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 Contact:
   Project Coordinator
   Prof. Theo Zouros
   Atomic & Molecular Physics
   Dept. of Physics
   Univ. of Crete, PO Box 2208,
  . GR-71003 Heraklion
   Tel:+30-2810394117
   Fax:+30-2810394301
   e-mail: tzouros@physics.uoc.gr

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Home > Work Packages > WP7 - Electron spectrometers - preparation, setup and operation
Work Packages

Work Packages: WP1  WP2  WP3  WP4  WP5  WP6  WP7  WP8  WP9  WP10  WP11  WP12 Timetable

Work Package 7: Electron spectrometers - preparation, setup and operation

Figure 0: Comparison of conventional (left) and paracentric (right) entry focusing viewed in a SIMION simulation. Offsetting the entry as in the paracentric case (right) is seen to improve focusing conditions degraded by the fringing fields at the entry and exit of the HDA. The HDA used in the APAPES measurements is a paracentric hemispherical deflector analyzer (HDA) with a 2-D position sensitive detector (PSD) (From Benis & Zouros, Nucl. Instrum. & Meth. Phys. Res. A440 (2000) 462).

Figure 1: Photo of setup showing HV rack and distribution of voltages.

Figure 2: Precision 5kV power supply N-97N. Default settings for running under computer control: TN3=100V (U Hand), TN2=5kV (Ust1). The final equation determining the HV output is then: HV = UHand *VTN3/10 + (Ust1 + VTN1 + VH1)*VTN2/10 where Ust1 and UHand are the 0-10V DAC inputs. VH2 is only use for protection and controls the maximum allowed HV output.

Figure 3: (Top) Photo of broken HDA exit grids (grid1 and 2 had holes, while grid 3 as seen is completely broken) and (Bottom) Electron spectrum taken with this broken grid (F=4 Rπ=81.6 mm, Egun=-950 eV, W=900 eV, Lens scheme=Omer). The small extra peak always remained at the same spot on the PSD while the other changed with energy as expected.

Description of work package

Work Package

7

Start:

Month 7

Finish:

Month 18

Cost:

Title:

WP7: Electron spectrometers - preparation, setup and operation

Description:

Research Teams:

RT1, RT2, RT3

7.1 Hemispherical Deflector Analyzer (HDA) - preparation and tests of operation:

7.2 Two-stage 450 parallel plate Analyzer (PPA) - preparation and tests of operation:

Existing HDA [Ben99a, b, Zou02a] and PPA [Zou97a] spectrometers brought from Kansas must be prepared for use, cleaned, resurfaced with conducting graphite coating (Aquadag) and tested for electrical high voltage break down to 5kV. Special positioning stands for both systems allowing for sensitive alignment must be built. Both MCP plates, found to develop dead spots or hot spots after heavy and channeltron detector, deteriorate over time will be replaced as needed, the cost included under consumables.

7.3 Final test of spectrometers -high voltage control and DAQ: Finally, the entire spectroscopy apparatus connected to the DAQ (WP6) will be tested first with an e-gun and later with collisional electrons.  Further improvement of the optics of deceleration stage in either type of spectrometer is also planned using the simulation software SIMION for maximum transmission optimization and improved energy resolution.

Deliverables:

1 Report and part of BS, MS or PhD thesis, DAQ software programs

WP7: Table of Activities in progress

CompletedActivityTarget Date
Placed HDA in chamber and roughly aligned it - tested vacuum
Dec 2013
Order electroformed mesh for HDA
Dec 2013
Connect all HV cabling to HDA and test connectivity
Jan 2014
Replace mesh in HDA and PSD where needed
Jan 2014
Open up HDA and clean thoroughly
Feb 2014
Place HDA back in chamber and align after gas cell has also been aligned
Mar 2014
Test signal cables to PSD with existing MCPs - test voltages to MCP
Mar 2014
Connect PSD to preamps and data acquisition (DAQ) system (Ivan Valastyan)
May 2014
Test HDA with first hot wire electron measurements (problems with lens performance encountered - no focusing!)
May 2014
Test HDA with first hot wire electron measurements- focusing problem solved after cleaning lens and using e-gun with less intense beam
Jul 2014
Tests of mu-metal shielding (ordered DC Milligauss Meter Model MGM from AlphaLab Inc.)
Sep 2014
Reinstalled hot wire e-gun without foil hole aperture (bare filament)
Jan 2015
Removal of PSD to instal piezo-electric motor
May 2015
Test complete h-variation system and measure lineshapes for various h (still waiting to replace problematic piezomotor control - also had problems with PSD cables getting disconnected). Measured line shapes with e- gun for hmin, hmin+6mm and hmin+12mm. hmin=23.075mm
Jun 2015
SIMION tandem ppa under construction and testing by Eleonore Defaux (in progress)
Jun/Jul 2015
SIMION tandem ppa under construction and testing by Eleonore Defaux (in progress)
Jun/Jul 2015
HDA exit grids discovered broken - all three were replaced on June 27 - see Fig. 3
Jun 27 2015
Final Report on operation of DAQ ready - work package completed
Dec 2015

WP7: Deliverables

Additional related results:

WP7: People involved

  • Prof. Theo Zouros - MRG RT1 (UoC)
  • Giannis Madesis (PhD student) - GEC RT1 (UoC)
  • Dr. Tasos Dimitriou (postdoc) - GEC RT1 (UoC)
  • Prof. Manolis Benis - MRG RT3 (UoI)
  • Dr. Bela Sulik - MRG RT1 (invited scientist - ATOMKI, Debrecen Hungary)
  • Fasmatech

WP7: Technical Notes

WP7: Additional Work

  • Installation of piezo-electric motor to move 2-D position sensitive detector (PSD) - varying the distance h for optimal energy resolution (see Refs. [1], [2], [3] below)
  • Video showing the motor moving the rod on which the PSD is attached [MTS file (57.2 MB)]

WP7: References

  1. T. J. M. Zouros and E. P. Benis, Optimal energy resolution of a hemispherical analyzer with virtual entry, Applied Physics Letters 86, 094105 (2005).
  2. T. J. M. Zouros, E.P. Benis, I. Chatzakis, Optimization of the energy resolution of an ideal ESCA-type hemispherical analyzer, Nucl. Instrum. & Methods in Phys. Res. B 235, 535-539 (2005).
  3. T. J. M. Zouros, Theoretical investigation of the energy resolution of an ideal hemispherical deflector analyzer and its dependence on the distance from the focal plane, J. Electron Spectroscopy and Related Phenomena 152, 67-77 (2006). Erratum: ibid. 153, 102–107 (2006).

Work Package 7 ( continued): after end of THALIS grant (31/12/2015)

Figure 4: Fig. 1 of Sise et al. JESRP 211 (2016) 19 showing the effect of the lens on line shape and resolution of our HDA.

Figure 5: Fig. 9 of Sise et al. JESRP 211 (2016) 19 showing the recently measured FWHM resolution of our HDA as a function of deceleration factor F.


WP7: Table of Activities in progress

CompletedActivityTarget Date
 
Jan 2017
 
Feb 2017

Last Update: 06/02/17 12:49:15

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