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548 results on '"Weise, H."'

1. Further improvement of medium temperature heat treated SRF cavities for high gradients

Author

Steder, L., Bate, C., Kasprzak, K., Reschke, D., Trelle, L., Weise, H., and Wiencek, M.

Subjects
Physics - Accelerator Physics
Abstract

The application of heat treatments on 1.3 GHz TESLA type cavities in ultra-high vacuum at 250{\deg}C to 350{\deg}C is called medium temperature or mid-T heat treatment. In various laboratories such treatments on superconducting radio frequency (SRF) cavities result reproducible in three main characteristic features for the quality factor $Q_0$ in dependency of the accelerating electric field strength $E_{acc}$. First, comparing mid-T heat treatment with a baseline treatment, a significant increase of $Q_0$ up to $5\cdot10^{10}$ at 2K can be observed. Second, with increasing accelerating gradient $E_{acc}$ the $Q_0$ increases up to a maximum around 16 to 20 MV/m. This effect is known as anti-Q-slope. The third observation for a mid-T heat treatment compared to a baseline treatment is an often reduced maximum gradient $E_{acc}$. The appearance of a high-field-Q-slope (HFQS) was reported after mid-T heat treatments of 3 hours at 350{\deg}C or of 20 hours at 300{\deg}C at DESY. Using the heating temperature and the heating time taken from the temperature profile of the furnace effective oxygen diffusion lengths $l$ were calculated. In the follow-up study presented here, a set of three single-cell cavities with diffusion lengths $l$ above 1700 nm, showing HFQS, were treated with an additional so-called low-T bake of 24-48 hours at 120{\deg}C to 130{\deg}C. The subsequent reproducible Q(E) -performances results indicate that the low-T bake procedure cures the HFQS like for cavities treated with the EuXFEL recipe of EP and following low-T treatments. As presented in the following, Q values of more than $3\cdot10^{10}$ at 16 MV/m and accelerating gradients of 32 to 40 MV/m are achieved., Comment: 6 pages, 7 figures

Published
2024

2. Correlation of srf performance to oxygen diffusion length of medium temperature heat treated cavities

Author

Bate, C., Kasprzak, K., Reschke, D., Steder, L., Trelle, L., Weise, H., Wiencek, M., and Wolff, J.

Subjects
Physics - Accelerator Physics
Abstract

This comprehensive study, being part of the European XFEL R\&D effort, elucidates the influence of medium temperature (mid-T) heat treatments between 250{\deg}C and 350{\deg}C on the performance of 1.3~GHz superconducting radiofrequency (SRF) niobium cavities. Utilizing a refurbished niobium retort furnace equipped with an inter-vacuum chamber and cryopumps at DESY, we have embarked on an investigation to enhance the state-of-the-art SRF cavity technology. Our research reveals that mid-T heat treatments significantly boost the quality factor ($Q_0$) of the cavities, achieving values between $2\cdot10^{10}$ to $5\cdot10^{10}$ at field strengths around 16~MV/m, while the maximum field strengths are limited to 25-35~MV/m and enhanced sensitivity to trapped magnetic flux is observed. Moreover, we delve into the effects of surface impurity concentration changes, particularly the diffusion of oxygen content, and its impact on performance enhancements. By categorizing treatments based on calculated diffusion lengths using the whole temperature profile, we recognize patterns that suggest an optimal diffusion length conducive to optimizing cavity performance. SIMS results from samples confirm the calculated oxygen diffusion lengths in most instances. Deviations are primarily attributed to grain boundaries in fine-grain materials, necessitating repeated measurements on single-crystal materials to further investigate this phenomenon. Investigations into cooling rates and the resulting spatial temperature gradients across the cavities ranging from 0.04 to 0.2~K/mm reveal no significant correlation with performance following a mid-T heat treatment. However, the increased sensitivity to trapped magnetic flux leads to new challenges in the quest for next-generation accelerator technologies since the requirement for magnetic hygiene gets stricter., Comment: 15 pages, 24 figures

Published
2024

3. High gradients at SRF photoinjector cavities with low RRR copper cathode plug screwed to the cavity back wall

Author

Vogel, E., Sekutowicz, J., Bazyl, D., Büttner, T., van der Horst, B., Iversen, J., Klinke, D., Muhs, A., Reschke, D., Sägebarth, S., Schilling, P., Schmökel, M., Steder, L., Thie, J. -H., Weise, H., and Wiencek, M.

Subjects
Physics - Accelerator Physics
Abstract

In recent years we increased the typical maximum peak field on axis gradients obtained in L-band superconducting RF (SRF) photoinjector cavities at vertical tests to around 55 MV/m. This was achieved with niobium cathode plugs directly screwed to the cavity back wall omitting an RF choke filter and a load lock system for cathodes. Copper demonstrated being a suitable cathode material in normal conducting injector cavities used at X-Ray Free Electron Lasers (XFELs) operating with pulsed RF. In this article we present the first experimental confirmation that peak field on axis gradients around 55 MV/m and beyond can be achieved in L-band SRF photoinjector cavities with copper cathode plugs screwed to the cavity back wall. We view this as a major milestone for the development of a high gradient photoinjector operating continuous wave (CW)., Comment: 4 pages, 7 figures, to be submitted to PRAB

Published
2023

5. Snowmass'21 Accelerator Frontier Report

Author

Gourlay, S., Raubenheimer, T., Shiltsev, V., Arduini, G., Assmann, R., Barbier, C., Bai, M., Belomestnykh, S., Bermudez, S., Bhat, P., Faus-Golfe, A., Galambos, J., Geddes, C., Hoffstaetter, G., Hogan, M., Huang, Z., Lamont, M., Li, D., Lund, S., Milner, R., Musumeci, P., Nanni, E., Palmer, M., Pastrone, N., Pellemoine, F., Prebys, E., Qin, Q., Power, J., Roser, T., Sabbi, G., Stratakis, D., Sun, Y. -E., Tang, J., Valishev, A., Weise, H., Zimmermann, F., Zlobin, A. V., and Zwaska, R.

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

In 2020-2022, extensive discussions and deliberations have taken place in corresponding topical working groups of the Snowmass Accelerator Frontier (AF) and in numerous joint meetings with other Frontiers, Snowmass-wide meetings, a series of Colloquium-style Agoras, cross-Frontier Forums on muon and electron-positron colliders and the collider Implementation Task Force (ITF). The outcomes of these activities are summarized in this Accelerator Frontier report., Comment: contribution to Snowmass'21, v.2 (final)

Published
2022

6. Key directions for research and development of superconducting radio frequency cavities

Author

Belomestnykh, S., Posen, S., Bafia, D., Balachandran, S., Bertucci, M., Burrill, A., Cano, A., Checchin, M., Ciovati, G., Cooley, L. D., Semione, G. Dalla Lana, Delayen, J., Eremeev, G., Furuta, F., Gerigk, F., Giaccone, B., Gonnella, D., Grassellino, A., Gurevich, A., Hillert, W., Iavarone, M., Knobloch, J., Kubo, T., Kwok, W. K., Laxdal, R., Lee, P. J., Liepe, M., Martinello, M., Melnychuk, O. S., Nassiri, A., Netepenko, A., Padamsee, H., Pagani, C., Paparella, R., Pudasaini, U., Reece, C. E., Reschke, D., Romanenko, A., Ross, M., Saito, K., Sauls, J., Seidman, D. N., Solyak, N., Sung, Z., Umemori, K., Valente-Feliciano, A. -M., Delsolaro, W. Venturini, Walker, N., Weise, H., Welp, U., Wenskat, M., Wu, G., Xi, X. X., Yakovlev, V., Yamamoto, A., and Zasadzinski, J.

