Solve the hypertriton lifetime puzzle

2019 Fiscal Year Annual Research Report

• Project/Area Number: 17H04842
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: MA YUE 国立研究開発法人理化学研究所, 開拓研究本部, 専任研究員 (80639576)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: Helium 4 Lambda / calorimeter

Outline of Annual Research Achievements

With the great support of 若手A funding, we have made two important progresses in the last fiscal year:
1, our experimental proposal has been conditionally approved by J-PARC PAC. So that we will be assigned 3 days beam time with K-(^4He, ^4_{Lambda}He)pi0 reaction to verify the feasibility of the experiment.
2, we have constructed our key detector: a Cherenkov based electromagnetic calorimeter for tagging the high energy gamma ray decayed from pi0 during (K-,pi0) reaction. The actual performance of this calorimeter was tested with positron beam up to 800MeV at ELPH, Tohoku University. Current data analysis demonstrated a reasonable performance compared with design value.

In summary, we have achieved our goal for last fiscal year and ready for data taking from now on.

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

The beam time was delayed due to the COVID19 pandemic. The J-PARC is working hard to catch up the schedule but still not very clear for the specific time table.

Strategy for Future Research Activity

We are ready for the beam time and data taking. The most important task for this year is to carry out the feasibility test with K-(^4He, ^4_{Lambda}He)pi0 reaction and concentrate on the data analysis. Provided a positive result, we will submit official proposal for our physical data taking i.e. Hypertriton and pin down its lifetime puzzle.