques relevant to national nuclear and homeland security.
Nuclear Resonance Fluorescence (NRF) Measurements
Faculty: C.R. Howell and W. Tornow
Funding: DHS/DNDO-ARI and DOE/NNSA
Photofission Induced with Polarized g-ray Beams
Faculty: M.W. Ahmed and H.R. Weller
Funding: DHS/DNDO-ARI
2
Non-Intrusive Active Interrogation Systems
s(g,g’) data using Nuclear Resonance Fluorescence (NRF)
Iron (35 cm thick)
Lead (20 cm thick)
Gamma-ray Transmission
3.0E-04
2.0E-04
1.0E-04
0.0E+00
0.0
2.0
4.0
6.0
8.0
10.0
Gamma-ray Energy (MeV)
Tunable g-ray source
Courtesy LLNL
Need to characterize states in
actinides that can be excited by
dipole EM transitions with g-ray
energies 2 < Eg < 4 MeV
3
Objectives of NRF Measurements
• Search for states that can be excited by dipole EM
transitions (2 < Eg < 4 MeV)
• Determine:
• Integrated cross section
• Branching ratios
• Spin and parity of the excited states (for nuclei with J=0+ ground state)
• Isotopes: 240Pu, 237Np, 233U
4
The Challenge of finding low-spin states at Ex > 2 MeV
5
Challenge of finding low-spin states at Ex > 2 MeV
(non band states)
240Pu
6
NRF Measurement Strategy
• Use Bremsstrahlung beam to conduct a search for
dipole transitions over a broad g-ray energy range, e.g.
(2 < Eg < 4 MeV)
• Next use monoenergetic g-ray beam to make high
sensitivity measurements at selected energies based
on results obtained with bremsstrahlung beams. Use
linear polarization to provide information about the
multipolarity of the observed g-ray transitions.
7
Search for low-spin states in 240Pu
with bremsstrahlung beam
• Discovered 9 g-ray
transitions to the
ground state
• Measured branching
ratio between
transition to the
ground state and
the 1st excited states
B.J. Quiter et al., Phys. Rev. C 86, 034307 (2012)
Measurements made at the High Voltage Research Lab. at MIT
bremsstrahlung beam produced by 3-MeV electron beam
8
Experiment Setup for NRF Measurements at HIGS
PIs: C.R. Howell and W. Tornow
Pb wall
collimator
Beam dump
Evacuated tube
Target
Paddles
HPGe Detectors
Cu plate
Flux Monitor
9
50
Example
TOF and g-ray Energy Spectra
0
2450
2500
2550
2600
2650
Energy (keV)
1000
1200
1800
2000
2200
2400
2600
Tl
2614.5
2578
2566
208
2547
Good RF
Accidental RF
2494
100
1600
Time (AU)
Detector 1 - Run 330, 334 (5 hr 21 min)
Good vs. Accidental RF
200
150
1400
2535
800
Good RF Cut
Accidental RF Cut
2523
1600
1400
1200
1000
800
600
400
200
0
2504
Counts
Eg = 2.55 MeV,
horizontal HPGe detector (5 hrs 21 min)
Detector 1 RF w/ Energy Cut Above 1850 keV
Counts
240Pu:
50
0
2450
2500
2550
2600
2650
Energy (keV)
Detector 1 RF w/ Energy Cut Above 1850 keV
1600
Good RF Cut
10
Determination of Spin and Parity
240
350
RunsE330,
334 (5 hr 21 min) - Pu @ 2.55 MeV
g = 2.55 MeV(5 hrs 21 min)
Horizontal and Vertical RF Subtracted
Horizontal
Vertical
2578
300
2566
Jπ
1+/-
Energy (keV)
Ex
250
200
Counts
240Pu:
2535
150
100
2523
2504
2547
2+
42.8
0+
0.0
2492
240Pu
50
0
2450
2500
2550
2600
2650
Energy (keV)
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Concept for material analysis – Polarized
Photofission
Faculty: M.W. Ahmed and H.R. Weller
φ = 90°
φ = 0°
•
•
Polarized g-ray induces fission of
target nuclei
Prompt neutrons are detected
both parallel and perpendicular
to the plane of polarization of the
incident g-ray
g-ray beam
12
Setup for photofission measurements
13
Implementation of concept
No Neutrons
Fission Neutrons
Fission + (g,n) Neutrons
Clean Signal
238U
Neutrons
Eg (MeV)
5.7
Fission Threshold
6.2
(g,n) Threshold
o Typical energy range Eg = 5.8 - 7.0 MeV
o Only other stable isotopes which can produce neutrons at these
energies are 2H and 9Be
o The neutron energy detection threshold is 1.5 MeV
o All neutrons are fission neutrons
14
Example of neutron assembly of fissile vs
nonfissile nucleus in Polarized Photofission
15
Measurements of neutron assembly in
polarized photofission
