120683961
Narrow Spacing Drift Chamber
Linearity and efficiency of a 3-mm spacing drift chamber was examined with an electron beam. A spatial coordinate is measurable with an accuracy of 0.2 mm.
119906527
MEASUREMENT OF THE POLARIZATION PARAMETER IN BACKWARD $pi$$sup +$p ELASTIC SCATTERING AT 1.60, 1.80, 2.11, AND 2.31 GeV/c.
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.
121021517
A honeycomb sandwich structure vacuum jacket for cryogenic targets
Abstract Cryogenic targets (H 2 , D 2 and 4 He) have been built for use in the study of photonuclear reactions with a π sr spectrometer, TAGX, at the 1.3 GeV Tokyo electron synchrotron. A new type of vacuum jacket, fabricated from plastic honeycomb core and Mylar skins, has been used in the target system for more than 5000 hours. The average radiation thickness and the average density of this jacket are measured to be 3.3 × 10 −3 X 0 and 0.15 g/cm 3 , respectively.
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.
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.
125636037
TEST OF THE DELAY LINE FOR Z READOUT OF THE TOPAZ INNER DRIFT CHAMBER
22610759
Correlated Frequency-Changes of Trapped Vertical p-mode Oscillations and kHz QPOs
AbstractWe have examined the frequencies of trapped two-armed (m = 2) nearly verticaloscillations (vertical p-mode) in vertically isothermal disks with toroidal magneticﬁelds. The magnetic ﬁelds are stratiﬁed so that the Alfv´en speed, c A , is constant inthe vertical direction. We have particularly focused our attention on how frequenciesof the fundamental mode (n r = 0) and ﬁrst overtone (n r = 1) in the radial directionchange with correlation, when theratioc 2A /cs changes, c s beingthe isothermal acousticspeed. The results show that in the case where the oscillations are fundamentalmode (n=1) in the vertical direction, the correlated frequency changes of the above-mentioned oscillations seem towell describe, withstandard values ofthe mass andspinof the central sources, the frequency correlation of kHz QPOs observed in neutron-starX-ray binaries.Key words:accretion, accrection disks — quasi-periodic oscillations — verticalp-mode oscillations — waves — X-rays; stars1. IntroductionMany authors now think that the kilo-hertz quasi-periodic oscillations (kHz QPOs) ob-served in low-mass X-ray binaries (LMXBs) are some kinds of disk oscillations in a strong gravi-tational ﬁeld. Understanding their origin is of importance, since it will become a promising toolto evaluate the mass and spin of the central sources as well as the disk structure surrounding thesources. Many models of kHz QPOs related to disk oscillations and waves have been proposed.None of them, however, can suﬃciently well describe the observed frequency correlation of thetwin kHz QPOs (Lin et al. 2010).As one of possible models of kHz QPOs, for example, we proposed a disk-oscillationmodel in deformed disks (Kato and Fukue 2006), based on the fact that in deformed disks aset of oscillations with positive and negative wave energies are excited resonantly (Kato 2004,1
39233375
Beam-beam experience at KEKB
KEKB has achieved the peak luminosity of 4.1 x 10{sup 33} cm{sup -2} sec{sup -1} and the present capability for delivering integrated luminosity is 224 pb{sup -1}/day. This paper describes (1) the recent performance and the problems of KEKB and (2) the comparison of beam-beam simulations with experiments at KEKB.
8862999
Recent progress of KEKB
We summarize the machine operation of KEKB during past one year focusing on progress for this period.
89614487
High energy electron acceleration by stochastic acceleration mechanism
A stochastic acceleration mechanism which explains the high energy electron acceleration by intense laser pulses is analyzed by Fokker‐Planck approach. The Fokker‐Planck equation describing is derived from the equation of motion of electrons interacting with filamented laser field. The time evolution of electron distribution function, energy distribution, effective temperature are obtained for initially rest plasma. The acceleration of 10 MeV electron beam is examined and shown to be effective.