118562535
Recoil proton polarization of proton compton scattering in the resonance region
SummaryThe recoil proton polarization of proton Compton scattering (γp→γp) was measured in the photon energy range from 500 MeV to 1000 MeV atθ∗=100° and from 400MeV to 800 MeV atθ∗=130°. A recoil proton and a scattered photon were detected in coincidence with a magnetic spectrometer and a photon detector. The recoil proton polarization was measured with a carbon polarimeter. The results are compared with a phenomenological analysis based on an isobar model and a dynamical analysis based on the dispersion relation.RiassuntoÈ stata misurata la polarizzazione del protone di rinculo nello scattering di Compton del protone (γp→γp) nell'intervallo d'energia del fotone da 500 a 1000 MeV perθ∗=100°, e da 400 a 800 MeV perθ∗=130°. Sono stati individuati un protone di rinculo e un fotone diffuso contemporaneamente con uno spettrometro magnetico e un rivelatore di fotoni. La polarizzazione del protone di rinculo è stata misurata con un polarimetro a carbonio. Si confrontano i risultati con un'analisi fenomenologica basata su un modello a isobare e con un'analisi dinamica basata sulla relazione di disperisone.РезюмеПроведено измерение поляризации протонов отдачи при комптоновском рассеянии на протонах в области энергий фотонов от 500 МэВ до 1000 МэВ приθ∗=100° и от 400 МэВ до 800 МэВ приθ∗=130°. Протон отдачи и рассеянный фотон детектируются на совпадение с помощяю магнитного спектрометра и детектора фотонов. Поляризация протона отдачи измеряется с помщью углеродного поляриметра. Полуенные результаты сравниваются с феноменологическим анализом, основанным на изобарной модели, и динамическим анализом, основанным на дисперсионном соотношении.
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.
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.
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.
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.
67760438
LONG-PERIOD MONITORING OF ELECTRO-POLISHING ELECTROLYTE IN EP FACILITY AT KEK
We have constructed an Electro-polishing (EP) Facility in the Superconducting RF Test Facility (STF) at KEK at the end of 2007. We have begun to operate the EP facility from 2008 and performed the EP processes 41 times with the same EP-electrolyte. In this article, we report the detailed results of the EP-electrolyte monitoring as well as the observation of changing electronic current oscillation in the EP processes. INTRODUCTION In the EP facility, the capacity of the EP-electrolyte reservoir tank is 2,000 L. This size is relatively large if compared with EP facilities in other laboratories. It means that the quality control of EP electrolyte is more difficult because the status of EP-electrolyte changes as the aging of EP-electrolyte proceeds. In the real EP-process operations, we circulated the EP electrolyte of 1,100 L which was firstly delivered into the tank in January 2008 and was disposed in May 2009. During this period, we performed the EP processes 41 times and periodically measured the concentration of Nb, Al, HF in the EP electrolyte. In this article, we report the detailed results of the EP-electrolyte monitoring as well as the observation of changing electronic current oscillation in the EP processes during this period in the EP facility at STF/KEK. [1] [2]. EP PROCESS AT STF-KEK The schematic of EP-electrolyte flow in the EP process is shown in figure 1. The schematic of water flow in the water-rinse process is shown in figure 2, where the process happens just after EP-electrolyte is drained out. The standard EP process at KEK is shown in figure 3, where the flange of cavity is Chemical Polished (CP’ed), the inner surface of cavity is EP’ed, water-rinsed, detergent-rinsed in the ultrasonic hot-water bath, running water-rinsed in hot-water bath, and High-Pressure-Rinsed. Figure 1: Schematic of EP-electrolyte flow. Figure 2: Schematic of water flow in water rinse process. Figure 3: EP process .