8 research outputs found
The GlueX DIRC Project
The GlueX experiment was designed to search for and study the pattern of
gluonic excitations in the meson spectrum produced through photoproduction
reactions at a new tagged photon beam facility in Hall D at Jefferson
Laboratory. The particle identification capabilities of the GlueX experiment
will be enhanced by constructing a DIRC (Detection of Internally Reflected
Cherenkov light) detector, utilizing components of the decommissioned BaBar
DIRC. The DIRC will allow systematic studies of kaon final states that are
essential for inferring the quark flavor content of both hybrid and
conventional mesons. The design for the GlueX DIRC is presented, including the
new expansion volumes that are currently under development.Comment: 8 pages, 6 figure
Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering: Determined by the OLYMPUS Experiment
The OLYMPUS collaboration reports on a precision measurement of the
positron-proton to electron-proton elastic cross section ratio, ,
a direct measure of the contribution of hard two-photon exchange to the elastic
cross section. In the OLYMPUS measurement, 2.01~GeV electron and positron beams
were directed through a hydrogen gas target internal to the DORIS storage ring
at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and
time-of-flight scintillators detected elastically scattered leptons in
coincidence with recoiling protons over a scattering angle range of to . The relative luminosity between the two beam species
was monitored using tracking telescopes of interleaved GEM and MWPC detectors
at , as well as symmetric M{\o}ller/Bhabha calorimeters at
. A total integrated luminosity of 4.5~fb was collected. In
the extraction of , radiative effects were taken into account
using a Monte Carlo generator to simulate the convolutions of internal
bremsstrahlung with experiment-specific conditions such as detector acceptance
and reconstruction efficiency. The resulting values of , presented
here for a wide range of virtual photon polarization ,
are smaller than some hadronic two-photon exchange calculations predict, but
are in reasonable agreement with a subtracted dispersion model and a
phenomenological fit to the form factor data.Comment: 5 pages, 3 figures, 2 table
High intensity polarized electron source
A proposed new high-luminosity electronâion collider requires a polarized electron source of extremely high intensity. The MIT-Bates Laboratory, in collaboration with Brookhaven National Laboratory (BNL), has developed a new polarized electron gun that can be operated at currents in the mA range. This paper describes the design of the gun and beam line and also presents the results of the beam tests.DOE (Grants DE-ÂFG02-Â94ER40818, DE-ÂSC0005807 and DE-ÂSC0008741
A new cryogenic apparatus to search for the neutron electric dipole moment
© 2019 IOP Publishing Ltd and Sissa Medialab. A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with a major improvement in sensitivity compared to the existing limit in the search for a neutron Electric Dipole Moment (EDM). This apparatus uses superfluid 4He to produce a high density of Ultra-Cold Neutrons (UCN) which are contained in a suitably coated pair of measurement cells. The experiment, to be operated at the Spallation Neutron Source at Oak Ridge National Laboratory, uses polarized 3He from an Atomic Beam Source injected into the superfluid 4He and transported to the measurement cells where it serves as a co-magnetometer. The superfluid 4He is also used as an insulating medium allowing significantly higher electric fields, compared to previous experiments, to be maintained across the measurement cells. These features provide an ultimate statistical uncertainty for the EDM of 2-3à 10-28 e-cm, with anticipated systematic uncertainties below this level
LERF - New life for the jefferson laboratory FEL
© ERL 2017, the 59th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs.All right reserved. In 2012 Jefferson Laboratory's energy recovery linac (ERL) driven Free Electron Laser successfully completed a transmission test in which high current CW beam (4.3 mA at 100 MeV) was transported through a 2 mm aperture for 7 hours with beam losses as low as 3 ppm. The purpose of the run was to mimic an internal gas target for DarkLight [1] - an experiment designed to search for a dark matter particle. The ERL was not run again until late 2015 for a brief re-commissioning in preparation for the next phase of DarkLight. In the intervening years, the FEL was rebranded as the Low Energy Recirculator Facility. In 2016 several weeks of operation were allocated to configure the machine for DarkLight with the purpose of exercising - for the first time - an internal gas target in an ERL. Despite a number of challenges, including the inability to energy recover without losses (precluding CW operation), beam was delivered to a target of thickness 1018 cm-2 which represents a three order of magnitude increase in thickness from previous internal target experiments. Details of the machine configuration and operational experience will be discussed
LERF - New Life for the Jefferson Lab FEL
International audienceIn 2012 Jefferson Laboratory's energy recovery linac (ERL) driven Free Electron Laser successful completed a transmission test in which high current CW beam (4.3 mA at 100 MeV) was transported through a 2 mm aperture for 7 hours with beam losses as low as 3 ppm. The purpose of the run was to mimic an internal gas target for DarkLight* - an experiment designed to search for a dark matter particle. The ERL was not run again until late 2015 for a brief re-commissioning in preparation for the next phase of DarkLight. In the intervening years, the FEL was rebranded as the Low Energy Recirculator Facility (LERF), while organizationally the FEL division was absorbed into the Accelerator division. In 2016 several weeks of operation were allocated to configure the machine for Darklight with the purpose of exercising - for the first time - an internal gas target in an ERL. Despite a number of challenges, including the inability to energy recover, beam was delivered to a target of thickness 10Âčâž cmâ»ÂČ which represents a 3 order of magnitude increase in thickness from previous internal target experiments. Details of the machine configuration and operational experience will be discussed
Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering Determined by the OLYMPUS Experiment
The OLYMPUS collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, , a direct measure of the contribution of hard two-photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of 20° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved GEM and MWPC detectors at 12°, as well as symmetric MÞller/Bhabha calorimeters at 1:29°. A total integrated luminosity of was collected. In the extraction of , radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of , presented here for a wide range of virtual photon polarization 0:456 < < 0:978, are smaller than hadronic two-photon exchange calculations predict, but are consistent with phenomenological models