J. Urakawa - KEK, Tsukuba

J. Urakawa
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Name
J. Urakawa
Affiliation
KEK, Tsukuba
City
Tsukuba
Country
Japan

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Physics - Accelerator Physics (30)
 
High Energy Physics - Experiment (12)
 
Physics - Instrumentation and Detectors (8)
 
Physics - Optics (2)
 
Physics - Strongly Correlated Electrons (1)
 
Computer Science - Networking and Internet Architecture (1)
 
High Energy Physics - Phenomenology (1)

Publications Authored By J. Urakawa

We have been developing optical resonant cavities for laser-Compton scattering experiment at the Accelerator Test Facility in KEK. The main subject of the R&D is to increase laser pulse energy by coherently accumulating the pulses in an optical resonant cavity. We report previous results, current status and future prospects, including a new idea of an optical resonant cavity. Read More

Investigation of coherent Smith-Purcell Radiation (SPR) spectral characteristics was performed both experimentally and by numerical simulation. The measurement of SPR spectral line shapes of different diffraction orders was carried out at KEK LUCX facility. A pair of room-temperature Schottky barrier diode (SBD) detectors with sensitivity bands of $60-90$~GHz and $320-460$~GHz was used in the measurements. Read More

A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and a high repetition frequency, which is not feasible by using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity, and has become a major technical issue in developing such cavities. We developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. Read More

