New Constraints on Radiative Decay of Long-Lived Particles in Big Bang Nucleosynthesis with New 4^4He Photodisintegration Data

A recent measurement of $^4$He photodisintegration reactions, $^4$He($\gamma$,$p$)$^3$H and $^4$He($\gamma$,$n$)$^3$He with laser-Compton photons shows smaller cross sections than those estimated by other previous experiments at $E_\gamma \lesssim 30$ MeV. We study big-bang nucleosynthesis with the radiative particle decay using the new photodisintegration cross sections of $^4$He as well as previous data. The sensitivity of the yields of all light elements D, T, $^3$He, $^4$He, $^6$Li, $^7$Li and $^7$Be to the cross sections is investigated. The change of the cross sections has an influence on the non-thermal yields of D, $^3$He and $^4$He. On the other hand, the non-thermal $^6$Li production is not sensitive to the change of the cross sections at this low energy, since the non-thermal secondary synthesis of $^6$Li needs energetic photons of $E_\gamma \gtrsim 50$ MeV. The non-thermal nucleosynthesis triggered by the radiative particle decay is one of candidates of the production mechanism of $^6$Li observed in metal-poor halo stars (MPHSs). In the parameter region of the radiative particle lifetime and the emitted photon energy which satisfies the $^6$Li production above the abundance level observed in MPHSs, the change of the photodisintegration cross sections at $E_\gamma \lesssim 30$ MeV as measured in the recent experiment leads to $\sim 10$% reduction of resulting $^3$He abundance, whereas the $^6$Li abundance does not change for this change of the cross sections of $^4$He($\gamma$,$p$)$^3$H and $^4$He($\gamma$,$n$)$^3$He. The $^6$Li abundance, however, could show a sizable change and therefore the future precise measurement of the cross sections at high energy $E_\gamma \gtrsim$ 50 MeV is highly required.Comment: 10 pages, 7 figures, conclusion not changed, to be published in PR

ゴルジノラクトンの合成研究

講演番号：4ⅢL 2

Quantitative assessment of harmonic power doppler myocardial perfusion imaging with intravenous levovist™ in patients with myocardial infarction: comparison with myocardial viability evaluated by coronary flow reserve and coronary flow pattern of infarct-related artery

BACKGROUND: Myocardial contrast echocardiography and coronary flow velocity pattern with a rapid diastolic deceleration time after percutaneous coronary intervention has been reported to be useful in assessing microvascular damage in patients with acute myocardial infarction. AIM: To evaluate myocardial contrast echocardiography with harmonic power Doppler imaging, coronary flow velocity reserve and coronary artery flow pattern in predicting functional recovery by using transthoracic echocardiography. METHODS: Thirty patients with anterior acute myocardial infarction underwent myocardial contrast echocardiography at rest and during hyperemia and were quantitatively analyzed by the peak color pixel intensity ratio of the risk area to the control area (PIR). Coronary flow pattern was measured using transthoracic echocardiography in the distal portion of left anterior descending artery within 24 hours after recanalization and we assessed deceleration time of diastolic flow velocity. Coronary flow velocity reserve was calculated two weeks after acute myocardial infarction. Left ventricular end-diastolic volumes and ejection fraction by angiography were computed. RESULTS: Pts were divided into 2 groups according to the deceleration time of coronary artery flow pattern (Group A; 20 pts with deceleration time ≧ 600 msec, Group B; 10 pts with deceleration time < 600 msec). In acute phase, there were no significant differences in left ventricular end-diastolic volume and ejection fraction (Left ventricular end-diastolic volume 112 ± 33 vs. 146 ± 38 ml, ejection fraction 50 ± 7 vs. 45 ± 9 %; group A vs. B). However, left ventricular end-diastolic volume in Group B was significantly larger than that in Group A (192 ± 39 vs. 114 ± 30 ml, p < 0.01), and ejection fraction in Group B was significantly lower than that in Group A (39 ± 9 vs. 52 ± 7%, p < 0.01) at 6 months. PIR and coronary flow velocity reserve of Group A were higher than Group B (PIR, at rest: 0.668 ± 0.178 vs. 0.248 ± 0.015, p < 0.0001: during hyperemia 0.725 ± 0.194 vs. 0.295 ± 0.107, p < 0.0001; coronary flow velocity reserve, 2.60 ± 0.80 vs. 1.31 ± 0.29, p = 0.0002, respectively). CONCLUSION: The preserved microvasculature detecting by myocardial contrast echocardiography and coronary flow velocity reserve is related to functional recovery after acute myocardial infarction

IAEA coordinated research project on nuclear data for charged-particle monitor reactions and medical isotope production

An IAEA coordinated research project was launched in December 2012 to establish and improve the nuclear data required to characterise charged-particle monitor reactions and extend data for medical radionuclide production. An international team was assembled to undertake work addressing the requirements for more accurate cross-section data over a wide range of targets and projectiles, undertaken in conjunction with a limited number of measurements and more extensive evaluations of the decay data of specific radionuclides. These studies are nearing completion, and are briefly described below

Mo Production via

A new production method of 99Mo using accelerator neutrons via the 100Mo(n,2n)99Mo reaction was proposed. Intense neutrons with a most probable energy of 14 MeV can be produced by bombarding Be or C with 40 MeV deuteron beams. Research and development works of 99Mo produced by neutrons from the 3H(d,n)4He reaction were carried out. High quality 99mTc was obtained by employing a sublimation method. Accelerator neutrons are shown to have a great potential to produce a wide variety of radioisotopes

Production scheme for diagnostic-therapeutic radioisotopes by accelerator neutrons

Interest has been growing in the development of medical radioisotopes used for noninvasive nuclear medicine imaging of disease and cancer therapy. Especially the development of an alternative production scheme of 99Mo, the mother radioisotope of 99mTc used for imaging, is required, because the current supply chain of the reactor product 99Mo is fragile worldwide. We have proposed a new production scheme of 99Mo as well as therapeutic radioisotopes, such as 64Cu and 67Cu, using accelerator neutrons provided by the natC(d,n) reaction. Based on this scheme we have obtained high-quality 99mTc, 64Cu, and 67Cu suitable for clinical use by developing both production and separation methods of the radioisotopes. We proposed a new facility to constantly and reliably produce a wide variety of high-quality, carrier-free radioisotopes, including 99Mo, with accelerator neutrons. We report on the development of the proposed scheme and future prospects of the facility toward the domestic production of medical radioisotopes

DIODE LASER SPECTROSCOPY OF THE FCO RADICAL

Author Institution:The FCO radical was detected in the gas phase by the diode laser spectrometer. Bands corresponding to the C-O stretching $(\nu_{1}, 5.4\mu m)$ and the C-F stretching $(\nu_{2}, 10\mu m)$ were observed. To confirm that the observed spectra are due to FCO, we also observed $F^{13}CO$ spectrum in the $\nu_{1}$ band. The FCO radical was generated by an A.C. discharge in the mixtures of\\ (1) $C_{2}F_{4}$, (100mTorr) $+ O_{2}$ (100mTorr) $+$ He\\ (2) $SF_{6}$ (B0mTorr) $+$ CO (150mTorr) $+$ He\\ (3) $C_{2}F_{4}$ (B0mTorr) $+$ CO (150mTorr) $+$ He\\ each gave the same signal to noise ratio, when the reactants were flown through the multiple reflection cell at the total pressure of 1 Torr. We determined the rotational constants, the centrifugal distortion constants and the spin-rotation interaction constants in each vibrational states, both of $F^{12}CO$ and $F^{13}CO$