HYSPEC POLARIZATION ISSUES

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HYSPEC POLARIZATION ISSUES
April 7th, 2006
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• Polarizers and analyzers
• Polarizer Heusler What about the focusing
  the polarization?
• Analyzers Supermirrors 3He One size does
  not fit all Supermirrors cold neutrons
  3He thermal hotter neutrons
• Ferromagnets magnetic fields One sided
  polarization
• But first some important background info

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Two pieces of background information 1) A
baseline change SING is a construction (not an
RD) project CD-2 established a baseline
budget and schedule(Progress is measured against
this.)Baseline change is the procedure to
(significantly) change the baseline Baseline
change before CD-3 is good, after CD-3 is
badGood something that improves a
project Depending upon impact baseline change
can be approved at various levels Note if
acceleration of schedule occurs that will be a
baseline change
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Two pieces of background information 2) A new
member of the IDT? Discussions between PSI SNS
HYSPEC PIs for PSI to join the HYSPECIDT PSI
interested in contributing a supermirror
polarization analyzer to HYSPEC (IDT input on
characteristics of such an analyzer)Under those
circumstances, what should we do with the HYSPEC
baseline? How should we improve the range of
capabilities of HYSPEC?A baseline change at
CD-3 time
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Heusler

• Fixed vertical focus horizontal focus
• Variable vertical focus spin rotation
• On HYSPEC factor of 6 for vertical focus,
  1.2 for horizontal focus

Horizontal focus
Vertical focus spin rotation
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• Questions about supermirror analyzers?
• Is it important to measure both spin states
  simultaneously or is it acceptable to measure
  them one after the other, possibly
  periodically ?
• How important is it to have a clean beam onto
  the detector (cross contamination between the
  spin states, complicated data analysis) ?
• How important is the intensity (transmission)
  versus the contamination? (Priorities)

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• A 3He Polarization Analyzer
• Optimized for energy range 15 ? 90meV ?
• Is low (zero) field acceptable or do we want to
  use magnets?
• Do we need to cover the whole solid angle of the
  detector?
• Swap cells, on-line filling, in-situ pumping?
• MEOP or SEOP or whatever is economic?

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• Horizontal magnetic field
• One sided polarization for ferromagnets
• Full polarization analysis (), (-),(-),
  (--) with supermirrors
• Qs not totally parallel to field 60 (30)
  detector bank Close enough is good enough?

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