A Super Strong Permanent Magnet Quadrupole for the Final Focus in a Linear Collider
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Mihara, T.↗
Engineering topics
Mihara, T.
Publications and source records attributed to Mihara, T..
A Superstrong Adjustable Permanent Magnet for the Final Focus Quadrupole in a Linear Collider
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Mihara, T.↗
Superstrong Adjustable Permanent Magnet for a Linear Collider Final Focus
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Mihara, T.↗
Behavior of high-burnup advanced LWR fuels under accident conditions
Advanced fuels for LWRs which consist of cladding materials with high corrosion resistance and pellets with lower fission gas release have been developed by utilities and fuel vendors to improve the fuel performance even in the high burnup region and also raise the safety level of current nuclear power plants to a higher one. In order to evaluate the adequacy of present safety criteria and safety margins in terms of such advanced fuels and provide a database for future regulation of them, JAEA has started a new extensive research program called ALPS-II program. The ALPS-II program is primarily composed of tests simulating a RIA (Reactivity Initiated Accident) (VA-5 and -6 tests) and a LOCA (Loss Of Coolant Accident) on high burnup advanced fuels irradiated in commercial PWR or BWRs and started in JFY 2008. Recently, post-test examinations on the fuel rods after the pulse irradiation tests of VA-5 and -6 were performed and the relationship between the failure limits of the high burnup advanced fuels with M-MDA{sup TM} cladding and the morphology of the hydrides precipitated in the cladding during normal operation was investigated. The difference in the crack surface morphology was observed between tests VA-5 and-6, which seemed to reflect the difference in the direction along which hydrides precipitate in the cladding. This indicates that the hydride precipitated in the cladding, which is considered to be dependent on the final heat treatment at fabrication, affects the fuel enthalpy at failure. In terms of the simulated LOCA test, integral thermal shock tests and high temperature oxidation tests have been conducted on high burnup PWR and BWR fuel cladding with advanced materials, and their fracture limits, high temperature oxidation rates, etc. were investigated. In the recent integral thermal shock tests for high burnup BWR cladding, namely Zry-2/LK3 material, no fractures were observed. In terms of the oxidation rate tests, the oxidation rate of irradiated M5{sup TM} was similar to those of unirradiated Zry-4 and M5{sup TM} and lower than the values estimated by the Baker-Just equation. From the results of these tests, it was found that in terms of these materials the fracture boundaries do not decrease and the oxidation does not significantly accelerate in the burnup level examined.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Extraordinary luminous soft X-ray transient MAXI J0158–744 as an ignition of a nova on a very massive O-Ne white dwarf
We present the observation of an extraordinary luminous soft X-ray transient, MAXI J0158–744, by the Monitor of All-sky X-ray Image (MAXI) on 2011 November 11. This transient is characterized by a soft X-ray spectrum, a short duration (1.3 × 10{sup 3} s < ΔT{sub d} < 1.10 × 10{sup 4} s), a rapid rise (<5.5 × 10{sup 3} s), and a huge peak luminosity of 2 × 10{sup 40} erg s{sup –1} in 0.7-7.0 keV band. With Swift observations and optical spectroscopy from the Small and Moderate Aperture Research Telescope System, we confirmed that the transient is a nova explosion, on a white dwarf in a binary with a Be star, located near the Small Magellanic Cloud. An early turn-on of the super-soft X-ray source (SSS) phase (<0.44 days), the short SSS phase duration of about one month, and a 0.92 keV neon emission line found in the third MAXI scan, 1296 s after the first detection, suggest that the explosion involves a small amount of ejecta and is produced on an unusually massive O-Ne white dwarf close to, or possibly over, the Chandrasekhar limit. We propose that the huge luminosity detected with MAXI was due to the fireball phase, a direct manifestation of the ignition of the thermonuclear runaway process in a nova explosion.
