Search

Your search keyword '"Gazdzicki P"' showing total 271 results
Start Over Author "Gazdzicki P"
271 results on '"Gazdzicki P"'

151. Pion Suppression in Nuclear Collisions

Author

Gazdzicki, Marek, Gorenstein, Mark I., and Mrowczynski, Stanislaw

Subjects
Nuclear Theory
Abstract

The pion multiplicity per participating nucleon in central nucleus-nucleus collisions at the energies 2-15 A GeV is significantly smaller than in nucleon-nucleon interactions at the same collision energy. This effect of pion suppression is argued to appear due to the evolution of the system produced at the early stage of heavy-ion collisions towards a local thermodynamic equilibrium and further isentropic expansion., Comment: a revised version, to be published in Eur. Phys. J. C (1998)

Published
1997
Full Text
View/download PDF

152. Strangeness in Nuclear Collisions

Author

Gazdzicki, Marek and Roehrich, Dieter

Subjects
High Energy Physics - Experiment
Abstract

Data on the mean multiplicity of strange hadrons produced in minimum bias proton--proton and central nucleus--nucleus collisions at momenta between 2.8 and 400 GeV/c per nucleon have been compiled. The multiplicities for nucleon--nucleon interactions were constructed. The ratios of strange particle multiplicity to participant nucleon as well as to pion multiplicity are larger for central nucleus--nucleus collisions than for nucleon--nucleon interactions at all studied energies. The data at AGS energies suggest that the latter ratio saturates with increasing masses of the colliding nuclei. The strangeness to pion multiplicity ratio observed in nucleon--nucleon interactions increases with collision energy in the whole energy range studied. A qualitatively different behaviour is observed for central nucleus--nucleus collisions: the ratio rapidly increases when going from Dubna to AGS energies and changes little between AGS and SPS energies. This change in the behaviour can be related to the increase in the entropy production observed in central nucleus-nucleus collisions at the same energy range. The results are interpreted within a statistical approach. They are consistent with the hypothesis that the Quark Gluon Plasma is created at SPS energies, the critical collision energy being between AGS and SPS energies., Comment: 28 pages

Published
1996
Full Text
View/download PDF

153. Pion and Strangeness Puzzles

Author

Gazdzicki, Marek

Subjects
High Energy Physics - Phenomenology
Abstract

The dependence of pion and strangeness production on the number of participant nucleons and collision energy is discussed for central A+A collisions. A possible interpretation of the experimental results assuming transition to QGP is sketched within a simple statistical approach., Comment: 13 pages, 5 figures, some modifications of text and figures

Published
1996
Full Text
View/download PDF

154. Comment on 'Strangeness enhancement in $p+A$ and S$+A$ interactions at energies near 200 $A$ GeV'

Author

Gaździcki, Marek and Heinz, Ulrich

Subjects
Nuclear Theory
Abstract

We argue that the recent analysis of strangeness production in nuclear collisions at 200 $A$ GeV/$c$ performed by Topor Pop {\it et al.} \cite{To:95} is flawed. The conclusions are based on an erroneous interpretation of the data and the numerical model results. The term ``strangeness enhancement" is used in a misleading way., Comment: 4 pages REVTEX 3.0, no figures; Comment submitted to Physical Review C

Published
1996
Full Text
View/download PDF

155. Modification of gas diffusion layers properties to improve water management

Author

Martin Tomas, Indro S. Biswas, Pawel Gazdzicki, Lucie Kullova, and Mathias Schulze

Subjects
Fuel cell, GDL, Water management, Performance, PTFE, Laser patterning, Energy conservation, TJ163.26-163.5, Renewable energy sources, TJ807-830
Abstract

Abstract In this paper we report an approach to improve water management of commercial GDLs by introducing hydrophobicity patterns. Specifically, line and grid patterns have been created in the MPL side by laser radiation. For an in-depth investigation of these modified GDLs the current density distribution was monitored during fuel cell operation. Additionally, the physical properties of these materials were investigated by a number of ex situ methods such as Fourier transform infrared microscopy, electrochemical impedance spectroscopy and water vapor sorption. Furthermore, a comparison of the physical properties of the patterned GDLs with chemically modified GDLs (treated in H2SO4 and H2O2) is provided. Our results show a clearly improved homogeneity of current density distribution of the patterned GDLs compared to untreated GDLs. This observation is likely due to a reduced local hydrophobicity which facilitates water diffusion along the flow field of the fuel cell. However, performance of the fuel cell was not affected by the MPL irradiation. Graphical Abstract

