HPS: A proposal to Search for Massive Photons at Jefferson Laboratory HPS HEAVY PHOTON SEARCH A Proposal to Search for Massive Photons at Jefferson Laboratory December 1, 2010 1 HPS: A proposal to Search for Massive Photons at Jefferson Laboratory Authors A. Grillo, V. Fadeyev University of California, Santa Cruz, CA 95064 M. Ungaro University of Connecticut, Department of Physics, Storrs, CT 06269 W. Cooper Fermi National Accelerator Laboratory, Batavia, IL 60510-5011 A. Micherdzinska The George Washington University, Department of Physics,Washington, DC 20052 G. Ron Hebrew University of Jerusalem, Jerusalem, Israel M. Battaglieri, R. De Vita INFN, Sezione di Genova, 16146 Genova, Italy M. Holtrop (Co-Spokesperson), K. Slifer, S. K. Phillips, E. Ebrahim University of New Hampshire, Department of Physics, Durham, NH 03824 M. Khandaker, C. Salgado Norfolk State University, Department of Physics, Norfolk, VA 23504 S. Bueltmann, L. Weinstein Old Dominion University, Department of Physics, Norfolk, VA 23529 A. Fradi, B. Guegan, M. Guidal, S. Niccolai, S. Pisano, E. Rauly, P. Rosier and D. Sokhan Institut de Physique Nucleaire d'Orsay, 91405 Orsay, France P. Schuster, N. Toro Perimeter Institute, Ontario, Canada N2L 2Y5 P. Stoler, A. Kubarovsky Rensselaer Polytechnic Institute, Department of Physics, Troy, NY 12181 2 HPS: A proposal to Search for Massive Photons at Jefferson Laboratory R. Essig, C. Field, M. Graham, G. Haller, R. Herbst, J. Jaros (Co-Spokesperson), C. Kenney, T. Maruyama, K. Moffeit, T. Nelson, H. Neal, A. Odian, M. Oriunno, R. Partridge, D. Walz SLAC National Accelerator Laboratory, Menlo Park, CA 94025 S. Boyarinov, V. Burkert, A. Deur, H. Egiyan, L. Elouadrhiri, A. Freyberger, F.-X. Girod, V. Kubarovsky, Y. Sharabian, S. Stepanyan (Co-Spokesperson), B. Wojtsekhowski Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 K. Griffioen The College of William and Mary, Department of Physics, Williamsburg, VA 23185 N. Dashyan, N. Gevorgyan, R. Paremuzyan, H. Voskanyan Yerevan Physics Institute, 375036 Yerevan, Armenia 3 HPS: A proposal to Search for Massive Photons at Jefferson Laboratory Table of Contents 1 Introduction ............................................................................................................................................................... 8 1.1 References ................................................................................................................................................ 10 2 Physics Motivation .................................................................................................................................................. 11 2.1 Motivation for New Physics Near the GeV Scale ................................................................... 11 2.2 Motivation for an A' from Dark Matter ...................................................................................... 14 2.3 Current Limits on Light U(1) Gauge Bosons ........................................................................... 18 2.4 References ................................................................................................................................................ 20 3 Signal and Backgrounds ......................................................................................................................................... 24 3.1 Heavy Photon Signal .......................................................................................................................... 24 3.2 Radiative and Bethe-Heitler Trident backgrounds ................................................................ 26 3.3 Beam Backgrounds .............................................................................................................................. 28 3.4 References ................................................................................................................................................ 28 4 Experimental Setup ................................................................................................................................................. 30 4.1 Overview .................................................................................................................................................. 30 4.2 Beamline Elements ............................................................................................................................... 31 4.2.1 Layout ................................................................................................................................................ 31 4.2.2 Running Conditions ..................................................................................................................... 34 4.2.3 Beamline Proposal ........................................................................................................................ 35 4.2.4 Targets ................................................................................................................................................ 38 4.3 Tracking and Vertexing System ..................................................................................................... 41 4.3.1 Design Considerations ................................................................................................................ 41 4.3.2 Sensors ............................................................................................................................................... 41 4.3.3 Readout Electronics ...................................................................................................................... 42 4.3.4 Detector Layout .............................................................................................................................. 45 4.3.5 Sensor Modules and Mechanical Support .......................................................................... 50 4.3.6 Vacuum Chamber ......................................................................................................................... 53 4.3.7 References ......................................................................................................................................... 55 4.4 Electromagnetic Calorimeter ........................................................................................................... 56 4.4.1 The Inner Calorimeter ................................................................................................................. 58 4.4.2 The Outer Calorimeter ................................................................................................................ 59 4.4.3 ECal Assembly ............................................................................................................................... 60 4.4.4 Electronics ........................................................................................................................................ 60 4.5 Muon System ......................................................................................................................................... 61 4.5.1 Simulation of the Muon System .............................................................................................. 61 4.5.2 Detector Concept ........................................................................................................................... 64 4.6 Electronics and DAQ .......................................................................................................................... 66 4 HPS: A proposal to Search for Massive Photons at Jefferson Laboratory 4.6.1 Electromagnetic Calorimeter Systems .................................................................................. 67 4.6.2 Silicon Vertex Tracker System ................................................................................................. 68 4.6.3 Muon System .................................................................................................................................... 69 4.6.4 System Timing ................................................................................................................................ 69 4.6.5 Level 1 Trigger ................................................................................................................................ 70 4.6.6 Trigger Deadtime .......................................................................................................................... 72 4.6.7 Dataflow ............................................................................................................................................ 72 4.6.8 Level 3 Sofware Filter .................................................................................................................. 73 4.6.9 Monitoring and Calibration ...................................................................................................... 74 4.6.10 Readout Controllers, Computing and Network ............................................................ 74 4.7 Offline Computing Model for the HPS Experiment .............................................................. 74 4.7.1 Data Taking ...................................................................................................................................... 74 4.7.2 Reconstruction Passes ................................................................................................................. 75 4.7.3 Monte Carlo ....................................................................................................................................