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Now showing items 1 - 5 of 5

  • The Heavy Photon Search beamline and its performance

    Baltzell, N.   Egiyan, H.   Ehrhart, M.   Field, C.   Freyberger, A.   Girod, F.-X.   Holtrop, M.   Jaros, J.   Kalicy, G.   Maruyama, T.   McKinnon, B.   Moffeit, K.   Nelson, T.   Odian, A.   Oriunno, M.   Paremuzyan, R.   Stepanyan, S.   Tiefenback, M.   Uemura, S.   Ungaro, M.   Vance, H.  

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  • A radial time projection chamber for alpha detection in CLAS at JLab

    Dupre, R.   Stepanyan, S.   Hattawy, M.   Baltzell, N.   Hafidi, K.   Battaglieri, M.   Bueltmann, S.   Celentano, A.   De Vita, R.   El Alaoui, A.   El Fassi, L.   Fenker, H.   Kosheleva, K.   Kuhn, S.   Musico, P.   Minutoli, S.   Oliver, M.   Perrin, Y.   Torayev, B.   Voutier, E.  

    A new Radial Time Projection Chamber (RTPC) was developed at the Jefferson Laboratory to track low-energy nuclear recoils to measure exclusive nuclear reactions, such as coherent deeply virtual Compton scattering and coherent meson production off He-4. In 2009, we carried out these measurements using the CEBAF Large Acceptance Spectrometer (CLAS) supplemented by the RTPC positioned directly around a gaseous He-4 target, allowing a detection threshold as low as 12 MeV for He-4. This article discusses the design, principle of operation, calibration methods and performances of this RTPC.
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  • The CLAS12 superconducting magnets

    Fair, R.   Baltzell, N.   Bachimanchi, R.   Biallas, G.   Burkert, V. D.   Campero-Rojas, P.   Elementi, L.   Elouadrhiri, L.   Eng, B.   Ghoshal, P. K.   Hogan, J.   Insley, D.   Kashikhin, V   Kashy, D.   Krave, S.   Kumar, O.   Laney, M.   Legg, R.   Lagerquist, V   Lester, M.   Lemon, T.   Lung, A.   Luongo, C.   Matalevich, J.   Mestayer, M. D.   Miller, R.   Moore, W.   Newton, J.   Nobrega, F.   Pastor, O.   Philip, S.   Rajput-Ghoshal, R.   Ganni, V. Rao   Rode, C.   Sandoval, N.   Spiegel, S.   Tilles, D.   Tremblay, K.   Velev, G.   Wilson, C.   M Wiseman   Young, G. R.  

    As part of the Jefferson Lab 12 GeV upgrade, the Hall B CLAS12 system requires two superconducting iron-free magnets - a torus and a solenoid. The physics requirements to maximize space for the detectors guided engineers toward particular coil designs for each of the magnets which, in turn, led to the choice of using conduction cooling. The torus consists of 6 trapezoidal NbTi coils connected in series with an operating current of 3770 A. The solenoid is an actively shielded 5 T magnet consisting of 5 NbTi coils connected in series operating at 2416 A. Within the hall, the two magnets are located in close proximity to each other and are completely covered both inside and outside by particle detectors. Stringent size limitations were imposed for both magnets and introduced particular design and fabrication challenges. This paper describes the design, construction, installation, commissioning, and operation of the two magnets.
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  • The CLAS12 Silicon Vertex Tracker

    Antonioli, M. A.   Baltzell, N.   Boyarinov, S.   Bonneau, P.   Christo, S.   Cuevas, C.   Defurne, M.   Derylo, G.   Elouadrhiri, L.   Eng, B.   Ewing, T.   Gilfoyle, G.   Gotra, Y.   Leffel, M.   Mandal, S.   Marzolf, B.   McMullen, M.   Merkin, M.   Miller, R.   Raydo, B.   Teachey, W.   Tucker, R.   Ungaro, M.   Yegneswaran, A.   Zana, L.   Ziegler, V  

    For the 12 GeV upgrade of Jefferson Laboratory, a Silicon Vertex Tracker (SVT) has been designed for the CLAS12 spectrometer using single-sided microstrip sensors fabricated by Hamamatsu Photonics. The sensors have a graded angle design to minimize dead areas and a readout pitch of 156 nm, with intermediate strips. Each double-sided SVT module hosts three daisy-chained sensors on each side with a full strip length of 33 cm. There are 512 channels per module, read out by four Fermilab Silicon Strip Readout (FSSR2) chips, featuring data-driven architecture, mounted on a rigid-flex hybrid board. The modules are assembled in a barrel configuration using a unique cantilevered geometry to minimize the amount of material in the tracking volume. This paper is focused on the design, qualification of the performance, and experience in operating and commissioning the tracker during the first year of the data taking.
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  • The Heavy Photon Search beamline and its performance

    Baltzell, N.   Egiyan, H.   Ehrhart, M.   Field, C.   Freyberger, A.   Girod, F. -X.   Holtrop, M.   Jaros, J.   Kalicy, G.   Maruyama, T.   McKinnon, B.   Moffeit, K.   Nelson, T.   Odian, A.   Oriunno, M.   Paremuzyan, R.   Stepanyan, S.   Tiefenback, M.   Uemura, S.   Ungaro, M.   Vance, H.  

    The Heavy Photon Search (HPS) is an experiment to search for a hidden sector photon, aka a heavy photon or dark photon, in fixed target electroproduction at the Thomas Jefferson National Accelerator Facility (JLab). The HPS experiment searches for the e(+)e(-) decay of the heavy photon with bump hunt and detached vertex strategies using a compact, large acceptance forward spectrometer, consisting of a silicon microstrip detector (SVT) for tracking and vertexing, and a PbWO4 electromagnetic calorimeter for energy measurement and fast triggering. To achieve large acceptance and good vertexing resolution, the first layer of silicon detectors is placed just 10 cm downstream of the target with the sensor edges only 500 mu m above and below the beam. Placing the SVT in such close proximity to the beam puts stringent requirements on the beam profile and beam position stability. As part of an approved engineering run, HPS took data in 2015 and 2016 at 1.05 GeV and 2.3 GeV beam energies, respectively. This paper describes the beam line and its performance during that data taking.
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