Influences of Co-Doping Cation on Properties of PWO∶F- Scintillating Crystal

Whereas the light yield of PWO crystal can be significantly improved by doping with either of F- and Sb3+, effects of heavily co-doping with by F-+Sb3+, F-+Ca2+, and F-+Ca2++Sb3+, respectively, on the properties of PWO scintillation crystals, including optical transmission, luminescence and light yield were studied. The result indicates that co-doping with three dopants, F-+Ca2++Sb3+, is a more effective measure than doping with single dopant F- for the improvement of scintillation properties of PWO crystals, including light yield.

Improvement on the Luminescence Property of Y, Sb Co-doped PbWO_4 Single Crystal

The effect of Y and Sb co-doping on the luminescence property of PbWO 4 crystals has been investigated. Compared with undoped PbWO4, the transmittance and emission peak intensity of Y∶Sb∶PbWO 4 crystals were obviously improved. In addition, its transmittance cutoff wavelength and emission peak shifted to the shorter one. The mechanism of effect of Y and Sb on the transmittance spectra was briefly discussed. The light yield of Y∶Sb∶PbWO 4 crystals was 25p.e./MeV, which was two times of that of undoped PbWO 4. Our experiments showed that Y and Sb co-doping was a selectable method to improve the luminescence property of PbWO 4.

Characterization of the new scintillator Cs2LiYCl6:Ce3+

The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.

Preparation and Microstructure of Porous ZrB_2 Ceramics Using Reactive Spark Plasma Sintering Method

Zirconium oxide （ZrO：） and boron carbide （B4C） were added to ZrB2 raw powders to prepare ZrB2 porous ceramics by reactive spark plasma sintering （RSPS）. The reactions between ZrO2 and B,C which produce ZrB2 and gas （such as CO and B2O3） result in pore formation. X-Ray Diffraction results indicated that the products phase was ZrB2 and the reaction was completed after the RSPS process. The porosity could be controlled by changing the ratio of synthesized ZrB2 to raw ZrB2 powders. The porosity of porous ceramics with 20 wt% and 40 wt% synthsized ZrB2 are 0.185 and 0.222, respectivly. And dense ZrB：SiC ceramic with a porosity of 0.057 was prepared under the same conditions for comparison. The pores were homogeneously distributed within the microstructure of the porous ceramics. The results indicate a promising method for preparing porous ZrB：based ceramics.

Loss of Light Yield of Doped Lead Tungstate Crystals After Irradiation

Loss of light yield of doped lead tungstate crystals after irradiation with a low dose rate has been observed.The La,Pr,and Y doping may improve radiation hardness,whereas Bi or Mo doping is harmful.

CEPC Technical Design Report

The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.

Highly Birefringent Photonic Crystal Fibers B Using Asymmetric Core Design

We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.

The technology for detection of gamma-ray burst with GECAM satellite

Introduction The main physical objective of the GECAM satellite is to detect gamma-ray bursts,which is related to gravitational waves of double compact object mergers.The GECAM satellite also detects and investigates various bursts of high-energy celestial bodies.Purposes and methods In this study,we designed,developed and calibrated the payload and launched it into orbit with GECAM satellite.The payload consists of the gamma ray detector(GRD,for detecting 4 keV–4 MeV X/γray),the charged particle detector(CPD,for detecting 150 keV–5 MeV charged particle),and the electronic box(EBOX).The all-sky field coverage is achieved via two 229-degree large-area satellites positioned 180 degrees apart and are on opposite sides of the geo-center.Each satellite is equipped with 25 GRDs and 8 CPDs;thus,the satellite can identify charged particle bursts in space.Gamma-ray detectors adopt lanthanum bromide crystal technology combined with silicon photomultipliers.This is the first time that this technology was used massively in space detectors.Conclusions The GECAM satellite can quickly determine the direction of gamma-ray bursts(positioning)via indexing and fitting method,while the transmit variability,energy spectrum and direction of the gamma-ray bursts guide subsequent observations through the Beidou-3 RDSS in quasi-real time.It will play an important role in the study of high energy celestial bursts.