Speaker
Description
To obtain one time-differential $\mu$SR spectrum using a conventional technique, we must wait around $10^2$ minutes. In the majority of $\mu$SR experiments, the $\mu$SR spectrum is recorded as a function of temperature. Thus, such a long recording time ($t_{record}$) has not been a serious problem, because the lead time ($t_{read}$) for stabilizing temperature requires typically 10-20 min, which is shorter than the recording time ($t_{lead}<t_{record}$). However, due to the developments of the high-intensity pulsed muon beam with a repetition of 25 Hz in J-PARC MUSE and the multi-detector counting system, the recent data recording time is very short compared with the time to stabilize the measurement condition ($t_{record}<t_{lead}$), which makes $t_{lead}$ a significant bottleneck for the advanced $\mu$SR measurements. In order to solve this problem, we are developing a novel data record and analysis technique to use a high-intensity muon beam more efficiently. In the novel technique named transient $\mu$SR, the sample environment, such as temperature and magnetic field, is continuously changing during the $\mu$SR measurements. Positron events in each muon pulse are recorded as multidimensional data, i.e., along with the number of pulses and the changing parameter. The whole data is then resorted as a function of the parameter. This transient $\mu$SR technique also enables us to study a transient phenomenon that is now unavailable with the standard $\mu$SR technique. It should be emphasized that the feasibility of this technique crucially depends on the intensity of the pulsed muon beam. We have also developed a new software based on ROOT to analyze the huge number of the $\mu$SR spectrum within a reasonable amount of time. We will introduce the analysis software how to analyze the transient $\mu$SR data and report the results obtained under dynamic sample environments.