Showing 1–19 of 19 results for author: Freyberger, A

The Continuous Electron Beam Accelerator Facility at 12 GeV

Authors: P. A. Adderley, S. Ahmed, T. Allison, R. Bachimanchi, K. Baggett, M. BastaniNejad, B. Bevins, M. Bevins, M. Bickley, R. M. Bodenstein, S. A. Bogacz, M. Bruker, A. Burrill, L. Cardman, J. Creel, Y. -C. Chao, G. Cheng, G. Ciovati, S. Chattopadhyay, J. Clark, W. A. Clemens, G. Croke, E. Daly, G. K. Davis, J. Delayen , et al. (114 additional authors not shown)

Abstract: This review paper describes the energy-upgraded CEBAF accelerator. This superconducting linac has achieved 12 GeV beam energy by adding 11 new high-performance cryomodules containing eighty-eight superconducting cavities that have operated CW at an average accelerating gradient of 20 MV/m. After reviewing the attributes and performance of the previous 6 GeV CEBAF accelerator, we discuss the upgrad… ▽ More This review paper describes the energy-upgraded CEBAF accelerator. This superconducting linac has achieved 12 GeV beam energy by adding 11 new high-performance cryomodules containing eighty-eight superconducting cavities that have operated CW at an average accelerating gradient of 20 MV/m. After reviewing the attributes and performance of the previous 6 GeV CEBAF accelerator, we discuss the upgraded CEBAF accelerator system in detail with particular attention paid to the new beam acceleration systems. In addition to doubling the acceleration in each linac, the upgrade included improving the beam recirculation magnets, adding more helium cooling capacity to allow the newly installed modules to run cold, adding a new experimental hall, and improving numerous other accelerator components. We review several of the techniques deployed to operate and analyze the accelerator performance, and document system operating experience and performance. In the final portion of the document, we present much of the current planning regarding projects to improve accelerator performance and enhance operating margins, and our plans for ensuring CEBAF operates reliably into the future. For the benefit of potential users of CEBAF, the performance and quality measures for beam delivered to each of the experimental halls is summarized in the appendix. △ Less

Submitted 29 August, 2024; originally announced August 2024.

Comments: 66 pages, 73 figures, 21 tables

Report number: JLAB-ACC-23-3940

Journal ref: Phys. Rev. Accel. Beams 27 (2024) 084802

Measuring the cross section of the $^{15}$N($α$,$γ$)$^{19}$F reaction using a single-fluid bubble chamber

Authors: D. Neto, K. Bailey, J. F. Benesch, B. Cade, B. DiGiovine, A. Freyberger, J. M. Grames, A. Hofler, R. J. Holt, R. Kazimi, D. Meekins, M. McCaughan, D. Moser, T. O'Connor, M. Poelker, K. E. Rehm, S. Riordan, R. Suleiman, R. Talwar, C. Ugalde

Abstract: $^{15}$N($α$,$γ$)$^{19}… ▽ More $^{15}$N($α$,$γ$)$^{19}$F is believed to be the primary means of stellar nucleosynthesis of fluorine. Here we present the use of a single-fluid bubble chamber to measure the cross section of the time-inverse photo-dissociation reaction. The method benefits from a luminosity increase of several orders of magnitude due to the use of a thicker liquid target -- when compared to thin films or gas targets -- and from the reciprocity theorem. We discuss the results of an experiment at the Thomas Jefferson National Accelerator Facility, where the cross section of the photodisintegration process $^{19}$F($γ$, $α$)$^{15}$N was measured by bombarding a superheated fluid of C$_3$F$_8$ with bremsstrahlung $γ$-rays produced by impinging a 4 - 5.5 MeV electron beam on a Cu radiator. From the photodissociation yield the cross section was extracted by performing a convolution with a Monte Carlo-generated $γ$-ray beam spectrum. The measurement produced a cross section that was then time inverted using the reciprocity theorem. The cross section for the $^{15}$N($α$,$γ$)$^{19}$F reaction was determined down to a value in the range of hundreds of picobarns. With further improvements of the experimental setup the technique could potentially push cross section measurements down to the single picobarn range. △ Less

Submitted 6 March, 2023; v1 submitted 24 February, 2023; originally announced February 2023.

