LCLS

LCLS Beam Based Undulator K Measurement Workshop

Redwood Room C/D, SLAC

Monday, November 14, 2005

A one-day workshop will be held at the Stanford Linear Accelerator Center to define a strategy for using spontaneous undulator radiation to measure the K value of every individual LCLS Undulator Segment, with the beam, i.e. after installation in the Undulator Hall. To reach the objective, the physics and the technologies necessary need to be identified. Workshop discussions will include the areas of
  • Usable spectral features of spontaneous radiation
  • Strategies for beam-based K measurements
  • Specifications for suitable instruments
  • Scheduling issues
Three Work Packages have been defined and assigned to three different groups. (see description below) Work described by these Work Packages will be carried out in preparation of the workshop and presented and discussed at the workshop. The agenda has been included on this page.

Contacts:

Workshop Organizer: Heinz-Dieter Nuhn, SLAC +1-650-926-2275
Administration: Helen O'Donnell, SLAC +1-650-926-3368

Agenda:

Monday, November 14, 2005    
09:00 - 09:30 Introduction and Charge HD. Nuhn, SLAC
  Work Package 1    
09:30 - 10:30 Undulator Effective-K Measurements
  Using Angle-Integrated Spontaneous Radiation 		B. Yang, ANL

R. Dejus, ANL
10:30 - 10:45 Discussion  
10:45 - 11:00 Coffee Break  
  Work Package 2    
11:00 - 11:45 "Pinhole Measurement"
  Approach to K Measurements
  using Spontaneous Radiation
 J. Welch, SLAC
11:45 - 12:15 Use of FEL Off-Axis Zone Plate
  Spectrometer to measure relative
  K by the Pinhole/Centroid method 		R. Bionta, LLNL


S. Reiche, UCLA
12:15 - 12:20 Discussion  
12:20 - 13:30 Lunch  
  Work Package 3    
13:30 - 14:15 Introduction
A Grating Spectrograph for the LCLS 		J. Hastings, SLAC
P. Heimann, LBNL
S. Hulbert, BNL
14:15 - 15:00 Discussion  
15:00 - 15:15 Coffee Break  
  Summary    
15:15 - 17:00 Discussion of Spectral Features,
  Measurement Strategies and
  Summary 		J. Arthur, SLAC  
17:00 Adjourn  
     

Work Package Descriptons:

Work Package 1: Angle-Integrated Measurement

Group: B.Yang, R. Dejus
Task: Examine robustness of angle-integrated measurements of undulator spectrum. Consider effects of errors in beam alignment, undulator magnet structure, straightness of vacuum pipe, alignment of spectrometer, etc. Consider effects of location of undulator segment being tested. Determine what are realistic values for the precision with which the value of K can be determined for an undulator segment at the beginning, middle, and end of the undulator.

This task explores the use of the high-energy edge of the fundamental spectral peak (the third harmonic may also be considered) of a single undulator to measure its K parameter. The measuring spectrometer will be located in the LCLS FEE, roughly 100 m downstream from the final undulator segment. Realistic values for the angular acceptance of the measurement (limited by beam-pipe apertures, or apertures at the measuring point) should be considered.

Work Package 2: Pinhole Measurement

Group: J. Welch, R. Bionta, S. Reiche
Task: Examine robustness of pinhole measurements of undulator spectrum. Consider effects of errors in beam alignment, undulator magnet structure, straightness of vacuum pipe, alignment of pinhole and spectrometer, etc. Consider effects of location of undulator segment being tested. Determine what are realistic values for the precision with which the value of K can be determined for an undulator segment at the beginning, middle, and end of the undulator.

This task explores the use of the fundamental spectral peak (the third harmonic may also be considered) of a single undulator, as seen through a small angular aperture, to measure its K parameter. The measuring spectrometer will be located in the LCLS FEE, roughly 100 m downstream from the final undulator segment. Realistic values for the angular acceptance of the measurement should be determined, and the effects of misalignment of the aperture or undulator axis should be carefully considered.

Work Package 3: Single-Shot Spectral Measurement

Group: J. Hastings, et al.
Task: Assume that a single shot spectral measurement is needed for an LCLS spontaneous undulator pulse. What are the best options for doing the measurement? What spectral resolution can be obtained using these methods? What are the effects of beam jitter, spectrometer misalignment, etc?

This task explores the design and performance of x-ray spectrometers capable of providing centroid or edge position with high resolution, on a single-shot of radiation from a single LCLS undulator. The spectrometer will most likely be located in the LCLS FEE, about 100 m downstream from the final undulator segment.

Presentation Equipment:

Provisions for presenting talks from a CD or a PC laptop are available as wells as using the old overhead projector.

Documents:

Icon  Name                      Last modified      Size  Description
[DIR] Parent Directory                               -   
[DIR] talks/                    20-Sep-2005 13:04    -
Last Updated: 16 Nov 2005
Content Owner: Heinz-Dieter Nuhn, SLAC
Page Editor: LCLS Web Master

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