[Cuga] Pizza Seminar - Wednesday, January 20, 2010---a message from Hari Areti

[Rachel Harris]

"The pain and the joy of polarized solid hydrogen ­ the HDice 
experiments at Jefferson Lab"

Speaker: Andrew Sandorfi

12 Noon, January 20, 2010
Cebaf Center F113

Please RSVP to harris at jlab.org by
5PM on Tuesday, January 19, 2010

Abstract:
Solid deuterium-hydride, HD, forms a quantum crystal with many unusual
properties. It provides a pure target in which both H and D can be polarized
at high fields (15 tesla) and low temperatures (0.01 K). Their spins freeze
into position with time, so that they can eventually be removed from this
extreme environment and placed into the center of a detector such as CLAS
where more conventional fields (~ 1Ž2 tesla) and modest temperatures (~ 
1Ž2 K)
can maintain their spin orientations for years. The purity, polarization and
small holding fields of such targets provide large gains for many
experiments.
I will describe the physics and the gymnastics of the HDice polarization
process, and then discuss their application in three diverse experiments.
Experiment E06-101 will seek to unravel the N* spectrum in a simultaneous
measurement of all 16 possible polarization observables in Lambda
photo-production from the neutron. This will provide a direct determination
of the reaction amplitude (a first in 50 years) and greatly increase the
sensitivity to the nucleon¹s spectrum. There are expectations that the
polarization of HD can be maintained with modest electron currents. Pending
a direct test, experiment E08-021 will measure DVCS with transversely
polarized HD to access the elusive E Generalized Parton Distribution needed
to construct a 2+1 dimensional image of the proton. Finally, for something
completely different, there are plans to use HD and 3He to test polarization
survival in a plasma. The use of polarized fuel in a Tokamak could
potentially bring a fusion reactor over the ignition point.