2016Aug
Authors: The CLIC, CLICdp collaborations, :, M. J. Boland, U. Felzmann, P. J. Giansiracusa, T. G. Lucas, R. P. Rassool, C. Balazs, T. K. Charles, K. Afanaciev, I. Emeliantchik, A. Ignatenko, V. Makarenko, N. Shumeiko, A. Patapenka, I. Zhuk, A. C. Abusleme Hoffman, M. A. Diaz Gutierrez, M. Vogel Gonzalez, Y. Chi, X. He, G. Pei, S. Pei, G. Shu, X. Wang, J. Zhang, F. Zhao, Z. Zhou, H. Chen, Y. Gao, W. Huang, Y. P. Kuang, B. Li, Y. Li, J. Shao, J. Shi, C. Tang, X. Wu, L. Ma, Y. Han, W. Fang, Q. Gu, D. Huang, X. Huang, J. Tan, Z. Wang, Z. Zhao, T. Laštovička, U. Uggerhoj, T. N. Wistisen, A. Aabloo, K. Eimre, K. Kuppart, S. Vigonski, V. Zadin, M. Aicheler, E. Baibuz, E. Brücken, F. Djurabekova, P. Eerola, F. Garcia, E. Haeggström, K. Huitu, V. Jansson, V. Karimaki, I. Kassamakov, A. Kyritsakis, S. Lehti, A. Meriläinen, R. Montonen, T. Niinikoski, K. Nordlund, K. Österberg, M. Parekh, N. A. Törnqvist, J. Väinölä, M. Veske, W. Farabolini, A. Mollard, O. Napoly, F. Peauger, J. Plouin, P. Bambade, I. Chaikovska, R. Chehab, M. Davier, W. Kaabi, E. Kou, F. LeDiberder, R. Pöschl, D. Zerwas, B. Aimard, G. Balik, J. -P. Baud, J. -J. Blaising, L. Brunetti, M. Chefdeville, C. Drancourt, N. Geoffroy, J. Jacquemier, A. Jeremie, Y. Karyotakis, J. M. Nappa, S. Vilalte, G. Vouters, A. Bernard, I. Peric, M. Gabriel, F. Simon, M. Szalay, N. van der Kolk, T. Alexopoulos, E. N. Gazis, N. Gazis, E. Ikarios, V. Kostopoulos, S. Kourkoulis, P. D. Gupta, P. Shrivastava, H. Arfaei, M. K. Dayyani, H. Ghasem, S. S. Hajari, H. Shaker, Y. Ashkenazy, H. Abramowicz, Y. Benhammou, O. Borysov, S. Kananov, A. Levy, I. Levy, O. Rosenblat, G. D'Auria, S. Di Mitri, T. Abe, A. Aryshev, T. Higo, Y. Makida, S. Matsumoto, T. Shidara, T. Takatomi, Y. Takubo, T. Tauchi, N. Toge, K. Ueno, J. Urakawa, A. Yamamoto, M. Yamanaka, R. Raboanary, R. Hart, H. van der Graaf, G. Eigen, J. Zalieckas, E. Adli, R. Lillestøl, L. Malina, J. Pfingstner, K. N. Sjobak, W. Ahmed, M. I. Asghar, H. Hoorani, S. Bugiel, R. Dasgupta, M. Firlej, T. A. Fiutowski, M. Idzik, M. Kopec, M. Kuczynska, J. Moron, K. P. Swientek, W. Daniluk, B. Krupa, M. Kucharczyk, T. Lesiak, A. Moszczynski, B. Pawlik, P. Sopicki, T. Wojtoń, L. Zawiejski, J. Kalinowski, M. Krawczyk, A. F. Żarnecki, E. Firu, V. Ghenescu, A. T. Neagu, T. Preda, I-S. Zgura, A. Aloev, N. Azaryan, J. Budagov, M. Chizhov, M. Filippova, V. Glagolev, A. Gongadze, S. Grigoryan, D. Gudkov, V. Karjavine, M. Lyablin, A. Olyunin, A. Samochkine, A. Sapronov, G. Shirkov, V. Soldatov, A. Solodko, E. Solodko, G. Trubnikov, I. Tyapkin, V. Uzhinsky, A. Vorozhtov, E. Levichev, N. Mezentsev, P. Piminov, D. Shatilov, P. Vobly, K. Zolotarev, I. Bozovic Jelisavcic, G. Kacarevic, S. Lukic, G. Milutinovic-Dumbelovic, M. Pandurovic, U. Iriso, F. Perez, M. Pont, J. Trenado, M. Aguilar-Benitez, J. Calero, L. Garcia-Tabares, D. Gavela, J. L. Gutierrez, D. Lopez, F. Toral, D. Moya, A. Ruiz Jimeno, I. Vila, T. Argyropoulos, C. Blanch Gutierrez, M. Boronat, D. Esperante, A. Faus-Golfe, J. Fuster, N. Fuster Martinez, N. Galindo Muñoz, I. García, J. Giner Navarro, E. Ros, M. Vos, R. Brenner, T. Ekelöf, M. Jacewicz, J. Ögren, M. Olvegård, R. Ruber, V. Ziemann, D. Aguglia, N. Alipour Tehrani, A. Andersson, F. Andrianala, F. Antoniou, K. Artoos, S. Atieh, R. Ballabriga Sune, M. J. Barnes, J. Barranco Garcia, H. Bartosik, C. Belver-Aguilar, A. Benot Morell, D. R. Bett, S. Bettoni, G. Blanchot, O. Blanco Garcia, X. A. Bonnin, O. Brunner, H. Burkhardt, S. Calatroni, M. Campbell, N. Catalan Lasheras, M. Cerqueira Bastos, A. Cherif, E. Chevallay, B. Constance, R. Corsini, B. Cure, S. Curt, B. Dalena, D. Dannheim, G. De Michele, L. De Oliveira, N. Deelen, J. P. Delahaye, T. Dobers, S. Doebert, M. Draper, F. Duarte Ramos, A. Dubrovskiy, K. Elsener, J. Esberg, M. Esposito, V. Fedosseev, P. Ferracin, A. Fiergolski, K. Foraz, A. Fowler, F. Friebel, J-F. Fuchs, C. A. Fuentes Rojas, A. Gaddi, L. Garcia Fajardo, H. Garcia Morales, C. Garion, L. Gatignon, J-C. Gayde, H. Gerwig, A. N. Goldblatt, C. Grefe, A. Grudiev, F. G. Guillot-Vignot, M. L. Gutt-Mostowy, M. Hauschild, C. Hessler, J. K. Holma, E. Holzer, M. Hourican, D. Hynds, Y. Inntjore Levinsen, B. Jeanneret, E. Jensen, M. Jonker, M. Kastriotou, J. M. K. Kemppinen, R. B. Kieffer, W. Klempt, O. Kononenko, A. Korsback, E. Koukovini Platia, J. W. Kovermann, C-I. Kozsar, I. Kremastiotis, S. Kulis, A. Latina, F. Leaux, P. Lebrun, T. Lefevre, L. Linssen, X. Llopart Cudie, A. A. Maier, H. Mainaud Durand, E. Manosperti, C. Marelli, E. Marin Lacoma, R. Martin, S. Mazzoni, G. Mcmonagle, O. Mete, L. M. Mether, M. Modena, R. M. Münker, T. Muranaka, E. Nebot Del Busto, N. Nikiforou, D. Nisbet, J-M. Nonglaton, F. X. Nuiry, A. Nürnberg, M. Olvegard, J. Osborne, S. Papadopoulou, Y. Papaphilippou, A. Passarelli, M. Patecki, L. Pazdera, D. Pellegrini, K. Pepitone, E. Perez Codina, A. Perez Fontenla, T. H. B. Persson, M. Petrič, F. Pitters, S. Pittet, F. Plassard, R. Rajamak, S. Redford, Y. Renier, S. F. Rey, G. Riddone, L. Rinolfi, E. Rodriguez Castro, P. Roloff, C. Rossi, V. Rude, G. Rumolo, A. Sailer, E. Santin, D. Schlatter, H. Schmickler, D. Schulte, N. Shipman, E. Sicking, R. Simoniello, P. K. Skowronski, P. Sobrino Mompean, L. Soby, M. P. Sosin, S. Sroka, S. Stapnes, G. Sterbini, R. Ström, I. Syratchev, F. Tecker, P. A. Thonet, L. Timeo, H. Timko, R. Tomas Garcia, P. Valerio, A. L. Vamvakas, A. Vivoli, M. A. Weber, R. Wegner, M. Wendt, B. Woolley, W. Wuensch, J. Uythoven, H. Zha, P. Zisopoulos, M. Benoit, M. Vicente Barreto Pinto, M. Bopp, H. H. Braun, M. Csatari Divall, M. Dehler, T. Garvey, J. Y. Raguin, L. Rivkin, R. Zennaro, A. Aksoy, Z. Nergiz, E. Pilicer, I. Tapan, O. Yavas, V. Baturin, R. Kholodov, S. Lebedynskyi, V. Miroshnichenko, S. Mordyk, I. Profatilova, V. Storizhko, N. Watson, A. Winter, J. Goldstein, S. Green, J. S. Marshall, M. A. Thomson, B. Xu, W. A. Gillespie, R. Pan, M. A Tyrk, D. Protopopescu, A. Robson, R. Apsimon, I. Bailey, G. Burt, D. Constable, A. Dexter, S. Karimian, C. Lingwood, M. D. Buckland, G. Casse, J. Vossebeld, A. Bosco, P. Karataev, K. Kruchinin, K. Lekomtsev, L. Nevay, J. Snuverink, E. Yamakawa, V. Boisvert, S. Boogert, G. Boorman, S. Gibson, A. Lyapin, W. Shields, P. Teixeira-Dias, S. West, R. Jones, N. Joshi, R. Bodenstein, P. N. Burrows, G. B. Christian, D. Gamba, C. Perry, J. Roberts, J. A. Clarke, N. A. Collomb, S. P. Jamison, B. J. A. Shepherd, D. Walsh, M. Demarteau, J. Repond, H. Weerts, L. Xia, J. D. Wells, C. Adolphsen, T. Barklow, M. Breidenbach, N. Graf, J. Hewett, T. Markiewicz, D. McCormick, K. Moffeit, Y. Nosochkov, M. Oriunno, N. Phinney, T. Rizzo, S. Tantawi, F. Wang, J. Wang, G. White, M. Woodley

