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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

The JLab Eta Factory (JEF) experiment at Jefferson Lab

The GlueX spectrometer is a large acceptance spectrometer installed in Hall~D at Jefferson Lab with good coverage for both charged and neutral particles. In particular photons in the forward direction are detected using the Forward Calorimeter, an array of lead glass blocks. The main physics program is to search for evidence for hybrid mesons. The recently-approved JLab Eta Factory (JEF) experiment extends the GlueX physics program to study rare decays of ? mesons with a particular emphasis on the ???0?? channel. In addition to probing O(p6) terms in chiral perturbation theory, this channel can be used to search for evidence for lepto-phobic dark matter. A potential extension to the Standard Model posits a dark gauge boson (B) that couples predominately with quarks and can be observed in the ???B, B??0? decay chain. The JEF program also plans to search for C-violating/P-conserving decays of the ? meson. In order to achieve the requisite resolution to observe these rare channels, this experiment calls for an upgrade to the existing GlueX Forward Calorimeter. After a brief description of the GlueX detector, I will focus on the JEF program with a particular emphasis on the B-boson search and I will discuss plans for the future.

Taylor, Simon↗
DOE OSTI2016

Jefferson Lab: Present and Future

The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab (JLab) comprise a unique facility for nuclear physics research whose upgrade is presently underway, with completion expected in 2017. The upgraded facility will accelerate electron beams to 11 GeV for experiments in the existing Halls A, B and C. In addition, a 12 GeV beam can be provided to a new experimental hall, Hall D, to generate a 9 GeV tagged photon beam. This upgrade will enable a new experimental program with substantial discovery potential to address important topics in hadronic, nuclear, and electroweak physics. Further in the future, it is envisioned that the Laboratory will evolve into an electron-ion colliding beam facility (EIC).

Rossi, Patrizia↗
DOE OSTI2015

Beam position reconstruction for the g2p experiment in Hall A at Jefferson Lab

Beam-line equipment was upgraded for experiment E08-027 (g2p) in Hall A at Jefferson Lab. Two beam position monitors (BPMs) were necessary to measure the beam position and angle at the target. A new BPM receiver was designed and built to handle the low beam currents (50-100 nA) used for this experiment. Two new super-harps were installed for calibrating the BPMs. In addition to the existing fast raster system, a slow raster system was installed. We found that before and during the experiment, these new devices were tested and debugged, and their performance was also evaluated. In order to achieve the required accuracy (1-2 mm in position and 1-2 mrad in angle at the target location), the data of the BPMs and harps were carefully analyzed, as well as reconstructing the beam position and angle event by event at the target location. Finally, the calculated beam position will be used in the data analysis to accurately determine the kinematics for each event.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Beam results for the new super-conducting booster at Jefferson Lab

The performance results of a new super-conducting booster for the CEBAF injector at Jefferson Lab, could be of interest for other similar electron injectors. A recent addition of this new booster has provided us the ability to achieve a more adiabatic acceleration and therefore an improvement to the beam dynamics and beam brightness. It has also simplified the design and operation of the section of the injector responsible for accelerating the electron beam from a few hundred keV to several MeV (typically 6.7 MeV). The addition of the new booster was part of an upgrade to the CEBAF injector to improve the beam quality for future physics experiments with high sensitivity to beam quality. The booster consists of two cavities: a 2-cell cavity followed by a 7-cell cavity. This combination allows for a wide range of input electron beam energies, from 130 keV to more than 300 keV. In fact, during the last year, the booster was successfully operated with 140,180, and 200 keV input beam energies as the electron gun was being upgraded. This paper describes the new booster, presents beam optics data results from different beam studies, commissioning, and the physics quality beam operation.

Accelerator Physics↗
DOE OSTI2018

Cavity Processing and Testing Activities at Jefferson Lab for LCLS-II Production

Cryomodule production for LCLS-II is well underway at Jefferson Lab. This paper explains the process flow for production cavities, from being received at the Test Lab to being assembled onto cavity strings. Taking our facility and infrastructure into consideration, process optimization and process control are implemented to ensure high quality products.

