To directly measure the DT neutrons from inertial confinement fusion with a high time resolution, a new type of neutron conversion composed of a CH2 conversion layer, a metal moderation layer, and a ...CsI secondary electron emission layer is proposed. The conversion screen is based on the principle that recoil protons produced by elastic scattering of the neutrons in CH2 interact with CsI to generate secondary electrons. The moderation layer can filter the energy spectrum of protons to prevent low-energy protons from reaching CsI, which shortens the duration of the secondary electron pulse and improves the temporal resolution of the conversion screen. Based on the Monte Carlo method, both the neutron impulse and background γ-rays response of this conversion screen were calculated. The simulation indicates that the temporal resolution of the conversion screen can reach up to 4.9 ps when the thickness of the gold layer is 100 µm. The detection efficiency of secondary electrons/neutrons can reach 7.4 × 10−3. The detection efficiency of the neutron conversion screen for secondary electrons/γ-rays is an order of magnitude lower than the neutron impulse response, and the response time of γ-rays is 20 ps earlier than the neutron pulses. This means that using this conversion screen is beneficial to distinguish between neutrons and γ-rays and has a good signal-to-noise ratio.
According to the requirements of high-energy particle detection for a large photocathode detection surface, low transit time spread (TTS), and low-cost photomultiplier tube (PMT), a kind of 20-in. ...hybrid large-area PMT based on the silicon (Si) electron multiplier array was designed and optimized. This study tracked the trajectories of photoelectrons from the photocathode to the silicon electron multiplier array based on the Monte Carlo and finite-integral method. The critical effects on the TTS characteristic of the large-area PMT, including the focusing electrode structure, glass shell structure, different potential differences, and relative distance from the photocathode vertex to the silicon electron multiplier array, were studied in detail. After optimizing the structure of the glass shell, the 20-in. hybrid PMT based on the ultra-small Si electron multiplier array with 40 mm collection diameter can achieve an excellent TTS of about 1.87 ns from the photocathode to the Si electron multiplier array at a collection potential difference of 2000 V.
Single-photon light detection and ranging (LiDAR) provides the single-photon sensitivity and picosecond time resolution, which is rapidly developing in three-dimensional (3D) imaging applications. ...Spatial resolution and imaging quality of LiDAR based on the single-photon avalanche-diode (SPAD) array detectors are difficult to improve, because currently available SPAD arrays still have small size array, due to the semiconductor manufacturing process limitation, and the functional circuitry around pixels reduces the fill factor. Herein, we propose a photon-efficient LiDAR method that guarantees the coupling relationship between the photosensitive area of each pixel and the corresponding beam spot illuminated on the target and uses 1/4 field of view (FoV) scanning imaging in the photosensitive area. The proposed method can effectively improve the spatial resolution of LiDAR system based on SPAD array detectors. Resolution test experiments show that the best observed (transversal) resolution is 3.1748 lp/mm at a working distance of 2.3 m, over tenfold larger than that of previous methods. Three-dimensional experiments prove that the system can achieve 3D high-resolution single-photon imaging, which is valuable in the fields of remote sensing and long-range target recognition.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The capacitance–voltage characteristics of metal–insulator–semiconductor structures based on Hg1−xCdxTe (x = 0.218) with CdTe passivation are studied before and after the passivation annealing ...process. We found that after vacuum annealing at 300 °C for 24 h, the micromorphology of the passivation layer was significantly improved, and as the fixed charge density decreased from 1.3 × 1012 cm−2 to 1.0 × 1010 cm−2, the fast surface state density decreased from 2 × 1013 cm−2 eV−1 to 3 × 1012 cm−2 eV−1, with a minimum value of 1.2 × 1011 cm−2 eV−1. From these findings, combined with the secondary ion mass spectroscopy analysis, we conclude that the annealing process propagates an equivalent electrical surface for CdTe/HgCdTe uniformly from the principal physical interface to the inside of the bulk material, effectively improving the characteristics of the CdTe passivation layer.
An interferometric semiconductor x-ray detection system is proposed in this paper. The system is based on the RadOptic effect, and it utilizes Fabry–Perot interferometry to measure radiation-induced ...changes in the optical refractive index of a semiconductor (GaAs). In this work, the intrinsic time resolution and the sensitivity of a Fabry–Perot interferometric sensor were systemically studied. Based on the transient free carrier absorption model, the prototype system was established to quantitatively measure the time-dependent x-ray flux with the deconvolution algorithm for the first time. The time resolution of the detection system was approximately 21 ps, and the output signal induced by an x-ray pulse showed a high signal-to-noise ratio and immunity to electromagnetic interference. This interferometer will enable x-ray bang-time and fusion burn-history measurements in inertial confinement fusion with higher time resolution.