Comments: Corrected Typos. Accepted for Publication in Physical Review C

Searching for Prompt and Long-Lived Dark Photons in Electro-Produced $e^+e^-$ Pairs with the Heavy Photon Search Experiment at JLab

Authors: P. H. Adrian, N. A. Baltzell, M. Battaglieri, M. Bondi, S. Boyarinov, C. Bravo, S. Bueltmann, P. Butti, V. D. Burkert, D. Calvo, T. Cao, M. Carpinelli, A. Celentano, G. Charles, L. Colaneri, W. Cooper, C. Cuevas, A. D'Angelo, N. Dashyan, M. De Napoli, R. De Vita, A. Deur, M. Diamond, R. Dupre, H. Egiyan , et al. (59 additional authors not shown)

Abstract: The Heavy Photon Search experiment (HPS) at the Thomas Jefferson National Accelerator Facility searches for electro-produced dark photons. We report results from the 2016 Engineering Run consisting of 10608/nb of data for both the prompt and displaced vertex searches. A search for a prompt resonance in the $e^+e^-$ invariant mass distribution between 39 and 179 MeV showed no evidence of dark photo… ▽ More The Heavy Photon Search experiment (HPS) at the Thomas Jefferson National Accelerator Facility searches for electro-produced dark photons. We report results from the 2016 Engineering Run consisting of 10608/nb of data for both the prompt and displaced vertex searches. A search for a prompt resonance in the $e^+e^-$ invariant mass distribution between 39 and 179 MeV showed no evidence of dark photons above the large QED background, limiting the coupling of ε^2 {\geq} 10^-5, in agreement with previous searches. The search for displaced vertices showed no evidence of excess signal over background in the masses between 60 and 150 MeV, but had insufficient luminosity to limit canonical heavy photon production. This is the first displaced vertex search result published by HPS. HPS has taken high-luminosity data runs in 2019 and 2021 that will explore new dark photon phase space. △ Less

Submitted 12 July, 2023; v1 submitted 20 December, 2022; originally announced December 2022.

Comments: 28 pages, 46 figures

Report number: JLAB-PHY-23-3738

Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab -- 2018 update to PR12-16-001

Authors: M. Battaglieri, A. Bersani, G. Bracco, B. Caiffi, A. Celentano, R. De Vita, L. Marsicano, P. Musico, F. Panza, M. Ripani, E. Santopinto, M. Taiuti, V. Bellini, M. Bondi', P. Castorina, M. De Napoli, A. Italiano, V. Kuznetzov, E. Leonora, F. Mammoliti, N. Randazzo, L. Re, G. Russo, M. Russo, A. Shahinyan , et al. (100 additional authors not shown)

Abstract: This document complements and completes what was submitted last year to PAC45 as an update to the proposal PR12-16-001 "Dark matter search in a Beam-Dump eXperiment (BDX)" at Jefferson Lab submitted to JLab-PAC44 in 2016. Following the suggestions contained in the PAC45 report, in coordination with the lab, we ran a test to assess the beam-related backgrounds and validate the simulation framework… ▽ More This document complements and completes what was submitted last year to PAC45 as an update to the proposal PR12-16-001 "Dark matter search in a Beam-Dump eXperiment (BDX)" at Jefferson Lab submitted to JLab-PAC44 in 2016. Following the suggestions contained in the PAC45 report, in coordination with the lab, we ran a test to assess the beam-related backgrounds and validate the simulation framework used to design the BDX experiment. Using a common Monte Carlo framework for the test and the proposed experiment, we optimized the selection cuts to maximize the reach considering simultaneously the signal, cosmic-ray background (assessed in Catania test with BDX-Proto) and beam-related backgrounds (irreducible NC and CC neutrino interactions as determined by simulation). Our results confirmed what was presented in the original proposal: with 285 days of a parasitic run at 65 $μ$A (corresponding to $10^{22}$ EOT) the BDX experiment will lower the exclusion limits in the case of no signal by one to two orders of magnitude in the parameter space of dark-matter coupling versus mass. △ Less

Submitted 8 October, 2019; originally announced October 2019.