Published
2017
Full Text
View/download PDF

158. Production of phi-mesons in p+p, p+Pb and central Pb+Pb collisions at Ebeam = 158 A GeV

Author

Afanasiev, S.V., Anticic, T., Bachler, J., Barna, D., Barnby, L.S., Bartke, J., Barton, R.A., Betev, L., Bialkowska, H., Billmeier, A., Blume, C., Blyth, C.O., Boimska, B., Bracinik, J., Brady, F.P., Brun, R., Buncic, P., Carr, L., Cebra, D., Cooper, G.E., Cramer, J.G., Csato, P., Eckardt, V., Eckhardt, F., Ferenc, D., Fischer, H.G., Fodor, Z., Foka, P., Freund, P., Friese, V., Ftacnik, J., Gal, J., Ganz, R., Gazdzicki, M., Gladysz, E., Grebieszkow, J., Harris, J.W., Hegyi, S., Hlinka, V., Hohne, C., Igo, G., Ivanov, M., Jacobs, P., Janik, R., Jones, P.G., Kadija, K., Kolesnikov, V.I., Kowalski, M., Lasiuk, B., Levai, P., Malakhov, A.I., Margetis, S., Markert, C., Mayes, B.W., Melkumov, G.L., Mischke, A., Molnar, J., Nelson, J.M., Odyniec, G., Oldenburg, M.D., Palla, G., Panagiotou, A.D., Petridis, A., Pikna, M., Pinsky, L., Poskanzer, A.M., Prindle, D.J., Puhlhofer, F., Reid, J.G., Renfordt, R., Retyk, W., Ritter, H.G., Rohrich, D., Roland, C., Roland, G., Rybicki, A., Sammer, T., Sandoval, A., Sann, H., Semenov, A.Yu., Schafer, E., Schmitz, N., Seyboth, P., Sikler, F., Sitar, B., Skrzypczak, E., Snellings, R., Squier, G.T.A., Stock, R., Strmen, P., Strobele, H., Susa, T., Szarka, I., Szentpetery, I., Sziklai, J., Toy, M., Trainor, T.A., Trentalange, S., Ullrich, T., and Varga, D.

Published
2000

159. Centrality Dependence of Directed and Elliptic Flow at the SPS

Author

Poskanzer, Arthur M., Voloshin, Sergei A., NA49 Collaboration, Bachler, J., Barna, D., Barnby, L.S., Bartke, J., Barton, R.A., Betev, L., Bialkowska, H., Billmeier, A., Blume, C., Blyth, C.O., Boimska, B., Bracinik, J., Brady, F.P., Brockmann, R., Brun, R., Buncic, P., Carr, L., Cebra, D., Cooper, G.E., Cramer, J.G., Csato, P., Eckardt, V., Eckhardt, F., Ferenc, D., Fischer, H.G., Fodor, Z., Foka, P., Freund, P., Friese, V., Ftacnik, J., Gal, J., Ganz, R., Gazdzicki, M., Gladysz, E., Grebieszkow, J., Harris, J.W., Hegyi, S., Hlinka, V., Hohne, C., Igo, G., Ivanov, M., Jacobs, P., Janik, R., Jones, P.G., Kadija, K., Kolesnikov, V.I., Kowalski, M., Lasiuk, B., Levai, P., Malakhov, A.I., Margetis, S., Markert, C., Mayes, B.W., Melkumov, G.L., Molnar, J., Nelson, J.M., Odyniec, G., Oldenburg, M.D., Palla, G., Panagiotou, A.D., Petridis, A., Pikna, M., Pinsky, L., Poskanzer, A.M., Prindle, D.J., Puhlhofer, F., Reid, J.G., Renfordt, R., Retyk, W., Ritter, H.G., Rohrich, D., Roland, C., Roland, G., Rybicki, A., Sammer, T., Sandoval, A., Sann, H., Semenov, A.Yu., Schafer, E., Schmitz, N., Seyboth, P., Sikler, F., Sitar, B., Skrzypczak, E., Snellings, R., Squier, G.T.A., Stock, R., Strmen, P., Stroebele, H., Susa, T., Szarka, I., Szentpetery, I., Sziklai, J., Toy, M., Trainor, T.A., Trentalange, S., and Ullrich, T.

Subjects
relativistic SPS NA49 flow centrality
Abstract

New data with a minimum bias trigger for 158 GeV/nucleon Pb + Pb have been analyzed. Directed and elliptic flow as a function of rapidity of the particles and centrality of the collision are presented. The centrality dependence of the ratio of elliptic flow to the initial space elliptic anisotropy is compared to models.

Published
1999

160. First Results from NA49 on Pb+Pb Collisions at 158 GeV/Nucleon

Author

Margetis, S., Alber, T., Appelshauser, H., Bachler, J., Bartke, J., Bialkowska, H., Bieser, F., Bloomer, M.A., Blyth, C.O., Bock, R., Bormann, C., Brady, F.P., Brockmann, R., Buncic, P., Caines, H.L., Cebra, D., Chan, P., Cooper, G., Cramer, J.G., Cramer, P.B., Csato, P., Derado, I., Dunn, J., Eckardt, V., Eckhardt, F., Euler, S., Ferguson, M.I., Fischer, H.G., Fodor, Z., Foka, P., Freund, P., Fuchs, M., Gal, J., Gazdzicki, M., Gladysz, E., Grebieszkow, J., Gunther, J., Harris, J.W., Heck, W., Hegyi, S., Hill, L.A., Huang, I., Howe, M.A., Igo, G., Irmscher, D., Jacobs, P., Jones, P.G., Kadija, K., Kecskemeti, J., Kosiec, J., Kowalski, M., Kuhmichel, A., Lasiuk, B., Mitchell, J.W., Mock, A., Nelson, J.M., Odyniec, G.J., Palinkas, J., Palla, G., Panagiotou, A.D., Petridis, A., Piper, A., Poskanzer, A.M., Prindle, D.J., Puhlhofer, F., Rauch, W., Renfordt, R., Retyk, W., Ritter, Hans G., Rohrich, D., Rudolph, H., Runge, K., Sandoval, A., Sann, H., Schaefer, E., Schmitz, N., Schonfelder, S., Seyboth, P., Seyerlein, J., Sikler, F., Skrzypczak, E., Stefansky, P., Stock, R., Stroebele, H., Szentpetery, I., Sziklai, J., Toy, M., Trainor, T.A., Trentalange, S., Vassiliou, M., Vesztergombi, G., Vranic, D., Wenig, S., Whitten, C., Wienold, T., Wood, L., Zimanyi, J., Zhu, X.-Z., and Zybert, R.