nonfissile
fissile
16
Applied and Interdisciplinary Research in the
tandem lab at TUNL
1. (n,2nx) and (n, f) cross section measurements on actinides
Faculty: W. Tornow and C.R. Howell
2. Plant research with short-live radioisotopes
Faculty: C.R. Howell
3. Water purification by filtration
Faculty: C.R. Howell
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Plant Physiology Studies Using Radioisotope Tracing
Duke Physics:
Calvin Howell, Alexander Crowell,
Laurie Cumberbatch, Brent Fallin
Duke Biology:
Chantal Reid
Jefferson Lab:
Brian Kross, Seung Joon Lee, Jack McKisson,
John McKisson, Andrew Weisenberger, Wenze Xi,
Carl Zorn
University of MD:
Mark Smith
West Virginia University:
Federal Sponsors:
DOE: Office of Nuclear Physics
DOE Biological and Environmental Research
NSF: Biological Infrastructure
Alexander Stolin
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Evidence for Influence of Human Activities on
Atmospheric CO2 Levels
“Industrial Revolution”
19
Long-time scale Picture of Atmospheric CO2 Levels
from Antarctic ice core samples
Current atm. CO2 concentration
Milanković cycles:
Earth’s orbital eccentricity:
100 kyrs
Earth’s axis tilt (22.1 ↔ 24.5): 42 kyrs
Earth’s axis wobble:
23 kyrs
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Research Objectives
1. Primary food
source on Earth
2. Helps regulate
atmospheric CO2
levels
 to identify and measure the effects of changes in environmental
conditions on the allocation of carbon (sugars) and nitrogen;
 to measure the physical parameters in plant physiology models of
substance translocation and allocation, e.g., phloem loading and root
exudation;
 to measure plant responses to herbivores; and
 to measure dynamic change in photorespiration rate in response to
changes in environmental conditions.
21
Isotope production and use
p + 14N  11C + α
≈100 m
22
Plant Physiology Research using Radioisotope tracing
Goal: Explore dynamical response of plants to changes in its local environment and
external resource availability
 Radioisotopes produced in tandem lab
 Measurements made at the Phytotron (in
environment controlled growth chamber)
Larry Cumberbatch, Duke Medical
Physics, PhD thesis project
Collaboration with JLab detector group
Local Participants:
Faculty: Howell, Reid (Biology)
Research Scientist: Crowell
PhD Student: Cumberbatch
Published in Physics in Medicine and Biology (2012)
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PhytoPET System
• Developed at JLAB
• Based on H8500 PSPMT and
pixelated LYSO crystals
• Flash ADC readout over Gb
ethernet
• Multiple configurations
possible
Weisenberger et al., NIM A, 718 (2013) 157.
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Corn Growth Conditions
•
•
•
Young corn plants (~ 1-2 weeks old)
labeled with 11CO2
B73 variety – has a sequenced genome
Transplant into clear media (Gelzan) to
facilitate registration of root images
25
Translocation of Sugars
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Quantitative Analysis
1
2
3
4
v (1 → 2) ≈ 6.0 mm/min v (2 → 3) ≈ 0.1 mm/min
v (3 → 4) ≈ 0.3 mm/min
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Characterization of membranes for water purification by
Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil
Detection (ERD) analyses
Students: Peter Attayek (UG), Eliot Meyer, Lin Lin, Grayson Rich, Joshua Powell
Faculty: Orlando Coronell, Thomas Clegg  Collaborators: Hugon Karwowski, Nalin Parikh
(Left) A new target system was developed to
enable analysis of organic samples by
Rutherford backscattering spectrometry (RBS)
and elastic recoil detection analyses
(Below) The target system is used to study the
active layer of membranes for water desalination
and reuse, including their elemental composition
and charge density
Attayek et al., Submitted for publication
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