The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e- collider under development. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in a staged approach with three centre-of-mass energy stages ranging from a few hundred GeV up to 3 TeV. The first stage will focus on precision Standard Model physics, in particular Higgs and top-quark measurements. Read More

This paper proposes a Scalable Internet Bandwidth Reservation Architecture (SIBRA) as a new approach against DDoS attacks, which, until now, continue to be a menace on today's Internet. SIBRA provides scalable inter-domain resource allocations and botnet-size independence, an important property to realize why previous defense approaches are insufficient. Botnet-size independence enables two end hosts to set up communication regardless of the size of distributed botnets in any Autonomous System in the Internet. Read More

We demonstrated the operation of a high finesse optical cavity without utilizing an active feedback system to stabilize the resonance. The effective finesse, which is a finesse including the overall system performance, of the cavity was measured to be $394,000 \pm 10,000$, and the laser power stored in the cavity was $2.52 \pm 0. Read More

We present the response time measurements of a Cs2Te photocathode illuminated with two 100 fs duration, variable time separation laser pulses at 266 nm wavelength. The response time was confirmed in dispersive region downstream of a 12-cell standing wave S-band acceleration structure using a well-known RF zero-crossing technique. At the same time it was also measured by changing mechanical path-length difference between two micro-bunches. Read More

In this brief overview we will reflect on the process of the design of the linear collider (LC) final focus (FF) optics, and will also describe the theoretical and experimental efforts on design and practical realisation of a prototype of the LC FF optics implemented in the ATF2 facility at KEK, Japan, presently being commissioned and operated. Read More

A laserwire transverse electron beam size measurement system has been developed and operated at the Accelerator Test Facility 2 (ATF2) at KEK. Special electron beam optics were developed to create an approximately 1 x 100 {\mu}m (vertical x horizontal) electron beam at the laserwire location, which was profiled using a 150 mJ, 71 ps laser pulse with a wavelength of 532 nm. The precise characterisation of the laser propagation allows the non-Gaussian transverse profiles of the electron beam caused by the laser divergence to be deconvolved. Read More

Compton inverse radiation emitted due to backscattering of laser pulses off the relativistic electrons possesses high spectral density and high energy of photons - in hard x-ray up to gamma-ray energies - because of short wavelength of laser radiation as compared with the classical electromagnetic devices such as undulators. In this report, the possibility of such radiation to monochromatization by means of collimation is studied. Two approaches have been considered for the description of the spectral-angular density of Compton radiation based on the classical field theory and on the quantum electrodynamics. Read More

Model-independent analysis (MIA) methods are generally useful for analysing complex systems in which relationships between the observables are non-trivial and noise is present. Principle Component Analysis (PCA) is one of MIA methods allowing to isolate components in the input data graded to their contribution to the variability of the data. In this publication we show how the PCA can be applied to digitised signals obtained from a cavity beam position monitor (CBPM) system on the example of a 3-cavity test system installed at the Accelerator Test Facility 2 (ATF2) at KEK in Japan. Read More

We present an initial test of a new type of a pre-bunched beam pumped free electron maser based on Stimulated Coherent Diffraction Radiation (SCDR) generated in an open resonator. An ultra-fast Schottky Barrier Diode (time response $<1\,$ns) has enabled to investigate the properties of the radiation stored in the cavity as well as the intrinsic properties of the cavity itself. We observed a turn-by-turn SCDR generated by a multibunch beam. Read More

