| 1. |
- Abt, I, et al.
(författare)
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Inclusive V-0 production cross sections from 920 GeV fixed target proton-nucleus collisions
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 29:2, s. 181-190
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Tidskriftsartikel (refereegranskat)abstract
- Inclusive differential cross sections dsigma(pA)/dx(F) and dsigma(pA)/dp(t)(2) for the production of K-S(0), Lambda, and (&ULambda;) over bar particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to roots = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections dsigma(pA)(K-S(0))/dsigma(pA)(Lambda) and dsigma(pA)((&ULambda;) over bar)/dsigma(pA) (Lambda) are measured to be 6.2 +/- 0.5 and 0.66 +/- 0.07, respectively, for x(F) approximate to -0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions da,Ald t also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections sigma(pA) on the atomic mass A of the target material is discussed, and the deduced cross sections per nucleon sigma(pN) are compared with results obtained at other energies.
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| 2. |
- Abt, I, et al.
(författare)
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Measurement of the b(b)over-bar production cross section in 920 GeV fixed-target proton-nucleus collisions
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:3, s. 345-355
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Tidskriftsartikel (refereegranskat)abstract
- Using the HERA-B detector, the b (b) over bar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b (b) over bar production was tagged via inclusive bottom quark decays into J/psi by exploiting the longitudinal separation of J/psi --> l(+)l(-) decay vertices from the primary proton-nucleus interaction. Both e(+)e(-) and mu(+)mu(-) channels have been reconstructed and the combined analysis yields the cross section sigma(b (b) over bar) = 32(-12)(+14)(stat) (+6)(-7)(sys) nb/nucleon.
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| 3. |
- Aastrup, T., et al.
(författare)
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Experimental in situ studies of copper exposed to humidified air
- 2000
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 42:6, s. 957-967
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Tidskriftsartikel (refereegranskat)abstract
- Three complementary experimental techniques for in situ surface analysis have been combined for the first time in order to explore the chemistry and physics of a copper surface exposed to humidified air. Infrared reflection absorption spectroscopy, quartz crystal microbalance and atomic force microscopy provide a congruent picture of the processes occurring at the surface. At a given relative humidity, cuprous oxide forms according to an approximately logarithmic rate law. In addition, an aqueous adlayer of constant mass physisorbs on the surface. Increased relative humidity stimulates the physisorption of water and enhances the nucleation rate of oxide grains, thereby increasing the formation rate of cuprous oxide.
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| 4. |
- Aastrup, T., et al.
(författare)
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In situ studies of the initial atmospheric corrosion of copper influence of humidity, sulfur dioxide, ozone, and nitrogen dioxide
- 2000
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 147:7, s. 2543-2551
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Tidskriftsartikel (refereegranskat)abstract
- Infrared reflection absorption spectroscopy and quartz crystal microbalance, integrated into a one-surface analytical system, and complemented with tapping mode atomic force microscopy, has been used to explore the metal/atmosphere interfacial region under atmospheric pressure conditions. This unique combination of ill situ techniques, all possessing submonolayer sensitivity, has revealed information on the different accelerating roles of ozone (O-3) and nitrogen dioxide (NO2) on the SO2-induced atmospheric corrosion of copper. The formation of reaction products could be followed quantitatively with respect to chemical identity and kinetics. Exposure in SO2-containing humidified air resulted in CuSO3. xH(2)O-like species, formed atop a cuprous oxide, designated Cu2O, all over the copper surface. O-3 introduction resulted in an accelerated mass gain with an increased formation rate of both Cu2O and of CuSO4. xH(2)O all over the surface. NO2 introduction resulted in less mass gain than observed under SO2 and O-3, with no formation of new Cu2O, an initial oxidation of CuSO3. xH(2)O to CuSO4. xH(2)O, and with sulfite oxidation gradually replaced by copper nitrate formation, possibly as CuNO3(OH)(3) The formation rates of the dominating end products, CuSO4. xH(2)O in SO2/O-3 and Cu2NO3(OH)(3) in SO2/NO2 seemed to be limited by the supply of the gaseous constituents.
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| 5. |
- Wadsak, M., et al.
(författare)
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A comparison of preparation methods of copper surfaces for in situ scanning force microscopy investigations
- 2000
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 157:02-jan, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- Scanning force microscopy (SFM) studies of atmospheric corrosion of pure copper require a clean, homogeneous and smooth metal surface in order to image small changes. In this study various preparation methods for samples of copper sheets were tested: chemical etching, mechanical polishing as well as electrochemical polishing. In addition to copper sheet samples also specimen of sputtered copper obtained by physical vapour deposition on quartz substrates were chemically etched. In conclusion, mechanical polishing with monocrystalline diamond paste and electrochemical polishing of copper sheet yielded the most suitable surface condition for in situ investigations by means of SFM. Tapping mode atomic force microscopy (TM-AFM) was applied to gain information about the topography changes of the copper surface. Furthermore, the root mean square (rms) roughness of the sample surfaces was determined and delivered additional arguments for the applicability of the various surface treatments for in situ studies.
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| 6. |
- Wadsak, M., et al.
(författare)
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Combined in-situ investigations of atmospheric corrosion of copper with SFM and IRAS coupled with QCM
- 2000
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 454, s. 246-250
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Tidskriftsartikel (refereegranskat)abstract
- Scanning force microscopy (SFM) and infrared reflection absorption spectroscopy (IRAS) coupled with quartz crystal microbalance (QCM) were used for in-situ investigations of the atmospheric corrosion of pure copper. Based on chemical and kinetic studies obtained by IRAS/QCM, tapping mode atomic force microscopy (TM-AFM) and phase detection imaging (PDI) were applied to gain information about the topography changes of the sample surface with emphasis on the shape and lateral distribution of the corrosion products. Investigations were carried out in synthetic air with 60 and 80% relative humidity (RI-I). At 60% RH, small features partly covering the surface could be observed with TM-AFM. These features were identified as cuprous oxide with IRAS. Contrary to these results, a fast formation of a layer of cuprous oxide entirely covering the sample surface was observed at 80% RH with TM-AFM. QCM investigations showed a higher formation rate of cuprous oxide at 80% than at 60% RH but in both cases, a high corrosion rate at the beginning of the exposure, which decreases with progressing time.
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| 7. |
- Wadsak, M., et al.
(författare)
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Multianalytical in situ investigation of the initial atmospheric corrosion of bronze
- 2002
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 44:4, s. 791-802
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Tidskriftsartikel (refereegranskat)abstract
- Atomic force microscopy (AFM) and infrared reflection absorption spectroscopy (IRAS) were used for in situ investigations of the initial atmospheric corrosion of bronze. In addition ex situ XPS investigations were carried out on the samples before and after the exposure, as well as on the sputtered bronze sample. Investigations were carried out in synthetic air with 80% relative humidity (RH) and synthetic air with 80% RH with 250 ppb SO2. At 80% RH, small features covering the surface were observed with AFM, whereas IRAS detected that more water is adsorbed on the bronze sample surface compared to pure copper. Large features on top of smaller features were observed with AFM on the bronze surface exposed to SO2-containing humidified air. These large features were identified as copper sulfite. Furthermore, cuprous oxide was detected approximately 500 min after the introduction Of SO2. This fact and the XPS results indicate the formation of a protective lead oxide layer already during the preparation of the sample, which is destroyed by the SO2-containing environment and leads to the formation of cuprous oxide and copper sulfite.
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