Subjects
Physics - Accelerator Physics
Abstract

Radio frequency superconductivity is a cornerstone technology for many future HEP particle accelerators and experiments from colliders to proton drivers for neutrino facilities to searches for dark matter. While the performance of superconducting RF (SRF) cavities has improved significantly over the last decades, and the SRF technology has enabled new applications, the proposed HEP facilities and experiments pose new challenges. To address these challenges, the field continues to generate new ideas and there seems to be a vast room for improvements. In this paper we discuss the key research directions that are aligned with and address the future HEP needs., Comment: contribution to Snowmass 2021

Published
2022

7. European Strategy for Particle Physics -- Accelerator R&D Roadmap

Author

Adolphsen, C., Angal-Kalinin, D., Arndt, T., Arnold, M., Assmann, R., Auchmann, B., Aulenbacher, K., Ballarino, A., Baudouy, B., Baudrenghien, P., Benedikt, M., Bentvelsen, S., Blondel, A., Bogacz, A., Bossi, F., Bottura, L., Bousson, S., Brüning, O., Brinkmann, R., Bruker, M., Brunner, O., Burrows, P. N., Burt, G., Calatroni, S., Cassou, K., Castilla, A., Catalan-Lasheras, N., Cenni, E., Chancé, A., Colino, N., Corde, S., Corner, L., Cros, B., Cross, A., Delahaye, J. P., Devanz, G., Etienvre, A. -I., Evtushenko, P., Faus-Golfe, A., Fazilleau, P., Ferrario, M., Gallo, A., García-Tabarés, L., Geddes, C., Gerigk, F., Gianotti, F., Gilardoni, S., Grudiev, A., Gschwendtner, E., Hoffstaetter, G., Hogan, M., Hooker, S., Hutton, A., Ischebeck, R., Jakobs, K., Janot, P., Jensen, E., Kühn, J., Kaabi, W., Kayran, D., Klein, M., Knobloch, J., Koratzinos, M., Kuske, B., Lamont, M., Latina, A., Lebrun, P., Leemans, W., Li, D., Long, K., Longuevergne, D., Losito, R., Lu, W., Lucchesi, D., Lundh, O., Métral, E., Marhauser, F., Michizono, S., Militsyn, B., Mnich, J., Montesinos, E., Mounet, N., Muggli, P., Musumeci, P., Nagaitsev, S., Nakada, T., Neumann, A., Newbold, D., Nghiem, P., Noe, M., Oide, K., Osterhoff, J., Palmer, M., Pastrone, N., Pietralla, N., Prestemon, S., Previtali, E., Proslier, T., Quettier, L., Raubenheimer, T., Rimmer, B., Rivkin, L., Rochepault, E., Rogers, C., Rosaz, G., Roser, T., Rossi, L., Ruber, R., Schulte, D., Seidel, M., Senatore, C., Shepherd, B., Shi, J., Shipman, N., Specka, A., Stapnes, S., Stocchi, A., Stratakis, D., Syratchev, I., Tanaka, O., Tantawi, S., Tennant, C., Tsesmelis, E., Vaccarezza, C., Valente, A. -M., Védrine, P., Vieira, J., Vinokurov, N., Weise, H., Wenskat, M., Williams, P., Wing, M., Yamamoto, A., Yamamoto, Y., Yokoya, K., and Zimmermann, F.

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation., Comment: 270 pages, 58 figures. Editor: N. Mounet. LDG chair: D. Newbold. Panel chairs: P. V\'edrine (HFM), S. Bousson (RF), R. Assmann (plasma), D. Schulte (muon), M. Klein (ERL). Panel editors: B. Baudouy (HFM), L. Bottura (HFM), S. Bousson (RF), G. Burt (RF), R. Assmann (plasma), E. Gschwendtner (plasma), R. Ischebeck (plasma), C. Rogers (muon), D. Schulte (muon), M. Klein (ERL)

Published
2022
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9. A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