Report number: PR12-16-001

Search for a Dark Photon in Electro-Produced $e^{+}e^{-}$ Pairs with the Heavy Photon Search Experiment at JLab

Authors: P. H. Adrian, N. A. Baltzell, M. Battaglieri, M. Bondí, S. Boyarinov, S. Bueltmann, V. D. Burkert, D. Calvo, M. Carpinelli, A. Celentano, G. Charles, L. Colaneri, W. Cooper, C. Cuevas, A. D'Angelo, N. Dashyan, M. De Napoli, R. De Vita, A. Deur, R. Dupre, H. Egiyan, L. Elouadrhiri, R. Essig, V. Fadeyev, C. Field , et al. (52 additional authors not shown)

Abstract: The Heavy Photon Search experiment took its first data in a 2015 engineering run using a 1.056 GeV, 50 nA electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility, searching for an electro-produced dark photon. Using 1.7 days (1170 nb$^{-1}$) of data, a search for a resonance in the $e^{+}e^{-}$ invariant mass distribution between 19 and 81 MeV/c$^2$ showed no evidence… ▽ More The Heavy Photon Search experiment took its first data in a 2015 engineering run using a 1.056 GeV, 50 nA electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility, searching for an electro-produced dark photon. Using 1.7 days (1170 nb$^{-1}$) of data, a search for a resonance in the $e^{+}e^{-}$ invariant mass distribution between 19 and 81 MeV/c$^2$ showed no evidence of dark photon decays above the large QED background, confirming earlier searches and demonstrating the full functionality of the experiment. Upper limits on the square of the coupling of the dark photon to the Standard Model photon are set at the level of 6$\times$10$^{-6}$. In addition, a search for displaced dark photon decays did not rule out any territory but resulted in a reliable analysis procedure that will probe hitherto unexplored parameter space with future, higher luminosity runs. △ Less

Submitted 5 December, 2018; originally announced December 2018.

Comments: 8 pages, Proceedings of the 39th International Conference on High Energy Physics (ICHEP 2018), 4-11 July, 2018, Seoul, Korea

Search for a Dark Photon in Electro-Produced $e^{+}e^{-}$ Pairs with the Heavy Photon Search Experiment at JLab

Authors: P. H. Adrian, N. A. Baltzell, M. Battaglieri, M. Bondí, S. Boyarinov, S. Bueltmann, V. D. Burkert, D. Calvo, M. Carpinelli, A. Celentano, G. Charles, L. Colaneri, W. Cooper, C. Cuevas, A. D'Angelo, N. Dashyan, M. De Napoli, R. De Vita, A. Deur, R. Dupre, H. Egiyan, L. Elouadrhiri, R. Essig, V. Fadeyev, C. Field , et al. (52 additional authors not shown)

Abstract: The Heavy Photon Search experiment took its first data in a 2015 engineering run at the Thomas Jefferson National Accelerator Facility, searching for a prompt, electro-produced dark photon with a mass between 19 and 81 MeV/$c^2$. A search for a resonance in the $e^{+}e^{-}$ invariant mass distribution, using 1.7 days (1170 nb$^{-1}$) of data, showed no evidence of dark photon decays above the larg… ▽ More The Heavy Photon Search experiment took its first data in a 2015 engineering run at the Thomas Jefferson National Accelerator Facility, searching for a prompt, electro-produced dark photon with a mass between 19 and 81 MeV/$c^2$. A search for a resonance in the $e^{+}e^{-}$ invariant mass distribution, using 1.7 days (1170 nb$^{-1}$) of data, showed no evidence of dark photon decays above the large QED background, confirming earlier searches and demonstrating the full functionality of the experiment. Upper limits on the square of the coupling of the dark photon to the Standard Model photon are set at the level of 6$\times$10$^{-6}$. Future runs with higher luminosity will explore new territory. △ Less

Submitted 3 August, 2018; v1 submitted 30 July, 2018; originally announced July 2018.

Journal ref: Phys. Rev. D 98, 091101 (2018)

Dispersive Corrections to the Born Approximation in Elastic Electron-Nucleus Scattering in the Intermediate Energy Regime

Authors: P. Gueye, A. A. Kabir J. Glister, B. W. Lee, R. Gilman, D. W. Higinbotham, E. Piasetzky, G. Ron, A. J. Sarty, S. Strauch, A. Adeyemi, K. Allada, W. Armstrong, J. Arrington, H. Arenhovel, A. Beck, F. Benmokhtar, B. L. Berman, W. Boeglin, E. Brash, A. Camsonne, J. Calarco, J. P. Chen, S. Choi, E. Chudakov, L. Coman , et al. (67 additional authors not shown)

