General Purpose Transistor Characterized as Dosimetry Sensor of Proton Beams

Area of Science:

• Materials Science
• Radiation Detection
• Semiconductor Physics

Background:

• Proton beam dosimetry is crucial for radiation therapy and research.
• Standard dosimeters can be expensive or complex.
• Commercial electronic components offer potential for low-cost sensing solutions.

Purpose of the Study:

• To evaluate a commercial pMOS transistor (MOSFET) as a dosimeter for low-energy proton beams.
• To determine the optimal bias voltage for maximizing sensitivity and minimizing signal fading.
• To assess the feasibility of using off-the-shelf electronic devices for proton dosimetry.

Main Methods:

• Characterization of Vishay 3N163 pMOS transistors as proton beam dosimeters.
• Proton irradiations conducted at the National Accelerator Centre (Seville, Spain).
• Application of varying bias voltages (0, 1, 5, 10 V) and monitoring silicon temperature.
• Analysis of sensitivity and short-fading effects to determine optimal operating conditions.

Main Results:

• Averaged sensitivity showed a linear dependence on applied bias voltage.
• A bias voltage of 1 V yielded optimal sensitivity (11.4 ± 0.9) mV/Gy.
• The 1 V bias voltage minimized fading effect uncertainty to (-0.09 ± 0.11) Gy at 40 Gy absorbed dose.
• The parasitic diode of the MOSFET was utilized for silicon temperature monitoring.

Conclusions:

• Commercial pMOS transistors are viable and promising sensors for proton beam dosimetry.
• Optimized bias voltage significantly improves dosimeter performance and reliability.
• This approach offers a cost-effective alternative to specialized proton dosimeters.