Kozi Nakai

Magnetic Moment of F17 – Nuclear Magnetic Resonance by Polarization Following O16 (d, n) F17 Reaction –

The nuclear magnetic resonance of F 17 ( T 1/2 =66 sec) has been observed using the polarization of recoil nuclei produced by the reaction O 16 ( d , n ) F 17 and the β-decay anisotropy as the indicator of the polarization. The accomplishment of the experiment was essentially due to the persistence of the polarization by specific experimental methods, i.e. , the use of a strong magnetic field (\({\gtrsim}5\) kG) in the direction of polarization and the use of pure CaF 2 crystals as the stopping material of recoil ions. The observed asymmetry of β-counting was about 2% and a spin relaxation time T 1 comparable to the half-life of F 17 was observed. The value obtained of the magnetic moment of F 17 is µ=4.7224±0.0012 nm with the diamagnetic correction.

Magnetic Moments of Short-Lived β-Radioactive Nuclei, 12B and 12N

The magnetic moments of 12 B( T 1/2 =20 ms) and 12 N( T 1/2 =11 ms) have been determined by an NMR method using the recoil polarization and the asymmetric β decay. The nuclear polarization was preserved by using a holding static magnetic field and a recoil stopper of metal foil. Several kinds of metal foils were employed. Relative shifts of the order of 10 -3 between the centers of NMR by different metals and the resonance widths comparable to the dipolar broadening were observed. The results obtained for the magnetic moments are µ( 12 B, 1 + )=+(1.003±0.001) nm and µ( 12 N, 1 + )=+(0.4571±0.0005) nm.

Hyperfine Interactions of 12B Implanted in Ferromagnetic Nickel

Temperature dependences of hyperfine interactions of 12 B implanted in Ni were investigated in the temperature range of 6 K–730 K by the NMR method with use of polarized 12 B produced in a nuclear reaction and the asymmetric β decay. Two kinds of hyperfine fields with different signs were observed ( B hf + =+4.161 ±0.022 kG and B hf - = -1.611 ±0.021 kG at 6 K), which indicated that the implanted 12 B were trapped in two different sites (S + and S - , respectively). The spin-lattice relaxation times T 1 and the population rates at the two sites were studied. Near the Curie temperature, an effect of critical slowing-down of the spin-spin correlation was observed as steep variation of T 1 . The behavior of local field around T C was also studied by varying the external field. Results of these experiments near T C indicate itinerant nature of the electron-spin structure in nickel.

Nuclear magnetic resonance of 20 ms 12B

Abstract NMR of 12B has been observed with 12B implanted in metal by reaction 11B(d,p)12B and polarized by the asymmetric β decay. The magnetic moment is determined as μ( 12 B ) = 1.003 ± 0.001 nm .

Selective accumulation of [62Zn]-labeled glycoconjugated porphyrins as multi-functional positron emission tomography tracers in cancer cells

Positron-emission tomography (PET) can be used to visualize active stage cancer. Fluorine-18 ([(18)F])-labeled 2-([(18)F])2-deoxy-2-fluoroglucose (([(18)F])-FDG), which accumulates in glucose-dependent tissues, is a good cancer-targeting tracer. However, ([(18)F])-FDG is obscured in glucose-dependent normal tissues. In this study, we assessed the cancer-selective accumulation of zinc-labeled glycoconjugated 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (ZnGlc1-4), both in vitro and in vivo. Experiments using both normal and cancer cells confirmed the relationship between cancer cell-selective accumulation and the substitution numbers and orientations of glycoconjugated porphyrins. ZnGlctrans-2 accumulated at greater levels in cancer cells compared with other glycoconjugated porphyrins. PET imaging showed that ZnGlctrans-2 accumulated in tumor.

Feasibility studies towards future self-sufficient supply of the 99Mo-99mTc isotopes with Japanese accelerators

In order to establish a self-sufficient supply of 99mTc, we studied feasibilities to produce its parent nucleus, 99Mo, using Japanese accelerators. The daughter nucleus, 99mTc, is indispensable for medical diagnosis. 99Mo has so far been imported from abroad, which is separated from fission products generated in nuclear reactors using enriched 235U fuel. We investigated 99mTc production possibilities based on the following three scenarios: (1) 99Mo production by the (n, 2n) reaction by spallation neutrons at the J-PARC injector, LINAC; (2) 99Mo production by the (p, pn) reaction at Ep = 50–80 MeV proton at the RCNP cyclotron; (3) 99mTc direct production with a 20 MeV proton beam from the PET cyclotron. Among these three scenarios, scenario (1) is for a scheme on a global scale, scenario (2) works in a local area, and both cases take a long time for negotiations. Scenario (3) is attractive because we can use nearly 50 PET cyclotrons in Japan for 99mTc production. We here consider both the advantages and disadvantages among the three scenarios by taking account of the Japanese accelerator situation.

Hyperfine Study of the 19F Isomer as a Substitute for Oxygen in MnO

The paramagnetic shift of the 19 F isomer ( I =5/2, T 1/2 =88 nsec) at the oxygen site in MnO at room temperature was measured to be 2.6±0.5% by the time differential purturbed angular distribution method. The probe of 19 F isomer, produced by 16 O(α, p) 19 F reaction, took the place of the oxygen. The shift is compared with those obtained by 17 O NMR in MnO and by 19 F NMR in few fluorides, and is attributed to the covalent nature of the usual-fluorine bond.

Image analysis of SCITIC for hyperon scattering experiments

A new scintillation-track-image detector, SCITIC, has been developed and successfully used as an active target for hyperon-scattering experiments. The principle and practical use in experiments of SCITIC have bean reported. In this paper, we present the results of a reanalysis of SCITIC data by a new method. The new method assures more precise three-dimensional (3D) track reconstruction than before by introducing a way of critically checking and an iterating data processing. After a brief presentation of the experimental setup and procedure of data taking, details of the image analysis are discussed. With the new analysis, the precision of the data for the Σ+p scattering experiment was improved leading to the conclusion that the Σ+p spin–orbit interaction is comparable to the NN interaction, and that the angular dependence of analyzing power is in good agreement with a theoretical prediction.