Ying Wu

Journal Article Optics express · January 2024 With wavelength tunability, free-electron lasers (FELs) are well-suited for generating orbital angular momentum (OAM) beams in a wide photon energy range. We report here the first experimental demonstration of OAM beam generation using an oscillator FEL wi ... Full text Cite

Enabling Storage Ring FEL for lasing below 170 nm and production of 120 MeV circularly polarized γ-ray by VUV mirrors

Conference 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023 · January 1, 2023 The operation of a storage ring free-electron laser (FEL) is constrained by the shortest wavelength that its cavity can support. To address this limitation, significant efforts have been made in recent decades to develop high-reflective FEL mirrors support ... Full text Cite

Synchrotron radiation interferometry for beam size measurement at low current and in large dynamic range

Journal Article Physical Review Accelerators and Beams · August 1, 2022 The Synchrotron Radiation Interferometry (SRI) has become a widely used technique to measure the small transverse size of the electron beam in the storage ring. In a typical SRI system for the routine storage ring operation, synchrotron radiation from a di ... Full text Cite

Proton Compton Scattering from Linearly Polarized Gamma Rays.

Journal Article Physical review letters · April 2022 Differential cross sections for Compton scattering from the proton have been measured at scattering angles of 55°, 90°, and 125° in the laboratory frame using quasimonoenergetic linearly (circularly) polarized photon beams with a weighted mean energy value ... Full text Cite

International Workshop on Next Generation Gamma-Ray Source

Journal Article Journal of Physics G: Nuclear and Particle Physics · December 2, 2021 Link to item Cite

Lasing below 170 nm using an oscillator FEL

Journal Article Journal of Applied Physics · November 14, 2021 The short wavelength operation of free-electron laser (FEL) oscillators is limited by the availability of high-reflectivity, thermally stable, and radiation-resistant FEL mirrors in the vacuum UV (VUV) wavelength. We report our recent work to extend the sh ... Full text Cite

Transverse mode analysis for free-space laser beams using Bayesian analysis.

Journal Article Applied optics · April 2021 Reliable and rapid assessment of the transverse mode quality of a free-space laser beam has a wide range of applications in laser development, research, and utilization. It has become even more important with recent advances in developing orbital angular m ... Full text Cite

First measurement of the asymmetry and the Gerasimov-Drell-Hearn integrand from the He 3- (γ-,p) H 2 reaction at an incident photon energy of 29 MeV

Journal Article Physical Review C · March 1, 2021 The first measurement of the He3 - (γ - ,p)H2 process was performed at the High Intensity γ-ray Source (HIγS) facility at Triangle Universities Nuclear Laboratory using a circularly polarized, monoenergetic γ-ray beam and a longitudinally polarized He3 tar ... Full text Cite

Phase retrieval for short wavelength orbital angular momentum beams using knife-edge diffraction

Journal Article Optics Communications · November 1, 2020 Laser beams operating in high order transverse modes, especially orbital angular momentum (OAM) modes, have been used increasingly in many frontier research areas. The characterization of these laser modes and the related component analysis can be carried ... Full text Cite

Polarization control of a free-electron laser oscillator using helical undulators of opposite helicities

Journal Article Physical Review Accelerators and Beams · June 1, 2020 Polarized photon beams provide a unique experimental tool for the study of various polarization-dependent physical processes. Here, we report the experimental demonstration of full polarization control of an oscillator free-electron laser (FEL) using helic ... Full text Cite

Compton scattering from $^{4}\mathrm{He}$ at the TUNL $\mathrm{HI}\ensuremath{\gamma}\mathrm{S}$ facility

Journal Article PRC · March 30, 2020 Full text Open Access Link to item Cite

Time Projection Chamber (TPC) detectors for nuclear astrophysics studies with gamma beams

Journal Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · February 21, 2020 Gamma-Beams at the HIγS facility in the USA and anticipated at the ELI-NP facility, now constructed in Romania, present unique new opportunities to advance research in nuclear astrophysics; not the least of which is resolving open questions in oxygen forma ... Full text Cite

The gamma factory project at cern: A new generation of research tools made of light

Conference Acta Physica Polonica B, Proceedings Supplement · January 1, 2020 The Gamma Factory project offers the possibility of creating novel research tools by producing relativistic beams of highly ionised atoms in CERN's accelerator complex and exciting their atomic degrees of freedom by lasers to produce strongly collimated hi ... Full text Cite

Precision control of gamma-ray polarization using a crossed helical undulator free-electron laser

