Development of an "-TOF" detector for correlated measurement of atomic masses and decay properties

Niwase, Toshitaka*; Ito, Yuta   ; 13 of others*

We have developed a novel detector, referred to as an "-TOF detector", for correlated measurements of atomic masses and decay properties of low-yield, short-lived radioactive isotopes using a multi-reflection time-of-flight mass spectrograph. By correlating measured time-of-flight signals with decay events, it will be possible to suppress background events and obtain accurate, high-precision mass and half-life values even in cases of very low event rates. An offline test of the -TOF detector has shown that the time-of-flight detection efficiency for 5.48 MeV -rays is more than 90% and yields a time resolution of 250.6(68) ps and an alpha-energy resolution of 141.1(9) keV. Using a two-dimensional spectrum of the correlated -ray energy and time-of-flight, the -rays from mixed sources could be resolved. Subsequent testing using -emitting nuclei extracted offline from a gas cell provide verification of the -ray based characterization.