In a conventional positron source driven by a few GeV electron beam, a high amount of heat is loaded into a positron converter target to generate intense positrons required by linear colliders, and which would eventually damage the converter target. A hybrid target, composed of a single crystal target as a radiator of intense gamma--rays, and an amorphous converter target placed downstream of the crystal, was proposed as a scheme which could overcome the problem.This paper describes the development of an intense positron source with the hybrid target. Read More

2013Jan
Affiliations: 1Kyungpook Natl. U., 2Royal Holloway, U. of London, 3KEK, Tsukuba, 4Royal Holloway, U. of London, 5Royal Holloway, U. of London, 6SLAC, 7Kyungpook Natl. U., 8KEK, Tsukuba, 9Pohang Accelerator Lab., 10Pohang Accelerator Lab., 11Kyungpook Natl. U., 12Pohang Accelerator Lab., 13Royal Holloway, U. of London, 14KEK, Tsukuba, 15SLAC, 16SLAC, 17Cornell U., Phys. Dept., 18Royal Holloway, U. of London, 19SLAC, 20Pohang Accelerator Lab., 21Pohang Accelerator Lab., 22Fermilab, 23Pohang Accelerator Lab., 24Brookhaven, 25SLAC, 26KEK, Tsukuba, 27KEK, Tsukuba, 28KEK, Tsukuba, 29SLAC

The Accelerator Test Facility 2 (ATF2) is a scaled demonstrator system for final focus beam lines of linear high energy colliders. This paper describes the high resolution cavity beam position monitor (BPM) system, which is a part of the ATF2 diagnostics. Two types of cavity BPMs are used, C-band operating at 6. Read More

2012Nov
Authors: J. L. Abelleira Fernandez, C. Adolphsen, P. Adzic, A. N. Akay, H. Aksakal, J. L. Albacete, B. Allanach, S. Alekhin, P. Allport, V. Andreev, R. B. Appleby, E. Arikan, N. Armesto, G. Azuelos, M. Bai, D. Barber, J. Bartels, O. Behnke, J. Behr, A. S. Belyaev, I. Ben-Zvi, N. Bernard, S. Bertolucci, S. Bettoni, S. Biswal, J. Blümlein, H. Böttcher, A. Bogacz, C. Bracco, J. Bracinik, G. Brandt, H. Braun, S. Brodsky, O. Brüning, E. Bulyak, A. Buniatyan, H. Burkhardt, I. T. Cakir, O. Cakir, R. Calaga, A. Caldwell, V. Cetinkaya, V. Chekelian, E. Ciapala, R. Ciftci, A. K. Ciftci, B. A. Cole, J. C. Collins, O. Dadoun, J. Dainton, A. De. Roeck, D. d'Enterria, P. DiNezza, M. D'Onofrio, A. Dudarev, A. Eide, R. Enberg, E. Eroglu, K. J. Eskola, L. Favart, M. Fitterer, S. Forte, A. Gaddi, P. Gambino, H. García Morales, T. Gehrmann, P. Gladkikh, C. Glasman, A. Glazov, R. Godbole, B. Goddard, T. Greenshaw, A. Guffanti, V. Guzey, C. Gwenlan, T. Han, Y. Hao, F. Haug, W. Herr, A. Hervé, B. J. Holzer, M. Ishitsuka, M. Jacquet, B. Jeanneret, E. Jensen, J. M. Jimenez, J. M. Jowett, H. Jung, H. Karadeniz, D. Kayran, A. Kilic, K. Kimura, R. Klees, M. Klein, U. Klein, T. Kluge, F. Kocak, M. Korostelev, A. Kosmicki, P. Kostka, H. Kowalski, M. Kraemer, G. Kramer, D. Kuchler, M. Kuze, T. Lappi, P. Laycock, E. Levichev, S. Levonian, V. N. Litvinenko, A. Lombardi, J. Maeda, C. Marquet, B. Mellado, K. H. Mess, A. Milanese, J. G. Milhano, S. Moch, I. I. Morozov, Y. Muttoni, S. Myers, S. Nandi, Z. Nergiz, P. R. Newman, T. Omori, J. Osborne, E. Paoloni, Y. Papaphilippou, C. Pascaud, H. Paukkunen, E. Perez, T. Pieloni, E. Pilicer, B. Pire, R. Placakyte, A. Polini, V. Ptitsyn, Y. Pupkov, V. Radescu, S. Raychaudhuri, L. Rinolfi, E. Rizvi, R. Rohini, J. Rojo, S. Russenschuck, M. Sahin, C. A. Salgado, K. Sampei, R. Sassot, E. Sauvan, M. Schaefer, U. Schneekloth, T. Schörner-Sadenius, D. Schulte, A. Senol, A. Seryi, P. Sievers, A. N. Skrinsky, W. Smith, D. South, H. Spiesberger, A. M. Stasto, M. Strikman, M. Sullivan, S. Sultansoy, Y. P. Sun, B. Surrow, L. Szymanowski, P. Taels, I. Tapan, T. Tasci, E. Tassi, H. Ten. Kate, J. Terron, H. Thiesen, L. Thompson, P. Thompson, K. Tokushuku, R. Tomás García, D. Tommasini, D. Trbojevic, N. Tsoupas, J. Tuckmantel, S. Turkoz, T. N. Trinh, K. Tywoniuk, G. Unel, T. Ullrich, J. Urakawa, P. VanMechelen, A. Variola, R. Veness, A. Vivoli, P. Vobly, J. Wagner, R. Wallny, S. Wallon, G. Watt, C. Weiss, U. A. Wiedemann, U. Wienands, F. Willeke, B. -W. Xiao, V. Yakimenko, A. F. Zarnecki, Z. Zhang, F. Zimmermann, R. Zlebcik, F. Zomer