Author

Decking, W., Abeghyan, S., Abramian, P., Abramsky, A., Aguirre, A., Albrecht, C., Alou, P., Altarelli, M., Altmann, P., Amyan, K., Anashin, V., Apostolov, E., Appel, K., Auguste, D., Ayvazyan, V., Baark, S., Babies, F., Baboi, N., Bak, P., Balandin, V., Baldinger, R., Baranasic, B., Barbanotti, S., Belikov, O., Belokurov, V., Belova, L., Belyakov, V., Berry, S., Bertucci, M., Beutner, B., Block, A., Blöcher, M., Böckmann, T., Bohm, C., Böhnert, M., Bondar, V., Bondarchuk, E., Bonezzi, M., Borowiec, P., Bösch, C., Bösenberg, U., Bosotti, A., Böspflug, R., Bousonville, M., Boyd, E., Bozhko, Y., Brand, A., Branlard, J., Briechle, S., Brinker, F., Brinker, S., Brinkmann, R., Brockhauser, S., Brovko, O., Brück, H., Brüdgam, A., Butkowski, L., Büttner, T., Calero, J., Castro-Carballo, E., Cattalanotto, G., Charrier, J., Chen, J., Cherepenko, A., Cheskidov, V., Chiodini, M., Chong, A., Choroba, S., Chorowski, M., Churanov, D., Cichalewski, W., Clausen, M., Clement, W., Cloué, C., Cobos, J. A., Coppola, N., Cunis, S., Czuba, K., Czwalinna, M., D’Almagne, B., Dammann, J., Danared, H., de Zubiaurre Wagner, A., Delfs, A., Delfs, T., Dietrich, F., Dietrich, T., Dohlus, M., Dommach, M., Donat, A., Dong, X., Doynikov, N., Dressel, M., Duda, M., Duda, P., Eckoldt, H., Ehsan, W., Eidam, J., Eints, F., Engling, C., Englisch, U., Ermakov, A., Escherich, K., Eschke, J., Saldin, E., Faesing, M., Fallou, A., Felber, M., Fenner, M., Fernandes, B., Fernández, J. M., Feuker, S., Filippakopoulos, K., Floettmann, K., Fogel, V., Fontaine, M., Francés, A., Martin, I. Freijo, Freund, W., Freyermuth, T., Friedland, M., Fröhlich, L., Fusetti, M., Fydrych, J., Gallas, A., García, O., Garcia-Tabares, L., Geloni, G., Gerasimova, N., Gerth, C., Geßler, P., Gharibyan, V., Gloor, M., Głowinkowski, J., Goessel, A., Gołębiewski, Z., Golubeva, N., Grabowski, W., Graeff, W., Grebentsov, A., Grecki, M., Grevsmuehl, T., Gross, M., Grosse-Wortmann, U., Grünert, J., Grunewald, S., Grzegory, P., Feng, G., Guler, H., Gusev, G., Gutierrez, J. L., Hagge, L., Hamberg, M., Hanneken, R., Harms, E., Hartl, I., Hauberg, A., Hauf, S., Hauschildt, J., Hauser, J., Havlicek, J., Hedqvist, A., Heidbrook, N., Hellberg, F., Henning, D., Hensler, O., Hermann, T., Hidvégi, A., Hierholzer, M., Hintz, H., Hoffmann, F., Hoffmann, Markus, Hoffmann, Matthias, Holler, Y., Hüning, M., Ignatenko, A., Ilchen, M., Iluk, A., Iversen, J., Iversen, J., Izquierdo, M., Jachmann, L., Jardon, N., Jastrow, U., Jensch, K., Jensen, J., Jeżabek, M., Jidda, M., Jin, H., Johansson, N., Jonas, R., Kaabi, W., Kaefer, D., Kammering, R., Kapitza, H., Karabekyan, S., Karstensen, S., Kasprzak, K., Katalev, V., Keese, D., Keil, B., Kholopov, M., Killenberger, M., Kitaev, B., Klimchenko, Y., Klos, R., Knebel, L., Koch, A., Koepke, M., Köhler, S., Köhler, W., Kohlstrunk, N., Konopkova, Z., Konstantinov, A., Kook, W., Koprek, W., Körfer, M., Korth, O., Kosarev, A., Kosiński, K., Kostin, D., Kot, Y., Kotarba, A., Kozak, T., Kozak, V., Kramert, R., Krasilnikov, M., Krasnov, A., Krause, B., Kravchuk, L., Krebs, O., Kretschmer, R., Kreutzkamp, J., Kröplin, O., Krzysik, K., Kube, G., Kuehn, H., Kujala, N., Kulikov, V., Kuzminych, V., La Civita, D., Lacroix, M., Lamb, T., Lancetov, A., Larsson, M., Le Pinvidic, D., Lederer, S., Lensch, T., Lenz, D., Leuschner, A., Levenhagen, F., Li, Y., Liebing, J., Lilje, L., Limberg, T., Lipka, D., List, B., Liu, J., Liu, S., Lorbeer, B., Lorkiewicz, J., Lu, H. H., Ludwig, F., Machau, K., Maciocha, W., Madec, C., Magueur, C., Maiano, C., Maksimova, I., Malcher, K., Maltezopoulos, T., Mamoshkina, E., Manschwetus, B., Marcellini, F., Marinkovic, G., Martinez, T., Martirosyan, H., Maschmann, W., Maslov, M., Matheisen, A., Mavric, U., Meißner, J., Meissner, K., Messerschmidt, M., Meyners, N., Michalski, G., Michelato, P., Mildner, N., Moe, M., Moglia, F., Mohr, C., Mohr, S., Möller, W., Mommerz, M., Monaco, L., Montiel, C., Moretti, M., Morozov, I., Morozov, P., Mross, D., Mueller, J., Müller, C., Müller, J., Müller, K., Munilla, J., Münnich, A., Muratov, V., Napoly, O., Näser, B., Nefedov, N., Neumann, Reinhard, Neumann, Rudolf, Ngada, N., Noelle, D., Obier, F., Okunev, I., Oliver, J. A., Omet, M., Oppelt, A., Ottmar, A., Oublaid, M., Pagani, C., Paparella, R., Paramonov, V., Peitzmann, C., Penning, J., Perus, A., Peters, F., Petersen, B., Petrov, A., Petrov, I., Pfeiffer, S., Pflüger, J., Philipp, S., Pienaud, Y., Pierini, P., Pivovarov, S., Planas, M., Pławski, E., Pohl, M., Polinski, J., Popov, V., Prat, S., Prenting, J., Priebe, G., Pryschelski, H., Przygoda, K., Pyata, E., Racky, B., Rathjen, A., Ratuschni, W., Regnaud-Campderros, S., Rehlich, K., Reschke, D., Robson, C., Roever, J., Roggli, M., Rothenburg, J., Rusiński, E., Rybaniec, R., Sahling, H., Salmani, M., Samoylova, L., Sanzone, D., Saretzki, F., Sawlanski, O., Schaffran, J., Schlarb, H., Schlösser, M., Schlott, V., Schmidt, C., Schmidt-Foehre, F., Schmitz, M., Schmökel, M., Schnautz, T., Schneidmiller, E., Scholz, M., Schöneburg, B., Schultze, J., Schulz, C., Schwarz, A., Sekutowicz, J., Sellmann, D., Semenov, E., Serkez, S., Sertore, D., Shehzad, N., Shemarykin, P., Shi, L., Sienkiewicz, M., Sikora, D., Sikorski, M., Silenzi, A., Simon, C., Singer, W., Singer, X., Sinn, H., Sinram, K., Skvorodnev, N., Smirnow, P., Sommer, T., Sorokin, A., Stadler, M., Steckel, M., Steffen, B., Steinhau-Kühl, N., Stephan, F., Stodulski, M., Stolper, M., Sulimov, A., Susen, R., Świerblewski, J., Sydlo, C., Syresin, E., Sytchev, V., Szuba, J., Tesch, N., Thie, J., Thiebault, A., Tiedtke, K., Tischhauser, D., Tolkiehn, J., Tomin, S., Tonisch, F., Toral, F., Torbin, I., Trapp, A., Treyer, D., Trowitzsch, G., Trublet, T., Tschentscher, T., Ullrich, F., Vannoni, M., Varela, P., Varghese, G., Vashchenko, G., Vasic, M., Vazquez-Velez, C., Verguet, A., Vilcins-Czvitkovits, S., Villanueva, R., Visentin, B., Viti, M., Vogel, E., Volobuev, E., Wagner, R., Walker, N., Wamsat, T., Weddig, H., Weichert, G., Weise, H., Wenndorf, R., Werner, M., Wichmann, R., Wiebers, C., Wiencek, M., Wilksen, T., Will, I., Winkelmann, L., Winkowski, M., Wittenburg, K., Witzig, A., Wlk, P., Wohlenberg, T., Wojciechowski, M., Wolff-Fabris, F., Wrochna, G., Wrona, K., Yakopov, M., Yang, B., Yang, F., Yurkov, M., Zagorodnov, I., Zalden, P., Zavadtsev, A., Zavadtsev, D., Zhirnov, A., Zhukov, A., Ziemann, V., Zolotov, A., Zolotukhina, N., Zummack, F., and Zybin, D.

Published
2020
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10. Potential of the FLASH FEL technology for the construction of a kW-scale light source for the next generation lithography

Author

Schneidmiller, E. A., Vogel, V. F., Weise, H., and Yurkov, M. V.

