SMURF Research at Texas A

1
SMURF Research at Texas AM

• Dr. Tye W. Botting
• Texas AM University

2

• Special
• Microbeam
• Utilization
• Research
• Facility

3
Overview

• Introduction
• Brief Background
• Current Research
• Future Interests
• Closing Comments

4
Background

• Synthetic Organic Chemistry
• natural product precursor development

• Environmental Testing
• analytical equipment troubleshooting

• Nuclear Chemistry
• fission dynamics

5
Fission Dynamics

• Neutron calorimetry
• 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
(http//cyclotron.tamu.edu)
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
• 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
• 2MV Tandem Van de Graaff

• Electron accelerator
• 100keV electrostatic accelerator

• X-ray apparatus
• 1 Gray/min at Emax250keV

• 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.
(http//www.pelletron.com)
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 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.