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ABSTRACT: The electrical conductivity and temperature coefficient of resistance of polycrystalline platinum nanofilms have been investigated experimentally and theoretically. The results show that these electrical properties have been greatly reduced mainly by grain boundary scattering. By applying the theory of
Mayadas and co-workers [Appl. Phys. Lett. 14, 345 (1969)
;
Phys. Rev. B 1, 1382 (1970)
] to predict the electrical conductivity and temperature coefficient of resistance with the same reflection coefficient, however, obvious discrepancies have been found. These discrepancies indicate that Drude’s relation for bulk metals cannot be applied directly in the nanosized grain interior of polycrystalline metallic films.
Applied Physics Letters 09/2006; 89(11):114102-114102-3. · 3.84 Impact Factor
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ABSTRACT: The surface and grain-boundary effects on the in-plane thermal conductivity of polycrystalline platinum nanofilms have been investigated. The thicknesses of the nanofilms range from 15.0 to 63.0 nm and the mean grain sizes measured by x-ray diffraction vary from 9.5 to 26.4 nm. The thermal conductivities of the nanofilms measured by a direct electrical heating method are greatly reduced from the bulk values. The measured results are compared with the values predicted by the Qiu and Tien model and the Kumar and Vradis theory. It is found that the reduction in the thermal conductivity is mainly caused by grain-boundary scattering and the reflection coefficient of electrons striking the grain boundaries is around 0.35. The relaxation time model is also applied to study the size effects to check whether the Matthiessen rule is still valid in predicting the in-plane thermal conductivity of polycrystalline metallic nanofilms. The results indicate that by considering only grain-boundary scattering and background scattering the Matthiessen rule is still valid. If surface scattering, however, is included, deviations of the Matthiessen rule from other theories mentioned above have been found.
Journal of Physics Condensed Matter 08/2006; 18(34):7937. · 2.55 Impact Factor
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C. Bacci,
K.Z. Bao,
F. Barone,
B. Bartoli,
D. Bastieri,
P. Bernardini,
S. Bussino,
E. Calloni, B.Y. Cao,
R. Cardarelli, [......],
A.F. Yuan,
X.D. Yue,
H.M. Zhang,
J.L. Zhang,
N.J. Zhang,
T.J. Zhang,
X.Y. Zhang,
Zhaxiciren,
Zhaxisangzhu,
Q.Q. Zhu
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ABSTRACT: We present the ARGO-YBJ experiment, a full coverage detector placed at high altitude (∼4300 m a.s.l.) that exploits the RPC technique. Results of a test experiment performed at Yanbajing site, with a full coverage RPC carpet of 50 m2 are also presented.
Nuclear Physics B - Proceedings Supplements. 01/1999;
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C. Bacci,
K.Z. Bao,
F. Barone,
B. Bartoli,
P. Bernardini,
R. Buonomo,
S. Bussino,
E. Calloni, B.Y. Cao,
R. Cardarelli, [......],
X.D. Yue,
A.F. Yuan,
H.M. Zhang,
J.L. Zhang,
N.J. Zhang,
T.J. Zhang,
X.Y. Zhang,
Zhaxisangzhu,
Zhaxiciren,
Q.Q. Zhu
[show abstract]
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ABSTRACT: A 50 m2 RPC carpet was operated at the YanBaJin Cosmic Ray Laboratory (Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive Air Showers was studied. Efficiency and time-resolution measurements at the pressure and temperature conditions typical of high mountain laboratories, are reported.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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C Bacci,
K.Z. Bao,
F. Barone,
B. Bartoli,
D. Bastieri,
P. Bernardini,
R. Buonomo,
S Bussino,
E. Calloni, B.Y. Cao, [......],
X.D. Yue,
A. F. Yuan,
H M Zhang,
J L Zhang,
N. J. Zhang,
T.J. Zhang,
X Y Zhang,
Zhaxisangzhu,
Zhaxiciren,
Q. Q. Zhu
[show abstract]
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ABSTRACT: ARGO-YBJ (Astrophysical Radiation with Ground-based Observatory at YangBaJing) is a detector optimized to study small size air showers. It consists of a layer of Resistive Plate Counters (RPCs) covering an area of ~ 6500 m$^2$ and will be located in the Yangbajing Laboratory (Tibet, China) at 4300 m a.s.l. ARGO-YBJ will be devoted to a wide range of fundamental issues in cosmic rays and astroparticle physics, including in particular gamma-ray astronomy and gamma-ray bursts physics in the range $10~{\rm GeV} \div 500~{\rm TeV}$. The sensitivity of ARGO-YBJ to detect high energy GRBs is presented.
http://dx.doi.org/10.1051/aas:1999367.
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C. Bacci,
K.Z. Bao,
F. Barone,
B. Bartoli,
P. Bernardini,
S. Bussino,
E. Calloni, B.Y. Cao,
R. Cardarelli,
S. Catalanotti, [......],
X.D. Yue,
A.F. Yuan,
M. Zha,
H.M. Zhang,
J.L. Zhang,
N.J. Zhang,
X.Y. Zhang,
Zhaxisangzhu,
Zhaxiciren,
Q.Q. Zhu
[show abstract]
[hide abstract]
ABSTRACT: Bakelite RPCs, assembled according to the ARGO design, have been operated in the high altitude Laboratory of YBJ using dedicated electronics to pick-up the streamer signal. Here we report on the results concerning absorbed current, single counting rate, efficiency and time resolution. Environmental data concerning the operating temperature inside the ARGO experimental hall are also reported.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