The present note relies on the recently published conceptual design report of the LHeC and extends the first contribution to the European strategy debate in emphasising the role of the LHeC to complement and complete the high luminosity LHC programme. The brief discussion therefore focuses on the importance of high precision PDF and $\alpha_s$ determinations for the physics beyond the Standard Model (GUTs, SUSY, Higgs). Emphasis is also given to the importance of high parton density phenomena in nuclei and their relevance to the heavy ion physics programme at the LHC. Read More

2012Nov
Authors: J. L. Abelleira Fernandez, C. Adolphsen, P. Adzic, A. N. Akay, H. Aksakal, J. L. Albacete, B. Allanach, S. Alekhin, P. Allport, V. Andreev, R. B. Appleby, E. Arikan, N. Armesto, G. Azuelos, M. Bai, D. Barber, J. Bartels, O. Behnke, J. Behr, A. S. Belyaev, I. Ben-Zvi, N. Bernard, S. Bertolucci, S. Bettoni, S. Biswal, J. Blümlein, H. Böttcher, A. Bogacz, C. Bracco, J. Bracinik, G. Brandt, H. Braun, S. Brodsky, O. Brüning, E. Bulyak, A. Buniatyan, H. Burkhardt, I. T. Cakir, O. Cakir, R. Calaga, A. Caldwell, V. Cetinkaya, V. Chekelian, E. Ciapala, R. Ciftci, A. K. Ciftci, B. A. Cole, J. C. Collins, O. Dadoun, J. Dainton, A. De. Roeck, D. d'Enterria, P. DiNezza, M. D'Onofrio, A. Dudarev, A. Eide, R. Enberg, E. Eroglu, K. J. Eskola, L. Favart, M. Fitterer, S. Forte, A. Gaddi, P. Gambino, H. García Morales, T. Gehrmann, P. Gladkikh, C. Glasman, A. Glazov, R. Godbole, B. Goddard, T. Greenshaw, A. Guffanti, V. Guzey, C. Gwenlan, T. Han, Y. Hao, F. Haug, W. Herr, A. Hervé, B. J. Holzer, M. Ishitsuka, M. Jacquet, B. Jeanneret, E. Jensen, J. M. Jimenez, J. M. Jowett, H. Jung, H. Karadeniz, D. Kayran, A. Kilic, K. Kimura, R. Klees, M. Klein, U. Klein, T. Kluge, F. Kocak, M. Korostelev, A. Kosmicki, P. Kostka, H. Kowalski, M. Kraemer, G. Kramer, D. Kuchler, M. Kuze, T. Lappi, P. Laycock, E. Levichev, S. Levonian, V. N. Litvinenko, A. Lombardi, J. Maeda, C. Marquet, B. Mellado, K. H. Mess, A. Milanese, J. G. Milhano, S. Moch, I. I. Morozov, Y. Muttoni, S. Myers, S. Nandi, Z. Nergiz, P. R. Newman, T. Omori, J. Osborne, E. Paoloni, Y. Papaphilippou, C. Pascaud, H. Paukkunen, E. Perez, T. Pieloni, E. Pilicer, B. Pire, R. Placakyte, A. Polini, V. Ptitsyn, Y. Pupkov, V. Radescu, S. Raychaudhuri, L. Rinolfi, E. Rizvi, R. Rohini, J. Rojo, S. Russenschuck, M. Sahin, C. A. Salgado, K. Sampei, R. Sassot, E. Sauvan, M. Schaefer, U. Schneekloth, T. Schörner-Sadenius, D. Schulte, A. Senol, A. Seryi, P. Sievers, A. N. Skrinsky, W. Smith, D. South, H. Spiesberger, A. M. Stasto, M. Strikman, M. Sullivan, S. Sultansoy, Y. P. Sun, B. Surrow, L. Szymanowski, P. Taels, I. Tapan, T. Tasci, E. Tassi, H. Ten. Kate, J. Terron, H. Thiesen, L. Thompson, P. Thompson, K. Tokushuku, R. Tomás García, D. Tommasini, D. Trbojevic, N. Tsoupas, J. Tuckmantel, S. Turkoz, T. N. Trinh, K. Tywoniuk, G. Unel, T. Ullrich, J. Urakawa, P. VanMechelen, A. Variola, R. Veness, A. Vivoli, P. Vobly, J. Wagner, R. Wallny, S. Wallon, G. Watt, C. Weiss, U. A. Wiedemann, U. Wienands, F. Willeke, B. -W. Xiao, V. Yakimenko, A. F. Zarnecki, Z. Zhang, F. Zimmermann, R. Zlebcik, F. Zomer

