| Budget Amount *help |
¥23,530,000 (Direct Cost: ¥18,100,000、Indirect Cost: ¥5,430,000)
Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2019: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2018: ¥14,170,000 (Direct Cost: ¥10,900,000、Indirect Cost: ¥3,270,000)
Fiscal Year 2017: ¥7,410,000 (Direct Cost: ¥5,700,000、Indirect Cost: ¥1,710,000)
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| Outline of Final Research Achievements |
We have proposed a new experiment (J-PARC E73) to solve the hypertriton lifetime puzzle with a novel production method (K-, pi0). We demonstrated the feasibility with 4He target as J-PARC T77 experiment in 2020. We collected a world record of ~1k ^4_{\Lambda}H events with ~10 times better signal to noise ratio than previous KEK results. Our new approach may also find application for other experiments need pi0 identification such as neutron-rich hypernuclear gamma-ray spectroscopy.
As a pilot run of the E73 experiment, we have successfully measured the hypertriton production cross section in May 2021. We have clearly observed pi- from both 2-body and 3-body decay of hypertriton ground state. This observation provides the first direct determination for the hypertriton ground state spin. We are looking forward to accumulating enough statistics and solve the hypertriton lifetime puzzle in the near future with our original approach.
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| Academic Significance and Societal Importance of the Research Achievements |
As the lightest hypernucleus, hypertriton provides the foundation for our understanding for YN interaction. With the support of this Kakenhi, our J-PARC E73 experiment essentially improved our understanding for hypertriton with our original production method (K-, pi0).
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