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

Special Microbeam Utilization Research Facility

Overview Introduction Brief Background Current Research Future Interests Closing Comments

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

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 (http://cyclotron.tamu.edu)

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

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

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

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

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

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.

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…

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

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

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

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

Accelerator Tank Magnet Ion Source

Magnet Accelerator Tank

Pelletron Charging System Illustration courtesy of... National Electrostatics Corp. (http://www.pelletron.com)

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

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

Cell culture dishes

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

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!

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

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

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

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

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

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