Dear Polarization Enthusiasts,
A number of factors have converged to make the possibility of looking for
self-polarization in the South Hall Ring realistic. These include high
currents stored (over 200 mA), long beam lifetimes (40+ min even with 100
mA without storage cell), the Compton polarimeter working over a wide
range of beam currents, and the spin flipper installed and functioning.
Under normal running conditions, the polarization lifetime in the South
Hall Ring should be very long (almost a day at 850 MeV and greater for
lower energies). However, if the Siberian Snake is imperfectly tuned, the
Derbenev-Kondratenko formula predicts that the depolarization term will be
enhanced, thereby reducing the polarization lifetime. Furthermore, the
polarization is expected to decay not to zero, but to an equilibrium value
dependent on the Ring optics (of the order of 5%). We would like to
measure the polarization lifetime and equilibrium value under various
conditions as a way of confirming the contributions of the kinetic
polarization term.
Last weekend, it was demonstrated that the beam could be injected
and stored with the Snake mistuned by 2% and 5%. Our calculations
predict that we should begin to see significant depolarization over a
period of a few hours with the Snake detuned by 2%. We would like to
measure depolarization curves for each of these cases.
We have conditional (on no higher priority activity interrupting like ABS
work) approval to use the beam tonight and over the weekend. We will
start tonight with a 2% detuned Snake. I will post a more detailed run
plan for the weekend depending on what we measure tonight.
I have included the weekend schedule below based on the input of people
who I know are interested. At this point, we have at least one person
available to be here at any given time, but any other volunteers are
encouraged to participate. Please let me know if you would like to
be added to the schedule.
Thurs (tonight): 20-8: Bill, Taylan
Fri: 8-20: Hall open
20-8: Townsend, Taylan
Sat: 8-16: Bill
14-22: Tancredi
20-8: Taylan
Sun: 8-20: Townsend
20-8: Taylan
22-8: Bill
-- ********************************************************************** Wilbur A. Franklin * Phone: 617-253-9518 Bates Linear Accelerator Center * FAX: 617-253-9599 P.O. Box 846 * Email: wafrankl@mit.edu Middleton, MA 01949 * **********************************************************************
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