The ablation and acceleration of diamond-like high-density carbon foils irradiated by thermal X-ray radiations are investigated with radiation hydrodynamics simulations. The time-dependent front of ...the ablation wave is given numerically for radiation temperatures in the range of 100–300 eV. The mass ablation rates and ablation pressures can be derived or implied from the coordinates of ablation fronts, which agree well with reported experiment results of high-density carbon with radiation temperatures Trad in the range of 160–260 eV. It is also found that the $T_{{\rm rad}}^3$ scaling law for ablation rates does not apply to Trad above 260 eV. The trajectories of targets and hydrodynamic efficiencies for different target thicknesses can be derived from the coordinates of ablation fronts using a rocket model and the results agree well with simulations. The peak hydrodynamic efficiencies of the acceleration process are investigated for different foil thicknesses and radiation temperatures. Higher radiation temperatures and target thicknesses result in higher hydrodynamic efficiencies. The simulation results are useful for the design of fusion capsules.
We propose an effective method to realize the quantum phase gate the system in which the transmon qubits are capacitively coupled to of one qubit simultaneously controlling N qubits. We use a ...superconducting transmission line resonator driven by a strong microwave field. In our scheme, the phase gate can be realized in a time （nanosecond-scale） much shorter than deco herence time （microsecond-scale）, and it is more immune to the l/（charge noise and has longer dephasing time due to the fa vorable properties of the transmon qubits in the system.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In object detection, multiscale features are necessary to deal with objects with different size. Using Feature Pyramid Network (FPN) as the backbone network is a very popular paradigm in existing ...object detectors, we call this paradigm FPN+. However, feature fusion of FPN is insufficient to express object of similar size but different appearance due to the unidirectional feature fusion. We motivate and present Adaptive Multiscale Feature (AMF), a new multiscale feature fusion method with bidirectional feature fusion, using to solve the one-direction fusion of FPN. AMF module fuses multiscale features from two aspects: (1) shattering features by the way of CLSM; (2) fusing features by the way of channel-wise attention. The proposed AMF improves the expression ability of multiscale features of the backbone network, and effectively improves the performance of the object detector. The proposed feature fusion method can be added to all object detector, such as the one-stage detector, the two-stage detector, anchor-based detector and anchor-free based detector. Experimental results on the COCO 2014 dataset show that the proposed AMF module performs the popular FPN based detector. Whether anchored-free based detectors or anchored based detectors, performance of detector can be improved through AMF. And the resulting best model can achieve a very competitive mAP on COCO 2014 dataset.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chemical vapor deposition (CVD) is a widely used method for graphene synthesis, but it struggles to produce large-area uniform bilayer graphene (BLG). This study introduces a novel approach to meet ...the demands of large-scale integrated circuit applications, challenging the conventional reliance on uniform BLG over extensive areas. We developed a unique method involving the direct growth of bilayer graphene arrays (BLGA) on Cu foil substrates using patterned titanium (Ti) as a diffusion barrier. The use of the Ti layer can effectively control carbon atom diffusion through the Cu foil without altering the growth conditions or compromising the graphene quality, thereby showcasing its versatility. The approach allows for targeted BLG growth and achieved a yield of 100% for a 10 × 10 BLG units array. Then a 10 × 10 BLG memristor array was fabricated, and a yield of 96% was achieved. The performances of these devices show good uniformity, evidenced by the set voltages concentrated around 4 V, and a high resistance state (HRS) to low resistance state (LRS) ratio predominantly around 107, reflecting the spatial uniformity of the prepared BLGA. This study provides insight into the BLG growth mechanism and opens new possibilities for BLG-based electronics.
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IJS, KILJ, NUK, PNG, UL, UM
The frequency recognition algorithm for multiple exposures (FRAME) is a progressive single-shot high-speed videography technique that employs the spatial-frequency multiplexing concept to provide ...high temporal and spatial resolution. However, the inherent crosstalk from the zero-frequency component to the carrier-frequency component leads to resolution degradation and artifacts. To improve recovered frames’ quality, we propose a FRAME reconstruction method using guided filters for a removal of the zero-frequency component, which can minimize the artifacts while enhance spatial resolution. A total variation (TV) denoising operation is involved to remove artifacts further to achieve optimized performances. Simulations and experiments were conducted to demonstrate the robust and efficient post-processing capability of the proposed method. With a two-frame experimental system, the results of a USAF 1951 resolution target reveal a 1.8-fold improvement in spatial resolution from 16 lp/mm to 28.5 lp/mm. For complex dynamic scenarios, the wide field of high-speed fuel spray was shot and the proposed method can resolve two droplets with a 30 μ m distance which outperforms the traditional method.
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