Published
1995

161. Transverse Momentum Dependence of Bose-Einstein Correlations in 200A GeV/c S+A Collisions

Author

Alber, Th., Bachler, J., Bartke, J., Bialkowska, H., Bloomer, M.A., Bock, R., Braithwaite, W.J., Brinkmann, D., Brockmann, R., Buncic, P., Chan, P., Cramer, P.B., Cramer, J.G., Derado, I., Eckardt, V., Eschke, J., Favuzzi, C., Ferenc, D., Fleischmann, B., Foka, P., Freund, P., Fuchs, M., Gazdzicki, M., Gladysz, E., Harris, J.W., Hoffman, M., Jacobs, P., Kabana, S., Kadija, K., Kosiec, J., Kowalski, M., Kuhmichel, A., Lahanas, M., Lee, J.Y., Ljubicic, A., Margetis, S., Mitchell, J.T., Morse, R.J., Nappi, E., Odyniec, G.J., Paic, G., Panagiotou, A.D., Petridis, A., Piper, A., Posa, F., Poskanzer, A.M., Puhlhofer, F., Rauch, W., Renfordt, R., Retyk, W., Rohrich, D., Roland, G., Rothard, H., Runge, K., Sandoval, A., Schambach, J., Schmitz, N., Schmoetten, E., Schneider, I., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stefansky, P., Stock, R., Stroebele, H., Trainor, T.A., Vasileiadis, G., Vassiliou, M., Vranic, D., Wenig, S., and Wosiek, B.

Published
1994

162. Advancement of Segmented Cell Technology in Low Temperature Hydrogen Technologies

Author

Indro Biswas, Daniel G. Sánchez, Mathias Schulze, Jens Mitzel, Benjamin Kimmel, Aldo Saul Gago, Pawel Gazdzicki, and K. Andreas Friedrich

Subjects
fuel cell, electrolysis, hydrogen, operando measurement, degradation, Technology
Abstract

The durability and performance of electrochemical energy converters, such as fuel cells and electrolysers, are not only dependent on the properties and the quality of the used materials. They strongly depend on the operational conditions. Variations in external parameters, such as flow, pressure, temperature and, obviously, load, can lead to significant local changes in current density, even local transients. Segmented cell technology was developed with the purpose to gain insight into the local operational conditions in electrochemical cells during operation. The operando measurement of the local current density and temperature distribution allows effective improvement of operation conditions, mitigation of potentially critical events and assessment of the performance of new materials. The segmented cell, which can replace a regular bipolar plate in the current state of the technology, can be used as a monitoring tool and for targeted developments. This article gives an overview of the development and applications of this technology, such as for water management or fault recognition. Recent advancements towards locally resolved monitoring of humidity and to current distributions in electrolysers are outlined.

Published
2020
Full Text
View/download PDF

163. An Experiment on Particle and Jet Production at Midrapidity

Author

Kadija, K., Paic, G., Vranic, D., Brady, F.P., Draper, J.E., Romero, J.L., Carroll, J., Ghazikhanian, V., Gulmez, E., Igo, G.J., Trentalange, S., Whitten, C., Cherney, M., Heck, W., Renfordt, R.E., Rohrich, D., Stock, R., Stroebele, H., Wenig, S., Hallman, T., Madansky, L., Anderson, B., Keane, D., Madey, R., Watson, J., Bieser, F., Bloomer, A.M., Cebra, D., Christie, W., Friedlander, E., Greiner, D., Gruhn, C., Harris, J.W., Huang, H., Jacombs, P., Lindstrom, P., Matix, H., McParland, C., Naudet, C.J., Odyniec, G.J., Olson, D., Poskanzer, A.M., Rai, G., Rasmussen, J.O., Ritter, Hans G., Schambach, J., Schroeder, L.S., Siedl, P.A., Symons, T.J.M., Tonse, S.R., Wieman, H.H., Carmony, D.D., Choi, Y., Hirsch, A., Hjort, E., Porile, N.T., Scharenberg, R.P., Srivastava, B.K., Tincknell, M.L., Chacon, A.D., Wolf, K.L., Dominik, W., Gazdzicki, M., Braithwaite, W.J., Cramer, J.G., Prindle, D., Trainor, T.A., Breskin, A., Chechik, R., Fraenkel, Z., Shor, A., and Tserruya, I.

Published
1990

164. The Small Acceptance Vertex Detector of NA61/SHINE

Author

Deveaux M., Aduszkiewicz A., Ali Y., Baszczyk M., Brylinski W., Dorosz P., Di Luise S., Feofilov G., Gazdzicki M., Igolkin S., Jablonski M., Kovalenko V., Koziel M., Kucewicz W., Larsen D., Lazareva T., Martinengo P., Merzlaya A., Mik L., Planeta R., Snoch A., Vechernin V., Tefelski D., Suljic M., and Staszel P.