Journal Article Nature Photonics · September 1, 2019 Polarized gamma-ray beams are a precise and selective probe for studying fundamental questions about nuclear structure and hadron properties. Improvements to this probe require new experimental approaches that can produce high-flux gamma-ray beams with eas ... Full text Cite

Design and dynamic studies for a compact storage ring to generate gamma-ray light source based on Compton backscattering technique

Journal Article Physical Review Accelerators and Beams · April 18, 2019 As the development of nuclear physics and atomic sciences progresses, monochromatic and high-flux gamma-ray light sources are highly demanded by many experiments in these fields. We have designed a compact storage ring for gamma-ray source generation based ... Full text Cite

Gamma factory at CERN - Novel research tools made of light

Conference Acta Physica Polonica B · January 1, 2019 We discuss the possibility of creating novel research tools by producing and storing highly relativistic beams of highly ionised atoms in the CERN accelerator complex, and by exciting their atomic degrees of freedom with lasers to produce high-energy photo ... Full text Cite

Gamma factory for CERN initiative - Progress report

Conference Proceedings of Science · January 1, 2019 The Gamma Factory (GF) initiative proposes to use partially stripped ion (PSI) beams as drivers of a new type of high-intensity and high-energy (0.1-400MeV) photon source. As part of the ongoing Physics Beyond Collider studies, initial beam tests were carr ... Cite

Transverse beam profile measurement system for the Duke storage ring

Journal Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · December 11, 2018 The transverse beam emittance is a crucial parameter determining the brightness of an electron storage ring based synchrotron radiation source. The beam emittance is typically determined using the transverse electron beam size and the beta function at a pa ... Full text Cite

The Gamma Factory proposal for CERN

Conference CERN-Proceedings · January 1, 2018 This contribution discusses the possibility of broadening the present CERN research programme by a new component making use of a novel concept of the light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma ... Full text Cite

Low energy compact storage ring design for Compton gamma-ray light source

Conference IPAC 2017 - Proceedings of the 8th International Particle Accelerator Conference · July 1, 2017 Gamma-ray sources with high flux and spectral densities are highly demanded by many nuclear experiments. We design a low energy compact storage ring to produce gamma-ray with energy in the range of 4-20 MeV based on Compton backscattering technique. The st ... Cite

Compensation for booster leakage field in the Duke storage ring

Journal Article Chinese Physics C · January 1, 2017 The High Intensity Gamma-ray Source (HIGS) at Duke University is an accelerator-driven Compton gamma-ray source, providing high flux gamma-ray beam from 1 MeV to 100 MeV for photo-nuclear physics research. The HIGS facility operates three accelerators, a l ... Full text Cite

Polarization control of storage ring FELs using cross polarized helical undulators

Conference Proceedings of the 38th International Free-Electron Laser Conference, FEL 2017 · January 1, 2017 For more than two decades, accelerator researchers have been working to gain control of polarization of synchrotron radiation and FELs using non-optical means. In 2005, using mixed linear and helical undulators, the first experimental demonstration of pola ... Full text Cite

Study of magnetic hysteresis effects in a storage ring using precision tune measurement

Journal Article Chinese Physics C · December 1, 2016 With the advances in accelerator science and technology in recent decades, the accelerator community has focused on the development of next-generation light sources, for example diffraction-limited storage rings (DLSRs), which require precision control of ... Full text Cite

Storage ring two-color free-electron laser

Journal Article Physical Review Accelerators and Beams · July 1, 2016 We report a systematic experimental study of a storage ring two-color free-electron laser (FEL) operating simultaneously in the infrared (IR) and ultraviolet (UV) wavelength regions. The two-color FEL lasing has been realized using a pair of dual-band high ... Full text Cite

Direct and high resolution beta-function measurements for storage ring lattice characterization

Conference IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference · January 1, 2016 Betatron functions are a set of commonly used merits to characterize the lattice performance of a circular accelerator. The betatron functions in many accelerators can be computed using a lattice model trained or calibrated using a set of closed orbit resp ... Cite

Measurement of the doubly-polarized He3→(γ→,n)pp reaction at 16.5 MeV and its implications for the GDH sum rule

Journal Article Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics · November 12, 2015 We report new measurements of the double-polarized photodisintegration of 3He at an incident photon energy of 16.5 MeV, carried out at the High Intensity γ-ray Source (HIγS) facility located at Triangle Universities Nuclear Laboratory (TUNL). The spin-depe ... Full text Cite

Widely Tunable Two-Color Free-Electron Laser on a Storage Ring.