79 ASTRONOMY AND ASTROPHYSICS↗
The accretion disk and ionized absorber of the 9.7 hr dipping black hole binary MAXI J1305–704
We report the results from X-ray studies of the newly discovered black hole candidate MAXI J1305–704 based on Suzaku and Swift observations in the low/hard and high/soft states, respectively. The long Suzaku observation shows two types of clear absorption dips, both of which recur on a dip interval of 9.74 ± 0.04 hr, which we identify with the orbital period. There is also partially ionized absorption in the nondip (persistent) emission in both the high/soft state and, very unusually, the low/hard state. However, this absorption (in both states) has substantially lower ionization than that seen in other high inclination systems, where the material forms a homogeneous disk wind. Here instead the absorption is most likely associated with clumpy, compact structures associated with the dipping material, which we see uniquely in this source likely because we view it at a very large inclination angle. A large inclination angle is also favored, together with a low black hole mass, to explain the high disk temperature seen in the fairly low luminosity high/soft state, as Doppler boosting enhances the disk temperature at high inclination. The disk radius inferred from these data is significantly smaller than that of the soft component seen in the low/hard state, supporting models where the disk is truncated at low luminosities. We find, however, that the lack of variability power on timescales of ∼50 s in the Suzaku low/hard state data is difficult to explain, even with a low-mass black hole.
79 ASTRONOMY AND ASTROPHYSICS↗
A PROPELLER-EFFECT INTERPRETATION OF MAXI/GSC LIGHT CURVES OF 4U 1608-52 AND Aql X-1 AND APPLICATION TO XTE J1701-462
We present the luminosity dwell-time distributions during the hard states of two low-mass X-ray binaries containing a neutron star (NS), 4U 1608-52 and Aql X-1, observed with MAXI/GSC. The luminosity distributions show a steep cutoff on the low-luminosity side at {approx}1.0 Multiplication-Sign 10{sup 36} erg s{sup -1} in both sources. The cutoff implies a rapid luminosity decrease in their outburst decay phases and this decrease can be interpreted as being due to the propeller effect. We estimate the surface magnetic field of 4U 1608-52 to be (0.5-1.6) Multiplication-Sign 10{sup 8} G and Aql X-1 to be (0.6-1.9) Multiplication-Sign 10{sup 8} G from the cutoff luminosity and apply the same propeller mechanism to the similar rapid luminosity decrease observed in the transient Z source, XTE J1701-462, with RXTE/ASM. Assuming that the spin period of the NS is on the order of milliseconds, the observed cutoff luminosity implies a surface magnetic field on the order of 10{sup 9} G.
79 ASTRONOMY AND ASTROPHYSICS↗
Summary of a joint US-Japan study of potential approaches to reduce the attractiveness of various nuclear materials for use in a nuclear explosive device by a terrorist group
This paper summarizes the results of a joint US-Japan study to establish a mutual understanding, through scientific-based study, of potential approaches to reduce the attractiveness of various nuclear materials for use in a terrorist nuclear explosive device (NED). 4 approaches that can reduce materials attractiveness with a very high degree of effectiveness are: -) diluting HEU with natural or depleted U to an enrichment of less than 10% U-235; -) storing Pu in nuclear fuel that is not man portable and with a dose rate greater or equal to 10 Gy/h at 1 m; -) storing Pu or HEU in heavy items, i.e. not transportable, provided the removal of the Pu or HEU from the item requires a purification/processing capability; and -) converting Pu and HEU to very dilute forms (such as wastes) that, without any security barriers, would require very long acquisition times to acquire a Category I quantity of Pu or of HEU. 2 approaches that can reduce materials attractiveness with a high degree of effectiveness are: -) converting HEU-fueled research reactors into LEU-fueled research reactors or dilute HEU with natural or depleted U to an enrichment of less than 20% U-235; -) converting U/Al reactor fuel into U/Si reactor fuel. Other approaches have been assessed as moderately or totally inefficient to reduce the attractiveness of nuclear materials.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Possible Detection of an Emission Cyclotron Resonance Scattering Feature from the Accretion-Powered Pulsar 4U 1626-67
We present analysis of 4U 1626-67, a 7.7 s pulsar in a low-mass X-ray binary system, observed with the hard X-ray detector of the Japanese X-ray satellite Suzaku in 2006 March for a net exposure of ~88 ks. The source was detected at an average 10-60 keY flux of approx 4 x 10-10 erg / sq cm/ s. The phase-averaged spectrum is reproduced well by combining a negative and positive power-law times exponential cutoff (NPEX) model modified at approx 37 keY by a cyclotron resonance scattering feature (CRSF). The phase-resolved analysis shows that the spectra at the bright phases are well fit by the NPEX with CRSF model. On the other hand. the spectrum in the dim phase lacks the NPEX high-energy cutoff component, and the CRSF can be reproduced by either an emission or an absorption profile. When fitting the dim phase spectrum with the NPEX plus Gaussian model. we find that the feature is better described in terms of an emission rather than an absorption profile. The statistical significance of this result, evaluated by means of an F test, is between 2.91 x 10(exp -3) and 1.53 x 10(exp -5), taking into account the systematic errors in the background evaluation of HXD-PIN. We find that the emission profile is more feasible than the absorption one for comparing the physical parameters in other phases. Therefore, we have possibly detected an emission line at the cyclotron resonance energy in the dim phase.