Subjects
Physics, QC1-999
Abstract

Charmonium production in heavy ion collisions is considered as an important diagnostic probe for studying the phase diagram of strongly interacting matter for potential phase transitions. The interpretation of existing data from the CERN SPS is hampered by a lack of knowledge on the properties of open charm particle production in the fireball. Moreover, open charm production in heavy ion collisions by itself is poorly understood. To overcome this obstacle, the NA61/SHINE was equipped with a Small Acceptance Vertex Detector (SAVD), which is predicted to make the experiment sensitive to open charm mesons produced in A-A collisions at the SPS top energy. This paper will introduce the concept and the hardware of the SAVD. Moreover, first running experience as obtained in a commissioning run with a 150 AGeV/c Pb+Pb collision system will be reported.

Published
2018
Full Text
View/download PDF

166. Recent results from NA61/SHINE

Author

Gazdzicki Marek

Subjects
Physics, QC1-999
Abstract

This paper briefly presents the NA61/SHINE facility at the CERN SPS and its measurements motivated by physics of strong interactions, neutrinos and cosmic rays.

Published
2015
Full Text
View/download PDF

170. Search for the Quark-Gluon Plasma (1989): The NA35 Experiment at the CERN SPS

Author

Pugh, H.G., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S.I., Marzo, C. De, Derado, I., Eckardt, V., Eschke, J., Favuzzi, C., Fent, J., Ferenc, D., Fessler, H., Freund, P., Gazdzicki, M., Gebauer, H.J., Gladysz, E., Guerra, C., Harris, J.W., Hartig, E., Heck, W., Humanic, T., Kadija, K., Kuhmichel, A., Lehanas, M., Lee, Y., Margetis, S., Nappie, E., Odyniec, G.J., Paic, G., Panagiotou, A.D., Petridis, A., Pfennig, J., Posa, F., Pretzl, K.P., Puhlhofer, F., Rai, G., Ranieri, A., Raugh, W., Renfordt, R., Rohrich, D., Rothard, H., Schouten, T., Schroeder, L.S., Selvaggi, G., Seyboth, P., Seyerlein, J., Skrzypczak, E., Sinelli, P., Stock, R., Stroebele, H., Thomas, A., Teitelbaum, L.P., Tonse, S.R., Vesztergombi, G., Branic, D., Wenig, S., and Wensveen, M.

Published
1989

171. Fluctuations of multiplicities in rapidity windows in sulphur-sulphur collisions at 200A GeV

Author

Bächler, J., Bartke, J., Białkowska, H., Bock, R., Brockmann, R., Buncic, P., Chase, S. I., Derado, I., Eckardt, V., Eschke, J., Ferenc, D., Fleischmann, B., Fuchs, M., Gazdzicki, M., Gebauer, H. J., Gładysz, E., Harris, J. W., Heck, W., Hoffmann, M., Kabana, S., Kadija, K., Keidel, R., Kosiec, J., Kowalski, M., Kühmichel, A., Lahanas, M., Lee, Y., LeVine, M., Ljubicic, Jr., A., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Piper, A., Posa, F., Pugh, H. G., Pühlhofer, F., Rai, G., Rauch, W., Renfordt, R., Röhrich, D., Rothard, H., Runge, K., Sandoval, A., Schmidt, E., Schmitz, N., Schmoetten, E., Schneider, I., Seyboth, P., Seyerlein, J., Skrzypczak, E., Stefanski, P., Stock, R., Ströbele, H., Teitelbaum, L., Tonse, S., Vassileiadis, G., Vesztergombi, G., Vranic, D., Wenig, S., and NA 35 Collaboration

Published
1992
Full Text
View/download PDF

172. Charged particle multiplicities in nuclear collisions at 200 GeV/N

Author

Bächler, J., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Buncic, P., Chase, S. I., Derado, I., Eckardt, V., Eschke, J., Favuzzi, C., Ferenc, D., Fleischmann, B., Foka, P., Fuchs, M., Gazdzicki, M., Gebauer, H. J., Gladysz, E., Guerra, C., Harris, J. W., Heck, W., Hoffmann, M., Humanic, T., Kabana, S., Kadija, K., Karabarbounis, A., Keidel, R., Kosiec, J., Kowalski, M., Kühmichel, A., Lahanas, M., Lee, J. Y., LeVine, M., Ljubicic, Jr., A., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Piper, A., Posa, F., Pugh, H. G., Pühlhofer, F., Rai, G., Rauch, W., Renfordt, R., Röhrich, D., Roland, G., Rothard, H., Runge, K., Sandoval, A., Schmidt, E., Schmitz, N., Schmoetten, E., Schneider, I., Schroeder, L. S., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Teitelbaum, L., Thomas, A., Tonse, S., Vasileiadis, G., Vesztergombi, G., Vranic, D., Wenig, S., and NA35 Collaboration

