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Photon W value for krypton in the M-shell transition region
1National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, Umezono, Tsukuba, Ibaraki 305-8568, Japan. norio.saito@aist.go.jp
Radiation Research
|August 14, 2001
Summary
This study measured absolute W values for krypton using X-ray energies from 85 to 1000 eV. Researchers observed significant oscillations in W values near the krypton 3d electron ionization edge.
Area of Science:
- Atomic and Molecular Physics
- X-ray Physics
- Radiation Chemistry
Background:
- The W value, representing the average energy required to produce an ion pair, is crucial for radiation dosimetry and understanding radiation interactions.
- Previous measurements of W values for noble gases, including krypton, have shown variations depending on the incident radiation energy and type.
- Accurate determination of W values is essential for fields like medical imaging, radiation detection, and nuclear engineering.
Purpose of the Study:
- To precisely measure the absolute W values for krypton across a range of X-ray energies (85-1000 eV).
- To investigate the influence of X-ray energy, particularly near inner-shell ionization edges, on the W values.
- To compare experimental results with theoretical models, including those accounting for multiple photoionization effects.
Main Methods:
- Utilized monochromatic synchrotron radiation for incident X-rays to ensure energy purity.
- Employed a multiple-electrode ion chamber technique to accurately measure X-ray beam intensity and photoabsorption cross-section.
- Optimized electron storage ring operation and used thin filters to enhance X-ray beam purity.
Main Results:
- Absolute W values for krypton were determined for X-ray energies between 85 and 1000 eV.
- A notable oscillatory behavior in W values was observed in the energy region surrounding the krypton 3d electron ionization edge.
- The experimental data were compared with existing literature values for low-energy electrons and theoretical calculations.
Conclusions:
- The study provides new, precise absolute W values for krypton in the soft X-ray energy range.
- The observed oscillations highlight the significant impact of inner-shell ionization processes on energy deposition and ion pair formation.
- The findings contribute to a better understanding of X-ray interactions with matter and validate theoretical models incorporating complex ionization phenomena.