Journal Article Physical review letters · October 2015 With a wide wavelength tuning range, free-electron lasers (FELs) are well suited for producing simultaneous lasing at multiple wavelengths. We present the first experimental results of a novel two-color storage ring FEL. With three undulators and a pair of ... Full text Cite

Nuclear Physics Research at the High Intensity Gamma-Ray Source (HIγS)

Journal Article Nuclear Physics News · July 3, 2015 The High Intensity γ-Ray Source (HIγS), operated by the Triangle Universities Nuclear Laboratory and located on the campus of Duke University, is presently able to provide nearly mono-energetic polarized gamma ray beams with energies ranging from 1 to 100 ... Full text Cite

Measuring Duke storage ring lattice using tune based technique

Conference 6th International Particle Accelerator Conference, IPAC 2015 · January 1, 2015 The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34 m long straight section of the storage ring is used to host up to four FEL wigglers in several different configurations. A total of six wigglers, two plan ... Cite

Light source and accelerator physics research program at Duke university

Conference 6th International Particle Accelerator Conference, IPAC 2015 · January 1, 2015 The light source and accelerator physics research program at Duke Free-Electron Laser Laboratory (DFELL), Triangle Universities Nuclear Laboratory, is focused on the development of the storage ring based free-electron lasers (FELs), and an FEL driven state ... Cite

Developing an improved pulsed mode operation for Duke storage ring based FEL

Conference 6th International Particle Accelerator Conference, IPAC 2015 · January 1, 2015 The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an e-beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Currently, the energy range of the gamma-ray beam is from 1 MeV to about 100 MeV, with the maximum total ... Cite

Extending ok5 wiggler operational limit at duke fel/higs facility

Conference 6th International Particle Accelerator Conference, IPAC 2015 · January 1, 2015 Since 2007 the HIGS facility has been operated to produce both linearly and circularly polarized gamma-ray beams using two FELs, the planar OK-4 FEL and helical OK-5 FEL. Presently, with the OK-5 FEL operating at 192 nm, we can produce circularly-polarized ... Cite

Experimental study of a two-color storage ring FEL ?

Conference 6th International Particle Accelerator Conference, IPAC 2015 · January 1, 2015 Multi-color Free-electron Lasers (FELs) have been developed on linac based FELs over the past two decades. On the storage ring, the optical klystron (OK) FEL in its early days was demonstrated to produce lasing at two adjacent wavelengths with their spectr ... Cite

Characterizing betatron tune knobs at Duke storage ring

Conference 6th International Particle Accelerator Conference, IPAC 2015 · January 1, 2015 A good control of the electron beam betatron tune is critical for the operation of a storage ring. As the driver for Duke free-electron lasers (FELs) and the High Intensity Gammaray Source (HIGS), the Duke storage ring is operated in a wide energy range (0 ... Cite

Conditioning of BPM pickup signals for operations of the Duke storage ring with a wide range of single-bunch current

Journal Article Chinese Physics C · October 1, 2014 The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers (FELs), and the High Intensity Gamma-ray Source (HIGS). It is operated with a beam current ranging from about 1 mA to 100 mA per bunch for various operat ... Full text Cite

Spin-dependent cross sections from the three-body photodisintegration of He 3 at incident energies of 12.8 and 14.7 MeV

Journal Article Physical Review C - Nuclear Physics · February 11, 2014 The first measurement of the three-body photodisintegration of polarized He3 using a circularly polarized photon beam has been performed at incident energies of 12.8 and 14.7 MeV. This measurement was carried out at the high-intensity γ-ray source located ... Full text Cite

Relative spectral response measurement of spectrometers using undulator radiation

Journal Article Journal of Instrumentation · January 1, 2014 Undulator radiation with known spectral characteristics is recognized as an excellent light source that can be used to measure the spectral response of a variety of spectral measurement devices in a wide range from infrared to x-ray. This technique has bee ... Full text Cite

A segmented, enriched N-type germanium detector for neutrinoless double beta-decay experiments

Journal Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · January 1, 2014 We present data characterizing the performance of the first segmented, N-type Ge detector, isotopically enriched to 85% 76Ge. This detector, based on the Ortec PT6×2 design and referred to as SEGA (Segmented, Enriched Germanium Assembly), was developed as ... Full text Open Access Cite

Commissioning and operation of wiggler switchyard system for duke FEL and HIGS

Journal Article IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference · December 24, 2013 To enable the Duke storage ring FEL to operate in VUV with adequate gain, a major storage ring upgrade was carried out in 2012 to install two additional helical FEL wigglers with a wiggler switchyard system. Using the switchyard, a quick changeover can be ... Cite

