Ultralow-noise single-photon detection based on precise temperature controlled photomultiplier with enhanced electromagnetic shielding

We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By improvement of the electromagnetic shielding and introduction of the self-differencing method, the dark counts（DCs） are cut down to ~1%. We further develop an ultra-stable PMT cooling subsystem and observe that the DC goes down by a factor of 3.9 each time the temperature drops 10°C. At -20°C it is reduced 400 times with respect to the room temperature（25°C）, that is, it becomes only 2 counts per second, which is on par with the superconducting nanowire detectors. Meanwhile, despite a 50% loss, the detection efficiency is still 13%. Our detector is available for ultra-precise single-photon detection in environments with strong electromagnetic disturbances.

A sulfur-substituted hemicyanine for cancer photothermal therapy without influence of intracellular viscosity

Although photothermal therapy(PTT) has emerged as an appealing strategy for cancer treatment, the development of photothermal agents capable of precisely controlling temperature remains a challenge. In this paper, we present a novel synthetic photosensitizer based on a sulfur-substituted hemicyanine. It was discovered that replacing an oxygen atom in a hemicyanine derivative with a sulfur atom significantly enhances photothermal efficiency and enables lysosome targeting in cancer cells.More importantly, because of the rigid planer structure of the sulfur-substituted hemicyanine, which differs from traditional photothermal agents(PTAs) based on twisted intramolecular charge transfer(TICT) or group rotation mechanisms, the efficiency of photothermal conversion is not affected by intracellular viscosity, allowing precise temperature control during PTT.Further modifying the agent with a glutathione-responsive moiety allows the PTAs to be activated only in cancer cells. The newly proposed PTA achieves efficient PTT in a tumor-bearing mouse model while having negligible toxic side effects on healthy tissues.

A precision ADC sampling system design

Introduction The high-energy photon source,which has been built in Huairou,Beijing,has high requirements on magnetic field dithering.Magnetic field dithering is mainly determined by the stability of the output current of the power supply.In order to ensure the stability of the output current of quadrupole magnet power supply,the power supply sampling control loop needs to be precisely designed.In this paper,a precision ADC sampling system based on internal temperature control is designed to carry out precise control of the sampling ADC.Materials In this design,precise ADC chip is used to complete the precise sampling of the system.The precise sampling system contains a DAC system for high-speed settings.Methods In order to verify the design of the system,high-precision quadrupolemagnet power supply is used for measurement.Conclusion The experimental results show that the temperature variation range of precision temperature control ADC system is±0.1°C.By using the precise temperature controlADCsystem,the output current stability of the high-precision quadrupole magnet power supply is effectively improved.