This document provides a brief overview of the recently published report on the design of the Large Hadron Electron Collider (LHeC), which comprises its physics programme, accelerator physics, technology and main detector concepts. The LHeC exploits and develops challenging, though principally existing, accelerator and detector technologies. This summary is complemented by brief illustrations of some of the highlights of the physics programme, which relies on a vastly extended kinematic range, luminosity and unprecedented precision in deep inelastic scattering. Read More

2012Sep
Affiliations: 1Fermilab, 2Fermilab, 3Fermilab, 4Fermilab, 5Fermilab, 6Fermilab, 7Fermilab, 8Fermilab, 9Fermilab, 10Fermilab, 11KEK, Tsukuba, 12KEK, Tsukuba

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented. Read More

2012Jul
Affiliations: 1Orsay and KEK, Tsukuba, 2Valencia U., IFIC, 3SLAC, 4Daresbury, 5Oxford U., JAI, 6KEK, Tsukuba, 7KEK, Tsukuba, 8Beijing, Inst. High Energy Phys., 9SLAC, 10Oxford U., JAI, 11Royal Holloway, U. of London, 12Savoie U., 13Royal Holloway, U. of London, 14Royal Holloway, U. of London, 15Oxford U., JAI, 16Oxford U., JAI, 17Oxford U., JAI, 18Oxford U., JAI, 19CERN, 20Royal Holloway, U. of London, 21DESY, 22Valencia U., IFIC, 23KEK, Tsukuba, 24Beijing, Inst. High Energy Phys., 25Savoie U., 26Fermilab, 27Ecole Polytechnique, 28KEK, Tsukuba, 29Kyungpook Natl. U., 30KEK, Tsukuba, 31Pohang Accelerator Lab., 32Pohang Accelerator Lab., 33Kyoto U., Inst. Chem. Res., 34Savoie U., 35Daresbury, 36Tokyo U., 37Royal Holloway, U. of London, 38Kyungpook Natl. U., 39Kyungpook Natl. U., 40Pohang Accelerator Lab., 41Tokyo U., 42KEK, Tsukuba, 43KEK, Tsukuba, 44KEK, Tsukuba, 45SLAC, 46University Coll. London, 47KEK, Tsukuba, 48SLAC, 49Royal Holloway, U. of London, 50KEK, Tsukuba, 51Tokyo U., 52SLAC, 53Tohoku U., 54KEK, Tsukuba, 55Tokyo U., 56Pohang Accelerator Lab., 57Brookhaven, 58SLAC, 59Oxford U., JAI, 60SLAC, 61SLAC, 62Orsay and KEK, Tsukuba, 63Oxford U., JAI, 64Orsay, 65Fermilab, 66Tohoku U., 67Manchester U., 68CERN, 69SLAC, 70SLAC, 71Tokyo U., 72KEK, Tsukuba, 73Oxford U., JAI, 74Hiroshima U., 75KEK, Tsukuba, 76KEK, Tsukuba, 77CERN, 78KEK, Tsukuba, 79Oxford U., JAI, 80Ecole Polytechnique, 81SLAC, 82Oxford U., JAI, 83Fermilab, 84SLAC, 85SLAC, 86Liverpool U., 87SLAC, 88Tokyo U., 89Tokyo U., 90SLAC, 91Tokyo U., 92KEK, Tsukuba, 93SLAC, 94CERN

ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometer level beam stability. Several advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European, and U. Read More

