China Spallation Neutron Source

A bstract The vertex detector is crucial for precision measurements of the Higgs boson at the electron-positron Higgs factory. Benchmarked with $$ H\to c\overline{c} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mover> <mml:mi>c</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> and $$ H\to s\overline{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>s</mml:mi> <mml:mover> <mml:mi>s</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> measurements in the $$ \nu \overline{\nu}H $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ν</mml:mi> <mml:mover> <mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>H</mml:mi> </mml:math> channel, we perform an optimisation study on the inner radius and spatial resolution of the vertex detector using the Jet Origin Identification (JOI) framework, which determines the parton flavour of jets using advanced Artificial Intelligence (AI) algorithm. We observe that, compared to the reference detector configuration, halving the inner radius and spatial resolution improves the transverse and longitudinal impact parameter resolution approximately by a factor of two, while increasing the accuracy and significance of the $$ H\to c\overline{c}/s\overline{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mover> <mml:mi>c</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>/</mml:mo> <mml:mi>s</mml:mi> <mml:mover> <mml:mi>s</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> measurement by 4% and 8%, respectively. Conversely, doubling these parameters results in comparable degradation, with variations in the inner radius being the dominant factor. Our results provide guidance for detector design and highlight promising prospects for identifying the $$ H\to s\overline{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>H</mml:mi> <mml:mo>→</mml:mo> <mml:mi>s</mml:mi> <mml:mover> <mml:mi>s</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> decay mode at future Higgs factories.

Periodic structures that may exist within the neutron imaging detector can introduce periodic noise into the imaging results, directly degrading image quality and further affecting the performance of deconvolution. This periodic noise appears as four-pointed star-shaped peaks in the amplitude spectrum of the frequency domain. However, the distribution of honeycomb-like noise structures in neutron imaging results makes it difficult to detect using conventional thresholding methods. We propose a method that applies a dilation operation before threshold detection to enhance the contrast between peaks and the surrounding areas. Then, a notch filter is used to smooth the peaks containing noise information, thereby removing the periodic noise structure. This approach effectively eliminates honeycomb structures of approximately 40 micrometers and improves the image quality after deconvolution processing.

The pursuit of simple yet high-performance materials is important for advancing organic photovoltaics, though structurally simple polymer donors typically underperform. This study reveals precise control over polymer aggregation and donor-acceptor compatibility is key to optimizing active layer morphology. We design three linear conjugated polymers with systematically chlorinated backbones to finely modulate aggregation tendency and surface tension. This strategy concurrently regulates film-formation kinetics and donor-acceptor compatibility. PTTz-Cl50 exhibits ideal aggregation and optimal compatibility with BTP-eC9, enabling sequential deposition that forms a bicontinuous interpenetrating network with appropriate domain size and marked phase purity. This microstructure provides sufficient interfacial area for exciton dissociation while retaining high-purity charge transport pathways. Consequently, the device demonstrates rapid exciton dissociation, efficient charge transport, and suppressed recombination, enhancing both short-circuit current and fill factor. This yield a high power conversion efficiency of 20.42% for linear conjugated polymers, underscoring the promise of low-cost materials for efficient devices.