Doppler Broadening Analysis of Steel Specimens Using Accelerator Based In Situ Pair Production

Journal Article · Tue Mar 10 04:00:00 EDT 2009 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3120185· OSTI ID:21289679

Makarashvili, V; Wells, D P ^[1]; Roy, A K ^[2]

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1. Department of Physics, Idaho State University, Campus Box 8106, Pocatello, ID 83209 (United States)
2. Department of Mechanical Engineering, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas NV 89154 (United States)

Positron Annihilation Spectroscopy (PAS) techniques can be utilized as a sensitive probe of defects in materials. Studying these microscopic defects is very important for a number of industries in order to predict material failure or structural integrity. We have been developing gamma-induced pair-production techniques to produce positrons in thick samples ({approx}4-40 g/cm{sup 2}, or {approx}0.5-5 cm in steel). These techniques are called 'Accelerator-based Gamma-induced Positron Annihilation Spectroscopy'(AG-PAS). We have begun testing the capabilities of this technique for imaging of defect densities in thick structural materials. As a first step, a linear accelerator (LINAC) was employed to produce photon beams by stopping 15 MeV electrons in a 1 mm thick tungsten converter. The accelerator is capable of operating with 30-60 ns pulse width, up to 200 mA peak current at 1 kHz repetition rate. The highly collimated bremsstrahlung beam impinged upon our steel tensile specimens, after traveling through a 1.2 m thick concrete wall. Annihilation radiation was detected by a well-shielded and collimated high-purity germanium detector (HPGe). Conventional Doppler broadening spectrometry (DBS) was performed to determine S, W and T parameters for our samples.

• OSTI ID: 21289679
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1099; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNIHILATION
BREMSSTRAHLUNG
CONCRETES
DEFECTS
DOPPLER BROADENING
ELECTRON BEAMS
ELECTRONS
EMISSION SPECTROSCOPY
GAMMA DETECTION
GE SEMICONDUCTOR DETECTORS
LINEAR ACCELERATORS
NONDESTRUCTIVE TESTING
PAIR PRODUCTION
PHOTON BEAMS
POSITRONS
STEELS
TUNGSTEN