Iwakiri, W. B.↗
The Be/X-Ray Binary A0535+26 During Its Recent 2009/2010 Outbursts
The Be/X-ray binary A0535+26 showed a giant outburst in December 2009 that reached approximately 5.14 Crab in thc 15-50 keV range. Unfortunately, due to Sun constraints it could not be observed by most X-ray satellites. The outburst was preceded by four weaker outbursts associated with the periastron passage of the neutron star. The fourth of them, in August 2009, presented a peculiar double-peaked light curve, with a first peak lasting about 9 days that reached a (15- 50 keV) flux of 440 mCrab. The tl ux then decreased to less than 220 mCrab, and increased again reaching 440 mCrab around the periastron. The outburst was monitored with INTEGRAL, RXTE, and Suzaku TOO observations. One orbital period (approximately 111 days) after the 2009 giant outburst, a new and unexpectedly bright outburst took place (approximately 1.4Crab in the 15-50 keV range). It was monitored with TOO observations with INTEGRAL, RXTE, Suzaku, and Swift. First results of the spectral and timing analysis of these observations are presented. with a specific focus on the cyclotron lines present in thc system and its variation with the mass accretion rate.
Caballero, I.↗
X-ray search for dark lens objects
The quasi-stellar object (QSO) MG 2016+112 is searched for and probably identified as an X-ray cluster of galaxies by the Advanced Satellite for Cosmology and Astrophysics (ASCA) observations. The MG 2016+112 is a gravitational lensed system with three confirmed lensed images of the QSO at a redshift of 3.27. The X-ray spectrum suggests that the new record of the highest redshift of clusters of galaxies, from which X-ray and iron K-line emission were detected, was reached.
Hattori, M.↗
Geometry and pulse profiles of x-ray pulsars: Asymmetric relativistic fits to 4U1538 - 52 and vela x-1
Model calculation of inhomogenuous magnetized neutron star atmospheres are used to analyze the phase-dependent spectra of 4U 1538-52 and Vela X-1 taking into account general relativistic effects. A chi (exp 2) fitting procedure is used on the Ginga data for these objects to determine the geometry and the magnetic structure of the polar caps, as well as their size and location on the surface of the stars. Other parameters determined by the fit are the masses and radii of neutron stars, the accretion rates, and the rotation and magnetic inclination angles including an azimuthal offset to reproduce the asymmetry of the pulse shapes. We find that general relativistic effects play a significant role in determining the derived cap sizes, the fluxes, and the observational appearance of the pulses. There is evidence that the polar caps are unequal and nonantipodal, suggesting either an off-center or bent magnetic axis, or a strong nondipole component. The magnetic field structure is approximated by a two-component model. The rotation axes are inferred to be moderately close to the mean magnetic axes and seen at large inclinations with respect to the line of sight.
Bulik, T.↗
Multiwavelength observations of Hercules X-1/HZ Herculis
We present first results from a multiwavelength campaign to observe the binary pulsar system Her X-1/ HZ Her. The campaign spanned 4 days during 1993 August: observations were taken with five satellites (IUE, EUVE, ROSAT, ASCA, and CGRO/BATSE) and several ground-based facilities. A substantial, unexpected drop in flux at X-ray energies, with no change in absorbing column density, was observed. The pulse period has increased from the previous measurement, contrary to the usual spin-up, and no pulsed emission is detected above 0.9 keV in the low state. The optical and UV fluxes continued to show 1.7 day modulation attributed to X-ray heating of the companion star. However, the significant reduction in UV flux observed around eclipse implies an absence of the normally observed excess attributed to X-ray heating of the disk. We conclude that we have observed an anomalous low state, seen only once before (Parmar et al. 1985), in which the X-ray flux is not redistributed but obscured. We suggest explanations for the behavior of the flux at different wavelengths.