Subjects
Physics - Accelerator Physics
Abstract

The driving engine of the Free Electron Laser in Hamburg (FLASH) is an L-band superconducting accelerator. It is designed to operate in burst mode with 800 microsecond pulse duration at a repetition rate of 10 Hz. The maximum accelerated beam current during the macropulse is 9 mA. Our analysis shows that the FLASH technology has great potential since it is possible to construct a FLASH like free electron laser operating at the wavelength of 13.5 and 6.8 nanometer with an average power up to 2.6 kW. Such a source meets the physical requirements for the light source for the next generation lithography., Comment: 18 pages, 9 figures

Published
2011

13. Author Correction: A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator

Author

Decking, W., Abeghyan, S., Abramian, P., Abramsky, A., Aguirre, A., Albrecht, C., Alou, P., Altarelli, M., Altmann, P., Amyan, K., Anashin, V., Apostolov, E., Appel, K., Auguste, D., Ayvazyan, V., Baark, S., Babies, F., Baboi, N., Bak, P., Balandin, V., Baldinger, R., Baranasic, B., Barbanotti, S., Belikov, O., Belokurov, V., Belova, L., Belyakov, V., Berry, S., Bertucci, M., Beutner, B., Block, A., Blöcher, M., Böckmann, T., Bohm, C., Böhnert, M., Bondar, V., Bondarchuk, E., Bonezzi, M., Borowiec, P., Bösch, C., Bösenberg, U., Bosotti, A., Böspflug, R., Bousonville, M., Boyd, E., Bozhko, Y., Brand, A., Branlard, J., Briechle, S., Brinker, F., Brinker, S., Brinkmann, R., Brockhauser, S., Brovko, O., Brück, H., Brüdgam, A., Butkowski, L., Büttner, T., Calero, J., Castro-Carballo, E., Cattalanotto, G., Charrier, J., Chen, J., Cherepenko, A., Cheskidov, V., Chiodini, M., Chong, A., Choroba, S., Chorowski, M., Churanov, D., Cichalewski, W., Clausen, M., Clement, W., Cloué, C., Cobos, J. A., Coppola, N., Cunis, S., Czuba, K., Czwalinna, M., D’Almagne, B., Dammann, J., Danared, H., de Zubiaurre Wagner, A., Delfs, A., Delfs, T., Dietrich, F., Dietrich, T., Dohlus, M., Dommach, M., Donat, A., Dong, X., Doynikov, N., Dressel, M., Duda, M., Duda, P., Eckoldt, H., Ehsan, W., Eidam, J., Eints, F., Engling, C., Englisch, U., Ermakov, A., Escherich, K., Eschke, J., Saldin, E., Faesing, M., Fallou, A., Felber, M., Fenner, M., Fernandes, B., Fernández, J. M., Feuker, S., Filippakopoulos, K., Floettmann, K., Fogel, V., Fontaine, M., Francés, A., Martin, I. Freijo, Freund, W., Freyermuth, T., Friedland, M., Fröhlich, L., Fusetti, M., Fydrych, J., Gallas, A., García, O., Garcia-Tabares, L., Geloni, G., Gerasimova, N., Gerth, C., Geßler, P., Gharibyan, V., Gloor, M., Głowinkowski, J., Goessel, A., Gołębiewski, Z., Golubeva, N., Grabowski, W., Graeff, W., Grebentsov, A., Grecki, M., Grevsmuehl, T., Gross, M., Grosse-Wortmann, U., Grünert, J., Grunewald, S., Grzegory, P., Feng, G., Guler, H., Gusev, G., Gutierrez, J. L., Hagge, L., Hamberg, M., Hanneken, R., Harms, E., Hartl, I., Hauberg, A., Hauf, S., Hauschildt, J., Hauser, J., Havlicek, J., Hedqvist, A., Heidbrook, N., Hellberg, F., Henning, D., Hensler, O., Hermann, T., Hidvégi, A., Hierholzer, M., Hintz, H., Hoffmann, F., Hoffmann, Markus, Hoffmann, Matthias, Holler, Y., Hüning, M., Ignatenko, A., Ilchen, M., Iluk, A., Iversen, J., Iversen, J., Izquierdo, M., Jachmann, L., Jardon, N., Jastrow, U., Jensch, K., Jensen, J., Jeżabek, M., Jidda, M., Jin, H., Johansson, N., Jonas, R., Kaabi, W., Kaefer, D., Kammering, R., Kapitza, H., Karabekyan, S., Karstensen, S., Kasprzak, K., Katalev, V., Keese, D., Keil, B., Kholopov, M., Killenberger, M., Kitaev, B., Klimchenko, Y., Klos, R., Knebel, L., Koch, A., Koepke, M., Köhler, S., Köhler, W., Kohlstrunk, N., Konopkova, Z., Konstantinov, A., Kook, W., Koprek, W., Körfer, M., Korth, O., Kosarev, A., Kosiński, K., Kostin, D., Kot, Y., Kotarba, A., Kozak, T., Kozak, V., Kramert, R., Krasilnikov, M., Krasnov, A., Krause, B., Kravchuk, L., Krebs, O., Kretschmer, R., Kreutzkamp, J., Kröplin, O., Krzysik, K., Kube, G., Kuehn, H., Kujala, N., Kulikov, V., Kuzminych, V., La Civita, D., Lacroix, M., Lamb, T., Lancetov, A., Larsson, M., Le Pinvidic, D., Lederer, S., Lensch, T., Lenz, D., Leuschner, A., Levenhagen, F., Li, Y., Liebing, J., Lilje, L., Limberg, T., Lipka, D., List, B., Liu, J., Liu, S., Lorbeer, B., Lorkiewicz, J., Lu, H. H., Ludwig, F., Machau, K., Maciocha, W., Madec, C., Magueur, C., Maiano, C., Maksimova, I., Malcher, K., Maltezopoulos, T., Mamoshkina, E., Manschwetus, B., Marcellini, F., Marinkovic, G., Martinez, T., Martirosyan, H., Maschmann, W., Maslov, M., Matheisen, A., Mavric, U., Meißner, J., Meissner, K., Messerschmidt, M., Meyners, N., Michalski, G., Michelato, P., Mildner, N., Moe, M., Moglia, F., Mohr, C., Mohr, S., Möller, W., Mommerz, M., Monaco, L., Montiel, C., Moretti, M., Morozov, I., Morozov, P., Mross, D., Mueller, J., Müller, C., Müller, J., Müller, K., Munilla, J., Münnich, A., Muratov, V., Napoly, O., Näser, B., Nefedov, N., Neumann, Reinhard, Neumann, Rudolf, Ngada, N., Noelle, D., Obier, F., Okunev, I., Oliver, J. A., Omet, M., Oppelt, A., Ottmar, A., Oublaid, M., Pagani, C., Paparella, R., Paramonov, V., Peitzmann, C., Penning, J., Perus, A., Peters, F., Petersen, B., Petrov, A., Petrov, I., Pfeiffer, S., Pflüger, J., Philipp, S., Pienaud, Y., Pierini, P., Pivovarov, S., Planas, M., Pławski, E., Pohl, M., Polinski, J., Popov, V., Prat, S., Prenting, J., Priebe, G., Pryschelski, H., Przygoda, K., Pyata, E., Racky, B., Rathjen, A., Ratuschni, W., Regnaud-Campderros, S., Rehlich, K., Reschke, D., Robson, C., Roever, J., Roggli, M., Rothenburg, J., Rusiński, E., Rybaniec, R., Sahling, H., Salmani, M., Samoylova, L., Sanzone, D., Saretzki, F., Sawlanski, O., Schaffran, J., Schlarb, H., Schlösser, M., Schlott, V., Schmidt, C., Schmidt-Foehre, F., Schmitz, M., Schmökel, M., Schnautz, T., Schneidmiller, E., Scholz, M., Schöneburg, B., Schultze, J., Schulz, C., Schwarz, A., Sekutowicz, J., Sellmann, D., Semenov, E., Serkez, S., Sertore, D., Shehzad, N., Shemarykin, P., Shi, L., Sienkiewicz, M., Sikora, D., Sikorski, M., Silenzi, A., Simon, C., Singer, W., Singer, X., Sinn, H., Sinram, K., Skvorodnev, N., Smirnow, P., Sommer, T., Sorokin, A., Stadler, M., Steckel, M., Steffen, B., Steinhau-Kühl, N., Stephan, F., Stodulski, M., Stolper, M., Sulimov, A., Susen, R., Świerblewski, J., Sydlo, C., Syresin, E., Sytchev, V., Szuba, J., Tesch, N., Thie, J., Thiebault, A., Tiedtke, K., Tischhauser, D., Tolkiehn, J., Tomin, S., Tonisch, F., Toral, F., Torbin, I., Trapp, A., Treyer, D., Trowitzsch, G., Trublet, T., Tschentscher, T., Ullrich, F., Vannoni, M., Varela, P., Varghese, G., Vashchenko, G., Vasic, M., Vazquez-Velez, C., Verguet, A., Vilcins-Czvitkovits, S., Villanueva, R., Visentin, B., Viti, M., Vogel, E., Volobuev, E., Wagner, R., Walker, N., Wamsat, T., Weddig, H., Weichert, G., Weise, H., Wenndorf, R., Werner, M., Wichmann, R., Wiebers, C., Wiencek, M., Wilksen, T., Will, I., Winkelmann, L., Winkowski, M., Wittenburg, K., Witzig, A., Wlk, P., Wohlenberg, T., Wojciechowski, M., Wolff-Fabris, F., Wrochna, G., Wrona, K., Yakopov, M., Yang, B., Yang, F., Yurkov, M., Zagorodnov, I., Zalden, P., Zavadtsev, A., Zavadtsev, D., Zhirnov, A., Zhukov, A., Ziemann, V., Zolotov, A., Zolotukhina, N., Zummack, F., and Zybin, D.

