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HYSPEC POLARIZATION ISSUES

HYSPEC POLARIZATION ISSUES. April 7th, 2006. Polarizers and analyzers Polarizer – Heusler What about the focusing & the polarization? Analyzers – Supermirrors & 3 He One size does not fit all Supermirrors: cold neutrons 3 He: thermal & hotter neutrons

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HYSPEC POLARIZATION ISSUES

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  1. HYSPEC POLARIZATION ISSUES April 7th, 2006

  2. Polarizers and analyzers • Polarizer – Heusler What about the focusing & the polarization? • Analyzers – Supermirrors & 3He One size does not fit all Supermirrors: cold neutrons3He: thermal & hotter neutrons • Ferromagnets & magnetic fields One sided polarization But first some important background info…

  3. Two pieces of background information 1) A baseline change: SING is a construction (not an R&D) 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 bad[Good = 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

  4. Two pieces of background information 2) A new member of the IDT? Discussions between PSI – SNS – HYSPEC PI’s 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

  5. 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

  6. 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)

  7. 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?

  8. Horizontal magnetic field • One sided polarization for ferromagnets • Full polarization analysis (++), (+-),(-+), (--) with supermirrors • Q’s not totally parallel to field 60° (=±30°) detector bank Close enough is good enough?

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