Compensation schemes for operation of FEL wigglers on duke storage ring

Journal Article IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference · December 24, 2013 The Duke Free-electron laser is the photon driver for the High Intensity Gamma-ray Source (HIGS). To extend the capabilities of the FEL and HIGS to higher photon energy regions, an FEL wiggler switchyard system was developed in the recent years. This syste ... Cite

Protection of VUV FEL mirrors using soft orbit bump at duke FEL / HIγS facility

Journal Article IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference · December 24, 2013 The Duke FEL and High Intensity Gamma-ray Source (HIγS) facility is operated with an electron beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Presently, the energy range of the gamma-beam is from 1 MeV to about 100 MeV, with the maximum to ... Cite

Design of a soft orbit bump for FEL mirror protection at duke FEL/HIGS facility

Journal Article IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference · December 24, 2013 In an oscillator Free-Electron Laser (FEL) with a high energy electron beam, it is critical to minimize harmful high-energy radiation on the downstream FEL mirror in order to increase its lifetime. At the High Intensity Gammaray Source (HIGS) facility at D ... Cite

Accelerator physics and light source research program at duke university

Journal Article IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference · December 24, 2013 The accelerator physics and light source research program at the Duke Free-Electron Laser Laboratory, Triangle Universities Nuclear Laboratory, is focused on the development of the storage ring based free-electron lasers (FELs), and a state-of-the-art Comp ... Cite

First measurements of spin-dependent double-differential cross sections and the Gerasimov-Drell-Hearn Integrand from 3He(γ,n)pp at incident photon energies of 12.8 and 14.7 MeV.

Journal Article Physical review letters · May 2013 The first measurement of the three-body photodisintegration of longitudinally polarized (3)He with a circularly polarized γ-ray beam was carried out at the High Intensity γ-ray Source facility located at Triangle Universities Nuclear Laboratory. The spin-d ... Full text Cite

Unambiguous identification of the second 2+ state in 12C and the structure of the Hoyle state.

Journal Article Physical review letters · April 2013 The second J(π)=2+ state of 12C, predicted over 50 years ago as an excitation of the Hoyle state, has been unambiguously identified using the 12C(γ,α0)(8)Be reaction. The alpha particles produced by the photodisintegration of 12C were detected using an opt ... Full text Cite

Active interrogation of nuclear materials using LaBr3: Ce detectors

Journal Article Energy Procedia · January 1, 2013 Active interrogation in 235U was demonstrated with LaBr3:Ce scintillation detectors using the nuclear resonance fluorescence (NRF) technique. An NRF experiment was performed at the High Intensity y-ray Source (HlyS) facility using quasi-monochromatic circu ... Full text Cite

Detection of photon-induced excitations in ²³⁵U with LaBr 3:Ce scintillating detectors

Journal Article IEEE Nuclear Science Symposium Conference Record · December 1, 2012 Excitations in 235U were measured with LaBr3:Ce scintillation detectors using the nuclear resonance fluorescence (NRF) technique. A NRF experiment was performed at the High Intensity γ-ray Source (HIγS) facility using quasi-monochromatic circularly or line ... Full text Cite

Electron beam diagnostics based on transverse feedback system at duke storage ring

Journal Article IPAC 2012 - International Particle Accelerator Conference 2012 · December 1, 2012 To combat electron beam instabilities, a field programmable gate array (FPGA) based bunch-by-bunch transverse feedback (TFB) has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multi-bunch oper ... Cite

Soft orbit bump for duke storage ring VUV FEL operation

Journal Article IPAC 2012 - International Particle Accelerator Conference 2012 · December 1, 2012 The Duke FEL and High Intensity Gamma-ray Source (HIS) facility is operated with anelectron beam from 0.24 to 1.2 GeV and an FEL photon beam from 190 to 1060 nm. The energyrange of the gamma-ray beam is from 1 MeV to about 100 MeV, with the maximum totalga ... Cite

New storage ring lattice for the duke fel wiggler switchyard system

Journal Article IPAC 2012 - International Particle Accelerator Conference 2012 · December 1, 2012 The Duke storage ring is a dedicated driver for the OK- 4 FEL and OK-5 FEL, and forthe state-of-the-art Compton gamma-ray source, High Intensity Gamma-Ray Source (HIGS). Toproduce FEL lasing below 190 nm and gammaray beams above 100 MeV, the FEL system nee ... Cite

Cold cathode thyratron based high-voltage kicker generators at the duke accelerators: Six year experience

Journal Article IPAC 2012 - International Particle Accelerator Conference 2012 · December 1, 2012 The performance of the Duke storage ring based light sources, the Duke storage ring FEL and High Intensity Gamma-ray Source (HIGS), has been greatly improved since 2007 as the result of operating a new full-energy, top-off booster injector (0.18 - 1.2 GeV) ... Cite

