- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Pulse dilation gas Cherenkov detector for ultra-fast gamma reaction history at the NIF (invited)
摘要： The Cherenkov mechanism used in Gas Cherenkov Detectors (GCDs) is exceptionally fast. However, the temporal resolution of GCDs, such as the Gamma Reaction History diagnostic at the National Ignition Facility (NIF), has been limited by the current state-of-the-art photomultiplier tube technology to ～100 ps. The soon-to-be deployed Pulse Dilation Photomultiplier Tube (PD-PMT) at NIF will allow for temporal resolution comparable to that of the gas cell or ～10 ps. Enhanced resolution will contribute to the quest for ignition in a crucial way through precision measurements of reaction history and ablator areal density (ρR) history, leading to better constrained models. Features such as onset of alpha heating, shock reverberations, and burn truncation due to dynamically evolving failure modes may become visible for the ?rst time. Test measurements of the PD-PMT at Atomic Weapons Establishment con?rmed that design goals have been met. The PD-PMT provides dilation factors of 2 to 40× in 6 increments. The GCD-3 recently deployed at the NIF has been modi?ed for coupling to a PD-PMT and will soon be making ultrafast measurements.
关键词： Gas Cherenkov Detectors,Pulse Dilation Photomultiplier Tube,National Ignition Facility,temporal resolution,Cherenkov mechanism
更新于2025-09-09 09:28:46
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A new High-Resolution Imaging System (HiRIS2) detector for preclinical SPECT imaging
摘要： The aim of the work is to describe a new high-performance scintigraphic detector, derived from our previous work based on a Position Sensitive Photomultiplier Tube (PSPMT) with 256 output anodes. This detector is suitable for direct integration into multi-modality imaging systems. Indeed, the detector has been developed in order to be integrated into a pre-clinical system. The detector is based on an H9500 Hamamatsu PSPMT coupled to an LYSO pixelated scintillator and a low-energy tungsten collimator with parallel square holes. In order to limit the overall size of the device, a dedicated compact electronics has been developed. The device design was performed using Monte Carlo transport calculations to aid the development. Our results show a detector performance suitable for application on small animals. The intrinsic spatial resolution was experimentally determined to be about 1.6 mm. The measured energy resolution was ～16% at 140 keV and the maximum recorded sensitivity was ～76 cps/MBq. In addition, the results agree quite well with those of Monte Carlo simulations. We have successfully improved the performance of our previous detector design in order to integrate the new device into a complex system focused on pre-clinical imaging.
关键词： Position sensitive photomultiplier tube,GATE,Scintigraphic small animal imaging,Single photon emission,SPECT
更新于2025-09-04 15:30:14
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Prototype time-of-flight PET utilizing capacitive multiplexing readout method
摘要： Positron emission tomography (PET) is an imaging technique that provides the spatial distribution of radiopharmaceuticals labeled with positron emitting radioisotopes by detecting the gamma rays produced from positron-electron annihilation. Recently, a time-of-flight (TOF) PET has drawn an increasing attention because it is capable of reducing the scan time or injected dose with improved the signal-to-noise ratio (SNR) in reconstructed PET images by precisely localizing the emission point along the line-of-response using TOF information. This study presents a multiplexing method that can effectively reduce the number of readout channels of a silicon photomultiplier (SiPM) based TOF PET while achieving excellent timing resolution. A capacitive multiplexing method was employed that could improve the degradation of the timing performance occurring in a conventional resistive multiplexing method. In addition, a high-speed signal processing method is also presented for the TOF PET. A TOF PET prototype was developed to demonstrate the imaging capability of the TOF PET system. A flood histogram of a PET detector module, composed of an 8×8 array of 3.01×3.01×20.00 mm3 lutetium fine silicate (LFS) scintillators and an 8×8 array of 3.16×3.16 mm2 SiPMs, was acquired using the proposed method. All 64 scintillators were successfully resolved in the flood histogram. The average energy resolution and coincidence resolving time (CRT) were 14.2±1.1% and 431±41 ps full width at half maximum (FWHM), respectively. A tomographic image of the hot-rod phantom was successfully acquired using the TOF PET prototype, and rods with a size of 2.4 mm in diameter were clearly resolved in the reconstructed image.
关键词： PET imaging,silicon photomultiplier,Time-of-flight PET,capacitive multiplexing,timing resolution
更新于2025-09-04 15:30:14
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Well structure engineering to improve the responsivity of p-on-n SiPM developed at KAIST-NNFC
摘要： This paper describes the electrical and optical properties of the p-on-n silicon photomultiplier (SiPM) developed at KAIST-NNFC. In particular, we present a comparison of the new and old versions in terms of several SiPM characteristics to highlight the improvements achieved through internal structure engineering. The new-version sensors were fabricated on a 200 mm n-doped epitaxial silicon wafer with an abrupt p+/n junction structure identical to that used in the old-version sensors using 0.18 μm CMOS technology. Based on the previous work, several changes were applied to the improved sensors, such as rapid thermal processing (RTP) conditions and ion implantation conditions for junction formation. In the work, we demonstrate that the reverse current is reduced by more than a factor of 104 with the modified RTP conditions. Furthermore, we show that the breakdown voltage is decreased by nearly 20% and the PDE in the blue-light regime is enhanced by nearly a factor of two as a result of internal structure engineering.
关键词： Silicon photomultiplier,SiPM,p-on-n structure
更新于2025-09-04 15:30:14