利用强流ISOL束研究20Na的奇异衰变模式(英文)

北京放射性离子束装置（Beijing Radioactive Ion-beam Facility,BRIF）是基于在线同位素分离器技术的国家大科学平台。在BRIF装置上利用100 MeV的质子束轰击较厚的反应靶产生放射性核素;反应产物经离子源电离和在线分离,在线同位素分离段可引出100~300 keV的放射性核束,质量分辨率达20 000。在基金委科学仪器基础研究专项的支持下,建成了多用途的衰变实验终端,包括束流传输管道、通用靶室、带电粒子和γ探测器、集成电子学和数据获取系统等。利用100 MeV的质子束轰击MgO厚靶产生了流强高达1×105 pps的20Na放射性核束。通过高效率地同时测量β,γ和α,第一次直接观测到20Na非常稀有的β-γ-α衰变模式。Beijing Radioactive Ion-beam Facility(BRIF) has been commissioned as the national Radioactive Ion Beam(RIB) facility based on the Isotope Separator On Line(ISOL) technique since 2016. At BRIF, the radioactive nuclides are produced by the proton beam of 100 MeV bombarding a thick-target, the reaction products diffusing out of the target are ionized by an ion source and delivered to the online mass separator. In addition to the post-accelerated radioactive ion beams, BRIF can provide low-energy ISOL beams of 100 to 300 keV with a mass resolution of 20 000. A general-purpose decay station has been built including the ISOL beam transport line, a conventional reaction chamber, charge-particle and γ detectors with integrated electronics and data acquisition system. An intense 20Na ISOL beam up to 1×105 pps was produced by using the 100 MeV proton beam bombarding a MgO thick target. With high-efficiency measurements of β, γ and α simultaneously, very rare β-γ-α decay mode in 20Na has been directly observed for the first time in the present work.     

成像板发光原理及其特性

由于成像板(imaging plate,IP)对电磁辐射场不敏感,因而作为探测介质被广泛应用于激光驱动的辐射粒子诊断设备中,在使用前需要对其特性和物理机制进行研究.利用⁹⁰Sr/⁹⁰Y电子源测量BAS-SR和BAS-TR两种IP板的时间衰减曲线,同时对长时间辐照的衰减曲线进行修正;刻度了BAS-SR和BAS-TR两种IP板对⁹⁰Sr/⁹⁰Y电子源的绝对灵敏度,其分别为(0.033±0.002) PSL/e和(0.0180±0.0038) PSL/e (photostimulated light,PSL),与国际上大部分电子绝对刻度的结果基本相符,IP板对辐射粒子的绝对刻度依赖于IP板的类型、扫描设备和实验环境.此外对BAS-SR和BAS-TR两种IP板辐照后进行多次连续扫描,研究了信号强度变化趋势的规律.建立了用于描述辐射粒子在IP板荧光层中沉积能量、存储信息和信息读取微观物理过程的光激励发光模型,结合光激励发光模型建立的数学模型有效地阐释了IP板探测辐射粒子物理机制与其表现的特性之间的关系.这些研...