Design and Optimization of Longitudinal Feedback Kicker Cavity for HLS-II Storage Ring

Journal Article Chinese Phys. C · 2012 Cite

Betatron Tune Measurement System Based on Bunch-by-bunch Transverse Feedback at Duke Storage Ring

Journal Article Chinese Phys. C · 2012 Cite

Development of a bunch-by-bunch longitudinal feedback system with a wide dynamic range for the HIGS facility

Journal Article Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · March 2011 Full text Cite

Theoretical and simulation studies of characteristics of a Compton light source

Journal Article Phys. Rev. ST Accel. Beams · 2011 Compton scattering of a laser beam with a relativistic electron beam has been used to generate intense, highly polarized and nearly monoenergetic x-ray or gamma-ray beams at many facilities. The ability to predict the spatial, spectral, and temporal charac ... Cite

High energy gamma-ray spectroscopy with LaBr3 scintillation detectors

Journal Article Nucl. Instr. Methods A · 2011 Lanthanum bromide scintillation detectors produce very high light outputs (˜60,000 ph/MeV) within a very short decay time (typically ˜20 ns) which means that high instantaneous currents can be generated in the photocathode and dynode chain of the photomult ... Cite

A semi-analytical algorithm for modelling Compton gamma-ray beams

Journal Article IPAC 2010 - 1st International Particle Accelerator Conference · December 1, 2010 Compton scattering of a laser beam with a relativistic electron beam has been used to generate an intense, highly polarized, and nearly monoenergetic gamma-ray beam at several facilities. The ability of predicting the spatial and spectral distributions of ... Cite

Accelerator physics research and light source development at Duke University

Journal Article IPAC 2010 - 1st International Particle Accelerator Conference · December 1, 2010 The accelerator physics and light source development programs at the Duke Free-Electron Laser Laboratory (DFELL) focus on beam dynamics research, beam instability studies, FEL research, and the development of storage ring based free-electron lasers (FELs) ... Cite

Electron beam polarization measurement using touschek lifetime technique

Journal Article IPAC 2010 - 1st International Particle Accelerator Conference · December 1, 2010 Electron beam loss due to intra-beam scattering, the Tou-schek effect, in a storage ring depends on the electron beam polarization. The polarization of an electron beam can be determined from the difference in the Touschek lifetime compared with an unpolar ... Cite

Study of FEL mirror degradation at the DUKE FEL and higs facility

Journal Article IPAC 2010 - 1st International Particle Accelerator Conference · December 1, 2010 The Duke FEL and High Intensity Gamma-ray Source (HIγS) are operated with a wide range of electron beam energies (0.24-1.2 GeV) and photon beam wavelengths (190-1060 nm). Currently, the HIγS user operation is carried out in the gamma-beam energy range from ... Cite

Electron beam energy spread measurements using optical klystron radiation

Journal Article Physical Review Special Topics - Accelerators and Beams · August 4, 2010 Full text Open Access Cite

Polarization measurement of stored electron beam using Touschek lifetime

Journal Article Nucl. Instr. Methods A · 2010 Touschek lifetime of an electron beam in a storage ring depends on the beam polarization through the intrabeam scattering effect. Therefore, the electron beam polarization can be determined from the Touschek lifetime measurement. In this paper, we report o ... Cite

Influence of an imperfect energy profile on a seeded free electron laser performance,

Journal Article Phys. Rev. ST Accel. Beams · 2010 http://prst-ab.aps.org/abstract/PRSTAB/v13/i6/e060701 ... Open Access Cite

A 4D Monte Carlo Compton scattering code

Journal Article IEEE Nuclear Science Symposium Conference Record · December 1, 2009 Compton scattering of a laser beam and an electron beam in an accelerator has been used to generate an x-ray or gamma-ray beam at many facilities. To study the spatial, spectral and temporal characteristics of the Compton gamma-ray beam, we developed a 4-d ... Full text Cite

Multipole mixing ratios of transitions in $^{11}$B

Journal Article Phys. Rev. C · 2009 Photon scattering experiments with photon energies up to 3.6 MeV have been performed on the axially deformed nucleus 164Dy. We observe the -decay from the scissors mode to the -vibration for the first time in a well-deformed rotor. Previous ambiguities i ... Cite

End-to-end spectrum reconstruction method for analyzing Compton gamma-ray beams

Journal Article Nucl. Instr. Methods A · 2009 A gamma-ray beam produced by Compton scattering of a laser beam with a relativistic electron beam has been used for nuclear physics research at the high intensity g-ray source (HIgS) facility at Duke University. The success of many experiments using the ga ... Cite