Published
1991
Full Text
View/download PDF

173. Study of the energy flow in sulphur-and oxygen-nucleus collisions at 60 and 200 GeV/nucleon

Author

Bächler, J., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Buncic, P., Chase, S. I., Derado, I., Eckardt, V., Eschke, J., Favuzzi, C., Ferenc, D., Fleischmann, B., Foka, P., Fuchs, M., Gazdzicki, M., Gebauer, H. J., Gladysz, E., Guerra, C., Harris, J. W., Heck, W., Hoffmann, M., Humanic, T., Kabana, S., Kadija, K., Karabarbounis, A., Keidel, R., Kosiec, J., Kowalski, M., Kühmichel, A., Lahanas, M., Lee, J. Y., LeVine, M., Ljubicic, Jr., A., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Piper, A., Posa, F., Pugh, H. G., Pühlhofer, F., Rai, G., Rauch, W., Renfordt, R., Röhrich, D., Roland, G., Rothard, H., Runge, K., Sandoval, A., Schmidt, E., Schmitz, N., Schmoetten, E., Schneider, I., Schroeder, L. S., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Teitelbaum, L., Thomas, A., Tincknell, M., Tonse, S., Vasileiadis, G., Vesztergombi, G., Vranic, D., Wenig, S., and NA35 Collaboration

Published
1991
Full Text
View/download PDF

174. Neutral strange particle production in sulphur-sulphur and proton-sulphur collisions at 200 GeV/nucleon

Author

Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S. I., Derado, I., Eckardt, V., Eschke, J., Favuzzi, C., Ferenc, D., Fleischmann, B., Fuchs, M., Gazdzicki, M., Gebauer, H. J., Gladysz, E., Guerra, C., Hansen, O., Harris, J. W., Heck, W., Humanic, T., Kadija, K., Kabana, S., Karabarbounis, A., Keidel, K., Kosiec, J., Kowalski, M., Kühmichel, A., Lahanas, M., Lee, J. Y., LeVine, M., Ljubicic, A., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Piper, A., Posa, F., Pugh, H. G., Fühlhofer, F., Rai, G., Rauch, W., Renfordt, R., Röhrich, D., Rothard, H., Runge, K., Sandoval, A., Schmidt, E., Schmitz, N., Schmoetten, E., Schneider, I., Schroeder, L. S., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Teitelbaum, L., Thomas, A., Tonse, S., Vassileiadis, G., Vesztergombi, G., Vranic, D., Wenig, S., and NA35 Collaboration

Published
1990
Full Text
View/download PDF

175. Mitigated Start-Up of PEMFC in Real Automotive Conditions: Local Experimental Investigation and Development of a New Accelerated Stress Test Protocol.

Author

Bisello, Andrea, Colombo, Elena, Baricci, Andrea, Rabissi, Claudio, Guetaz, Laure, Gazdzicki, Pawel, and Casalegno, Andrea

Subjects
ACCELERATED life testing, STANDARD hydrogen electrode, CATALYST supports, CATHODES, PLATINUM
Abstract

This study combines local electrochemical diagnostics with ex situ analysis to investigate degradation mechanism associated to start-up/shut-down (SU/SD) of PEMFC and mitigation strategies adopted in automotive stacks. Local degradation resulting from repeated SU/SD was analyzed with and without mitigation strategies by means of a macro-segmented cell setup provided with Reference Hydrogen Electrodes (RHEs) at both anode and cathode to measure local electrodes potential and current. Accelerated Stress Test (AST) for start-up with and without mitigation strategies are proposed and validated. A ten-fold acceleration of performance loss due to un-mitigated SU/SD has been calculated with respect to AST for catalyst support. Under mitigated SU/SD, instead, a strong degradation was observed as localized at cathode inlet region (i.e. -38% ECSA loss and -22 mV voltage loss after 200 cycles) due to local potentials transient reaching up to 1.5 V vs RHE. These localized stress conditions were additionally reproduced in a zero-gradient and a new AST protocol (named start-up AST) was proposed to mimic the potential profile observed upon SU/SD cycling. Representativeness of the start-up AST for real world degradation was confirmed up to 200 cycles. Platinum dissolution and diffusion/precipitation within the polymer electrolyte was shown to be the dominant mechanism affecting performance loss. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

179. Negative particle production in nuclear collisions at 60 and 200 GeV/nucleon

Author

Bamberger, A., Bangert, D., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S. I., de Marzo, C., de Palma, M., Derado, I., Eckardt, V., Favucci, C., Fent, J., Ferenc, D., Freund, P., Gazdzicki, M., Gebauer, H. J., Geissler, K., Guerra, C., Harris, J. W., Heck, W., Humanic, T., Kadija, K., Karabarbounis, A., Keidel, R., Kowalski, M., Krischer, W., Lahanas, M., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Posa, F., Pretzl, K. P., Pugh, H. G., Pühlhofer, F., Rai, G., Ranieri, A., Rauch, W., Renfordt, R., Röhrich, D., Runge, K., Sandoval, A., Schall, D., Schmitz, N., Schouten, T., Schroeder, L. S., Selvaggi, G., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Thomas, A., Tincknell, M., Teitelbaum, L., Vesztergombi, G., Vranic, D., Wenig, S., and NA 35 Collaboration

Published
1988
Full Text
View/download PDF

180. First results on strangeness production in 60 and 200 GeV/nucleon heavy ion reactions from the NA 35 streamer chamber