(EP-2) We performed EP processes 41 times with the first electrolyte from January 2008 to May 2009. The removal weight of Nb in each EP process and summing up of each removal is shown in figure 4. Figure 4: Removal weight in each EP and summing up of each removal. MANAGEMENT OF EP-ELECTROLYTE We measured the concentration of niobium and aluminum in the EP electrolyte by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP) as shown in figure 5. The niobium concentration calculated by current integration (charge) and that of ICP agreed very well. It was found that the concentration of aluminum increases in the similar way to that of niobium. We also measured the fluorine concentration by steam distillation method and Ion Selective Electrode (ISE). All fluorine was measured as in the form of fluorine ion by this method. The picture of the analytical instruments and Proceedings of IPAC’10, Kyoto, Japan WEPEC027 07 Accelerator Technology T07 Superconducting RF 2947 samples of EP-electrolyte are shown in figure 6. We assumed that fluorine in the EP-electrolyte is composed of fluorine in the niobium oxygen complexes (H2NbFO5), in hydrogen fluoride (HF) and in fluorosulfuric acid (SO3F). This assumption was checked by the ion chromatgraph measurements of diluted EP-electrolyte and diluted fluosulfic acid (SO3FH) as shown in figure 7. Because we already measured the niobium concentration in EP-electrolyte by current integration and/or ICP, we can calculate the fluorine quantity in H2NbFO5. On the other hand, the total amont of fluorine is measured by steam distillation method and ISE. Then the sum of fluorine concentration in the form of HF and SO3F can be also calculated by subtracting fluorine in H2NbFO5 from the total fluorine. Figure 5: The changes of niobium and aluminum concentration in the function of days. Figure 6: Analytical instruments and samples of EPelectrolyte. Figure 7: Ion chromatograph of diluted EP-electrolyte and diluted fluorosulfuric acid. Figure 8: The fluorine concentration in the EP-electrolyte as the function of day. The fluorine concentration in the EP-electrolyte as the function of day during the period of one year and six months is shonw in figure 8. It is found that during the period about 16% of fluorine was used for the EP reaction to remove the niobium, and about 20% fluorine moved out from the EP-electrolyte into exhaust gas and rinsed water. MANAGEMENT OF EP-CURRENT We are recording various data in each EP process automatically in the sampling period of one second. We pay special attention to EP current oscillation in them. We compared the shapes of EP current oscillation in last one minute of each EP process. We found that this oscillation pattern changes as the niobium concentration increases as shown in fgure 9. Figure 9: The changes of oscillation pattern with regard to the niobium concentration. The each time-period of all plots is one minute. The EP current is about 250A. We found that the EP current oscillation pattern becomes smoother and the amplitude becomes smaller as the EPelectrolyte aging proceeds, particularly after the niobium concentration of aound 4~5g/L. THE INCOME AND EXPENDITURE OF FLUORINE / NIOBIUM Flow of chemicals in the EP system We performed EP processes 41 times during the period between January 2008 and May 2009. During this perid, we monitored the income and expenditure of chamicals in the EP system. The flow of the chamicals in the EP system is shown in figure 10. The brand-new EPelectrolyte is filled in the EP-tank of the system as income of chamicals. As described in the previous section, the chemicals in the EP-electrolyte escape into the exhast gas and rinsed water. The chemicals in exaust gas are absorbed in the alkaline water of two absorption towers. The alkaline water in two absorption towers was transferred into the waste-water tanks periodically. In the same wate-water tank, the rinsed water of EP processes is drained in. We measured the concentration of fluorine and niobium in waste-water in the same way as the EPelectrolyte. And finally we transferred the aged EPWEPEC027 Proceedings of IPAC’10, Kyoto, Japan 2948 07 Accelerator Technology T07 Superconducting RF electrolyte and waste-water for disposal out of the EP system as shown in figure 10. Figure 10: The flow of the chamicals in the EP system. The income is brand-new EP-electrolyte and the expenditure is aged EP-electrolyte and waste-water. Exhaust gas The exhaust gas is detoxified with two absorption towers, and the detoxified air is discharged in the atmosphere. The two absorption towers are put in series. And alkaline water circulates in the two towers to scrub the exhast gas. The fluorine concentration in alkaline water in each tower was measured periodically. The results of the measurements was that no hydrogen fluorine was found in second tower as shonw in figure 11. This means that the hydrogen fluoride in exhaust gas is completely removed by the two absorption towers. Alkaline absorption water is sent to the waste-water tank regularly. Figure 11: Fluorine concentration in absorption towers. Hydrogen fluoride in exhaust gas is removed completely with No.1 absorption tower. Monitor of income