Energy and energy spread measurements of an electron beam by Compton scattering method

Journal Article Phys. Rev. ST Accel. Beams · 2009 A gamma-ray beam produced by Compton scattering of a laser beam with an electron beam can be used to measure the electron beam parameters. In several published works, a simple fitting model has been applied to determine the electron beam energy and energy ... Cite

Water Cooled, In-cavity Apertures for High Power Operation of FEL Oscillators

Journal Article Nucl. Instr. Methods A · 2009 In an oscillator FEL, higher-order harmonic radiation from wigglers can cause serious damage to the downstream FEL resonator mirror and limit the maximum electron beam current for FEL operation due to thermal overload. These problems can be effectively dea ... Cite

Chiral Dynamics in Photo-Pion Physics: Theory, Experiment, and Future Studies at the HI$\gamma$S Facility

Journal Article Annual Review of Nuclear and Particle Science · 2009 We review photopion experiments on the nucleon in the near-threshold region.We compare the results with the predictions of the low-energy theorems of quantum chromodynamics calculated using chiral perturbation theory (ChPT), which is based on the spontaneo ... Cite

Competition Between Excited Core States and $1$ $\hbar \omega$ Single-particle Excitations at Comparable Energies in $^{207}$Pb from Photon Scattering

Journal Article Phys. Lett. B · 2009 The Pb(\vec{γ} ,γ') photon scattering reaction has been studied with the nearly monochromatic, linearly polarized photon beams at the High Intensity γ -ray Source (HIγ S) at the DFELL. Azimuthal scattering intensity asymmetries measured with respect to the ... Cite

Erratum: First observation of the splittings of the E1 p-wave amplitudes in low energy deuteron photodisintegration and its implications for the Gerasimov-Drell-Hearn sum rule integrand (Physical Review C (2008) 78 (034003))

Journal Article Physical Review C - Nuclear Physics · December 1, 2008 Full text Cite

A pass-by-pass gain measurement technique for oscillator FELs

Journal Article 30th International Free Electron Laser Conference, FEL 2008 · December 1, 2008 We present a new pass-by-pass gain measurement technique for a storage ring FEL. Typically, the FEL oscillator gain is obtained by measuring the growth of the envelope of an optical macropulse using a slow photo-detector. While successfully used for low-ga ... Cite

Controlling wiggler harmonic radiation to reduce damage to FEL cavity mirrors

Journal Article 30th International Free Electron Laser Conference, FEL 2008 · December 1, 2008 In an oscillator FEL, higher-order harmonic radiation from wigglers can cause serious damage to the downstream FEL resonator mirror or limit the maximum electron beam current for FEL operation due to thermal overload. With a helical wiggler, higher-order h ... Cite

First observation of the splittings of the E1 p-wave amplitudes in low energy deuteron photodisintegration and its implications for the Gerasimov-Drell-Hearn Sum Rule integrand

Journal Article Physical Review C - Nuclear Physics · September 17, 2008 Angular distributions of the cross section and linear analyzing powers have been measured for the d(γ→,n)p reaction at the High Intensity γ-ray Source with linearly polarized beams of 14 and 16 MeV. The outgoing neutrons were detected using the Blowfish de ... Full text Cite

Research Opportunities at the Upgraded HIGS Facility

Journal Article Progress in Particle and Nuclear Physics · 2008 Cite

Growth time of the longitudinal coupled bunch mode beam instability at the Duke FEL facility

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 To determine the required power of an amplifier for the longitudinal feedback (LFB) system, the growth time of the strongest longitudinal coupled bunch mode instability (CBMI) in the Duke storage ring should be measured in advance. In 2005, we measured str ... Full text Cite

Commissioning of the booster injector synchrotron for the HIGS facility at Duke University

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 A booster synchrotron (Duke booster) has been built and recently commissioned at Duke University Free Electron Laser Laboratory (DFELL) as part of the High Intensity Gamma-ray Source (HIGS) facility upgrade. HIGS is collaboration between the DFELL and Tria ... Full text Cite

Electron beam diagnostics for compact 1.2 GEV booster synchrotron

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 First operational experience has been gained with the linac and booster diagnostic system during the commissioning of the booster synchrotron at Duke University. The booster was designed and developed as an injector for the storage ring as a part of the Hi ... Full text Cite

Challenges for energy ramping in a compact booster synchrotron

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 A booster synchrotron has been recently commissioned at Duke University FEL Laboratory as a part of the High Intensity Gamma-ray Source (HIGS) facility. The booster provides top-off injection into the storage ring in the energy range of 0.24 - 1.2 GeV. In ... Full text Cite