Published
2020
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15. High-gradient RF structures and systems

Author

Bousson, S., Weise, H., Burt, G., Devanz, G., Gallo, A., Gerigk, F., Grudiev, A., Longuevergne, D., Proslier, T., and Ruber, R.

Abstract

Radio frequency (RF) systems are the workhorse of most particle accelerators and achieve high levels of performance and reliability. Despite five decades of improvement the community is still advancing RF performance with several novel developments. The next generation of particle accelerators will likely be still based on RF technology, but will require operational parameters in excess of state of the art, requiring an advanced R&D program. The R&D covers superconducting RF (SRF), normal conducting RF (NC RF) and ancillary systems such as RF sources, couplers, tuners and the systems that control them. The panel notes there is significant overlap between the R&D required for energy-recovery linacs (ERLs) and muon colliders and the activities mentioned here. There is also requirements for RF to serve as injectors to novel accelerators. It is clear that improved RF system performance is both within reach and also critical to the development of any future high energy physics (HEP) accelerator, but such development will require appropriate investment., CERN Yellow Reports: Monographs, Vol. 1 (2022): European Strategy for Particle Physics - Accelerator R&D Roadmap

Published
2022
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16. Vacancy-Dynamics in Niobium and its Native Oxides and their implications for Quantum Computing and Superconducting Accelerators

Author

Wenskat, M., Cizek, J., (0000-0001-7933-7295) Liedke, M. O., (0000-0003-3674-0767) Butterling, M., Stiehl, M., Dalla Lana Semione, G., Backes, C., Bate, C., Melikhova, O., (0000-0001-5782-9627) Hirschmann, E., (0000-0001-7575-3961) Wagner, A., Weise, H., Stierle, A., Aeschlimann, M., Hillert, W., Wenskat, M., Cizek, J., (0000-0001-7933-7295) Liedke, M. O., (0000-0003-3674-0767) Butterling, M., Stiehl, M., Dalla Lana Semione, G., Backes, C., Bate, C., Melikhova, O., (0000-0001-5782-9627) Hirschmann, E., (0000-0001-7575-3961) Wagner, A., Weise, H., Stierle, A., Aeschlimann, M., and Hillert, W.

Abstract

In recent years, superconducting radio-frequency (SRF) cavities have been considered as candidates for qubits in quantum computing, showing a significantly longer decoherence time compared to many other realizations. Originally, SRF cavities are the workhorse of modern particle accelerators and ongoing R&D pursuits to improve their properties, to increase the accelerating field and reduce the surface resistance in order to increase the energy reach and duty cycle of accelerators. Although few experimental milestones have been realized, the underlying mechanisms of the still observed losses have not been fully understood. In this contribution we are going to show that a recently reported temperature treatment of Nb SRF cavities in the temperature range of 573-673 K, which reduces the residual surface resistance to unprecedented values, is linked to a reorganization of the niobium oxide and near-surface vacancy structure and that this reorganization can explain the observed improved performance in both applications, quantum computing and SRF cavities.

Published
2022

17. FLASH Modalities Track (Oral Presentations) NEW R&D PLATFORM WITH UNIQUE CAPABILITIES FOR ELECTRON FLASH AND VHEE RADIATION THERAPY AND RADIATION BIOLOGY UNDER PREPARATION AT PITZ

Author

Stephan, F., primary, Aboulbanine, Z., additional, Amirkhanyan, Z., additional, Good, J., additional, Gross, M., additional, Krasilnikov, M., additional, Lishilin, O., additional, Oppelt, A., additional, Philipp, S., additional, Qian, H., additional, Stegmann, C., additional, Worm, S., additional, Leemans, W., additional, Schmitz, M., additional, Schnautz, T., additional, Weise, H., additional, Budach, V., additional, Ehrhardt, V., additional, Vozenin, M.-C., additional, Faus-Golfe, A., additional, Tsakanova, G., additional, Schüller, A., additional, Frohme, M., additional, Grebinyk, A., additional, Reindl, J., additional, Grüner, F., additional, and Staufer, T., additional

Published
2022
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19. First operation of a free-electron laser generating GW power radiation at 32 nm wavelength

Author

Ayvazyan, V., Baboi, N., Bähr, J., Balandin, V., Beutner, B., Brandt, A., Bohnet, I., Bolzmann, A., Brinkmann, R., Brovko, O. I., Carneiro, J. P., Casalbuoni, S., Castellano, M., Castro, P., Catani, L., Chiadroni, E., Choroba, S., Cianchi, A., Delsim-Hashemi, H., Di Pirro, G., Dohlus, M., Düsterer, S., Edwards, H. T., Faatz, B., Fateev, A. A., Feldhaus, J., Flöttmann, K., Frisch, J., Fröhlich, L., Garvey, T., Gensch, U., Golubeva, N., Grabosch, H.-J., Grigoryan, B., Grimm, O., Hahn, U., Han, J. H., Hartrott, M. V., Honkavaara, K., Hüning, M., Ischebeck, R., Jaeschke, E., Jablonka, M., Kammering, R., Katalev, V., Keitel, B., Khodyachykh, S., Kim, Y., Kocharyan, V., Körfer, M., Kollewe, M., Kostin, D., Krämer, D., Krassilnikov, M., Kube, G., Lilje, L., Limberg, T., Lipka, D., Löhl, F., Luong, M., Magne, C., Menzel, J., Michelato, P., Miltchev, V., Minty, M., Möller, W. D., Monaco, L., Müller, W., Nagl, M., Napoly, O., Nicolosi, P., Nölle, D., Nuñez, T., Oppelt, A., Pagani, C., Paparella, R., Petersen, B., Petrosyan, B., Pflüger, J., Piot, P., Plönjes, E., Poletto, L., Proch, D., Pugachov, D., Rehlich, K., Richter, D., Riemann, S., Ross, M., Rossbach, J., Sachwitz, M., Saldin, E. L., Sandner, W., Schlarb, H., Schmidt, B., Schmitz, M., Schmüser, P., Schneider, J. R., Schneidmiller, E. A., Schreiber, H.-J., Schreiber, S., Shabunov, A. V., Sertore, D., Setzer, S., Simrock, S., Sombrowski, E., Staykov, L., Steffen, B., Stephan, F., Stulle, F., Sytchev, K. P., Thom, H., Tiedtke, K., Tischer, M., Treusch, R., Trines, D., Tsakov, I., Vardanyan, A., Wanzenberg, R., Weiland, T., Weise, H., Wendt, M., Will, I., Winter, A., Wittenburg, K., Yurkov, M. V., Zagorodnov, I., Zambolin, P., and Zapfe, K.