Author

Bamberger, A., Bangert, D., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S. I., De Marzo, C., De Palma, M., Derado, I., Eckardt, V., Favuzzi, C., Fent, J., Ferenc, D., Fessler, H., Freund, P., Gazdzicki, M., Gebauer, H. J., Geissler, K., Guerra, C., Harris, J. W., Heck, W., Humanic, T., Kadija, K., Karabarbounis, A., Keidel, R., Kowalski, M., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Posa, F., Pretzl, K. P., Pugh, H. G., Pühlhoter, F., Rai, G., Ranieri, A., Rauch, W., Renfordt, R., Röhrich, D., Runge, K., Sandoval, A., Schall, D., Schmitz, N., Schroeder, L. S., Selvaggi, G., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Thomas, A., Tincknell, M., Teitelbaum, L., Vesztergombi, G., Vranic, D., Wenig, S., and NA 35 Collaboration

Published
1988
Full Text
View/download PDF

182. Study of the energy flow in16O-nucleus collisions at 60 and 200 GeV/nucleon

Author

Heck, W., Bamberger, A., Bangert, D., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S. I., DeMarzo, C., DePalma, M., Derado, I., Eckardt, V., Favuzzi, C., Fent, J., Ferenc, D., Fessler, H., Freund, P., Gazdzicki, M., Gebauer, H. J., Geissler, K., Guerra, C., Harris, J. W., Humanic, T., Kadija, K., Karabarbounis, A., Keidel, R., Kowalski, M., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A., Petridis, A., Pfennig, J., Posa, F., Pretzl, K. P., Pugh, H. G., Pühlhofer, F., Rai, G., Ranieri, A., Rauch, W., Renfordt, R., Röhrich, D., Runge, K., Sandoval, A., Schall, D., Schmitz, N., Schroeder, L. S., Selvaggi, G., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Thomas, A., Tincknell, M., Teitelbaum, L., Vesztergombi, G., Vranic, D., Wenig, S., and NA35 Collaboration

Published
1988
Full Text
View/download PDF

185. Pion interferometry with ultrarelavistic heavy-ion collisions from the NA35 experiment

Author

Bamberger, A., Bangert, D., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S. I., DeMarzo, C., DePalma, M., Derado, I., Eckardt, V., Favuzzi, C., Fent, J., Ferenc, D., Fessler, H., Freund, P., Gazdzicki, M., Gebauer, H. J., Geissler, K., Gladysz, E., Guerra, C., Harris, J. W., Heck, W., Humanic, T. J., Kadija, K., Karabarbounis, A., Keidel, R., Koisiec, J., Kowalski, M., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A., Petridis, A., Pfennig, J., Posa, F., Pretzl, K. P., Pugh, H. B., Pühlhofer, F., Rai, G., Ranieri, A., Rauch, W., Renfordt, R., Röhrich, D., Runge, K., Sandoval, A., Schall, D., Schmitz, N., Schroeder, L. S., Selvaggi, G., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Thomas, A., Tincknell, M., Teitelbaum, L., Vesztergombi, G., Vranic, D., Wenig, S., and NA35 Collaboration

Published
1988
Full Text
View/download PDF

186. A study ofK so, Λ and $$\bar \Lambda $$ production in 60 and 200 GeV per nucleon OAu and pAu collisions with a streamer chamber detector at the CERN SPSproduction in 60 and 200 GeV per nucleon OAu and pAu collisions with a streamer chamber detector at the CERN SPS

Author

Bamberger, A., Bartke, J., Bialkowska, H., Bock, R., Brockmann, R., Chase, S. I., De Marzo, C., De Palma, M., Derado, I., Eckardt, V., Favuzzi, C., Ferenc, D., Fessler, H., Freund, P., Gazdzicki, M., Gebauer, H. J., Guerra, C., Harris, J. W., Heck, W., Humanic, T., Kadija, K., Karabarbounis, A., Keidel, R., Kowalski, M., Lahanas, M., Margetis, S., Nappi, E., Odyniec, G., Paic, G., Panagiotou, A. D., Petridis, A., Pfennig, J., Posa, F., Pretzl, K. P., Pugh, H. G., Pühlhofer, F., Rai, G., Ranieri, A., Rauch, W., Renfordt, R., Röhrich, D., Runge, K., Sandoval, A., Schmitz, N., Schouten, T., Schroeder, L. S., Seyboth, P., Seyerlein, J., Skrzypczak, E., Spinelli, P., Stock, R., Ströbele, H., Thomas, A., Tincknell, M., Teitelbaum, L., Tonse, S., Vesztergombi, G., Vranic, D., Wenig, S., and NA35 Collaboration

Published
1989
Full Text
View/download PDF

187. Impact of Platinum Loading on Performance and Degradation of Polymer Electrolyte Fuel Cell Electrodes Studied in a Rainbow Stack.

Author

Gazdzicki, P., Mitzel, J., Dreizler, A. M., Schulze, M., and Friedrich, K. A.

