1. Brian Keeney, LLU-SCIPP Nanodosimeter A Silicon Telescope For Nanodosimetry Santa Cruz Institute for Particle Physics, UC Santa Cruz in collaboration with the Department of Radiation Medicine at Loma Linda University Medical Center

2. Brian Keeney, LLU-SCIPP Nanodosimeter Nanodosimetry for Biomedical Applications - Collaborators Loma Linda University Medical Center Reinhard SchulteGeorge Coutrakon Vladimir BashkirovPeter Koss Weizmann Institute of Science Amos BreskinGuy Garty Rachel ChechikItzhak Orion Sergei Shchemelinin University of California, San Diego John F. WardJamie Milligan Joe Aguilera Santa Cruz Institute for Particle Physics (University Of California, Santa Cruz) Abe SeidenWilko Kroeger Hartmut SadrozinskiPatrick Spradlin Robert P JohnsonBrian Keeney

3. Brian Keeney, LLU-SCIPP Nanodosimeter Ionization event (formation of water radicals) The mean diffusion distance of OH radicals before they react is only 2-3 nm delta rays Light damage- reparable Clustered damage- irreparable Water radicals attack the DNA e-e- Primary particle track OH Radiation Damage To DNA

4. Brian Keeney, LLU-SCIPP Nanodosimeter ~1/  1.5 MIP Rad measure p Linear Energy Transfer LET: Radiation damage in DNA occurs within 2-3nm Bethe-Bloch in ND

5. Brian Keeney, LLU-SCIPP Nanodosimeter 1nm solid 1 m @ 1 atm. Propane gas Low pressure propane gas X 1000 DNA 1 mm @.001 atm. Expanding the DNA

6. Brian Keeney, LLU-SCIPP Nanodosimeter Incoming Proton Ion E weak E strong 4 Silicon Detectors give position and LET, allow trigger on any combination of planes Low Pressure Gas Aperture Ion Counter electron Vacuum NOT TO SCALE X-Y Y-X 1 SSD is 0.4% Xo or 120keV LET at high energy Nanodosimetry in Low-Pressure Propane

7. Brian Keeney, LLU-SCIPP Nanodosimeter VME CRATE PC W/ DAQ PCI Card Localization of Protons 2 Silicon Strip Detector (SSD) Modules Ion Counter SSD Readout Integration of Silicon Modules and Nanodosimeter

8. Brian Keeney, LLU-SCIPP Nanodosimeter TOT  charge  LET! Time-Over-Threshold (TOT): Digitization of Position and Energy with large Dynamic Range

9. Brian Keeney, LLU-SCIPP Nanodosimeter 13.5 GeV Spectrum TOT Spectrum - Effect of Charge Sharing in SMD’s

10. Brian Keeney, LLU-SCIPP Nanodosimeter TOT Spectra For Protons of Different Energies- An absolute calibration of SSD

11. Brian Keeney, LLU-SCIPP Nanodosimeter Results Proton energy [MeV] Mean TOT [us] RMS TOT [us] Charge Deposition 400um Si by Bethe-Bloch [fC] TOT expected [us] 13,50071.45.36.5 25012.32.613.513.7 3953.46.45455 2770.47.567.569 2478.38.576.578 2284.49.88182 17.610511.599101 9.510815189105 7.410921243105

12. Brian Keeney, LLU-SCIPP Nanodosimeter TOT and Resolution Measured TOT expected through Bethe-Bloch

13. Brian Keeney, LLU-SCIPP Nanodosimeter Resolution Energy Resolution = LET Resolution /Slope of TOT(E) Curve

14. Brian Keeney, LLU-SCIPP Nanodosimeter 1.Silicon detectors provide information on position and energy or LET of primary particles for nanodosimetry 2.Silicon detectors have excellent spatial resolution (60  m) 3.We can measure proton LET to 10-20% in each of 4 planes 4.Given LET, we know energy to 20-25% in each plane through Bethe-Bloch from low energies up to 250 MeV 5.Silicon Detectors allow flexible triggering on primary particles. Conclusion