Calibration of the monochromator

Insert the Re(0001) single-crystal sample, or the W(110) crystal. Set the energy of the monochromator to 400 eV, after inserting and selecting the VLS 400 grating. Measure the difference in energy between the photoemission peak of Re 4f7/2 (W 4f7/2) in first and second harmonics. Change the DeltaGrOpt parameter of the selected grating so that the monochromator energy is equal to this value. Proceed iteratively until convergence is achieved. This procedure must be carried out at the beginning of each run.

Tango Server

The TANGO server stores the monochromator optical parameters which were last loaded. Those optimezed during commissioning in January 2016 are reported here for comparison and/or backup purpose.

Optical parameters

  • Yen = -25.8 mm
  • Yex = 104.819 mm
  • Yex = 104.769 mm [until 08/07/2018]
  • Yex = 104.7 mm [until 14/7/2017]
  • Entrance Angle  = 0 rads

DeltaMiOpt

  • deltaMiOpt = -0.00006050 rads [27/11/2022]
  • deltaMiOpt = -0.0001045 rads [26/11/2022]
  • deltaMiOpt = -0.0002645 rads [24/11/2022]
  • deltaMiOpt = -0.0002215 rads [until 8/07/2018]
  • deltaMiOpt = -0.000194 rads [until 5/12/2016]

DeltaGrOpt VLS 400

  • deltaGrOpt [VLS 400] = -0.000656 rads [25/11/2022]
  • deltaGrOpt [VLS 400] = -0.00052 rads [24/11/2022]
  • deltaGrOpt [VLS 400] = -0.0005737 rads [08/07/2018]
  • deltaGrOpt [VLS 400] = -0.0005637 rads [21/05/2018]
  • deltaGrOpt [VLS 400] = -0.0005817 rads [23/04/2018]
  • deltaGrOpt [VLS 400] = -0.0005637 rads [23/01/2018]
  • deltaGrOpt [VLS 400] = -0.0005737 rads [20/12/2017]
  • deltaGrOpt [VLS 400] = -0.0005677 rads
  • deltaGrOpt [VLS 400] = -0.00063 rads [5/12/2016]

DeltaGrOpt VLS 200

  • deltaGrOpt [VLS 200] = -0.001403  rads [25/11/2022]
  • deltaGrOpt [VLS 200] = -0.001248  rads [24/11/2022]
  • deltaGrOpt [VLS 200] = -0.0012970  rads [21/05/2018]
  • deltaGrOpt [VLS 200] = -0.0013140 rads [23/04/2018]
  • deltaGrOpt [VLS 200] = -0.0012977 rads [20/12/2017]
  • deltaGrOpt [VLS 200] = -0.0012877 rads
  • deltaGrOpt [VLS 200] = -0.001354 rads [5/12/2016]

DeltaGrOpt SG10

  • deltaGrOpt [SG10] = -0.00172200 rads

Heidenhein encoders

VLS 400, 400 eV: mirror: 2.98082; grating: 2.64081
VLS 400, 650 eV: mirror: 0.54658; grating: 0.12674
VLS 400, 200 eV: mirror: 7.59540 ; grating: 7.50931
VLS 200, 52 eV: mirror: 13.49247 ; grating: 14.06834

Feedback control system

The monochromator energy can be stabilized by activating a software feedback on the Tango Server. The feedback has to be activated by yhe users and disables automatically when a command is sent to the "monch" server on Tango.\

  • Period: this value is set by opening Jive and selecting Nanosp/Monoch/Monoch/Polling; the variable EnergyFeedbackStatus has to be selected and set to the desired value. Current default is 10000 ms. To enable click on the "Apply" button.
  • Energy Feedback band: mirror and grating are moved only if the difference between the set and measured energy is larger than this value. Current default is 10 meV

Piezo controller

The piezoelectric actuators for fine roll alignement of the monochromator grating roll are powered by dedicated amplifiers, which areremotely controlled by DAC. The optimum voltages are reported here.

  • Channel 1 [VLS 200] = 5.50 V [last checked on 14/07/2017]
  • Channel 2 [VLS 400] = 5.05 V [last checked on 14/04/2017]
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Last Updated on Monday, 27 May 2024 16:44