and expenditure The income and expenditure of fluorine/niobium are summarized in table 1, where all numbers are based on the measurements of fluorine and niobium concentrations. The income is composed of the total amount of fluorine in the brand-new EP-electrolyte and the total removal of niobium. The expenditure is composed of flurine and niobium in waste water in eight disposals and aged EPelectrolyte in one disposal. The expenditure of waste water and aged EP-electrolyte can be summed up and compared with the income. The income and expenditure of fluorine/niobium agreed very well. Fluorine of 10,213g in the EP-electrolyte escaped in waste water. This quantity is about 20% of the income. Niobium of 932g moved into the waste water. This quantity is about 10% of all the removal. Table 1: The income and expenditure of EP-electrolyte. INCOME (Electrolyte) Date Carry Volume (l) Fluorine (mg/l) Fluorine (g) Total Removal Weight(g) 2007/12/2 6 1100 49000 53900 9433 EXPENDITURE (Waste Water) Date Carry Volume (l) Fluorine (mg/l) Fluorine (g) Niobium (mg/l) Niobium (g) Disposal 2008/1/11 900 130 117 KEK 2008/2/1 600 350 210 KEK 2008/2/15 900 650 585 KEK 2008/2/29 1000 340 340 KEK 2008/6/19 7500 16
42191029
Multipole analysis for absolute magnetic field measured by multi-probe pulsed-NMR method
For accelerator dipole magnets, the study on multipole coefficients in a local region is useful for understanding magnet characteristics and checking construction procedure. The multi-probe pulsed-NMR method is a candidate for measurement of the local multipole coefficients. For the absolute fields measured by the multi-probe pulsed-NMR method, a rigorous application of the Fourier expansion is found to yield multipole coefficients. It is made clear that the direction of the dipole field is unable to be determined by the Fourier expansion alone. For estimating alignment accuracy of pulsed-NMR probes, the relationship between errors of multipole coefficients and those of probe position is derived by the Fourier expansion method. For applying of multi-probe pulsed-NMR method to accelerator dipole magnets, we designed and fabricated a field measuring system using two probes. The probes had NMR coils wound around glass ampoules with a diameter of about 1.4 mm. The NMR signal was processed with a phase lock loop circuit to produce the NMR frequency. Dipole field uniformity and multipole coefficients were measured at 0.35 T for a 1.5 m long dipole magnet. It was confirmed that the field data by this NMR system had an accuracy of 10/sup -6/.
17883234
A Vertical Resonance of g-Mode Oscillations in Warped Disks and QPOs in Low-Mass X-Ray Binaries
Resonant oscillations in warped disks are examined in order to explain high-frequency QPOs and horizontalbranch QPOs in low-mass X-ray binaries. Different from our previous work, addressed to the same subjects, we relax in this paper the assumption that the disks are isothermal in the vertical direction. That is, the pressure, density, and temperature are assumed to be distributed in the vertical direction with a polytropic relation, and the polytropic index changes as the disk state changes. By this generalization and by some subsidiaries we can qualitatively explain, within the framework of our resonance model, observed large frequency variations in neutron-star QPOs and little variations in black-hole QPOs. We consider vertical resonances of g-mode oscillations, since they are most appropriate to explain observations.
100337653
VARIOUS RINSING EFFECTS TO MITIGATE CONTAMINANTS BROUGHT BY BCP ON NIOBIUM SRF CAVITY SURFACE
Various rinsing processes have been widely used after the surface treatment for niobium cavities. After the chemical treatment of the cavities some residues from the etching acids are left on the surface. To examine rinsing effects in detail, we carried out BCP experiment followed by post-polishing methods on a series of niobium samples at KEK. As a result of the BCP process [1,2] some contaminants like fluorine, carbon, etc. have been detected at the surfaces which may be the prominent cause of limiting the performance of SRF cavities. To remove these contaminants, various rinsing processes such as ultra pure water rinse, ultrasonic pure water rinse, alcoholic rinse, detergent rinse, high pressure water rinse (HPR) have been used after the BCP. In this article, we report the effect of HPR with different high pressures on the contaminants. The surface of the samples treated with HPR was analyzed using X-ray photo-electron spectroscopy.
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.