Compensation of the beam dynamics effects caused by the extraction Lambertson septum of the HIGS booster

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 As part of the High Intensity Gamma-Ray Source (HIGS) upgrade, the booster synchrotron has been built and commissioned in 2006. It ramps the electron beam between 0.24 and 1.2 GeV for top-off injection into the Duke storage ring. The booster has vertical i ... Full text Cite

Accelerator physics research and light source development programs at Duke University

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 The Duke Free-Electron Laser Laboratory (DFELL) has recently completed two major accelerator/light source development projects - we successfully commissioned the world's first distributed optical klystron FEL (DOK-1 FEL) and a new 0.24 - 1.2 GeV booster sy ... Full text Cite

The feasibility study of measuring the polarization of a relativistic electron beam using a compton scattering gamma-ray source

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 The Compton scattering of a circularly polarized photon beam and a polarized electron beam leads to an asymmetric spatial distribution of the gamma rays. This asymmetry has been calculated for the High Intensity Gamma-ray Source (HIGS) beam at Duke Univers ... Full text Cite

New generation digital longitudinal feedback system for Duke FEL and HIγS facilities

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 To cure harmful longitudinal coupled-bunch mode beam instabilities during high-current and multi-bunch beam operations at the Duke Free Electron Laser (FEL) and High Intensity γ-ray Source (HIγS) facilities, we have been developing a new generation digital ... Full text Cite

A tune measurement system for lowcurrent and energy ramping operation of a booster synchrotron

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 A betatron tune measurement system is one of the most important diagnostic tools for any circular accelerator. For the commissioning of a booster synchrotron newly developed for top-off injection into the Duke storage ring, a versatile tune measurement sys ... Full text Cite

A direct electron beam energy spread measurement system for beam instability and FEL research

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 One of critical beam parameters for the storage ring based light sources is the energy spread of the electron beam. An accurate measurement of the energy spread remains a challenge. It is well known that the energy spread of the electron beam can degrade t ... Full text Cite

A physics based approach for ramping magnet control in a compact booster

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 At Duke University, a booster synchrotron was recently commissioned as part of the High Intensity Gamma-ray Source (HIGS) upgrade. For the ramping magnet power supply controls, a scheme was developed to present the high level operator interface in terms of ... Full text Cite

Power supply system for a compact 1.2 GEV booster synchrotron

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 Low cost power supply system for compact full energy booster synchrotron was designed, developed and successfully commissioned at Duke University. 500kW second hand thyristor controlled power supply has been completely rebuilt to provide high accuracy ramp ... Full text Cite

BPM signal conditioning for a wide range of single-bunch current operation in the Duke storage ring

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2007 The beam position monitor system of the Duke storage ring has been in operation since 1998. Recently, by injecting at higher energy with a booster synchrotron, the single bunch current threshold is much more increased. The high peak voltage associated with ... Full text Cite

Study of collective dipole excitations below the giant dipole resonance at HIγS

Journal Article AIP Conference Proceedings · April 4, 2007 The High-Intensity Gamma-ray Source utilizing intra-cavity back-scattering of free electron laser photons from relativistic electrons allows one to produce a unique beam of high-flux gamma rays with 100% polarization and selectable energy and energy resolu ... Full text Cite

Progress on PEEM3 - An aberration corrected X-ray photoemission electron microscope at the ALS

Conference AIP Conference Proceedings · March 27, 2007 A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous co ... Full text Cite

New findings for mixed-symmetry states

Journal Article AIP Conference Proceedings · March 13, 2006 This report summarizes experiments performed on 164Dy using photon scattering techniques. The scissors mode in 164Dy has been reinvestigated using unpolarized photons from bremsstrahlung and polarized photons from a free electron laser. The current experim ... Full text Cite

First evidence for spin-flip M1 strength in 40A

Journal Article Physical Review C · March 2006 www.aps.org ... Link to item Cite

High-Gain Lasing and Polarization Switch with a Distributed Optical-Klystron Free-Electron Laser

Journal Article Phys. Rev. Lett. · 2006 This Letter reports the first experimental results from the world's first distributed optical-klystron (DOK) free-electron laser (FEL), the DOK-1 FEL, at Duke University. The DOK-1 FEL is a hybrid system, comprised of four wigglers: two horizontal and two ... Link to item Cite

Parity Assignments in 172,174Yb using Polarized photons and the K Quantum Number in Rare Earth Nuclei

