Vol.8,

257

A new observable, yield ratio of d/ (d+t+³He+⁴He) produced in heavy ion reactions is suggested as a measure of entropy. It is found that in quantum statistical model (QSM) , which is quite commonly used for extracting the entropy, the relation between this ratio and entropy is almost linear and independent of break-up density and N/Z ratio of the system. The experimental data of ¹²C+¹⁹⁷ Au from 30MeV/u to 84 MeV/u and of ¹⁹⁷Au+¹⁹⁷Au from 100 MeV/u to 250 MeV/u are compared with QSM calculation results. The values of entropy are obtained for C+Au and Au+Au system without assumption on break-up density.

329

617

Aeroball system is attractive in several aspects because it can easily transport the map of neutron flux distribution to be measured from incore to outside of a reactor vessel. However, before the aeroball system is put to practical use in the heating reactor, there are four topics that have to be further studied. They are the stability of the activated positions, enhancement of signal/noise (S/N) ratio, distributed control and data-acquisition system and on-line neutron flux distribution reconstruction. Besides describing the reasons for them, this paper gives out the theory, concept and solution about the first two topics and it is helpful to give the possibility to enhance the reactor-power.

475

Experiments of steam-water two-phase flow frictional pressure drop in a vertical helical coil were carried out in the high-pressure water test loop of Xi'an Jiaotong University, The coil is made of stainless steel tube with an inner diameter of 16 mm, the helix diameter measured from tube axis to tube axis is 1.3 m, and helix angle of the coil is 3.65°. The experimental conditions are: pressure p=4~18MPa, mass velocity G=400~1400 kg/ (m²·s) , inner wall heat flux q=100~700 kW/m². Based on these data, a correlation for predicting the steam-water two-phase flow frictional pressure drop was derived, it can be used for the design of steam generator of HTGR.

401

257

Cross section σ_4D→4F was measured for the collision transfer process of Na (4D) + Na (3S) → Na (4F) + Na (3S) . The 4D state is excited by two-photon absorption using a tunable dye laser. Since the 4F→3D fluorescence can not be detected directly with the apparatus used the cascade 3D→3P fluorescence is monitored instead. Then the cross-section σ_4D→4F= (1.3 ± 0.3) ×10^-14cm² is got from the relative intensity of the fluorescence. A theoretical evaluation of σ_4D→4F is also given and compared with experimental results.

611

Scanning force microscope (SFM) was operated in the lateral-force mode with different loading forces. The mica samples were irradiated by Se ions with a kinetic energy of 11.4 MeV/u. The "full-height width" and the "half-height width" of track profiles were used to evaluate the ion-track diameter. For the former method, the average track diameter increases slowly with increasing loading force between SFM tip and sample. For the later method, the average diameters of ion track nearly keep a common value as the SFM loading force increases.

275

The morphological changes observed by electron microscopy indicate that after internal irradiation with ¹⁵³Sm-EDTMP bone tumor cells displayed feature of apoptosis, such as margination of condensed chromatin, chromatin fragmentation, as well as the membrane-bounded apoptotic bodies formation. The quantification analysis of fragmentation DNA for bone tumor cells induced by ¹⁵³Sm-EDTMP shows that the DNA fragmentation is enhanced with the prolongation of internally irradiated time. These characteristics suggest that ¹⁵³Sm-EDTMP internal irradiation could induce bone tumor cells to go to apoptosis.

364

The distribution of neutrons produced by the reaction of 50 MeV/u ¹²C-ion on a thick Cu target are studied. The neutrons are measured with threshold activation detectors. Al, F, C, Al and In activation samples were used to measure neutrons with energy greater than 7, 11, 20, 50 MeV and thermal neutrons, respectively. The fluence rate, energy and angular distributions of neutrons, total neutron yield of ¹²C-ion and the emission rate in the forward direction of neutrons over 11 and 20 MeV were obtained.

294

High quality SOI (silicon on insulator) materials were fabricated using highly selective and self-stopping full isolation by porous oxidized silicon (FIPOS) technology, then n-channel MOSFETs were successfully fabricated on the wafers. The discrete NMOS/FIPOS transistors with different width/length ratios were subjected to ⁶⁰Co γ-ray radiation and their subthreshold-current I_d-V_g curves were measured as a function of radiation dose. The transistors remain function after 5×10³ Gy (Si) radiation, but the threshold voltage has significantly shifted to negative and its major contribution comes from the radiation-induced trapped oxide charges. The threshold voltage shift turns back during the room-temperature annealing due to partially detrapping of the trapped holes in the oxide layers. The parasitic back-channel effects of the n-channel MOSFETs/FIPOS are negligible and their hardiness to total dose radiation is similar to that of bulk MOSFETs.

302

The systematic study on D-³He advanced fuel fusion in China has been performed. Comparisons between D-³He and D-T fuel cycles in physics, engineering, environmental safety and so on have been made. D-³He fusion offers significant advantages for reducing the neutron yield by a factor of 10-60. The ³He resource and mining possibility are investigated. The energy payback factor of 97 for mining lunar ³He resource is calculated. The operating parameter scope for D-³He fueled Tokamak reactor is analyzed. The prompt energy broadening for fusion products is calculated and results are consistent with those obtained by Lehner using a different method. Centrally peaked current drive with high efficiency is studied utilizing plasma synchrotron radiation. More than 80%of plasma current required can be driven passively. A D-³He fueled Tokamak commercial reactor-Mooncity was designed. Neutronics calculations show that the radioactivity, afterheat, BHP value for Mooncity are 10~60 times less than those for D-T fusion.

277

378

The yield of transtarget produced in the reaction of 47 MeV/u ¹²C bombardment on cesium compound targets are measured by means of nuclear chemical method and the offline γ spectrum technique. The measurement results show that reaction cross-sections of transtarget products are considerable. The isotope distribution peak position (mass number) of barium element is 129.7±0.2 and the distribution width parameter is 2.76±0.25. At the same time, the yields of products with up to five charge numbers larger than target nucleus have been obtained.

488

Field and laboratory investigations were carried out to study the transport and dispersion law of polluted sediments near wastewater outlet using neutron activation tracer technique. The direction of transport and dispersion of polluted sediments, dispersion amount in different directions, sedimentary region of polluted sediment and evaluation of polluted risk are given. This provided a new test method for the study of environmental science and added a new forecasted content for the evaluation of environmental influence.

393

The extraction of U (VI) with newly synthesized long chain alkyl amide, N,N-dibutyloctadecanamide (DBODA) , has been studied. The dependence of the extraction on nitric acid concentration, DBODA concentration and temperature from nitric acid solution has been investigated and the extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The separation factor between U (VI) and Th (IV) is higher and there is no third phase formation under the conditions studied.

618