Vrtilek, S. D.↗
Detections of hard X-ray emissions from bright early-type galaxies with ASCA
Five bright elliptical galaxies in the Virgo Cluster, NGC 4365, NGC 4374 (M84), NGC 4406 (M86), NGC 4472 (M49), and NGC 4636, were observed with ASCA. In addition to the extended thermal X-ray emission of temperature kT approximately 1 keV, harder X-rays with color temperature kT greater than or equal to 2 keV were detected from all of them. The 2-10 keV luminosities of this hard component for the five galaxies, integrated within 5 min, are distributed within a relatively narrow range of (1-4) x 10(exp 40) ergs/s. The hard X-ray component is primarily attributed to the integrated emission from discrete X-ray sources. In NGC 4406 and NGC 4374 the data indicate that the hard component is contributed additionally by foreground/background emission from the hot intracluster medium (ICM) of the Virgo Cluster. The hard component of NGC 4472 seems also contributed by the Virgo ICM emission, but in this case there is evidence that the ICM brightness is locally enhanced within approximately 10 min of NGC 4472.
Matsushita, K.↗
An ASCA GIS spectrum of S5 0014+813 AT z = 3.384
ASCA has detected the z = 3.384 quasar S5 0014+813 up to energies of 34 keV in the quasar rest frame using the two gas imaging spectrometer (GIS) instruments. The combined X-ray spectrum has a signal-to-noise ratio of over 50 sigma and is consistent with a single power law of energy slope 0.63 +/- 0.03 over the 0.8-8 keV (observed) energy range. The spectrum is also well fitted with a simple thermal bremsstrahlung model of kT = 40 +/- 4 keV (in the quasar frame), which raises obvious possibilities for contributions to the diffuse X-ray background. A maximum solid angle of Omega(sub d)/2(pi) = 0.4(90% confidence) can be placed on the strength of a Compton reflection component above the energy of the Fe K-edge. The Fe K 6.4 keV fluorescence line has a rest frame equivalent width less than 120 eV (90% confidence) at its redshifted energy of 1.46 keV. The weakness of these features differentiates this high-luminosity, high-redshift quasar from the majority of Seyfert galaxies using its X-ray spectrum alone. The GIS slope is consistent with the slope derived by the ROSAT Position Sensitive Proportional Counter (PSPC). The normalization at 1 keV in the ASCA observation is, however, a factor 30%-40% higher than in the ROSAT observation, suggesting a significant increase in the 1 keV (observed) flux over the 31.5 months between the two observations (7.2 months, rest frame).
Elvis, Martin↗
Ginga observations of Centaurus X-3
Attention is given to a series of observations of Centaurus X-3 made with Ginga on March 22-24, 1989, over a complete orbital cycle. The data set includes a preeclipse dip, the eclipse ingress and egress, the eclipse itself, and a phase of high steady emission after egress. The mideclipse ephemeris obtained yields an estimate of the rate of change of the orbital period of -(1.738 +/- 0.004) x 10 exp 6/yr, confirming the rate of change reported by Kelley et al. (1983) and improving the precision by a factor of 20. The pulse profiles obtained with Ginga during the high postegress phase are double-peaked at low energies, and show a reversal of phase of 180 deg. No pulsations are detected during the eclipse and at low energies during the preeclipse dip, indicating that X-ray emission at these phases is due to scattering by extended matter. The energy of the iron emission line varies between 6.5 and 6.7 keV during the observation, while its equivalent width varies between 0.18 and 1.5 keV.
Nagase, F.↗
New observations of the cyclotron absorption feature in Hercules X-1
The Ginga satellite observatory has been used to measure a cyclotron feature in the hard X-ray spectrum of the 1.24-s binary pulsar Hercules X-1 with a much greater energy resolution than in previous observations. The spectrum from 10-60 keV can be described with a simple analytical formula which indicates an absorption feature at about 34 keV rather than an emission feature at about 50 keV. From this, the surface magnetic field strength of Her X-1 is estimated to be (2.9 + or - 0.3) x 10 to the 12th G.
Mihara, T.↗