Published
2006
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21. A new powerful source for coherent VUV radiation: Demonstration of exponential growth and saturation at the TTF free-electron laser

Author

Ayvazyan, V., Baboi, N., Bohnet, I., Brinkmann, R., Castellano, M., Castro, P., Catani, L., Choroba, S., Cianchi, A., Dohlus, M., Edwards, H.T., Faatz, B., Fateev, A.A., Feldhaus, J., Flöttmann, K., Gamp, A., Garvey, T., Genz, H., Gerth, Ch., Gretchko, V., Grigoryan, B., Hahn, U., Hessler, C., Honkavaara, K., Hüning, M., Ischebeck, R., Jablonka, M., Kamps, T., Körfer, M., Krassilnikov, M., Krzywinski, J., Liepe, M., Liero, A., Limberg, T., Loos, H., Luong, M., Magne, C., Menzel, J., Michelato, P., Minty, M., Müller, U.-C., Nölle, D., Novokhatski, A., Pagani, C., Peters, F., Pflüger, J., Piot, P., Plucinski, L., Rehlich, K., Reyzl, I., Richter, A., Rossbach, J., Saldin, E.L., Sandner, W., Schlarb, H., Schmidt, G., Schmüser, P., Schneider, J.R., Schneidmiller, E.A., Schreiber, H.-J., Schreiber, S., Sertore, D., Setzer, S., Simrock, S., Sobierajski, R., Sonntag, B., Steeg, B., Stephan, F., Sytchev, K.P., Tiedtke, K., Tonutti, M., Treusch, R., Trines, D., Türke, D., Verzilov, V., Wanzenberg, R., Weiland, T., Weise, H., Wendt, M., Wilhein, T., Will, I., Wittenburg, K., Wolff, S., Yurkov, M.V., and Zapfe, K.

Published
2002
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23. Study of the statistical properties of the radiation from a VUV SASE FEL operating in the femtosecond regime

Author

Ayvazyan, V., primary, Carneiro, J.-P., additional, Castro, P., additional, Faatz, B., additional, Fateev, A.A., additional, Feldhaus, J., additional, Gerth, Ch., additional, Gretchko, V., additional, Grigoryan, B., additional, Hahn, U., additional, Honkavaara, K., additional, Hüning, M., additional, Ischebeck, R., additional, Jastrow, U., additional, Kammering, R., additional, Menzel, J., additional, Minty, M., additional, Nölle, D., additional, Pflüger, J., additional, Piot, Ph., additional, Plucinski, L., additional, Rehlich, K., additional, Rossbach, J., additional, Saldin, E.L., additional, Schlarb, H., additional, Schneidmiller, E.A., additional, Schreiber, S., additional, Sobierajski, R., additional, Steeg, B., additional, Stulle, F., additional, Sytchev, K.P., additional, Tiedtke, K., additional, Treusch, R., additional, Weise, H., additional, Wendt, M., additional, and Yurkov, M.V., additional

Published
2003
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24. Resilience trinity: Safeguarding ecosystem functioning and services across three different time horizons and decision contexts

Author

Weise, H., Auge, H., Baessler, C., Bärlund, I., Bennett, E.M., Berger, U., Bohn, F., Bonn, A., Borchardt, D., Brand, F., Chatzinotas, A., Corstanje, R., De Laender, F., Dietrich, P., Dunker, S., Durka, W., Fazey, I., Groeneveld, J., Guilbaud, C.S.E., Harms, H., Harpole, S., Harris, J., Jax, K., Jeltsch, F., Johst, K., Joshi, J., Klotz, S., Kühn, I., Kuhlicke, C., Müller, B., Radchuk, V., Reuter, H., Rinke, K., Schmitt‐Jansen, M., Seppelt, R., Singer, A., Standish, R.J., Thulke, H‐H, Tietjen, B., Weitere, M., Wirth, C., Wolf, C., Grimm, V., Weise, H., Auge, H., Baessler, C., Bärlund, I., Bennett, E.M., Berger, U., Bohn, F., Bonn, A., Borchardt, D., Brand, F., Chatzinotas, A., Corstanje, R., De Laender, F., Dietrich, P., Dunker, S., Durka, W., Fazey, I., Groeneveld, J., Guilbaud, C.S.E., Harms, H., Harpole, S., Harris, J., Jax, K., Jeltsch, F., Johst, K., Joshi, J., Klotz, S., Kühn, I., Kuhlicke, C., Müller, B., Radchuk, V., Reuter, H., Rinke, K., Schmitt‐Jansen, M., Seppelt, R., Singer, A., Standish, R.J., Thulke, H‐H, Tietjen, B., Weitere, M., Wirth, C., Wolf, C., and Grimm, V.

Abstract

Ensuring ecosystem resilience is an intuitive approach to safeguard the functioning of ecosystems and hence the future provisioning of ecosystem services (ES). However, resilience is a multi‐faceted concept that is difficult to operationalize. Focusing on resilience mechanisms, such as diversity, network architectures or adaptive capacity, has recently been suggested as means to operationalize resilience. Still, the focus on mechanisms is not specific enough. We suggest a conceptual framework, resilience trinity, to facilitate management based on resilience mechanisms in three distinctive decision contexts and time‐horizons: 1) reactive, when there is an imminent threat to ES resilience and a high pressure to act, 2) adjustive, when the threat is known in general but there is still time to adapt management and 3) provident, when time horizons are very long and the nature of the threats is uncertain, leading to a low willingness to act. Resilience has different interpretations and implications at these different time horizons, which also prevail in different disciplines. Social ecology, ecology and engineering are often implicitly focussing on provident, adjustive or reactive resilience, respectively, but these different notions of resilience and their corresponding social, ecological and economic tradeoffs need to be reconciled. Otherwise, we keep risking unintended consequences of reactive actions, or shying away from provident action because of uncertainties that cannot be reduced. The suggested trinity of time horizons and their decision contexts could help ensuring that longer‐term management actions are not missed while urgent threats to ES are given priority.

Published
2020

25. Vacancy-Hydrogen Interaction in Niobium during Low-Temperature Baking

Author

Wenskat, M., Čižek, J., (0000-0001-7933-7295) Liedke, M. O., (0000-0003-3674-0767) Butterling, M., Bate, C., Haušild, P., (0000-0001-5782-9627) Hirschmann, E., (0000-0001-7575-3961) Wagner, A., Weise, H., Wenskat, M., Čižek, J., (0000-0001-7933-7295) Liedke, M. O., (0000-0003-3674-0767) Butterling, M., Bate, C., Haušild, P., (0000-0001-5782-9627) Hirschmann, E., (0000-0001-7575-3961) Wagner, A., and Weise, H.

