1. SMURF Research at Texas A&M
Dr. Tye W. Botting
Texas A&M University

2. Special
Microbeam
Utilization
Research
Facility

3. Overview Introduction Brief Background Current Research
Future Interests
Closing Comments

4. Background Synthetic Organic Chemistry Environmental Testing
natural product precursor development
Environmental Testing
analytical equipment troubleshooting
Nuclear Chemistry
fission dynamics

5. Fission Dynamics Neutron calorimetry Timescale of nuclear fission
The TAMU Neutron Ball
Timescale of nuclear fission
compare two conflicting methods
4 reactions analyzed in detail
statistical model analysis of data
FOR MORE INFO...
TAMU Cyclotron Institute (

6. Rate of Nuclear Fission
Two “clocks” that did not seem to agree
Neutron evaporation clock
Giant Dipole Resonance (GDR) g-ray clock
Required 150+ detectors
~500 parameters per event
Required statistics produced 80+ GB of data
Statistical model calculations
Monte Carlo methods
Comparison with experiment yielded timescales

7. So, how fast is nuclear fission?
Very fast!
~110-20 seconds
for medium-energy reactions

8. Current Research Accelerator Development Physics / Engineering
Improvements and additions
Physics / Engineering
Krypton gas neutron detector
Hot water energy reclamation
Health Physics
Microdosimetry

9. Accelerator Development
Ion source stability
Beam development
Software development
Accelerator control
Microbeam targeting
Additions

10. Physics / Engineering
Improve understanding of the interaction of neutrons with matter
Develop new detector technologies
Energy conservation / reclamation

11. Health Physics
Our main objective is to achieve a better understanding of risk to human health from everyday exposure to low doses of ionizing radiation.

12. Health Physics…
Evalaution of risk at low radiation doses has been based on linear extrapolation of observed effects of very high doses.
There are problems with this approach…

13. Health Physics
High-dose radiation exposure results in individual cells receiving multiple hits
Low-dose radiation exposure consists of sparsely distributed single hits
No reason to expect that a low-dose linear extrapolation model should work

14. Our Approach
Investigate both high- and low- linear energy transfer (LET) radiations
positive ions (high LET)
electrons and X Rays (low LET)
Irradiate specific cells in vitro
use low doses directly
a line of cells on a dish, on individual cells
look for microscopic effects
mutations
cell-cell communication

15. Tools Positive ion accelerator Electron accelerator X-ray apparatus
2MV Tandem Van de Graaff
Electron accelerator
100keV electrostatic accelerator
X-ray apparatus
1 Gray/min at Emax=250keV
Hot water reflux apparatus
trial run in progress

16. 2MV Tandem Van de Graaff Alphatross Ion Source
Bending and Focusing Elements
Charging System
Tandem = “double ended”
Produces 4 MeV protons, 6 MeV alphas
Experimental Beam Lines
Neutron “beam”
Positive-Ion Microbeam

17. Accelerator Tank
Magnet
Ion Source

18. Magnet
Accelerator Tank

19. Pelletron Charging System
Illustration courtesy of...
National Electrostatics Corp. (

20. Experimental Beamlines
Neutron “beam”
Protons incident on LiF target
Positive-Ion Microbeam
5mm beam thickness
Targeting
Individual cell nuclei
Line traces

21. Microbeam Microscope Assembly Detectors (3 photomultipliers)
direct and camera
Detectors (3 photomultipliers)
special petri dishes go below
Fine collimators
2 sets of x and y axes
Beam Stop
Coarse collimators
1 set, only y axis

22. Cell culture dishes

23. Electron Accelerator Only 4 feet high
Different type of collimator assembly
Accelerator tube has up to 100,000 Volts to produce up to 100keV electrons

24. Results Accelerator Development Improved ion-source stability
Added positive-ion microbeam assembly
Made its endstation software functional
Developed usable proton and neutron beams
Added neutron production beam line and facility
Always a work in progress!

25. Results… Physics / Engineering
Krypton gas neutron detector experiments run
Data still being analyzed to determine next step(s)
Hot water energy conservation / reclamation
Designed apparatus
Construction nearing completion
Should begin trial runs within the month

26. Results… Health Physics X-ray irradiations (adapt and challenge)
Appears low doses good for cell survival upon later higher-dose exposure
Positive-ion irradiations
Mixed low-dose results (cell-line effect?)
Electron irradiations
Appears that low fluence low-LET radiation is not as damaging as predicted by the linear extrapolation model

27. Results Notes
An interesting observation has arisen that irradiation of petri dishes prior to cell culturing seems to contribute to in vitro cell death.

28. Future Directions At TAMU: Continued accelerator development
Continued microbeam work
Perhaps non-biological applications
Further refinement of the Kr n-detectors
Hot water energy reclamation trial runs
Acquiring PIXE/RBS capability

29. Wider Future Directions…
Using PIXE/RBS to characterize surface pollution and degradation
Further investigation of irradiation pre-treatment as a bio-inhibitory
Application of nuclear science methods in materials science in general

30. Thank you all very much for your time and for the opportunity to visit both NCPTT and NSULA.