Journal Article Physical Review C · December 2005 Open Access Link to item Cite

Trim power supplies for the Duke booster and storage ring

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 The on-going Duke storage ring upgrades and the development of a new booster synchrotron injector require more than 100 units of high performance unipolar and bipolar trim power supplies in the current range of -15 A to +15 A. However, most of the trim pow ... Full text Cite

Commissioning of the new RF system with the HOM damped RF cavity

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 A new 178 MHz RF system has been commissioned at Duke Storage Ring. It consists of a 140 kW tetrode transmitter; higher order modes (HOM) damped RF cavity and the necessary frequency and voltage control electronics. The cavity walls are made of copper-on-s ... Full text Cite

Status of the booster injector for the duke fel storage ring

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 This paper presents the current status of the booster synchrotron for the Duke Free Electron Laser Laboratory (DFELL) storage ring. The booster will provide full energy injection into the storage ring in a wide energy range from 0.27 to 1.2 GeV. When opera ... Full text Cite

3 KA power supplies for the Duke OK-5 FEL wigglers

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 The next generation electromagnetic OK-5/Duke storage ring FEL wigglers [1], [2] require three 3kA/70V power supplies with current stability about 20 ppm and current ripples less than 20 ppm in their full operating range. Duke FEL Laboratory acquired three ... Full text Cite

Improved long radius of curvature measurement system for FEL mirrors

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 The 53.73 meter long Duke free electron laser (FEL) cavity consists of two concave mirrors with radius of curvature longer than 27 meters. A proper radius of curvature is designed to achieve an optimal and stable operation of the FEL. This requires accurat ... Full text Cite

Measuring and understanding the momentum aperture in a storage ring

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 The momentum aperture of a storage ring is a very important parameter that strongly influences the performance, especially the beam lifetime. For the special case of synchrotron light sources with small emittance like the Advanced Light Source (ALS), the m ... Full text Cite

A control system for the duke booster synchrotron

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 The Duke Free Electron Laser Laboratory is developing a booster synchrotron to provide full energy injection into the Duke electron storage ring. In this paper, we describe the development of the control system for the booster. Requirements include the com ... Full text Cite

Observations and measurements of anomalous hollow electron beams in the duke storage ring

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 Anomalous hollow electron beams have been recently observed in the Duke storage ring. With a single bunch beam in a lattice with a negative chromaticity, a hollow beam can be created. This beam consists of a solid core beam inside and a large ring beam out ... Full text Cite

A new timing system for the Duke booster and storage ring

Journal Article Proceedings of the IEEE Particle Accelerator Conference · December 1, 2005 A dedicated booster synchrotron is being constructed at the Duke FEL Laboratory to provide full energy injection into the main electron storage ring. A new timing system has been developed to coordinate the injection of electron bunches from the linac to t ... Full text Cite

First lasingand initial operation ofa circularly polarized optical klystron ok-5 felandavariably polarized distributed optical klystron DOK-1 FEL at DUKE

Journal Article Proceedings of the 27th International Free Electron Laser Conference, FEL 2005 · December 1, 2005 To improve the capability and performance of its light sources, the Duke FEL lab (DFELL) is upgrading its storage ring based FEL. The existing linearly polarized OK-4 FEL wigglers are being replaced gradually by the next generation OK-5 wigglers capable of ... Cite

Photon analyzing power for the three-body breakup of ³He at Eγ = 15.0 MeV

Journal Article AIP Conference Proceedings · May 6, 2005 Photon analyzing power for the three-body breakup of 3He has been studied at Eγ = 15.0 MeV. The measurements were done at the HIγS facility at Duke University. © 2005 American Institute of Physics. ... Full text Cite

An X-ray Photoemission Electron Microscope Using Electron Mirror Aberration Corrector for the Study of Complex Materials

Journal Article Journal of Physics: Condensed Matter · April 2005 A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed at the advanced light source (ALS). An electron mirror combined with a sophisticated magnetic beam separator is used to provide simultaneous correction of spherica ... Link to item Cite

Anomalous Hollow Electron Beams in a Storage Ring

Journal Article Physical Review Letter · April 2005 This Letter reports the first observations of an anomalous hollow electron beam in the Duke storage ring. Created by exciting the single-bunch beam in a lattice with a negative chromaticity, the hollow beam consists of a solid core inside and a large ring ... Link to item Cite

Correction and alignment strategies for the beam separator of the photoemission electron microscope 3 (PEEM3)

Journal Article Rev. Sci. Instrum. · February 2005 A high-resolution aberration-corrected photoemission electron microscope (PEEM3) will be installed on an undulator beamline at the Advanced Light Source at the Lawrence Berkeley National Laboratory. The aim of this instrument is to provide a substantial fl ... Cite