Verification of the Surrogate Ratio Method

Effects of difference in the spin and parity distributions for the surrogate and neutron-induced reactions are investigated. Without assuming specific (schematic) spin-parity distributions, it was found that the surrogate ratio method can be employed to determine neutron fission and capture cross sections if 1) weak Weisskopf-Ewing condition (defined in this paper) is satisfied, 2) there exist two surrogate reactions whose spin-parity distributions of the decaying nuclei are almost equivalent, and 3) difference of the representative spin values between the neutron-induced and surrogate reactions is no much larger than 10 $\hbar$. If these conditions are satisfied, we need not to know the spin-parity distributions populated by the surrogate method. Instead, we should just select a pair of surrogate reactions which will populate the similar spin-parity distributions, using targets having similar structure and reactions having the similar reaction mechanisms. Achievable accuracy is estimated to be around 5 and 10 % for fission and capture channels, respectively, for nuclei of the Uranium region. The surrogate absolute method, on the contrary, can be marginally applicable to determination of fission cross sections. However, there will be little hope to apply this method for capture cross section measurements unless the spin-parity distributions in the neutron-induced and surrogate reactions are fairly close to each other or the difference can be corrected theoretically. The surrogate ratio method was shown also to be a robust method in the presence of breakup reactions, again, without assuming specific breakup reaction mechanisms.Comment: 5 figure

Spin-dependent observables in surrogate reactions

Observables emitted from various spin states in compound U nuclei are investigated to validate usefulness of the surrogate reaction method. It was found that energy spectrum of cascading $\gamma$-rays and their multiplicities, spectrum of evaporated neutrons, and mass-distribution of fission fragments show clear dependence on the spin of decaying nuclei. The present results indicate that they can be used to infer populated spin distributions which significantly affect the decay branching ratio of the compound system produced by the surrogate reactions

Analysis of proton-induced fragment production cross sections by the Quantum Molecular Dynamics plus Statistical Decay Model

The production cross sections of various fragments from proton-induced reactions on $^{56}$Fe and $^{27}$Al have been analyzed by the Quantum Molecular Dynamics (QMD) plus Statistical Decay Model (SDM). It was found that the mass and charge distributions calculated with and without the statistical decay have very different shapes. These results also depend strongly on the impact parameter, showing an importance of the dynamical treatment as realized by the QMD approach. The calculated results were compared with experimental data in the energy region from 50 MeV to 5 GeV. The QMD+SDM calculation could reproduce the production cross sections of the light clusters and intermediate-mass to heavy fragments in a good accuracy. The production cross section of $^{7}$Be was, however, underpredicted by approximately 2 orders of magnitude, showing the necessity of another reaction mechanism not taken into account in the present model.Comment: 12 pages, Latex is used, 6 Postscript figures are available by request from [email protected]

Irinotecan Hydrochloride (CPT-11) in Dialysis Patients with Gastrointestinal Cancer

We investigated changes in drug disposition and toxicities with CPT-11 in 15 dialysis patients with gastrointestinal cancers to clarify whether CPT-11 could be administered safely in such patients. For comparison, the same parameters were also investigated in 10 cancer patients not undergoing dialysis. Items investigated included (1) plasma concentrations of SN-38, SN-38G and CPT-11 at 0, 1, 12, 24, 36, 48 and 72h after administration, together with a comparison of mean AUC values for 3 dose levels of CPT-11 (50, 60 and 70mg/m2) in dialysis patients and controls;and (2) occurrence of adverse events. Several findings emerged from this study:(1) No significant difference was observed in the AUC for SN-38 or CPT-11 between the dialysis and control groups;(2) The AUC for SN-38G at each dose was significantly higher in dialysis patients;and (3) Grade 1-4 leucopenia was observed in 11 of the dialysis patients. One patient developed grade 4 leucopenia and died due to sepsis. Anorexia, diarrhea, nausea, alopecia and interstitial pneumonia occurred in 6 dialysis patients. We found changes in drug dispositions of CPT-11, SN-38 and SN-38G in dialysis patients, suggesting that hepatic excretion, especially that of SN-38G, was increased. No significant difference in occurrence of adverse events was observed between the 2 groups. This indicates that CPT-11 can be administered safely in patients on dialysis.</p

Anisotropies and Low-temperature Annealing Effect in Cold-rolled Nickel-Silver Alloy

The changes in hardness, elastic modulus and bending deflection with rolling reduction and with low-temperature annealing of nickel-silver were measured on the specimens cut parallel and transverse to the rolling direction of the sheet, and the results were considered in relation to the rolling structure. The anisotropies become more remarkable as the rolling reduction exceeds 50 per cent, and, in this region, the measured values are always higher in the transverse than in the other direction. This may be due to the development of the rolling texture and to the appearance of the flaw-like strain markings in the transverse direction. The low-temperature annealing makes the values of hardness and elastic modulus increase, and the maximum values are, in either case, obtained by heat-treatment at 350℃. Also, the larger the rolling reduction is, the higher the increasing ratio becomes. The change in hardness due to low-temperature annealing is larger as the grain size reduces, whereas the change in elasticity is hardly affected by the grain size. The anneal-hardening at each temperature does not show the two-stage hardening which has been observed in α-brass sheet, but shows a simple and smooth process. No difference in microstructure can be observed between as cold-rolled and as anneal-hardened state, although, in the previous work on α-brass, some structural changes thought to be a kind of polygonization were recognized after low-temperature annealing. The results of bending test correspond with those of elastic modulus

Analysis on the cryogenic stability and mechanical properties of the LHD helical coils

Transient normal-transitions have been observed in the superconducting helical coils of LHD. Propagation of a normal-zone is analyzed with a numerical simulation code that deals with the magnetic diffusion process in a pure aluminum stabilizer. During excitation tests, a number of spike signals are observed in the balance voltage of the helical coils, which seem to be caused by mechanical disturbances. The spike signals are analyzed by applying pulse height analysis and the mechanical properties of the coil windings are investigated

Stability and safety estimates and tests of a superconducting bus-line for large-scale superconducting coils

We have been developing a flexible superconducting bus-line as a unit electrical feeder between large-scale superconducting coils and their power supplies away from the coils. The designed superconducting bus-line consists of a pair of +/- aluminum stabilized NbTi/Cu compacted strand cables and a coaxial four-channel transfer line. A full-scale model of the SC bus-line (20 m long) has been constructed and tested successfully up to 40 kA without a quench under the short-circuit condition. Stability tests were also done by inducing a forced quench with heaters. A minimum propagation current larger than 32.5 kA was confirmed. Thus, the bus-line was cryogenically stabilized at the rated current of 30 kA. We have examined the test results and evaluated the stability and safety margins of this bus-line. The design criteria for a superconducting bus-line are also shown for large-scale superconducting coils with operating current as a parameter