Abstract: Measurements of elastic electron scattering data within the past decade have highlighted two-photon exchange contributions as a necessary ingredient in theoretical calculations to precisely evaluate hydrogen elastic scattering cross sections. This correction can modify the cross section at the few percent level. In contrast, dispersive effects can cause significantly larger changes from the Born a… ▽ More Measurements of elastic electron scattering data within the past decade have highlighted two-photon exchange contributions as a necessary ingredient in theoretical calculations to precisely evaluate hydrogen elastic scattering cross sections. This correction can modify the cross section at the few percent level. In contrast, dispersive effects can cause significantly larger changes from the Born approximation. The purpose of this experiment is to extract the carbon-12 elastic cross section around the first diffraction minimum, where the Born term contributions to the cross section are small to maximize the sensitivity to dispersive effects. The analysis uses the LEDEX data from the high resolution Jefferson Lab Hall A spectrometers to extract the cross sections near the first diffraction minimum of 12C at beam energies of 362 MeV and 685 MeV. The results are in very good agreement with previous world data, although with less precision. The average deviation from a static nuclear charge distribution expected from linear and quadratic fits indicate a 30.6% contribution of dispersive effects to the cross section at 1 GeV. The magnitude of the dispersive effects near the first diffraction minimum of 12C has been confirmed to be large with a strong energy dependence and could account for a large fraction of the magnitude for the observed quenching of the longitudinal nuclear response. These effects could also be important for nuclei radii extracted from parity-violating asymmetries measured near a diffraction minimum. △ Less

Submitted 30 March, 2020; v1 submitted 31 May, 2018; originally announced May 2018.

Comments: 14 pages, 10 figures

Report number: JLAB-PHY-18-2707

Journal ref: Eur. Phys. J. A 56 (2020) 126

Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab: an update on PR12-16-001

Authors: M. Battaglieri, A. Bersani, G. Bracco, B. Caiffi, A. Celentano, R. De Vita, L. Marsicano, P. Musico, M. Osipenko, F. Panza, M. Ripani, E. Santopinto, M. Taiuti, V. Bellini, M. Bondi', P. Castorina, M. De Napoli, A. Italiano, V. Kuznetzov, E. Leonora, F. Mammoliti, N. Randazzo, L. Re, G. Russo, M. Russo , et al. (101 additional authors not shown)

Abstract: This document is an update to the proposal PR12-16-001 Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab submitted to JLab-PAC44 in 2016 reporting progress in addressing questions raised regarding the beam-on backgrounds. The concerns are addressed by adopting a new simulation tool, FLUKA, and planning measurements of muon fluxes from the dump with its existing shielding around t… ▽ More This document is an update to the proposal PR12-16-001 Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab submitted to JLab-PAC44 in 2016 reporting progress in addressing questions raised regarding the beam-on backgrounds. The concerns are addressed by adopting a new simulation tool, FLUKA, and planning measurements of muon fluxes from the dump with its existing shielding around the dump. First, we have implemented the detailed BDX experimental geometry into a FLUKA simulation, in consultation with experts from the JLab Radiation Control Group. The FLUKA simulation has been compared directly to our GEANT4 simulations and shown to agree in regions of validity. The FLUKA interaction package, with a tuned set of biasing weights, is naturally able to generate reliable particle distributions with very small probabilities and therefore predict rates at the detector location beyond the planned shielding around the beam dump. Second, we have developed a plan to conduct measurements of the muon ux from the Hall-A dump in its current configuration to validate our simulations. △ Less

Submitted 8 January, 2018; v1 submitted 5 December, 2017; originally announced December 2017.

Comments: Document submitted to JLab PAC 45

Report number: FERMILAB-TM-2667-PPD

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

Authors: Marco Battaglieri, Alberto Belloni, Aaron Chou, Priscilla Cushman, Bertrand Echenard, Rouven Essig, Juan Estrada, Jonathan L. Feng, Brenna Flaugher, Patrick J. Fox, Peter Graham, Carter Hall, Roni Harnik, JoAnne Hewett, Joseph Incandela, Eder Izaguirre, Daniel McKinsey, Matthew Pyle, Natalie Roe, Gray Rybka, Pierre Sikivie, Tim M. P. Tait, Natalia Toro, Richard Van De Water, Neal Weiner , et al. (226 additional authors not shown)

Abstract: This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017. This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017. △ Less

Submitted 14 July, 2017; originally announced July 2017.

Comments: 102 pages + references

The Heavy Photon Search beamline and its performance

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

Abstract: 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, consistin… ▽ More 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 PbWO$_4$ 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 $μ$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. △ Less

Submitted 22 December, 2016; originally announced December 2016.

