염정열 교수

In the past, the main research and use of scintillators in extreme environments were mainly limited to high energy physics and the well-logging industry, but their applications are now expanding to reactor monitoring systems, marine and space exploration, nuclear fusion, radiation therapy, etc. In this article, we review and summarize single-crystal inorganic scintillator candidates that can be applied to radiation detection in extreme environments. Crucial scintillation properties to consider f

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Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Tw

Positron emission tomography (PET) is a molecular imaging modality that provides information at the molecular level. This system is composed of radiation detectors to detect incoming coincident annihilation gamma photons emitted from the radiopharmaceutical injected into a patient's body and uses these data to reconstruct images. A major trend in PET instrumentation is the development of time-of-flight positron emission tomography (ToF-PET). In ToF-PET, the time information (the instant the radi

The energy, timing, and DOI resolution information extracted from the side of long scintillation crystal elements coupled to dSiPM have been acquired for the first time. The authors conclude in this proof of concept study that such detector configuration has the potential to enable outstanding detector performance in terms of timing, energy, and DOI resolution.

A new multiwavelength visible-range-supported opto⁻ultrasound instrument using a light-emitting diode and ultrasound transducer was developed in order to produce multiwavelength visible light with minimized color aberration errors, and detect ultrasound signals emitted from the target. In the instrument, the developed optical systems can provide multiwavelength optical transmission with low optical aberration within 10-cm ranges that are reasonably flat in the modulation transfer function at spa

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing

A new silicon photomultiplier is fabricated for fast timing applications by SensL Technologies Ltd. This new family of silicon photomultiplier, herein referred to as fast SPM devices, is fabricated with a third terminal that has a low output capacitance to improve timing performance. Two fast SPMs (an N-on-P type and a prototype P-on-N type) are assessed for energy and timing performances in scintillation detectors. When coupled with L(Y)SO:Ce crystals, the optimal energy resolutions for the 511

We propose an integrated front-end data acquisition circuit for a hybrid ultrasound (US)-gamma probe. The proposed circuit consists of three main parts: (1) a preamplifier for the gamma probe, (2) a preprocessing analog circuit for the US, and (3) a digitally controlled analog switch. By exploiting the long idle time of the US system, an analog switch can be used to acquire data of both systems using a single output channel simultaneously. On the nuclear medicine (NM) gamma probe side, energy re

In optoacoustic (photoacoustic) systems, different echo signal intensities such as amplitudes, center frequencies, and bandwidths need to be compensated by utilizing variable gain or time-gain compensation amplifiers. However, such electronic components can increase system complexities and signal noise levels. In this paper, we introduce a double-Gauss lens to generate a large field of view with uniform light intensity due to the low chromatic aberrations of the lens, thus obtaining uniform echo

The medical ultrasound transducer is a principal component in ultrasound systems, as it significantly influences system performance. The high-voltage power amplifier (HVPA) is the key ultrasound transmitter component and interfaces with the medical ultrasound transducer. Therefore, the performance of the HVPA critically affects the echo signal quality of the ultrasound transducer. As they are inherently non-linear devices, harmonic distortion of echo signals generated by the ultrasound transduce

A multi-element silicon photomultiplier (SiPM) based time-of-flight (ToF) detector module for positron emission tomography (PET) has been developed. The detector module is based on a 4 × 4 array of LYSO-SiPM elements (Hamamatsu MPPC S10931-050P), with individual bias supply for each element. Each element is read out by a wideband, low-noise RF amplifier to maximize timing performance. All 16 outputs are digitized with a high-speed CAEN V1742 digitizer module (32 + 2 channels, 5 GS/s sampling, 12

A 12-Channel (Ch) CMOS Preamplifier-Shaper-Discriminator ASIC designed for avalanche photodiode (APD) and gas counter readout has been fabricated on a 2.4 mmtimes2.4 mm die area using ROHM 0.35-muCMOS technology. This mixed signal ASIC consists of both analog and digital components and a window type discriminator is easily implemented through the use of a digital encoder to encode outputs from two comparators. The charge sensitive preamplifier is based on gain-boosted (regulated) cascode topolog