Abstract

A recently discovered modified low-temperature baking leads to reduced surface losses and an increase of the accelerating gradient of superconducting TESLA shape cavities. We will show that the dynamics of vacancy-hydrogen complexes at low-temperature baking lead to a suppression of lossy nanohydrides at 2 K and thus a significant enhancement of accelerator performance. Utilizing Doppler broadening Positron Annihilation Spectroscopy, Positron Annihilation Lifetime Spectroscopy and instrumented nanoindentation, samples made from European XFEL niobium sheets were investigated. We studied the evolution of vacancies in bulk samples and in the sub-surface region and their interaction with hydrogen at different temperature levels during in-situ and ex-situ annealing.

Published
2020

26. Study of the statistical properties of the radiation from a VUV SASE FEL operating in the femtosecond regime

Author

Ayvazyan, V, Carneiro, J.-P, Castro, P, Faatz, B, Fateev, A.A, Feldhaus, J, Gerth, Ch, Gretchko, V, Grigoryan, B, Hahn, U, Honkavaara, K, Hüning, M, Ischebeck, R, Jastrow, U, Kammering, R, Menzel, J, Minty, M, Nölle, D, Pflüger, J, Piot, Ph, Plucinski, L, Rehlich, K, Rossbach, J, Saldin, E.L, Schlarb, H, Schneidmiller, E.A, Schreiber, S, Sobierajski, R, Steeg, B, Stulle, F, Sytchev, K.P, Tiedtke, K, Treusch, R, Weise, H, Wendt, M, and Yurkov, M.V

Published
2003
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28. O061 - FLASH Modalities Track (Oral Presentations) NEW R&D PLATFORM WITH UNIQUE CAPABILITIES FOR ELECTRON FLASH AND VHEE RADIATION THERAPY AND RADIATION BIOLOGY UNDER PREPARATION AT PITZ

Author

Stephan, F., Aboulbanine, Z., Amirkhanyan, Z., Good, J., Gross, M., Krasilnikov, M., Lishilin, O., Oppelt, A., Philipp, S., Qian, H., Stegmann, C., Worm, S., Leemans, W., Schmitz, M., Schnautz, T., Weise, H., Budach, V., Ehrhardt, V., Vozenin, M.-C., Faus-Golfe, A., Tsakanova, G., Schüller, A., Frohme, M., Grebinyk, A., Reindl, J., Grüner, F., and Staufer, T.

Published
2022
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29. Vacancy-Hydrogen Dynamics in Samples during Low Temperature Baking

Author

Wenskat, M., Bate, C., Cizek, J., (0000-0001-7933-7295) Liedke, M. O., Butterling, M., Hirschmann, E., (0000-0001-7575-3961) Wagner, A., Reschke, D., Weise, H., Wenskat, M., Bate, C., Cizek, J., (0000-0001-7933-7295) Liedke, M. O., Butterling, M., Hirschmann, E., (0000-0001-7575-3961) Wagner, A., Reschke, D., and Weise, H.

Abstract

The recent discovery of a modified low temperature baking process established an increased accelerating gradient of TESLA shaped cavities through reduction of surface losses. A possible explanation for the performance gain is the suppression of lossy nanohydrides via defect trapping, with vacancy-hydrogen (v+nH) complexes forming at the lower temperatures. Utilizing Doppler broadening Positron Annihilation Spectroscopy, Positron Annihilation Lifetime Spectroscopy and Nuclear Reaction Analysis, samples made from European XFEL niobium sheets and cavity cut-outs were investigated. The evolution of vacancies, hydrogen and their interaction at different temperature levels have been studied during in-situ and ex-situ annealing and in-situ cooldowns. Measurements of niobium samples and a correlation between RF, material properties, and v+nH distribution in cavity cut-outs have been carried out.

Published
2019

30. SRF gun development at DESY

Author

Vogel, E., Sekutowicz, J., Barbanotti, S., Hartl, I., Jensch, K., Klinke, D., Kostin, D., Moeller, W.-D., Schmoekel, M., Sievers, S., Steinhau-Kuehl, N., Sulimov, A., Thie, J.-H., Horst, B., Weise, H., Winkelmann, L., Smedley, J., Teichert, J., Wiencek, M., Lorkiewicz, J. A., Nietubyc, R., Vogel, E., Sekutowicz, J., Barbanotti, S., Hartl, I., Jensch, K., Klinke, D., Kostin, D., Moeller, W.-D., Schmoekel, M., Sievers, S., Steinhau-Kuehl, N., Sulimov, A., Thie, J.-H., Horst, B., Weise, H., Winkelmann, L., Smedley, J., Teichert, J., Wiencek, M., Lorkiewicz, J. A., and Nietubyc, R.

Abstract

A future upgrade of the European XFEL (E-XFEL) foresees an additional CW operation mode, which will increase the flexibility in the photon beam time structure [1, 2, 3]. One of the challenges of this operational mode is the need for a CW operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating CW. For more than a decade DESY, in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR, has performed R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL CW upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.

Published
2019

31. Exploring resilience with agent-based models: State of the art, knowledge gaps and recommendations for coping with multidimensionality

Author

Egli, Lukas, Weise, H., Radchuk, V., Seppelt, Ralf, Grimm, Volker, Egli, Lukas, Weise, H., Radchuk, V., Seppelt, Ralf, and Grimm, Volker

Abstract

Anthropogenic pressures increasingly alter natural systems. Therefore, understanding the resilience of agent-based complex systems such as ecosystems, i.e. their ability to absorb these pressures and sustain their functioning and services, is a major challenge. However, the mechanisms underlying resilience are still poorly understood. A main reason for this is the multidimensionality of both resilience, embracing the three fundamental stability properties recovery, resistance and persistence, and of the specific situations for which stability properties can be assessed. Agent-based models (ABM) complement empirical research which is, for logistic reasons, limited in coping with these multiple dimensions. Besides their ability to integrate multidimensionality through extensive manipulation in a fully controlled system, ABMs can capture the emergence of system resilience from individual interactions and feedbacks across different levels of organization. To assess the extent to which this potential of ABMs has already been exploited, we reviewed the state of the art in exploring resilience and its multidimensionality in ecological and socio-ecological systems with ABMs. We found that the potential of ABMs is not utilized in most models, as they typically focus on a single dimension of resilience by using variability as a proxy for persistence, and are limited to one reference state, disturbance type and scale. Moreover, only few studies explicitly test the ability of different mechanisms to support resilience. To overcome these limitations, we recommend to simultaneously assess multiple stability properties for different situations and under consideration of the mechanisms that are hypothesised to render a system resilient. This will help us to better exploit the potential of ABMs to understand and quantify resilience mechanisms, and hence support solving real-world problems related to the resilience of agent-based complex systems.