Dark Sectors 2016 Workshop: Community Report

Authors: Jim Alexander, Marco Battaglieri, Bertrand Echenard, Rouven Essig, Matthew Graham, Eder Izaguirre, John Jaros, Gordan Krnjaic, Jeremy Mardon, David Morrissey, Tim Nelson, Maxim Perelstein, Matt Pyle, Adam Ritz, Philip Schuster, Brian Shuve, Natalia Toro, Richard G Van De Water, Daniel Akerib, Haipeng An, Konrad Aniol, Isaac J. Arnquist, David M. Asner, Henning O. Back, Keith Baker , et al. (179 additional authors not shown)

Abstract: This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. △ Less

Submitted 30 August, 2016; originally announced August 2016.

Comments: 66 pages, 15 figures, 3 tables. Workshop website and agenda: http://www-conf.slac.stanford.edu/darksectors2016/ https://indico.cern.ch/event/507783/ Editors: J. Alexander, M. Battaglieri, B. Echenard, R. Essig, M. Graham, E. Izaguirre, J. Jaros, G. Krnjaic, J. Mardon, D. Morrissey, T. Nelson, M. Perelstein, M. Pyle, A. Ritz, P. Schuster, B. Shuve, N. Toro, R. Van De Water

Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab

Authors: M. Battaglieri, A. Bersani, B. Caiffi, A. Celentano, R. De Vita, E. Fanchini, L. Marsicano, P. Musico, M. Osipenko, F. Panza, M. Ripani, E. Santopinto, M. Taiuti, V. Bellini, M. Bondí, M. De Napoli, F. Mammoliti, E. Leonora, N. Randazzo, G. Russo, M. Sperduto, C. Sutera, F. Tortorici, N. Baltzell, M. Dalton , et al. (79 additional authors not shown)

Abstract: MeV-GeV dark matter (DM) is theoretically well motivated but remarkably unexplored. This proposal presents the MeV-GeV DM discovery potential for a $\sim$1 m$^3$ segmented CsI(Tl) scintillator detector placed downstream of the Hall A beam-dump at Jefferson Lab, receiving up to 10$^{22}$ electrons-on-target (EOT) in 285 days. This experiment (Beam-Dump eXperiment or BDX) would be sensitive to elast… ▽ More MeV-GeV dark matter (DM) is theoretically well motivated but remarkably unexplored. This proposal presents the MeV-GeV DM discovery potential for a $\sim$1 m$^3$ segmented CsI(Tl) scintillator detector placed downstream of the Hall A beam-dump at Jefferson Lab, receiving up to 10$^{22}$ electrons-on-target (EOT) in 285 days. This experiment (Beam-Dump eXperiment or BDX) would be sensitive to elastic DM-electron and to inelastic DM scattering at the level of 10 counts per year, reaching the limit of the neutrino irreducible background. The distinct signature of a DM interaction will be an electromagnetic shower of few hundreds of MeV, together with a reduced activity in the surrounding active veto counters. A detailed description of the DM particle $χ$ production in the dump and subsequent interaction in the detector has been performed by means of Monte Carlo simulations. Different approaches have been used to evaluate the expected backgrounds: the cosmogenic background has been extrapolated from the results obtained with a prototype detector running at INFN-LNS (Italy), while the beam-related background has been evaluated by GEANT4 Monte Carlo simulations. The proposed experiment will be sensitive to large regions of DM parameter space, exceeding the discovery potential of existing and planned experiments in the MeV-GeV DM mass range by up to two orders of magnitude. △ Less

Submitted 5 July, 2016; originally announced July 2016.

Comments: Proposal submitted to the 44th JLab PAC. 125 pages, 60 figures

Production of highly-polarized positrons using polarized electrons at MeV energies

Authors: D. Abbott, P. Adderley, A. Adeyemi, P. Aguilera, M. Ali, H. Areti, M. Baylac, J. Benesch, G. Bosson, B. Cade, A. Camsonne, L. S. Cardman, J. Clark, P. Cole, S. Covert, C. Cuevas, O. Dadoun, D. Dale, H. Dong, J. Dumas, E. Fanchini, T. Forest, E. Forman, A. Freyberger, E. Froidefond , et al. (40 additional authors not shown)

Abstract: The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-$Z$ target. Positron polarization up to 82\% have been measured for an… ▽ More The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-$Z$ target. Positron polarization up to 82\% have been measured for an initial electron beam momentum of 8.19~MeV/$c$, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community. △ Less

Submitted 28 June, 2016; originally announced June 2016.