2012Jun
Authors: J. L. Abelleira Fernandez, C. Adolphsen, A. N. Akay, H. Aksakal, J. L. Albacete, S. Alekhin, P. Allport, V. Andreev, R. B. Appleby, E. Arikan, N. Armesto, G. Azuelos, M. Bai, D. Barber, J. Bartels, O. Behnke, J. Behr, A. S. Belyaev, I. Ben-Zvi, N. Bernard, S. Bertolucci, S. Bettoni, S. Biswal, J. Blümlein, H. Böttcher, A. Bogacz, C. Bracco, G. Brandt, H. Braun, S. Brodsky, O. Brüning, E. Bulyak, A. Buniatyan, H. Burkhardt, I. T. Cakir, O. Cakir, R. Calaga, V. Cetinkaya, E. Ciapala, R. Ciftci, A. K. Ciftci, B. A. Cole, J. C. Collins, O. Dadoun, J. Dainton, A. De. Roeck, D. d'Enterria, A. Dudarev, A. Eide, R. Enberg, E. Eroglu, K. J. Eskola, L. Favart, M. Fitterer, S. Forte, A. Gaddi, P. Gambino, H. García Morales, T. Gehrmann, P. Gladkikh, C. Glasman, R. Godbole, B. Goddard, T. Greenshaw, A. Guffanti, V. Guzey, C. Gwenlan, T. Han, Y. Hao, F. Haug, W. Herr, A. Hervé, B. J. Holzer, M. Ishitsuka, M. Jacquet, B. Jeanneret, J. M. Jimenez, J. M. Jowett, H. Jung, H. Karadeniz, D. Kayran, A. Kilic, K. Kimura, M. Klein, U. Klein, T. Kluge, F. Kocak, M. Korostelev, A. Kosmicki, P. Kostka, H. Kowalski, G. Kramer, D. Kuchler, M. Kuze, T. Lappi, P. Laycock, E. Levichev, S. Levonian, V. N. Litvinenko, A. Lombardi, J. Maeda, C. Marquet, S. J. Maxfield, B. Mellado, K. H. Mess, A. Milanese, S. Moch, I. I. Morozov, Y. Muttoni, S. Myers, S. Nandi, Z. Nergiz, P. R. Newman, T. Omori, J. Osborne, E. Paoloni, Y. Papaphilippou, C. Pascaud, H. Paukkunen, E. Perez, T. Pieloni, E. Pilicer, B. Pire, R. Placakyte, A. Polini, V. Ptitsyn, Y. Pupkov, V. Radescu, S. Raychaudhuri, L. Rinolfi, R. Rohini, J. Rojo, S. Russenschuck, M. Sahin, C. A. Salgado, K. Sampei, R. Sassot, E. Sauvan, U. Schneekloth, T. Schörner-Sadenius, D. Schulte, A. Senol, A. Seryi, P. Sievers, A. N. Skrinsky, W. Smith, H. Spiesberger, A. M. Stasto, M. Strikman, M. Sullivan, S. Sultansoy, Y. P. Sun, B. Surrow, L. Szymanowski, P. Taels, I. Tapan, A. T. Tasci, E. Tassi, H. Ten. Kate, J. Terron, H. Thiesen, L. Thompson, K. Tokushuku, R. Tomás García, D. Tommasini, D. Trbojevic, N. Tsoupas, J. Tuckmantel, S. Turkoz, T. N. Trinh, K. Tywoniuk, G. Unel, J. Urakawa, P. VanMechelen, A. Variola, R. Veness, A. Vivoli, P. Vobly, J. Wagner, R. Wallny, S. Wallon, G. Watt, C. Weiss, U. A. Wiedemann, U. Wienands, F. Willeke, B. -W. Xiao, V. Yakimenko, A. F. Zarnecki, Z. Zhang, F. Zimmermann, R. Zlebcik, F. Zomer

The physics programme and the design are described of a new collider for particle and nuclear physics, the Large Hadron Electron Collider (LHeC), in which a newly built electron beam of 60 GeV, up to possibly 140 GeV, energy collides with the intense hadron beams of the LHC. Compared to HERA, the kinematic range covered is extended by a factor of twenty in the negative four-momentum squared, $Q^2$, and in the inverse Bjorken $x$, while with the design luminosity of $10^{33}$ cm$^{-2}$s$^{-1}$ the LHeC is projected to exceed the integrated HERA luminosity by two orders of magnitude. The physics programme is devoted to an exploration of the energy frontier, complementing the LHC and its discovery potential for physics beyond the Standard Model with high precision deep inelastic scattering measurements. Read More

As part of the positron source R&D for future $e^+-e^-$ colliders and Compton based compact light sources, a high finesse non-planar four-mirror Fabry-Perot cavity has recently been installed at the ATF (KEK, Tsukuba, Japan). The first measurements of the gamma ray flux produced with a such cavity using a pulsed laser is presented here. We demonstrate the production of a flux of 2. Read More

Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of $e^-$ -- $e^+$ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-P\'erot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and is used to produce an intense flux of polarized gamma rays by Compton scattering \cite{ipac-mightylaser}. Read More

The next generation of e+/e- colliders will require a very intense flux of gamma rays to allow high current polarized positrons to be produced. This can be achieved by converting polarized high energy photons in polarized pairs into a target. In that context, an optical system consisting of a laser and a four-mirror passive Fabry-Perot cavity has recently been installed at the Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized gamma rays by inverse Compton scattering. Read More

A possible solution to realize a conventional positron source driven by a several-GeV electron beam for the International Linear Collider is proposed. A 300 Hz electron linac is employed to create positrons with stretching pulse length in order to cure target thermal load. ILC requires about 2600 bunches in a train which pulse length is 1 ms. Read More

A beam size monitor so called Shintake monitor, which uses the inverse Compton scattering between the laser interference fringe and the electron beam was designed for and installed at ATF2. The commissioning at ATF2 was started in the end of 2008 and succeeded in the measurement of the fringe pattern from the scattered gamma-rays. The present status of the Shintake monitor is described here. Read More

The beam test for the Shintake monitor succeeded in measuring signal modulation with the laser interference fringe pattern in November 2009. We have studied the error sources, and evaluated the systematic error to be less than 30% for 1 minute measurements. This paper centers on the evaluation of the Shintake monitor performance through analyzing beam tests deta. Read More