Davis, Giles↗
DOE OSTI2014

Gluonic Excitations and Experimental Hall-D at Jefferson Lab

A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple qq^- pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.

Stevens, Justin↗
DOE OSTI2016

Nucleon spin structure studies at Jefferson Lab

We report on the low and moderate $Q^2$ nucleon spin structure measurements done at Jefferson Lab, examining specifically the inclusive program. We discuss what the data teach us about quark confinement and the emergence of the effective hadronic degrees of freedom from the fundamental partonic ones. We show how this experimental program has reached its goal by providing a precise mapping at low, intermediate and moderately high $Q^2$ which has resulted in many progress, e.g. with Chiral Perturbation Theory. Another example of a recent advance imputable to the JLab spin data is the improved understanding of $\alpha_s$ at low energy, which allowed Light--Front Holographic QCD, an approximation to non-perturbative QCD, to derive the hadron spectrum from $\Lambda_s$.

Deur, Alexandre↗
DOE OSTI2015

Jefferson Lab Science: Present and Future

The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab comprise a unique facility for experimental nuclear physics. Furthermore, this facility is presently being upgraded, which will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics. Further in the future, it is envisioned that the Laboratory will evolve into an electron-ion colliding beam facility.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Production of Charmonium at Threshold in Hall A and C at Jefferson Lab

Here, we describe in this paper two approved experiments in Hall A and Hall C at Jefferson Lab that will investigate the pure gluonic component of the strong interaction of Quantum ChromoDynamics by measuring the elastic J/ψ electro and photo-production cross section in the threshold region as well as explore the nature of the recently discovered LHCb charmed pentaquarks.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Quench-Back Management for Fast Decaying Currents in SHMS Superconducting Magnets at Jefferson Lab

The Super High Momentum Spectrometer (SHMS) of Hall C, part of the 12-GeV upgrade at Jefferson Lab, was successfully commissioned in 2017. Early operation demonstrated that fast current dumps decays of the SHMS Q2/Q3 and dipole superconducting magnets triggered quenches, causing some level of operational difficulty. Tests and detailed assessments suggest that nonquench induced fast current decay could result in substantial ac loss in the conductor and subsequently trigger a quench-back effect. The OPERA/ELECTRA software package was used to calculate the amount of heat deposited in the copper stabilizer from a fast current decay. The resistances of external energy dump resistors were lowered to slow the fast dumping of the magnet's current to reduce or eliminate the quench-back effect. A worst-case adiabatic quench scenario was analyzed, assuming no external dump resistor and no liquid helium surrounding the coil, to ensure the safety of the magnets. The stress levels in the coil imposed by winding, collaring preload, Lorentz force, and temperature gradient during a quench were also examined. The Tsai-Wu material failure criterion was used to determine the acceptable combined stress level. Linear orthotropic analysis of the coil indicates that the magnets can be operated safely with appropriately sized dump resistors. Fast dump tests with the modified dump resistors have been planned to verify the performance and suitability.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Jefferson Lab 12 GeV Science Program

The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab are presently being upgraded, which will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics. Further in the future, it is envisioned that the Laboratory will evolve into an electron-ion colliding beam facility.

McKeown, R. D.↗
DOE OSTI2025

A Beamdump facility at Jefferson Lab

The potential of the intense secondary muon, neutrino, and (hypothetical) light dark matter beams at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) is explored. These are produced in the high-power dumps with high-current electron beams. Light dark matter searches with the approved Beam Dump eXperiment (BDX) are driving the realization of a new underground vault behind Hall A that could be extended to a Beamdump Facility with little additional installations. High-energy muons created via the Bethe–Heitler process uniquely do not proceed through the more common pion production and decay channels. Several possible muon physics applications are highlighted. Neutrino detector technologies and experiments suitable for a beamdump facility are outlined.

