Studies on Self-Luminous Material and Coating with Long Persistent Yellow-Green Afterglow

The preparation, properties, expression and luminescent mechanism of self luminous material (SrAl 2O 4∶Eu 2+ , Dy 3+ ) were discussed. The long afterglow luminescent coating was prepared by adding proper luminescent powders SrAl 2O 4∶Eu 2+ , Dy 3+ and other aids into styrene/acrylic emulsion. The best prescription of the coating was defined. The properties of luminescent coating were determined. The primary factors which affect the coating properties were discussed.

Design of imaging system for CSNS near-target beam diagnostics

Introduction China Spallation Neutron Source(CSNS)is an accelerator-based pulsed neutron source which produces neutron with spallation reaction induced by proton bombarding tungsten target.With increasing beam powers and influences on target,near-target monitoring becomes extreme necessary.In this situation,an optical imaging system for proton beam diagnostics and monitoring near the target is being developed at CSNS,which can provide real-time images of the beam on target and beam distribution information.Target imaging system design and development In the design of CSNS target imaging system,coating of Cr^(3+):Al_(2)O_(3) is used to convert particle radiation into emission light.According to the geometry limits of CSNS target station,a special optical system was designed and fabricated to collect the emission light.When the proton beams strike on the target,the coating on the target will be excited,emitting luminescence at the same time.The mirrors and lenses of the optical system image the distribution of emission light into a radiation-hard imaging fiber,which transmits the images to the GigE camera located at low-dose area outside of the target station.Software was written on the LabView platform to control the camera and analyze the images on line.Mock-up of the imaging system was manufactured to test and evaluate the performances of the system.Some important characteristics of the system were obtained and studied.Conclusion Tests on the mock-up of the system present reliably expectation for beam diagnostics.The imaging system has been installed at CSNS recently.More work will be continued to improve the properties of the system.

Measurements and characteristics of Al_(2)O_(3):Cr^(3+) coating for the proton beam imaging system

Introduction To set up an online proton beam diagnostic system near the neutron production target of China Spallation Neutron Source(CSNS),a luminescence coating sprayed on the target windowand a corresponding optic system were fabricated.In the work,the fabrication of Al_(2)O_(3):Cr^(3+) coating was explored.Measurements on the sprayed samples were performed to analyze the characteristics of the Al_(2)O_(3):Cr^(3+) coating.Fabrication and tests of coating samples Three kinds of powders with different Cr concentrations were used to fabricate the luminescence coating samples.The flame spraying,plasma spraying and D-gun spraying processes were explored.Photoluminescence(PL),X-ray diffraction(XRD),scanned electron mirror(SEM)and radioluminescence experiment by 300 MeV deuterium beam were carried out to analyze and characterize the samples.Results The emission spectrum excited by 532-nm laser has two obvious peaks at 692.9 nm and 694.3 nm.The samples by flame spraying process with the powders obtained from melting method show higher luminescence intensity than the samples by plasma spraying process.It is observed that the luminescence intensity has some relationships with the alpha phase in the samples,which is deduced from the XRD and photoluminescence tests results.A lower temperature during the flame spraying process will help to keep more alpha phase in the material.The selected four samples show successful fluoresced results in the radioluminescence experiment.Conclusions The luminescence intensity of the coating is improved greatly by the studies on the fabrication process and the characteristics of the samples.The luminescence coating used in beam diagnostics will be fabricated by the confirmed technical process.More works will be continued to improve the characteristics of the luminescence light by controlling Cr concentration and annealing in 1200∼2000℃ environment in the future.