Development of a new inorganic crystal GAGG for the calorimeter which has capability of the separation betweens neutrons and gammas

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K13570
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: High Energy Accelerator Research Organization
• Principal Investigator: Shiomi Koji 大学共同利用機関法人高エネルギー加速器研究機構, 素粒子原子核研究所, 助教 (40648036)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: 電磁カロリメタ / 素粒子実験 / 測定器

Outline of Final Research Achievements

We developed an electromagnetic calorimeter which can distinguish neutrons from gammas, by using GAGG crystals. The response of GAGG crystals can be faster by co-doping Mg2+ ions. To separate neutrons from gammas, we can use the difference of the interactions in the crystals between neutrons and gammas due to its short radiation length and long interaction length. Information on the depth of the interaction positions in the crystals can be obtained from the observed pulse shape by gluing a GAGG crystal and a GAGG crystal co-doping with Mg2+, which has a shorter decay constant, compared with GAGG crystals. We made a prototype module and carried out a series of beam tests. We established a method to distinguish gammas from neutrons.

Free Research Field

数物系科学

Academic Significance and Societal Importance of the Research Achievements

近年開発されたGAGG結晶を使用し、中性子と電子を分離する新たな手法を確立し、KOTO STEP2実験に必要な中性子とγ線が識別可能な電磁カロリメーターとしての一つの例を示すことが出来た。電磁カロリメーターでのガンマ線や電子の同定において、ハドロン反応を除去を行うことは高エネルギー加速器を用いるコライダー実験全般でも重要なテーマである。そのため、本手法はKOTO実験以外の電磁カロリメーターに対しても、有益な手法と成り得る。