This paper presents the results of an analysis focused on the behavior of emittance, energy spread and radiated power, as well as their variations in relation to the complement of active insertion ...devices in National Synchrotron Light Source II (NSLS-II) operations. The spectra of radiated power of the installed insertion devices and analytic values of the emittance are compared to that measured by the NSLS-II online diagnostics. A conceptual design of a compensation wiggler that will maintain a constant emittance or energy spread is investigated for NSLS-II and a potential low emittance upgrade scenario.
In-vacuum undulators (IVU) are used extensively at light source facilities, in particular at medium-energy storage rings, where these devices are the main sources of high-brightness hard X-rays. The ...relatively small vertical magnetic gaps that are used in these planar undulators make them rather sensitive to misalignments of magnet arrays with respect to the electron orbit in the vertical plane. Based on commissioning results of undulator-based hard X-ray beamlines at the National Synchrotron Light Source II (NSLS-II)—a Department of Energy Office of Science User Facility at Brookhaven National Laboratory— IVU misalignment was found to be the most frequent cause of spectral “underperformance.” It is possible, nevertheless, to restore the performance using a spectrum-based IVU alignment procedure described in this article.
Three-pole wigglers at NSLS-II Musardo, M.; Tanabe, T.; Rank, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2024, Letnik:
1059, Številka:
C
Journal Article
Three-pole wigglers at NSLS-II Musardo, M.; Tanabe, T.; Rank, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2023, Letnik:
1059
Journal Article
Recenzirano
The National Synchrotron Light Source-II (NSLS-II) at Brookhaven National Lab (BNL) is a third-generation medium-energy storage ring with 3 GeV and sub-nm-rad horizontal emittance, equipped with a ...top-off capability of 500 mA. It is designed to deliver an extremely intense photon beam across a wide spectral range, from the far-infrared to the very hard X-ray region. This outstanding performance is achieved through a combination of bending magnets (BM), three-pole wigglers (3 PW), and advanced insertion device (ID) sources. Six three-pole wigglers have been constructed at the NSLS-II IDs Lab. These devices are used to produce broadband radiation with lower angular power density and to monitor the electron beam emittance and energy spread. Here, this paper describes the R&D activities focused on developing the required magnetic and mechanical designs, along with magnetic field optimization and the final magnetic measurement results. It also covers the spectral brightness, flux, power density, spatial and angular output properties of the 3 PWs, including their commissioning results and their effects on the performance of the NSLS-II storage ring.
Insertion devices have become the dominant photon source at synchrotron and free electron laser light source facilities the world over. Undulators, characterized by their small deflection parameter, ...exhibit a high degree of constructive interference in photon production from high energy charged particle beams leading to very high photon rates at specific harmonics of the fundamental frequency with relatively narrow spectral widths. Spectroscopic measurements of interest typically span several of these harmonic widths, which requires precision adjustment of an undulator’s magnetic gap to maintain peak flux within the much narrower bandwidth of a beamline monochromator at the desired energy. High precision insertion device controls are developed at NSLS-II including real-time linked control of monochromator hardware allowing for fast, high precision, hardware triggered, spectroscopic measurements. This fast fly scan method is described, compared statistically for self consistency, and shown to be far superior in both efficiency and accuracy as compared to standard step scan measurements.
A superconducting wiggler (SCW) with a peak field of 4.3 T has recently been installed at NSLS-II. The wiggler generates a high-flux X-ray beam with a photon energy range from 20 keV to 200 keV for ...the High Energy Engineering X-ray Scattering beamline. This device induces significant distortions in the electron beam orbit and optics. We have corrected these adverse effects using feed-forward tables. The effects of the SCW on the electron beam emittance, energy spread, and bunch length were calculated and measured. The beam-induced heating of the cryogenic vacuum chamber was also studied. Finally, the superconducting wiggler has been commissioned for user operations.
The Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and ...arranged into 16 “telescopes”, with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run 2 (2015–18) of the LHC, as well as preparations for Run 3, which will begin in 2022.
At present most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades in the next 5-10 years for their innermost tracking layers as well as luminosity monitors to be able to take ...data as the luminosity increases and CERN moves toward the High Luminosity-LHC (HL-LHC). These upgrades will most likely require more radiation tolerant technologies than exist today. As a result this is one area of intense research, and Chemical Vapour Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest radiation areas of all LHC experiments. This talk describes the preliminary radiation tolerance measurements of the highest quality polycrystalline CVD material for a range of proton energies and neutrons obtained with this material with the goal of elucidating the issues that should be addressed for future diamond based detectors. The talk presents the evolution of various semiconductor parameters as a function of dose.
Abstract Aims To evaluate the ability of a bladder pressure/volume diary (PVD) to identify patients at risk for elevated intravesical pressures. Methods Clean intermittent catheterization (CIC) ...dependent patients used ruler-based manometry to measure intravesical pressures prior to leakage or scheduled drainage at home. We prospectively collected clinical, urodynamic (UDS), and PVD data in patients with spina bifida who were optimized on anticholinergic therapy and on CIC. Measurements were taken in the supine position with relaxed abdominal muscles. We defined elevated pressures as detrusor pressures (Pdet) above 30cm of water measured by UDS. Receiver Operator Curves (ROC) were plotted to correlate PVD variables with abnormal intravesical pressures and the most sensitive variable in determining abnormal intravesical pressures was sought after as the endpoint. Results N=30, mean age 10 years (range 1-20 years). Home pressures (HP) measured at maximal CIC volume and mean PVD pressures were most reliable in predicting UDS pressures above 30cm of water AUC 0.93 and AUC 0.87 respectively. HP measured at maximal CIC volumes below 20cm of water were associated with normal bladder pressures on UDS (below 30cm of water) with a sensitivity of 100% and specificity of 80%. Conclusion Home manometry below 20cm of water provides a reliable measurement of safe pressures. PVD is feasible and can aid in monitoring pressures at home without the additional cost and morbidity of UDS. PVD may be a useful tool to help identify patients who would benefit from UDS.
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