124095029
Measurement of large-angle cross-sections for coherent pion photoproduction on deuteron
SummaryCoherent pion photoproduction from deuteron is studied by measuring the differential cross-sections at c.m. angles between 90° and 130° in a photon energy range from 500 to 1000 MeV. The experimental data are compared with a model calculation which takes into account two kinds of contributions, the nonresonant contribution consisting of pion photoproduction from single nucleons and pion rescattering and that from the dibaryon resonances3F3(2.26) and1G4(2.51). The model predictions for the photon asymmetry σ and the deuteron polarizationiT11 are also presented.RiassuntoSi studia la fotoproduzione coerente del pione dal deuterone misurando le sezioni d'urto differenziali ad angoli del centro di massa compresi tra 90° e 130° in un intervallo d'energia dei fotoni pari da 500 a 1000 MeV. Si confrontano i dati sperimentali con un calcolo di un modello che consideri due tipi di contributi, il contributo non risonante che consiste nella fotoproduzione di pioni da singoli nucleoni e rescattering di pioni., e quello dalle risonanze del dibarione3F3(2.26) e1G4(2.51). Si presentano anche le previsioni del modello per l'asimmetria σ dei fotoni e la polarizzazione dei deuteroniiT11.--РезюмеИсследуется когерентное фоторождение пионов на дейтоне, посредством измерения поперечных сечений в области углов от 90° до 130° в системе центра масс и в области энергий фотонов от 500 до 1000 МэВ. Экспериментальные данные сравниваются с модельными вячислениями, которые учитывают два типа вкладов: нерезонансный вклад, состоящий из фоторождения пионов на отдельных нуклонах, и перерассеяние пиона и вклад от дибарионных резонансов3F3(2.26) и1G4(2.51). Так же приводятся модельные предсказания для фотонной асимметрии σ и поляризации дейтонаiT11.
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.
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.
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.
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.
116197080
Test results of TRISTAN insertion quadrupole magnet in superfluid Helium
13244089
Lattice diagnostics using single kick closed orbit at KEKB
We have measured beta functions using single kick closed orbit at KEKB. The measured beta functions were compared with the model lattice and gradient errors were extracted from the result in a beta beat. The gradient errors were also obtained by changing strength of steering magnets and measuring beam positions as the second method. The methods of the error estimation and preliminary results are reported.
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.
118539083
Simultaneous resonant excitation of low-frequency eccentric wave and tilt wave on tidally deformed disks
Simultaneous excitation of low-frequency eccentric precessing mode (one-armed p-mode) and tilt mode on tidally deformed disks is considered. If the orbit of the secondary star is eccentric and its orbital plane is misaligned with the disk plane of the primary, the above-mentioned two low-frequency oscillation modes are simultaneously excited on the primary disk, the former having prograte precession and the latter having retrograde precession. This excitation of disk oscillations is due to a wave–wave resonant excitation process considered by Kato (2013, PASJ, 65, 75). If parameter values relevant to Be/X-ray binary systems are adopted, the periods of these excited oscillations are around 10 times the orbital period of the secondary, which may be comparable with the timescale of giant outbursts observed in Be/X-ray systems.
24439340
Direct electron acceleration by stochastic laser fields in the presence of self-generated magnetic fields.
A simple direct acceleration model is proposed, taking into account the stochastic phase disturbance of the coherent driving laser fields. A relativistic single particle simulation shows that plasma electrons are efficiently accelerated far above the ponderomotive energy. The energy and momentum distributions of the accelerated electrons are derived to examine the effects of the self-generated magnetic field on the characteristics of the electron beams. In addition to the beam collimation effect, the magnetic field is found to further enhance the electron acceleration, resulting in the generation of ultrahigh energy electrons.