Subjects
PROTON exchange membrane fuel cells, PLATINUM, CHEMICAL decomposition, ELECTRIC potential, DURABILITY
Abstract

Abstract: The paper focuses on the investigation of durability and performance of a low temperature polymer electrolyte membrane fuel cell (PEMFC) stack as a function of Pt loading in automotive test conditions. Major motivations are problems related to the need to reduce the amount of Pt in membrane electrode assemblies (MEAs) in order to make PEMFC more competitive. The particular challenge is to maintain sufficiently high performance and long‐term durability. The study shows that for cathode Pt loadings below 0.2 mg cm−2 and for current densities exceeding 1 A cm−2 a sudden drop of performance is observed. The same threshold value is found for the increase of irreversible voltage losses which lead to an intense reduction of PEMFC durability for cathodic loadings below 0.2 mg cm−2. Another durability issue at cathodic Pt loadings < 0.4 mg cm−2 is the acceleration of reversible degradation, which leads to a strong voltage drop during continues fuel cell operation (i.e., without a recovery interruption). [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

188. Operando and Ex-Situ Investigation of PEMFC Degradation

Author

Gazdzicki, Pawel, Mitzel, Jens, Sanchez, Daniel G, Assmann, Pia, Sousa, Joana, Morawietz, Tobias, Hiesgen, Renate, Haussler, Frank, Hunger, Jurgen, Schlumberger, Gunther, and Friedrich, Andreas

Abstract

Longevity is one of key requirements of PEMFC for automotive applications. Hence, understanding degradation phenomena and durability limitations is fundamental to increase PEMFC life time and to make this technology competitive In this contribution a selection of our recent work on these topics is presented. In particular, attention in dedicated to study effect of performance limitations at low Pt loadings and to investigate impact of operation conditions on local degradation phenomena such as drying, contaminations or heterogeneities during dynamic operation. Moreover, specific operando accelerated stress tests are being developed and the relative impact on various stressors on individual MEA components is studied. Eventually, we present results related to on-line fault monitoring using current density distribution measurements linked with impedance spectroscopy.

Published
2019

193. Highly active anode electrocatalysts derived from electrochemical leaching of Ru from metallic Ir0.7Ru0.3 for proton exchange membrane electrolyzers.

Author

Wang, Li, Saveleva, Viktoriia A., Zafeiratos, Spyridon, Savinova, Elena R., Lettenmeier, Philipp, Gazdzicki, Pawel, Gago, Aldo S., and Friedrich, K. Andreas

Abstract

Hydrogen produced by water splitting is a promising solution for a sustained economy from renewable energy sources. Proton exchange membrane (PEM) electrolysis is the utmost suitable technology for this purpose, although the quest for low cost, highly active and durable catalysts is persistent. Here we develop a nanostructured iridium catalyst after electrochemically leaching ruthenium from metallic iridium-ruthenium, Ir 0.7 Ru 0.3 O x (EC), and compare its physical and electrochemical properties to the thermally treated counterpart: Ir 0.7 Ru 0.3 O 2 (TT). Ir 0.7 Ru 0.3 O x (EC) shows an unparalleled 13-fold higher oxygen evolution reaction (OER) activity compared to the Ir 0.7 Ru 0.3 O 2 (TT). PEM electrolyzer tests at 1 A cm −2 show no increase of cell voltage for almost 400 h, proving that Ir 0.7 Ru 0.3 O x (EC) is one of the most efficient anodes so far developed. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

196. Highly active anode electrocatalysts derived from electrochemical leaching of Ru from metallic Ir0.7Ru0.3for proton exchange membrane electrolyzers

Author

Wang, Li, Saveleva, Viktoriia A., Zafeiratos, Spyridon, Savinova, Elena R., Lettenmeier, Philipp, Gazdzicki, Pawel, Gago, Aldo S., and Friedrich, K. Andreas

Abstract

Hydrogen produced by water splitting is a promising solution for a sustained economy from renewable energy sources. Proton exchange membrane (PEM) electrolysis is the utmost suitable technology for this purpose, although the quest for low cost, highly active and durable catalysts is persistent. Here we develop a nanostructured iridium catalyst after electrochemically leaching ruthenium from metallic iridium-ruthenium, Ir0.7Ru0.3Ox(EC), and compare its physical and electrochemical properties to the thermally treated counterpart: Ir0.7Ru0.3O2(TT). Ir0.7Ru0.3Ox(EC) shows an unparalleled 13-fold higher oxygen evolution reaction (OER) activity compared to the Ir0.7Ru0.3O2(TT). PEM electrolyzer tests at 1Acm−2show no increase of cell voltage for almost 400h, proving that Ir0.7Ru0.3Ox(EC) is one of the most efficient anodes so far developed.

Published
2017
Full Text
View/download PDF

197. Degradation Effects at the Porous Transport Layer/Catalyst Layer Interface in Polymer Electrolyte Membrane Water Electrolyzer

Author

Liu, Chang, Shviro, Meital, Bender, Guido, Gago, Aldo S., Morawietz, Tobias, Dzara, Michael J., Biswas, Indro, Gazdzicki, Pawel, Kang, Zhenye, Zaccarine, Sarah F., Pylypenko, Svitlana, Friedrich, K. Andreas, Carmo, Marcelo, and Lehnert, Werner

Abstract

The porous transport layer (PTL)/catalyst layer (CL) interface plays a crucial role in the achievement of high performance and efficiency in polymer electrolyte membrane water electrolyzers (PEMWEs). This study investigated the effects of the PTL/CL interface on the degradation of membrane electrode assemblies (MEAs) during a 4000 h test, comparing the MEAs assembled with uncoated and Ir-coated Ti PTLs. Our results show that compared to an uncoated PTL/CL interface, an optimized interface formed when using a platinum group metal (PGM) coating, i.e., an iridium layer at the PTL/CL interface, and reduced the degradation of the MEA. The agglomeration and formation of voids and cracks could be found for both MEAs after the long-term test, but the incorporation of an Ir coating on the PTL did not affect the morphology change or oxidation of IrOxin the catalyst layer. In addition, our studies suggest that the ionomer loss and restructuring of the anodic MEA can also be reduced by Ir coating of the PTL/CL interface. Optimization of the PTL/CL interface improves the performance and durability of a PEMWE.

