Novel Quantum Dot Assisted Semiconductor Gamma Ray Detector

To address homeland security needs, Physical Optics Corporation (POC) proposes to develop a new Gamma Ray Quantum Dot Semiconductor Heterostructure (GammaDot) sensor system. This compact modular system consists of Pb quantum dot (Q-dot) heterostructure laser module, a photodiode module, and a smart electronics module. The Pb Q-dot laser module consists of a stack of heterostructure lasers, which generates a laser output proportional to the incident gamma ray photons captured by Pb atoms. The photodiode module detects this output, and the detected signals are processed and interpreted by the smart electronics module to extract gamma ray spectral data. The GammaDot sensor system will have excellent energy resolution of <0.1% of FWHM, far superior to other detector technologies. The multilayer design enables the GammaDot sensor system to scan a high-energy bandwidth of 20 keV to 3 meV with 90% of the efficiency of the NaI crystal standard. Room-temperature operation and the low operating power of the components result in a low system power consumption of <0.5 W. Mass manufacturing will produce a system that is volume-priced at a few hundred dollars. In Phase I POC will demonstrate the feasibility of the concept by building and testing a proof-of-concept GammaDot sensor. In Phase II POC plans to develop a fully functional prototype that will be integrated with a power supply and data acquisition system. When completed, the entire system could be functionalized into an inexpensive handheld gamma ray spectrometer or adapted into an array system for imaging ¿ including baggage and cargo screening. GammaDot sensors can be adapted for detecting and imaging X-rays for biomedical applications. Because they can be pixilated and produced at ultralow cost, we foresee a large demand for these novel devices. Traditional high energy and nuclear physics experimental efforts could benefit from the compactness and position resolution of GammaDot sensor arrays. The unique arrangement of sensors in the system ensures unprecedented resolution and sensitivity over a wide energy bandwidth.