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Title: Synchrotron Light Interferometry at Jefferson Lab

Abstract

The hyper-nuclear physics program at JLAB requires an upper limit on the RMS momentum spread of {delta}p/p < 3 x 10{sup -5}. The momentum spread is determined by measuring the beam width at a dispersive location (D {approx} 4m) in the transport line to the experimental halls. Ignoring the epsilon-beta contribution to the intrinsic beam size, this momentum spread corresponds to an upper bound on the beam width of {sigma}{sub beam} < 120 {micro}m. Typical techniques to measure and monitor the beam size are either invasive or do not have the resolution to measure such small beam sizes. Using interferometry of the synchrotron light produced in the dispersive bend, the resolution of the optical system can be made very small. The non-invasive nature of this measurement allows continuous monitoring of the momentum spread. Two synchrotron light interferometers have been built and installed at JLAB, one each in the Hall-A and Hall-C transport lines. The devices operate over a beam current range from 20 {micro}A to 120 {micro}A and have a spatial resolution of 10um. The structure of the interferometers, the experience gained during its installation, beam measurements and momentum spread stability are presented. The dependence of the measured momentum spreadmore » on beam current will be presented.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
Sponsoring Org.:
USDOE Office of Energy Research (ER) (US)
OSTI Identifier:
838709
Report Number(s):
JLAB-ACC-04-18; DOE/ER/40150-3269
TRN: US0501495
DOE Contract Number:
AC05-84ER40150
Resource Type:
Conference
Resource Relation:
Conference: 9th European Particle Accelerator Conference (EPAC 2004), Lucerne (CH), 07/05/2004--07/09/2004; Other Information: PBD: 1 Jul 2004
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; BEAM CURRENTS; BEAM PROFILES; INTERFEROMETERS; INTERFEROMETRY; MONITORING; MONITORS; OPTICAL SYSTEMS; PHYSICS; RESOLUTION; SPATIAL RESOLUTION; STABILITY; SYNCHROTRONS; TRANSPORT

Citation Formats

Arne Freyberger, Pavel Chevtsov, Anthony Day, and William Hicks. Synchrotron Light Interferometry at Jefferson Lab. United States: N. p., 2004. Web.
Arne Freyberger, Pavel Chevtsov, Anthony Day, & William Hicks. Synchrotron Light Interferometry at Jefferson Lab. United States.
Arne Freyberger, Pavel Chevtsov, Anthony Day, and William Hicks. Thu . "Synchrotron Light Interferometry at Jefferson Lab". United States. doi:. https://www.osti.gov/servlets/purl/838709.
@article{osti_838709,
title = {Synchrotron Light Interferometry at Jefferson Lab},
author = {Arne Freyberger and Pavel Chevtsov and Anthony Day and William Hicks},
abstractNote = {The hyper-nuclear physics program at JLAB requires an upper limit on the RMS momentum spread of {delta}p/p < 3 x 10{sup -5}. The momentum spread is determined by measuring the beam width at a dispersive location (D {approx} 4m) in the transport line to the experimental halls. Ignoring the epsilon-beta contribution to the intrinsic beam size, this momentum spread corresponds to an upper bound on the beam width of {sigma}{sub beam} < 120 {micro}m. Typical techniques to measure and monitor the beam size are either invasive or do not have the resolution to measure such small beam sizes. Using interferometry of the synchrotron light produced in the dispersive bend, the resolution of the optical system can be made very small. The non-invasive nature of this measurement allows continuous monitoring of the momentum spread. Two synchrotron light interferometers have been built and installed at JLAB, one each in the Hall-A and Hall-C transport lines. The devices operate over a beam current range from 20 {micro}A to 120 {micro}A and have a spatial resolution of 10um. The structure of the interferometers, the experience gained during its installation, beam measurements and momentum spread stability are presented. The dependence of the measured momentum spread on beam current will be presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jul 01 00:00:00 EDT 2004},
month = {Thu Jul 01 00:00:00 EDT 2004}
}

Conference:
Other availability
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  • A synchrotron light interferometer has been built at Jefferson Lab in order to measure small beam sizes below the diffraction limit. The device is non-invasive and can monitor the profile of a few microampere electron beam. It follows the design pioneered by T. Mitsuhashi and is a valuable instrument for the CEBAF accelerator. The structure of the interferometer, the experience gained during its installation, and first beam measurement results with its use are presented. Future applications of this device include precise energy spread monitoring ({approx} 10-5) which is required by some Hall A nuclear physics experiments.
  • Optical Transition Radiation Interferometry (OTRI) has proven to be effective tool for measuring rms beam divergence. We present rms emittance measurement results of the 115 MeV energy recovery linac at the Thomas Jefferson National Laboratories Free electron Laser using OTRI. OTRI data from both near field beam images and far field angular distribution images give evidence of two spatial and angular distributions within the beam. Using the unique features of OTRI we segregate the two distributions of the beam and estimate separate rms emittance values for each component.
  • Jefferson Lab is planning a facility for studying ultra-fast dynamic processes, which will have a 1 kW average power IR/UV FEL combined with a 1 nm critical wavelength electron storage ring. Light pulses from the 2 sources will be synchronized at 125 MHz for pump-probe studies in chemistry, physics, materials science, medicine and biology. The FEL operates with pulses as short as 300 femtoseconds, which will provide the narrow bandwidth pump at high peak as well as average power. The FEL is currently operating and will soon be upgraded to operate at 10 kilowatt average power at an extended wavelengthmore » range from 250 nm to 10,000 nm. A compact superconducting storage ring has recently been donated to Jefferson Lab, and is capable of stored currents up to 800 mA. In addition to providing spectroscopy capabilities, the storage ring will also support x-ray lithography R and D, including a precision stepper-aligner for training purposes. The facility, which is expected to become available in 200 4, will be described and the capabilities detailed.« less
  • The Jefferson Laboratory IR FEL Driver provides an ideal test bed for studying a variety of beam dynamical effects. Recent studies focused on characterizing the impact of coherent synchrotron radiation (CSR) with the goal of benchmarking measurements with simulation. Following measurements to characterize the beam, we quantitatively characterized energy extraction via CSR by measuring beam position at a dispersed location as a function of bunch compression. In addition to operating with the beam on the rising part of the linac RF waveform, measurements were also made while accelerating on the falling part. For each, the full compression point was movedmore » along the backleg of the machine and the response of the beam (distribution, extracted energy) measured. Initial results of start-to-end simulations using a 1D CSR algorithm show remarkably good agreement with measurements. A subsequent experiment established lasing with the beam accelerated on the falling side of the RF waveform in conjunction with positive momentum compaction (R56) to compress the bunch. The success of this experiment motivated the design of a modified CEBAF-style arc with control of CSR and microbunching effects.« less
  • Baseline design of the JLEIC booster synchrotron is presented. Its aim is to inject and accumulate heavy ions and protons at 285 MeV, to accelerate them to about 7 GeV, and finally to extract the beam into the ion collider ring. The Figure-8 ring features two 2600 achromatic arcs configured with negative momentum compaction optics, designed to avoid transition crossing for all ion species during the course of acceleration. The lattice also features a specialized high dispersion injection insert optimized to facilitate the transverse phase-space painting in both planes for multi-turn ion injection. Furthermore, the lattice has been optimized tomore » ease chromaticity correction with two families of sextupoles in each plane. The booster ring is configured with super-ferric, 3 Tesla bends. We are presently launching optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime.« less