A New Experiment to Search for the Alpha Condensed State in ²⁴Mg with MAIKo TPC

Recently, exotic low-density states, which is called αcondensed states, have been suggested to emerge near the nα-decay thresholds in self-conjugate A = 4n nuclei. These αcondensed states are expected to give an insight into the low-density nuclear matter.

  The αcondensed states are considered to decay by emitting multiple low-energy αparticles, reflecting their exotic structures. We plan to search for the αcondensed states in ²⁴Mg by detecting multiple low-energy decay αparticles with MAIKo-TPC. We can measure decay particles over large angular coverage by installing a ²⁴Mg target in the sensitive volume of MAIKo-TPC.

   We should use a high-intensity beam at about 10¹⁰cps to achieve sufficient statistics in the experiment. When such a high-intensity beam is introduced to the ²⁴Mg in a conventional TPC, however, there occur serious problems such as distortion of the electric field or electric discharges due to many electrons and ions induced by the high-rate beam. In order to avoid these problems, we have developed a mask to make an insensitive region along the beam trajectories.

   In the present talk, we will report an overview of the experiment to search for the αcondensed state in ²⁴Mg and the result from the performance test of MAIKo-TPC using the high-intensity beam.