Comments: 5 pages, 4 figures

Journal ref: Phys. Rev. Lett. 116 (2016) 214801

The Heavy Photon Search Test Detector

Authors: Marco Battaglieri, Sergey Boyarinov, Stephen Bueltmann, Volker Burkert, Andrea Celentano, Gabriel Charles, William Cooper, Chris Cuevas, Natalia Dashyan, Raffaella DeVita, Camille Desnault, Alexandre Deur, Hovanes Egiyan, Latifa Elouadrhiri, Rouven Essig, Vitaliy Fadeyev, Clive Field, Arne Freyberger, Yuri Gershtein, Nerses Gevorgyan, Francois-Xavier Girod, Norman Graf, Mathew Graham, Keith Griffioen, Alexander Grillo , et al. (39 additional authors not shown)

Abstract: The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment's technical feasibility and to confirm th… ▽ More The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment's technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e$^+$e$^-$ invariant mass spectrum, above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW0$_{4}$ crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e$^+$e$^-$ pairs requires the first layer of silicon sensors be placed only 10~cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab. △ Less

Submitted 4 June, 2015; v1 submitted 23 June, 2014; originally announced June 2014.

Comments: Revised version to match published version, 16 pages, 18 figures, published in Nuclear Instruments and Methods in Physics Research Section A, editor: Per Hansson Adrian

Report number: SLAC-PUB-15999

Journal ref: Nuclear Inst. and Methods in Physics Research, A Volume 777, 21 March 2015, Pages 91-101, ISSN 0168-9002

Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab

Authors: BDX Collaboration, M. Battaglieri, A. Celentano, R. De Vita, E. Izaguirre, G. Krnjaic, E. Smith, S. Stepanyan, A. Bersani, E. Fanchini, S. Fegan, P. Musico, M. Osipenko, M. Ripani, E. Santopinto, M. Taiuti, P. Schuster, N. Toro, M. Dalton, A. Freyberger, F. -X. Girod, V. Kubarovsky, M. Ungaro, G. De Cataldo, R. De Leo , et al. (61 additional authors not shown)

Abstract: MeV-GeV dark matter (DM) is theoretically well motivated but remarkably unexplored. This Letter of Intent presents the MeV-GeV DM discovery potential for a 1 m$^3$ segmented plastic scintillator detector placed downstream of the beam-dump at one of the high intensity JLab experimental Halls, receiving up to 10$^{22}$ electrons-on-target (EOT) in a one-year period. This experiment (Beam-Dump eXperi… ▽ More MeV-GeV dark matter (DM) is theoretically well motivated but remarkably unexplored. This Letter of Intent presents the MeV-GeV DM discovery potential for a 1 m$^3$ segmented plastic scintillator detector placed downstream of the beam-dump at one of the high intensity JLab experimental Halls, receiving up to 10$^{22}$ electrons-on-target (EOT) in a one-year period. This experiment (Beam-Dump eXperiment or BDX) is sensitive to DM-nucleon elastic scattering at the level of a thousand counts per year, with very low threshold recoil energies ($\sim$1 MeV), and limited only by reducible cosmogenic backgrounds. Sensitivity to DM-electron elastic scattering and/or inelastic DM would be below 10 counts per year after requiring all electromagnetic showers in the detector to exceed a few-hundred MeV, which dramatically reduces or altogether eliminates all backgrounds. Detailed Monte Carlo simulations are in progress to finalize the detector design and experimental set up. An existing 0.036 m$^3$ prototype based on the same technology will be used to validate simulations with background rate estimates, driving the necessary R$\&$D towards an optimized detector. The final detector design and experimental set up will be presented in a full proposal to be submitted to the next JLab PAC. A fully realized experiment would be sensitive to large regions of DM parameter space, exceeding the discovery potential of existing and planned experiments by two orders of magnitude in the MeV-GeV DM mass range. △ Less

Submitted 11 June, 2014; originally announced June 2014.

