124431523
Strong-interaction form factor of proton in high-energy proton-proton elastic scattering
SummaryAn analysis of high-energy proton-proton elastic-scattering data is made in terms of one-particle exchange type amplitude. The results show that the proton form factor is constant at large momentum transfer. This may be interpreted as evidence for the existence of a pointlike core in the proton.RiassuntoSi esegue un'analisi dei dati dello scattering elastico protone-protone di alte energie in termini dell'ampiezza del tipo dello scambio di una particella. I risultati mostrano che il fattore di forma del protone è costante a grande trasferimento di impulso. Questo può essere interpretato come prova dell'esistenza di un nocciolo puntiforme nel protone.РезюмеВ терминах амплитуды с одно-частичным обменом проводится анализ данных по протон-протонному упругому рассеянию при высоких энергиях. Полученные результаты показывают, что протонный форм-фактор является постоянным при больших передаваемых импульсах. Это можно интерпретировать, как подтверждение существования точечной сердцевины в протоне.
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.
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.
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.
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.
122772838
Test results of a single aperture 10 tesla dipole model magnet for the Large Hadron Collider
A single aperture dipole magnet has been developed with a design magnetic field of 10 tesla by using Nb-Ti/Cu conductor to be operated at 1.8 K in pressurized super fluid helium, The magnet features double shell coil design by using high keystone Rutherford cable and compact non-magnetic steel collars to be adaptable in split/symmetric coil/collar design for twin aperture dipoles. A design central magnetic field of 10 tesla has been successfully achieved in excitation at 1.95 K in pressurized superfluid helium. Test results of the magnet with a summary of the design and fabrication are presented.
118396687
Tidal Instability and Superhump by a Wave-Wave Resonant Model
On a disk deformed to a non-axisymmetric form, a set of oscillations can be excited by their resonant interaction through the disk deformation (Kato et al. 2011). This resonant instability process has been proposed to suggest a possible cause of the high-frequency quasi-periodic oscillations (HF QPOs) observed in black-hole lowmass X-ray binaries. In the present paper, we examine whether the above-mentioned wave-wave resonant process can describe the tidal instability and superhump in dwarf novae. The results show that the process seems to well describe the observations. If this process is really the cause of the tidal instability and superhump, a two-armed oscillation with high frequency roughly on the magnitude of three times the orbital frequency is present on disks, although its expected amplitude may be small.
118371698
Electron Cloud Effects in the KEK‐PS and the KEK/JAERI Joint Project
An e‐p instability is potentially a serious problem for proton rings in JKJ, which forces us to study the e‐p instability in several high‐intensity proton rings. This work informs JKJ whether we have to take measures to cure the instability. A TiN coating on the chamber surface is one of remedies. Results of SEY measurements performed at KEK are discussed. The observation of electron cloud candidates at the KEK 12 GeV PS Main Ring is also presented.
17623960
Frequency Correlation of QPOs Based on a Resonantly Excited Disk-Oscillation Model
In previous papers, we have proposed a model that the high-frequency quasi-periodic oscillations (HF QPOs) observed in black-hole and neutron-star X-ray binaries are inertial-acoustic oscillations that are resonantly excited on a one-armed deformed disk by nonlinear couplings between the oscillations and the disk deformation. In this paper we show that in addition to the inertial-acoustic waves, one-armed corrugation waves are also excited in the deformed disks. They are low-frequency oscillations. We examine frequencies and their correlations among the inertial-acoustic oscillations and the corrugation waves that are excited, in order to know whether they can describe observed frequency correlations among kHz QPOs and low-frequency QPOs (LF QPOs) in neutron-star X-ray binaries. The results seem to well describe the observed correlations in Cir X-1, if we adopt $M= 1.5\sim 2.0 M_\odot$ and $a_* \sim 0.8$, where $M$ is the mass of the central star and $a_*$ is the dimensionless spin parameter of the metric. Finally, assumptions involved in this disk-oscillation model are briefly summarized and discussed.
126057573
Study of vertical beam blowup in KEKB low energy ring
Vertical beam blowup has been observed in the KEKB low energy positron ring (LER) since early operation. The main characteristics of the blowup are explained by single-beam head-tail instability caused by an electron cloud. About 4600 solenoids were installed in the LER in order to remove the electrons. This paper describes the experimental study of the vertical beam blowup emphasizing the effect of the solenoids.