Takashi Ohtsubo

NMR-ON studies on the magnetic hyperfine field at 140La in Fe

Nuclear magnetic resonance on oriented nuclei (NMR-ON) of La existing as a dilute impurity in Fe was observed for the first time. NMR-ON experiments were performed by detecting the 1596 keV γ rays ...

Observation of Muonic X-rays of Cosmic-Ray Muons Stopped in Al and Fe Targets

We successfully measured muonic X-rays of cosmic-ray muons stopped in Al and Fe targets. In order to identify the events that incoming cosmic-ray muons were stopped in the targets, a coincidence and anticoincidence system of three plastic scintillators was used. The X-rays associated with the atomic muon captures were measured with germanium detectors. Measurements using the Al and Fe targets were carried out for 33 and 16 days, respectively. A sufficient number of muonic X-ray events for identifying the elemental compositions of the target materials were clearly observed. This technique provides a means of nondestructive elemental analysis that does not require the use of particle accelerators.

Nuclear spin relaxation of extremely dilute impurities using brute-force NMRON

Brute-force nuclear magnetic resonance on oriented nuclei (BF-NMRON) was used to investigate the nuclear spin-relaxation times, T 1 , of 90 Nb in Nb and Cu, 96 Tc in Nb, 101 m Rh in Cu, and 110 m Ag in Ag with an external field of 11.922 T at about 10 mK. The observed relaxation times with known nuclear g-factors were used to estimate the converted relaxation rates, ( T 1 T g n 2 ) -1 , which were compared with those obtained from NMR and other methods. From the comparison, it was found that ( T 1 T g n 2 ) -1 of 90 Nb in Nb and 110 m Ag in Ag coincided with those of the bulk systems. ( T 1 T g n 2 ) -1 of 90 Nb in Cu was about four times larger than that of Nb bulk system. Both 96 Tc in Nb and 101 m Rh in Cu produced ( T 1 T g n 2 ) -1 values consistent with previous studies.