LET spectrum measurements in Cr-39 PNTD with AFM

Conference · Fri Jan 01 00:00:00 EST 2010

DOI:https://doi.org/10.1063/1.3586180· OSTI ID:1026830

Johnson, Carl Edward ^[1]; De Witt, Joel M ^[2]; Benton, Eric R ^[2]; Yasuda, Nakahiro ^[3]; Benton, Eugene V ^[4]

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1. Los Alamos National Laboratory
2. OSU, PHYSICS
3. NIRS, HIMAC
4. UNIV OF SAN FRANCISCO

Energetic protons, neutrons, and heavy ions undergoing collisions with target nuclei of varying Z can produce residual heavy recoil fragments via intra-nuclear cascade/evaporation reactions. The particles produced in these non-elastic collisions generally have such extremely short range ({approx}< 10 {mu}m) that they cannot be directly observed by conventional detection methods including CR-39 plastic nuclear track detector (PNTD) that has been chemically etched for analysis by standard visible light microscopy. However, high-LET recoil fragments having range on the order of several cell diameters can be produced in tissue during radiotherapy using proton and carbon beams. We have developed a method to analyze short-range, high-LET tracks in CR-39 plastic nuclear track detector (PNTD) using short duration chemical etching ({approx}< 1 {mu}m) followed by automated atomic force microscope (AFM) scanning. The post-scan data processing used in this work was based on semi-automated matrix analysis opposed to traditional grey-scale image analysis. This method takes advantage of the 3-D data obtained via AFM to achieve robust discrimination of nuclear tracks from other features. Through automation of AFM scanning, sufficient AFM scan frames were obtained to attain an LET spectrum spanning the LET range from 200-1500 keV/{mu}m. In addition to our experiments, simulations were carried out with the Monte Carlo transport code, FLUKA. To demonstrate this method, CR-39 PNTD was exposed to the proton therapy beam at Loma Linda University Medical Center (LLUMC) at 60 and 230 MeV. Additionally, detectors were exposed to I GeV protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). For these exposures CR-39 PNTD, Al and Cu target foils were used between detector layers.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 1026830
• Report Number(s): LA-UR-10-05385; LA-UR-10-5385; TRN: US1105142
• Resource Relation: Conference: CAARI 2010 ; August 8, 2010 ; Fort Worth Tx
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ATOMIC FORCE MICROSCOPY
AUTOMATION
CARBON IONS
DATA PROCESSING
DETECTION
DIELECTRIC TRACK DETECTORS
ETCHING
F CODES
HEAVY IONS
ION BEAMS
KEV RANGE
LET
MONTE CARLO METHOD
NEUTRONS
NUCLEI
PARTICLES
PARTICLE TRACKS
PROTONS
PROTON BEAMS
RADIATIONS
RADIOTHERAPY
RECOILS
SIMULATION
TARGETS
TRANSPORT