121673805
Polarimeter System for High-Energy Protons Using Carbon Plate and Liquid Hydrogen
In order to measure recoil proton polarization for the reaction γ+p→π°+p in a wide energy range, a polarimeter system has been constructed using carbon plate and liquid hydrogen as the scatterer. It consists of multi-wire proportional chambers, wire spark chambers, scintillation counter hodoscopes, and scatterers. Carbon plates for lower energy protons and liquid hydrogen for higher-energy protons were used as scatterers. The liquid-hydrogen polarimeter has worked reliably in continuous operation for a long time. The performance of the system in the experiment is described.
3231612
Neutral-pion photoproduction on the deuteron.
Large-angle cross sections for ..gamma..d..--> pi../sup 0/d are systematically measured in a photon energy range between 500 and 1000 MeV. A good fit is obtained by use of a Glauber model calculation which includes the dibaryon resonances /sup 3/F/sub 3/(2.26) and /sup 1/G/sub 4/(2.51), but the fit has an unusual nature in the role of resonance and nonresonance contributions.
119848927
A new type of liquid-3He target system using small mechanical refrigerators
Abstract A new type of liquid- 3 He target has been developed for photoabsorption experiments at intermediate energies. Using the cooling power of liquid 4 He at reduced vapour pressure, 3 He gas is liquefied into a cylindrical target cell of 180 ml and is maintained at 2.0 K during the experiment. Evaporated 4 He gas is evacuated by a rotary pump and returned into the 4 He bath in the cryostat, where two small mechanical refrigerators with cooling capacities of 3 W at 4.3 K and 10 W at 20 K are operated for the purpose of 4 He recondensation. A maintenance-free operation of more than 1000 hours has become possible by adopting the 4 He circulation system.
123710203
Precise measurement of Ag KLM and KLN Auger spectra
Abstract Ag KLM and KLN Auger spectra have been measured with a momentum resolution of 0.02%. With this resolution, most of the lines in these transitions are well separated and the complex spectral structure is revealed. Energies and intensities of these lines are precisely determined and compared with the results of the theoretical calculations.
121317828
MEASUREMENT OF POLARIZATION IN K$sup +$p ELASTIC SCATTERING AT 1.37, 1.45, 1.71, AND 1.89 GeV/c AND PHASE-SHIFT ANALYSIS.
123100999
Differential cross sections of neutral pion photoproduction from hydrogen in the energy region from 390 MeV to 975 MeV
The differential cross sections of the reaction γp→π0p have been measured at photon energies between 390 MeV and 975 MeV with an energy step of 20 or 25 MeV. The angular region covers 11 angles between 15° and 130° in the c.m.s. A combination of a magnetic spectrometer and photon detector was used for the measurement in the angular region from 50° to 130°. At forward angles of 15°, 35° and 50°, π0 mesons were detected using a π0 detector consisting of a pair of photon detectors. The data obtained with two different detection systems overlap at the angle of 50° and coincide with each other within the experimental error. The results are compared with those of phenomenological partial-wave analyses.
120600649
Field emission from carbon nanotubes in DC and pulsed mode
Abstract Multi-wall Carbon Nanotube (CNT) emitters were tested in a combined diode-RF electron gun. Field emission of the nanotubes was observed at 5–30 MV/m, using a 250 ns FWHM long pulse with a peak voltage of 80–470 kV. The field emission threshold is compatible with that found from previous DC testing. We have extracted from a continuous field emitter up to a nanoCoulomb of charge and measured an emittance of 4 mm mrad with a 2 pC electron beam. The total charge emission during RF operation, using the 1.5 GHz, 2 cell RF structure, was found dependent on its period. RF operation showed that back bombarding electrons with up to 5 MeV did not impair the emission stability of the CNTs.
15239790
Resonant Excitation of Disk Oscillations in Deformed Disks III : Revision of Mathematical Treatment
In previous studies, we have examined a resonant excitation of disk oscillations in deformed disks. In these studies, however, the mathematical treatment around the resonant points was not rigorous. In this paper the inadequate point is corrected, but with no essential changes in the final results. For this excitation process to work, disks must be general relativistic. That is, a non-monotonic radial distribution of the epicyclic frequency in relativistic disks is essential for the presence of the resonance, and for trapping oscillations. In this paper, the growth rate of resonant oscillations is expressed in a form more suitable for numerical calculations.
118501243
Trapped, Two-Armed, Nearly Vertical Oscillations in Polytropic Disks
We have examined trapping of two-armed nearly vertical oscillations in polytropic disks. Two-armed nearly vertical oscillations are interesting in the sense that they are trapped in an inner region of disks with proper frequencies, if the inner edge of disks is a boundary that reflects oscillations. The frequencies of the trapped oscillations cover the frequency range of kHz QPOs to low frequency QPOs in LMXBs, depending on the modes of oscillations. Low frequency trapped oscillations are particularly interesting since their trapped region is wide. These low frequency oscillations are, however, present only when $\Gamma(\equiv 1+1/N)$ is close to but smaller than 4/3 (when spin parameter $a_*$ is zero), where $N$ is the polytropic index. The above critical value 4/3 slightly increases as $a_*$ increases.
96731395
Graphitization of inner surface of copper beam duct of KEKB positron ring
In order to evaluate the best technique to reduce electron cloud instability, we measured the electron cloud density in copper ducts coated with titanium nitride and non-evaporable getter used in the KEK B-factory (KEKB) positron ring. In this study, we developed a new system for the graphitization of copper beam ducts. The graphitization of a copper surface by intense electron bombardment resulted in the reduction in the secondary electron yield (SEY) to 1.0 in a laboratory experiment and to 1.1 in a real beam duct. The electron cloud density in the graphitized duct is 30% lower than that in an uncoated copper duct. Thus, it has been confirmed that the graphitization of a beam duct leads to a reduction in the electron cloud density in the duct.
123062788
Constraints for transonic black hole accretion
Regularity conditions and global topological constraints leave some forbidden regions in the parameter space of the transonic isothermal, rotating matter onto black holes. Unstable flows occupy regions touching the boundaries of the forbidden regions. The astrophysical consequences of these results are discussed. 17 references.