| 51. |
- Ahmed, M., et al.
(författare)
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Search for the lepton-family-number nonconserving decay μ +→e +γ
- 2002
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Ingår i: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 65:11
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Tidskriftsartikel (refereegranskat)abstract
- The MEGA experiment, which searched for the muon- and electron-number violating decay μ +→e + γ, is described. The spectrometer system, the calibrations, the data taking procedures, the data analysis, and the sensitivity of the experiment are discussed. The most stringent upper limit on the branching ratio, B(μ + →e + γ)<1.2×10 -11 with 90% confidence, is derived from a likelihood analysis.
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| 52. |
- Gono, Y., et al.
(författare)
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Systematics of high-spin isomers in N=83 isotones and a high-spin isomer beam
- 2002
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Ingår i: European Physical Journal A. - 1434-6001 .- 1434-601X. ; 13:02-jan, s. 5-8
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Tidskriftsartikel (refereegranskat)abstract
- Isomers in N = 83 isotones of Z = 60 66 were studied systematically. Their spins and parities arc,49/2(+) and 27(+) for odd and odd-odd nuclei, respectively. Nearly constant excitation energies of these isomers indicated a decrease of a Z = 64 shell gap energy as Z decreases from 64 to 60 within the framework of a deformed independent-particle model (DIPM). Their configurations are [v(f(tau/2)h(9/2)i(13/2)), pi(h(11/2))(2)](49/2+) and [v(f(7/2)h(9/2)i(13/2)), pi(h(11/2))(2)(d(5/2))(-1)](27+) for odd and odd-odd nuclei, respectively. The shape of the yrast status changes suddenly at spin 49/2(odd) and 27(odd-odd) from a near spherical to an oblate shape. Transitions from isomers are highly hindered because of the shape changes. They may be categorized to be shape isomers. The development of a secondary beam produced by using these high-spin isomers is also described.
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| 53. |
- Molisch, Andreas, et al.
(författare)
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An efficient low-cost time-hopping impulse radio for high data rate transmission
- 2003
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Ingår i: Proceeding of the Sixth International Symposium on Wireless Personal Multimedia Communications.
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Konferensbidrag (refereegranskat)abstract
- We present an efficient, low-cost implementation of time-hopping impulse radio that fulfills the spectral mask mandated by the FCC and is suitable for high-data-rate, short-range communications. The system was proposed to the IEEE 802.15.3a group for standardization as high-datarate personal-area network (PAN). Key features are: (i) all-baseband implementation obviates the need for local oscillators and other passband components, (ii) all sampling and digital signal processing is done at 200MHz, (iii) fast acquisition is accomplished by novel search algorithms,(iv) the spectral can be shaped adaptively to accommodate different spectrum regulations and interference environments. We show that this system can provide 110Mbit/s at 7-10m distance, as well as higher data rates at shorter distances. Due to the spreading concept of time-hopping impulse radio, the system can sustain multiple piconets, and can suppress narrowband interference effectively.
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| 54. |
- Zhang, Shi-Li, et al.
(författare)
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Abnormal anti-Stokes Raman scattering of carbon nanotubes
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:3
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal anti-Stokes Raman scattering (AASR) was unambiguously observed in carbon nanotubes (CNT's). In contrast to traditional Raman scattering theory, the absolute value of the Raman frequency of the anti-Stokes peak is not the same as that of the corresponding Stokes peak. It was demonstrated that AASR scattering originates from the unique nanoscale cylindrical structure of CNT's that can be considered naturally as a graphite structure with an intrinsic defect from its rolling. The double-resonance Raman scattering theory was applied to interpret the scattering mechanism of the AASR phenomenon successfully and quantitatively.
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| 55. |
- Li, H. N., et al.
(författare)
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Electronic structure of Yb2.75C60
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 68:16
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Tidskriftsartikel (refereegranskat)
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| 56. |
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| 57. |
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| 58. |
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| 59. |
- Zhang, J. G., et al.
(författare)
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Microstructure and mechanical properties of spray formed ultrahigh-carbon steels
- 2004
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 383:1, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure and mechanical properties of the spray formed 1.25C-3.0Si-1.5Cr ultrahigh-carbon steel (UHCS) were described. The 1.25C-3.0Si-1.5Cr UHCS was processed by spray forming to break up carbide networks. The fine pearlites with average interlamellar spacing of 0.20 mum was observed in the as-sprayed microstructure. The ultimate tensile strength and the pearlite spacing can be related by the Hall-Petch equation. The as-sprayed 1.25C-3.0Si-1.5Cr UHCS consisting of fine lamellar pearlites has been shown to exhibit superplastic behavior at elevated temperature. The dramatic change of microstructure from fine lamellar pearlites to equiaxed grains stabilized by spheroidized particles during superplastic deformation has been observed. The estimation on the basis of thermodynamics shows that the content of chromium of 1.54 wt.% is needed to inhibit graphite formation in the l.25C-3.OSi-1.5Cr UHCS.
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| 60. |
- Zhang, Zhibin, et al.
(författare)
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Formation of C54TiSi(2) on Si(100) using Ti/Mo and Mo/Ti bilayers
- 2002
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Ingår i: International Journal of Modern Physics B. - 0217-9792. ; 16:1-2, s. 205-212
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Tidskriftsartikel (refereegranskat)abstract
- The effect of Mo on the formation of C54 TiSi2 on Si (100) substrates is studied using crosssectional transmission electron microscopy. For a Ti/Mo bilayer on Si, the interfacial Mo film reacts with Ti and Si to form C40 (Mo,Ti)Si-2 at 550 degreesC. Crystal grains of metastable C40 TiSi2 and equilibrium C54 TiSi2 are found in the region near the interfacial (Mo,Ti)Si-2 layer due to the template phenomenon. Increasing the temperature to 600 degreesC leads to the growth of C54 TiSi2 throughout the film. No C49 grains can be detected. The findings confirm that the usual sequence for the formation of C54 TiSi2, i.e. the C49 TiSi2 forms first followed by a phase transition to the C54 TiSi2, is altered by the interposed Mo layer. For a Mo/Ti bilayer on Si, the surface Mo layer is found to be present sequentially in (Mo,Ti)(5)Si-3 at 550 degreesC, C49 (Mo,Ti)Si-2 at 600 degreesC and C54 (Mo,Ti)Si-2 at 650 degreesC. The bulk Ti beneath forms the C54 TiSi2 following the usual route through the C49-C54 phase transition. However, this transition is now enhanced, in comparison with the C54 TiSi2 formation with pure Ti, by the C54 (Mo,Ti)Si-2 atop that plays the role as a template precisely as the interfacial C40 (Mo,Ti)Si-2.
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