Published
2019

32. Resilience trinity: safeguarding ecosystem services across three different time horizons and decision contexts

Author

Weise, H, primary, Auge, H, additional, Baessler, C, additional, Bärlund, I, additional, Bennett, E.M., additional, Berger, U, additional, Bohn, F, additional, Bonn, A, additional, Borchardt, D, additional, Brand, F, additional, Chatzinotas, A, additional, Corstanje, R, additional, De Laender, F, additional, Dietrich, P, additional, Dunker, S, additional, Durka, W, additional, Fazey, I, additional, Groeneveld, J, additional, Guilbaud, CSE, additional, Harms, H, additional, Harpole, S, additional, Harris, J, additional, Jax, K, additional, Jeltsch, F, additional, Johst, K, additional, Joshi, J, additional, Klotz, S, additional, Kühn, I, additional, Kuhlicke, C, additional, Müller, B, additional, Radchuk, V, additional, Reuter, H, additional, Rinke, K, additional, Schmitt-Jansen, M, additional, Seppelt, R, additional, Singer, A, additional, Standish, RJ, additional, Thulke, HH, additional, Tietjen, B, additional, Weitere, M, additional, Wirth, C, additional, Wolf, C, additional, and Grimm, V, additional

Published
2019
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33. A squeeze in the suitable fire interval: Simulating the persistence of fire-killed plants in a Mediterranean-type ecosystem under drier conditions

Author

Henzler, J., Weise, H., Enright, N.J., Zander, S., Tietjen, B., Henzler, J., Weise, H., Enright, N.J., Zander, S., and Tietjen, B.

Abstract

Mediterranean-type ecosystems (MTEs) harbor an exceptionally high biodiversity of vascular plants. At the same time, climatic conditions in many MTE regions are projected to become both drier and hotter, and fire intervals shorter. The Interval Squeeze conceptual model integrates the potential effects of a changing climate and fire regimes on perennial plant population persistence and postulates that warmer, drier conditions will negatively affect multiple plant demographic processes. Dependent on species-specific traits, the required fire intervals that allow for population persistence might become longer, while projected future fire intervals are shorter, leading to a potential mismatch. However, conceptual models are per se not able to quantify outcomes of multiple stochastic processes or to simulate temporal dynamics. Here, we develop a simple, process-based model for a fire-sensitive woody plant species to evaluate the response of demographic processes to future climatic conditions and to quantify the potential impact also of future changes in fire interval. This allowed us to assess key assumptions of the interval squeeze model, particularly in relation to demographic drivers. We simulated populations of Banksia hookeriana, a typical fire-killed shrub found in MTEs of South-West Australia which stores its seeds in a canopy (serotinous) seedbank and shows strong cohort recruitment in the first year after fire. We estimated suitable fixed fire intervals for population persistence under historic climatic conditions and evaluated impacts of a higher dry year frequency (as projected under future climate by two representative concentration pathways, RCP4.5 and RCP8.5). Our findings support the Interval Squeeze Model: the fire interval allowing plant population persistence is squeezed from currently 10–28 years to 13–28 years for RCP4.5. For RCP8.5 population persistence is not possible under any of the tested fire intervals because of low seed production and low sur

Published
2018

34. SRF gun development at DESY

Author

Vogel, E., Sekutowicz, J., Barbanotti, S., Hartl, I., Jensch, K., Klinke, D., Kostin, D., Moeller, W.-D., Schmoekel, M., Sievers, S., Steinhau-Kuehl, N., Sulimov, A., Thie, J.-H., Horst, B., Weise, H., Winkelmann, L., Smedley, J., Teichert, J., Wiencek, M., Lorkiewicz, J. A., Nietubyc, R., Vogel, E., Sekutowicz, J., Barbanotti, S., Hartl, I., Jensch, K., Klinke, D., Kostin, D., Moeller, W.-D., Schmoekel, M., Sievers, S., Steinhau-Kuehl, N., Sulimov, A., Thie, J.-H., Horst, B., Weise, H., Winkelmann, L., Smedley, J., Teichert, J., Wiencek, M., Lorkiewicz, J. A., and Nietubyc, R.

Abstract

A future upgrade of the European XFEL (E-XFEL) foresees an additional CW operation mode, which will increase the flexibility in the photon beam time structure [1, 2, 3]. One of the challenges of this operational mode is the need for a CW operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating CW. For more than a decade DESY, in collaboration with TJNAF, NCBJ, BNL, HZB and HZDR, has performed R&D to develop an all superconducting RF gun with a lead cathode. In the frame of E-XFEL CW upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping the gun cavity in a clean room to exchange the cathode. Thus it is practical only when the life time of the cathode is at least several months. In this paper we present the actual status of the R&D program, next steps and the longer term plans.

Published
2018

38. Theoretical foundations of human decision-making in agent-based land use models – A review

Author

Groeneveld, Jürgen, Müller, Birgit, Buchmann, Carsten, Dressler, Gunnar, Guo, Cheng, Hase, Jan Niklas, Hoffmann, Falk, John, Felix, Klassert, Christian, Lauf, Thomas, Liebelt, Veronika, Nolzen, Henning, Pannicke, Nadine, Schulze, Jule, Weise, H., Schwarz, Nina, Groeneveld, Jürgen, Müller, Birgit, Buchmann, Carsten, Dressler, Gunnar, Guo, Cheng, Hase, Jan Niklas, Hoffmann, Falk, John, Felix, Klassert, Christian, Lauf, Thomas, Liebelt, Veronika, Nolzen, Henning, Pannicke, Nadine, Schulze, Jule, Weise, H., and Schwarz, Nina

Abstract

Recent reviews stated that the complex and context-dependent nature of human decision-making resulted in ad-hoc representations of human decision in agent-based land use change models (LUCC ABMs) and that these representations are often not explicitly grounded in theory. However, a systematic survey on the characteristics (e.g. uncertainty, adaptation, learning, interactions and heterogeneities of agents) of representing human decision-making in LUCC ABMs is missing. Therefore, the aim of this study is to inform this debate by reviewing 134 LUCC ABM papers. We show that most human decision sub-models are not explicitly based on a specific theory and if so they are mostly based on economic theories, such as the rational actor, and mainly ignoring other relevant disciplines. Consolidating and enlarging the theoretical basis for modelling human decision-making may be achieved by using a structural framework for modellers, re-using published decision models, learning from other disciplines and fostering collaboration with social scientists.

Published
2016

39. Production of superconducting 1.3-GHz cavities for the European X-ray Free Electron Laser

Author

Singer, W., primary, Brinkmann, A., additional, Brinkmann, R., additional, Iversen, J., additional, Matheisen, A., additional, Moeller, W.-D., additional, Navitski, A., additional, Reschke, D., additional, Schaffran, J., additional, Sulimov, A., additional, Walker, N., additional, Weise, H., additional, Michelato, P., additional, Monaco, L., additional, Pagani, C., additional, and Wiencek, M., additional

Published
2016
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40. Report on joining TIARA and sustainable structures: Deliverable 3.6

Author

Bordais, L., Dael, A., Kircher, F., Launé, B., Mcintosh, P., Obradors, D., Pierini, P., Ruber, R., Schietinger, T., Sugita, K., Unnervik, A., Weise, H., and Wronka, S.

Subjects
JTI Joining the TIARA distributed acc. R&D infrast. [3.7], Accelerators and Storage Rings, R&D Infrastructures [3]
Published
2014

41. Infrastructure Need and Resource comparison: Deliverable 3.3

Author

Bordais, L., Dael, A., Kircher, F., Launé, B., Mcintosh, P., Obradors, D., Pierini, P., Ruber, R., Schietinger, T., Sugita, K., Tanguy, C., Unnervik, A., Weise, H., and Wronka, S.

Subjects
ACA Accessing the current, medium- end log term acc. R&D infras. Needs [3.2], Accelerators and Storage Rings, R&D Infrastructures [3]
Published
2014

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