Comments: 28 pages, 17 figures, submitted to JLab PAC 42

Fundamental Physics at the Intensity Frontier

Authors: J. L. Hewett, H. Weerts, R. Brock, J. N. Butler, B. C. K. Casey, J. Collar, A. de Gouvea, R. Essig, Y. Grossman, W. Haxton, J. A. Jaros, C. K. Jung, Z. T. Lu, K. Pitts, Z. Ligeti, J. R. Patterson, M. Ramsey-Musolf, J. L. Ritchie, A. Roodman, K. Scholberg, C. E. M. Wagner, G. P. Zeller, S. Aefsky, A. Afanasev, K. Agashe , et al. (443 additional authors not shown)

Abstract: The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms. The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms. △ Less

Submitted 11 May, 2012; originally announced May 2012.

Comments: 229 pages

Report number: ANL-HEP-TR-12-25, SLAC-R-991

Low Q^2 measurements of the proton form factor ratio $mu_p G_E / G_M$

Authors: G. Ron, X. Zhan, J. Glister, B. Lee, K. Allada, W. Armstrong, J. Arrington, A. Beck, F. Benmokhtar, B. L. Berman, W. Boeglin, E. Brash, A. Camsonne, J. Calarco, J. P. Chen, S. Choi, E. Chudakov, L. Coman, B. Craver, F. Cusanno, J. Dumas, C. Dutta, R. Feuerbach, A. Freyberger, S. Frullani , et al. (62 additional authors not shown)

Abstract: We present an updated extraction of the proton electromagnetic form factor ratio, mu_p G_E/G_M, at low Q^2. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio mu_p G_E/G_M co… ▽ More We present an updated extraction of the proton electromagnetic form factor ratio, mu_p G_E/G_M, at low Q^2. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio mu_p G_E/G_M compared to the original analysis. △ Less

Submitted 30 August, 2011; v1 submitted 29 March, 2011; originally announced March 2011.

Comments: 12 pages, 5 figures, archival paper for proton form factor extraction from Jefferson Lab "LEDEX" experiment

Polarization Observables in Deuteron Photodisintegration below 360 MeV

Authors: J. Glister, G. Ron, B. W. Lee, R. Gilman, A. J. Sarty, S. Strauch, D. W. Higinbotham, E. Piasetzky, K. Allada, W. Armstrong, J. Arrington, A. Beck, F. Benmokhtar, B. L. Berman, W. Boeglin, E. Brash, A. Camsonne, J. Calarco, J. P. Chen, Seonho Choi, E. Chudakov, L. Coman, B. Craver, F. Cusanno, J. Dumas , et al. (64 additional authors not shown)

Abstract: High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory con… ▽ More High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used. △ Less

Submitted 9 March, 2010; originally announced March 2010.

Comments: 5 pages, 2 figures

Report number: JLAB-PHY-10-1133

Journal ref: Phys. Lett. B 697 (2011) 194

Measurement of B(D_s+ -> mu+ nu_mu)/B(D_s+ -> phi mu+ nu_mu) and Determination of the Decay Constant f_{D_s}

Authors: K. Kodama, S. Torikai, N. Ushida, A. Mokhtarani, V. S. Paolone, J. T. Volk, J. O. Wilcox, P. M. Yager, R. M. Edelstein, A. P. Freyberger, D. B. Gibaut, R. J. Lipton, W. R. Nichols, D. M. Potter, J. S. Russ, C. Zhang, Y. Zhang, H. I. Jang, J. Y. Kim, B. R. Baller, R. J. Stefanski, K. Nakazawa, S. H. Chung, M. S. Park, I. G. Park , et al. (49 additional authors not shown)

Abstract: We have observed $23.2 \pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^+ -> μ^+ ν_μ$ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the $D_s^+ -> φμ^+ ν_μ$ yield measured previously in this experiment, we obtain $B(D_s^+ --> μ^+ ν_μ) / B(D_s^+ --> φμ^+ ν_μ) =0.16 \pm 0.06 \pm 0.03$. In addition, we extract the decay constan… ▽ More We have observed $23.2 \pm 6.0_{-0.9}^{+1.0}$ purely-leptonic decays of $D_s^+ -> μ^+ ν_μ$ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the $D_s^+ -> φμ^+ ν_μ$ yield measured previously in this experiment, we obtain $B(D_s^+ --> μ^+ ν_μ) / B(D_s^+ --> φμ^+ ν_μ) =0.16 \pm 0.06 \pm 0.03$. In addition, we extract the decay constant $f_{D_s}=194 \pm 35 \pm 20 \pm 14 MeV$. △ Less

Submitted 28 June, 1996; originally announced June 1996.

Comments: 15 pages including one figure

Report number: DPNU-96-33

Journal ref: Phys.Lett.B382:299-304,1996