The CLAS12 Spectrometer at Jefferson Laboratory

V. D. Burkert*, L. Elouadrhiri, K. P. Adhikari, S. Adhikari, M. J. Amaryan, D. Anderson, G. Angelini, M. Antonioli, H. Atac, S. Aune, H. Avakian, C. Ayerbe Gayoso, N. Baltzell, L. Barion, M. Battaglieri, V. Baturin, I. Bedlinskiy, F. Benmokhtar, A. Bianconi, A. S. BiselliP. Bonneau, F. Bossù, S. Boyarinov, W. J. Briscoe, W. K. Brooks, K. Bruhwel, D. S. Carman, A. Celentano, G. Charles, P. Chatagnon, T. Chetry, G. Christiaens, S. Christo, G. Ciullo, B. A. Clary, P. L. Cole, M. Contalbrigo, M. Cook, V. Crede, R. Cruz-Torres, C. Cuevas, A. D'Angelo, N. Dashyan, M. Defurne, A. Deur, R. De Vita, S. Diehl, C. Djalali, G. Dodge, R. Dupre, M. Ehrhart, L. El Fassi, B. Eng, T. Ewing, R. Fair, G. Fedotov, A. Filippi, T. A. Forest, M. Garçon, G. Gavalian, P. Ghoshal, G. P. Gilfoyle, K. Giovanetti, F. X. Girod, D. I. Glazier, E. Golovatch, R. W. Gothe, Y. Gotra, K. A. Griffioen, M. Guidal, V. Gyurjyan, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, F. Hauenstein, T. B. Hayward, D. Heddle, P. Hemler, O. A. Hen, K. Hicks, A. Hobart, J. Hogan, M. Holtrop, Y. Ilieva, I. Illari, D. Insley, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, G. Jacobs, H. S. Jo, R. Johnston, K. Joo, S. Joosten, T. Kageya, D. Kashy, C. Keith, D. Keller, M. Khachatryan, A. Khanal, A. Kim, C. W. Kim, W. Kim, V. Kubarovsky, S. E. Kuhn, L. Lanza, M. Leffel, V. Lucherini, A. Lung, M. L. Kabir, M. Leali, S. Lee, P. Lenisa, K. Livingston, M. Lowry, I. J.D. MacGregor, I. Mandjavidze, D. Marchand, N. Markov, V. Mascagna, B. McKinnon, M. McMullen, C. Mealer, M. D. Mestayer, Z. E. Meziani, R. Miller, R. G. Milner, T. Mineeva, M. Mirazita, V. Mokeev, P. Moran, A. Movsisyan, C. Munoz Camacho, P. Naidoo, S. Nanda, J. Newton, S. Niccolai, G. Niculescu, M. Osipenko, M. Paolone, L. L. Pappalardo, R. Paremuzyan, O. Pastor, E. Pasyuk, W. Phelps, O. Pogorelko, J. Poudel, J. W. Price, K. Price, S. Procureur, Y. Prok, D. Protopopescu, R. Rajput-Ghoshal, B. A. Raue, B. Raydo, M. Ripani, J. Ritman, A. Rizzo, G. Rosner, P. Rossi, J. Rowley, B. J. Roy, F. Sabatié, C. Salgado, S. Schadmand, A. Schmidt, E. P. Segarra, V. Sergeyeva, Y. G. Sharabian, U. Shrestha, Iu Skorodumina, G. D. Smith, L. C. Smith, D. Sokhan, O. Soto, N.Sparveris, S. Stepanyan, P. Stoler, S. Strauch, J. A. Tan, M. Taylor, D. Tilles, M. Turisini, N. Tyler, M. Ungaro, L. Venturelli, H. Voskanyan, E. Voutier, D. Watts, X. Wei, L. B. Weinstein, C. Wiggins, M. Wiseman, M. H. Wood, A. Yegneswaran, G. Young, N. Zachariou, M. Zarecky, J. Zhang, Z. W. Zhao, V. Ziegler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The CEBAF Large Acceptance Spectrometer for operation at 12 GeV beam energy (CLAS12) in Hall B at Jefferson Laboratory is used to study electro-induced nuclear and hadronic reactions. This spectrometer provides efficient detection of charged and neutral particles over a large fraction of the full solid angle. CLAS12 has been part of the energy-doubling project of Jefferson Lab's Continuous Electron Beam Accelerator Facility, funded by the United States Department of Energy. An international collaboration of 48 institutions contributed to the design and construction of detector hardware, developed the software packages for the simulation of complex event patterns, and commissioned the detector systems. CLAS12 is based on a dual-magnet system with a superconducting torus magnet that provides a largely azimuthal field distribution that covers the forward polar angle range up to 35, and a solenoid magnet and detector covering the polar angles from 35° to 125° with full azimuthal coverage. Trajectory reconstruction in the forward direction using drift chambers and in the central direction using a vertex tracker results in momentum resolutions of <1% and <3%, respectively. Cherenkov counters, time-of-flight scintillators, and electromagnetic calorimeters provide good particle identification. Fast triggering and high data-acquisition rates allow operation at a luminosity of 1035 cm−2s−1. These capabilities are being used in a broad program to study the structure and interactions of nucleons, nuclei, and mesons, using polarized and unpolarized electron beams and targets for beam energies up to 11 GeV. This paper gives a general description of the design, construction, and performance of CLAS12.

Original languageEnglish
Article number163419
Number of pages27
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Early online date18 Jan 2020
Publication statusPublished - 11 Apr 2020

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© 2020 Published by Elsevier B.V. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy.


  • CLAS12
  • Electromagnetic physics
  • Large acceptance
  • Luminosity
  • Magnetic spectrometer

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