[10p-N402-1~10] CS.1 2.3 加速器質量分析・加速器ビーム分析、7.5 イオンビーム一般のコードシェアセッション

▼ [10p-N402-8] The status of TOF-E detection system at MALT and its proceedings

〇(D)Li Zheng¹、Hiroyuki Matsuzaki¹、Takeyasu Yamagata¹ (1.Tokyo Univ.)

キーワード：Time of flight, Monte Carlo method, Detector response

Accelerator Mass Spectrometry (AMS) is the most sensitive technique for the measurement of the actinides, particularly ²³⁶U. A Time of Flight-Energy (TOF-E) detection system is the most appropriate technique to discriminate ²³⁶U ions from ²³⁸U, ²³⁵U and other interferences. Micro Analysis Laboratory, Tandem Accelerator aims to improve the sensitivity of ²³⁶U/²³⁸U from 3×10^-10 to 10^-13 with the installation of TOF-E detection system.Currently, MALT has acquired start timing signal using Microchannel Plate (MCP) as start timing detector. The stop timing detector and energy detector are under construction. Prior to the construction of realistic TOF-E detection system, a (Geometry and Tracking version 4) Geant4 Monte Carlo simulation of TOF-E detection system has been completed. Two detection configurations and three thicknesses of carbon foil as electron generator have been simulated. From simulation results, it shows that the thickness of carbon foil is one key factor to efficiency and time resolution. The thinner the carbon foil, the better efficiency and time resolution. Adopting the configurations of 2.4 meters of flight path and 3 ug/cm² of carbon foil, the flight time difference between ²³⁶U and ²³⁵U, and between ²³⁶U and ²³⁸U are, respectively, 3 ns and -6 ns and the full width at half maximum (FWHM) of ²³⁵U, ²³⁶U and ²³⁸U are identical, 1 ns. The results demonstrate that the above configuration is adequate to identify ²³⁶U from ²³⁵U, ²³⁸U. With the combination of simulation results and realistic beam experiment results, 2.63% of efficiency between start detector and silicon surface barrier detector (SBD) for U-AMS is acquired.