Published
2023
Full Text
View/download PDF

198. Influence of the Distribution of Platinum Deposits on the Properties and Degradation of Platinum-Impregnated Nafion Membranes.

Author

Helmly, Stefan, Ohnmacht, Benjamin, Gazdzicki, Pawel, Hiesgen, Renate, Gülzow, Erich, and Friedrich, K. Andreas

Subjects
PROTON exchange membrane fuel cells, PLATINUM, ELECTRODES, ELECTROLYTES, ARTIFICIAL membranes
Abstract

In proton exchange membrane fuel cells (PEMFCs), platinum (Pt) from the electrodes can be deposited in the electrolyte membrane, altering its properties and causing degradation. To investigate these impacts, in some studies, membranes with artificially deposited Pt were used, however, with contradictory results. In this study, we compared membranes impregnated with 0 to 4.4 wt% Pt. Specifically, the Pt particle distribution and mass transport in the membrane as well as the membrane decomposition is investigated after performing open circuit durability tests for ~140 h. The properties of the membrane electrode assemblies (MEAs) are studied by electrochemical characterization. The changes upon degradation are investigated by thickness determination, infrared spectroscopy, fluoride emission, hydrogen permeability, and electrical conductivity. Our investigation confirmed that the particle density, not the Pt amount, is the determining factor in the extent of membrane decomposition: fluoride emission decreased exponentially with particle density. We further found a considerable difference in the particle distribution between artificial and in-situ Pt deposits. Moreover, properties of both membrane types changed contrary to each other during the durability test. In conclusion, Pt-impregnated membranes do not reflect the state of degraded membranes with in-situ formed deposits but are suitable to investigate the influence of particle distributions. [ABSTRACT FROM AUTHOR]

Published
2014
Full Text
View/download PDF

199. Reactions of Methanol on Clean and Oxygen-Covered PtxRu1–x/Ru(0001) Surface Alloys

Author

Gazdzicki, Pawel, Thussing, Sebastian, and Jakob, Peter

Abstract

In this study the adsorption and reactions of methanol (CD3OH) on clean and oxygen-precovered PtxRu1–x/Ru(0001) surface alloys with x= 0–0.8 have been investigated using Fourier transform infrared spectroscopy and thermal desorption. Particular interest has been devoted to the influence of coadsorbed (atomic) oxygen. For increasing amounts of Pt the clean surface becomes gradually passivated in agreement with the inertness of the full Pt/Ru(0001) monolayer. On such oxygen-free layers the reaction pathway proceeds similar to clean Ru(0001). Yet, Pt enhances the thermal stability of the methoxy (CD3O) intermediate which represents the only stable reaction product species besides CO. On oxygen-precovered PtxRu1–x/Ru(0001) surface alloys the primary activation of methanol again leads to methoxy species. Depending on the Pt concentration within the Pt/Ru(0001) surface alloy, however, subsequent reactions vary substantially. For x< 0.4 total dehydrogenation to CO prevails, while for x> 0.4 formate (DCOO) is produced, eventually leading to CO2desorption. Formaldehyde formation and desorption are observed for x= 0.1–0.8. Similar to methanol reactions on O/Ru(0001) and O/Ptn/Ru(0001), no experimental evidence for a surface hydroxyl has been found.

Published
2011
Full Text
View/download PDF

200. Oxidation of Methanol on Oxygen Covered Ptn/Ru(0001) Layers

Author

Gazdzicki, Pawel, Thussing, Sebastian, and Jakob, Peter

Abstract

Thin pseudomorphic as well as thick “Pt(111)-like” Pt/Ru(0001) bimetallic substrates have been used to study the oxidation of methanol (CD3OH) to CO2. Specifically, molecular (cold deposited) and ordered atomic (annealed) oxygen precovered Ptn/Ru(0001) layers with n= 1–15 ML have been studied. Thereby, the thickness of the Pt films primarily influences the adsorption probability of O2and much less the energy barriers for methanol reactions. In particular, no indication of a strain effect could be detected, and the reactions of methanol on Ptn/Ru(0001) multilayer films closely follow the known reaction scheme on Pt(111) substrates: On O2/Ptn/Ru(0001), methanol is directly oxidized to formate (DCOO) and eventually desorbs as CO2(300 K). The formate producing reaction is thereby promoted by dissociating O2molecules (130 K) and, at higher temperatures (130–200 K), by disordered atomic oxygen. This is in contrast to methanol postadsorbed onto ordered atomic oxygen covered Ptn/Ru(0001) layers, which exhibit formaldehyde formation and decomposition to CO and H. Interestingly, during methanol dissociation at 160–200 K, a remarkable fraction of methanol molecules experiences an H ↔ D exchange of the hydroxyl group hydrogen, leading to the dominant desorption of CD3OD. Our observation that the relative fraction of desorbing CD3OH is exceptionally low implies a bold primary isotope effect, which we attribute to the dissimilar zero point energies associated with OH and OD vibrations of methanol.

Published
2011
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results