Accelerator Physics↗
DOE OSTI2024

N* Physics with CLAS12 at Jefferson Lab

Nucleons are the most fundamental bound three-body systems in Nature. With the CLAS12 spectrometer at Jefferson Lab, the spectrum and the structure of nucleon resonances is explored. This includes studies of exclusive piN, pi+pi-p, KLambda, and KSigma electroproduction reactions and the evolution of the electrocouplings of resonances with photon virtuality Q^2. Such type of studies with CLAS have revealed a complex interplay between a core of dressed quarks and an external meson-baryon cloud inside of the excited nucleon states. With CLAS12, also measurements of N -> N* transitions in the DIS region have been performed, addressing the three-dimensional structure of nucleon resonances through their transition GPDs (generalized parton distributions). In the future, the increase of the CEBAF energy and the upgrade of the CLAS12 spectrometer to study exclusive electroproduction channels at higher luminosities and photon virtualities will offer a unique opportunity to study the nucleon excitation mechanisms.

Achenbach, Patrick↗
DOE OSTI2025

AI-Optimized Polarization at Jefferson Lab

The AI-Optimized Polarization project seeks to develop experimental control applications for polarized targets and beams at Jefferson Lab using AI/ML. This paper will focus on two ongoing efforts involving a cryogenic polarized target and a linearly-polarized photon beam. Firstly, cryogenic targets, such as those used in Halls B and C (and approved for Hall D), are complex systems that are sensitive to a number of factors, including the temperature, beam currents, and the microwave and NMR apparatus. Secondly, the Hall D photon beam polarization depends on the optimal orientation of a diamond radiator, which produces coherent bremsstrahlung radiation from the electron beam incident upon it. Manual operation of both systems is tedious and error prone; implementing well-designed, interpretable control systems that incorporate AI is expected to lead to improved real-time polarization. AI optimization of nuclear physics experiments will lead, not just to cost-savings, but also to more efficient and higher-quality data, and this project will help to lay the foundation for future autonomous experiments.

Moran, Patrick [College of William and Mary, Willi↗
DOE OSTI2022

USING E-BEAM IRRADIATION BEAMLINE AT JEFFERSON LAB TO REMOVE 1,4-DIOXANE AND PFAS IN WASTEWATER

The designed e-beam irradiation beamline [1] at Jefferson Lab has been commissioned and applied to study the degradation removal of 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS) in wastewater by collaborating with Hampton Roads Sanitation District (HRSD), treating wastewater in southeast Virginia. The absorbed dose and dose distribution in the entire sample were achieved innovatively using Monte-Carlo simulations that were calibrated with opti-chromic dosimeter rods directly exposed to the e-beam. This research could be a stepstone to the future MW compact SRF accelerator [2] for wastewater remediation.

Li, X.↗
DOE OSTI2017

Spectroscopic Study of L Hypernuclei with Electron Beams at Jefferson Lab

The missing mass spectroscopy of L hypernuclei with the (e, e'K^+) reaction was started from 2000 at Jefferson Lab. In this fifteen years, various hypernuclei (A = 7 - 52) including hyperon (L, S^0) productions have been studied with newly developed experimental techniques. The (e, e'K^+) reaction spectroscopy of L hypernuclei features its capability of absolute missing mass calibration and production of new species of hypernuclei which are the isospin partners of well studied hypernuclei by (K^-, pi-) and (pi^+, K^+) reactions. In this paper, we will review how we established the (e, e'K^+) spectroscopic study of hypernuclei.

Nakamura, Satoshi↗
DOE OSTI2013

Dynamically polarized target for the g p 2 and G p E experiments at Jefferson Lab

We describe a dynamically polarized target that has been utilized for two electron scattering experiments in Hall A at Jefferson Lab. The primary components of the target are a new, high cooling power 4 He evaporation refrigerator, and a re-purposed, superconducting split-coil magnet. It has been used to polarize protons in irradiated NH 3 at a temperature of 1 K and at fields of 2.5 and 5.0 Tesla. The performance of the target material in the electron beam under these conditions will be discussed. The maximum polarizations of 28% and 95% were obtained at those fields, respectively. To satisfy the requirements of both experiments, the magnet had to be routinely rotated between angles of 0, 6, and 90 degrees with respect to the incident electron beam. This was accomplished using a new rotating vacuum seal which permits rotations to be performed in only a few minutes.

43 PARTICLE ACCELERATORS↗