We performed a photon generation experiment by laser-Compton scattering at the KEK-ATF, aiming to develop a Compton based polarized positron source for linear colliders. In the experiment, laser pulses with a 357 MHz repetition rate were accumulated and their power was enhanced by up to 250 times in the Fabry-Perot optical resonant cavity. We succeeded in synchronizing the laser pulses and colliding them with the 1. Read More

IP-BPM (Interaction Point Beam Position Monitor) is an ultra high resolution cavity BPM to be used at ATF2, a test facility for ILC final focus system. Control of beam position in 2 nm precision is required for ATF2. Beam tests at ATF extraction line proved a 8. Read More

A new laser-wire is being installed in the extraction line of the ATF at KEK. This device aims at demonstrating that laser-wires can be used to measure micrometre scale beam size. Read More

We describe a scheme for producing polarised positrons at the ILC from polarised X-rays created by Compton scattering of a few-GeV electron beam off a CO2 or YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. Read More

We demonstrated for the first time the production of highly polarized short-pulse positrons with a finite energy spread in accordance with a new scheme that consists of two-quantum processes, such as inverse Compton scatterings and electron-positron pair creations. Using a circularly polarized laser beam of 532 nm scattered off a high-quality electron beam with the energy of 1.28 GeV, we obtained polarized positrons with an intensity of 10^4 e+/bunch. Read More

We derive a simple relation for estimating the relative emittance growth in x and y due to intrabeam scattering (IBS) in electron storage rings. We show that IBS calculations for the ATF damping ring, when using the formalism of Bjorken-Mtingwa, a modified formalism of Piwinski (where eta squared divided by beta has been replaced by the dispersion invariant), or a simple high-energy approximate formula all give results that agree well. Comparing theory, including the effect of potential well bunch lengthening, with a complete set of ATF steady-state beam size vs. Read More

2001Jun

At the Accelerator Test Facility (ATF) at KEK intrabeam scattering (IBS) is a strong effect for an electron machine. It is an effect that couples all dimensions of the beam, and in April 2000, over a short period of time, all dimensions were measured as functions of current. In this report we derive a simple relation for the growth rates of emittances due to IBS. Read More

We present energy spread and bunch length measurements at the Accelerator Test Facility (ATF) at KEK, as functions of current, for different ring rf voltages, and with the beam both on and off the coupling resonance. We fit the on-coupling bunch shapes to those of an impedance model consisting of a resistor and an inductor connected in series. We find that the fits are reasonably good, but that the resulting impedance is unexpectedly large. Read More

In April 2000 the single bunch energy spread, bunch length, horizontal emittance, and vertical emittance were measured as functions of current in KEK's ATF damping ring. In this report the measurement results are analyzed in light of intrabeam scattering theory. The measurements are found to be relatively consistent with theory, although the measured effects appear to be stronger than theory. Read More

2000Oct
Affiliations: 1SLAC, Stanford, CA, 2KEK, Tsukuba, Japan, 3KEK, Tsukuba, Japan, 4KEK, Tsukuba, Japan

This report presents bunch length and energy spread measurements performed in April 2000 at the ATF Damping Ring, at KEK. Measurements were performed with the beam on and then off the linear (difference) coupling resonance. Due to strong intra-beam scattering in the ATF ring, the results depended strongly on the coupling. Read More

2000Aug
Affiliations: 1Science University of Tokyo, 2Science University of Tokyo, 3KEK, Ibaraki, Japan, 4KEK, Ibaraki, Japan, 5KEK, Ibaraki, Japan

A double kicker system which extracts the ultra-low emittance multi-bunch beam stably from ATF damping ring was developed. The performance of the system was studied comparing an orbit jitter with single kicker extraction in single bunch mode. The position jitter reduction was estimated from the analysis of the extraction orbits. Read More

The rf distribution system for the linear collider requires stable x-band(11.424GHz) rf phase signal over 25km length. In order to realize the distribution system, a fiber optic link using a phase stabilized optical fiber was tested. Read More

A conceptual design work and a basic experimental study of a new beam profile monitor have been performed. The monitor will be used to measure emittance of an electron beam in the ATF damping ring at KEK, in which the transverse beam size of about 10 micron is expected. It utilizes a CW laser and an optical cavity, instead of a material wire, to minimize interference with an electron beam. Read More

1997Sep
Affiliations: 1Tokyo Metropolitan University, 2Tokyo Metropolitan University, 3Tokyo Metropolitan University, 4Tokyo Metropolitan University, 5Toyama Prefectural University, 6Toyama Prefectural University

To investigate the non-Fermi liquid (NFL) behavior in a nonalloyed system CeNi_2Ge_2, we have measured the temperature and field dependences of the specific heat C on a CeNi_2Ge_2 single crystal. The distinctive temperature dependence of C/T (~a-b*T^(1/2)) is destroyed in almost the same manner for both field directions of B//c-axis and B//a-axis. The overall behavior of C(T,B) and the low-temperature upturn in magnetic susceptibility can be reproduced, assuming an anomalous peak of the quasi-particle-band density-of-states (DOS) at the Fermi energy possessing (epsilon)^(1/2) energy dependence. Read More