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\section{The Facilities}

\subsection{Septum Magnets (Contributed by J.J.~LeRose)}

\subsubsection{Overview}
The two septum magnets (left and right) were manufactured by BWXT Technologies of Lynchburg 
Virginia under contract with INFN Rome. They were designed to allow access to scattering angles
from 6 to 12.5 degrees up to the maximum momentum of each spectrometer with no degradation in
the optical properties of either spectrometer (except for some reduction in solid angle 
acceptance).

\subsubsection{Developments in 2003}

2003 saw much progress with the implementation of the septum magnets in Hall~A. The first septum,
the right one, arrived at Jlab in January and was installed in the Hall in March. The magnet had 
two serious problems, a heat leak between the warm bore and the cold mass, and the upper and 
lower coils were wired with opposite polarities (so-called ``bucked'' coils). The
warm bore heat leak problem was temporarily solved by installing a cooling system in the magnet
bore to reduce the temperature in the bore to the point (-100 degrees C) where the coils
could be cooled sufficiently to go superconducting. Unfortunately, this limited access to
the magnet bore making direct measurement of the magnetic field difficult. Consequently, it 
was not until well into commissioning that the ``bucked'' coil problem was
identified. Nevertheless, 
preliminary data were taken for the Small Angle GDH experiment (E97-110).
After a very difficult data taking effort in April and May the right septum was warmed to
room temperature and its cryostat was opened allowing access to the inter coil splices. At 
that time the 
incorrect wiring was corrected and verified by field measurements. 
Subsequently, the right septum was used again for the second run of E97-110 in both the 6 
and 9 degree configurations. This time the optics looked much better, having the correct magnetic
field makes all the difference. Good reconstruction of the sieve hole pattern was possible
without any optimization of the previoulsy calculated optics database. To date the right septum
 has achieved a maximum current of 438 Amps, exceeding the requirements for HAPPEXII (3.1 GeV/c 
at 9 degrees).

After E97-110 finished running in August the second septum (left) was delivered. It included
 design modifications (added heat sinks on the coil, new redesigned shield, slightly 
smaller bore tube with better insulation) to improve coil cooling in general and eliminate 
the warm bore heat leak. At that time the right septum was partially disassembled in order
to incorporate those same modifications. At the time of this writing (December 5, 2003) both
septum magnets are installed on the pivot in the Hall at 6 degrees and are cooling down 
in preparation for the Hypernuclear Spectroscopy Experiment (E94-107). After some preliminary
adjustments in the cryogenic feed system the left septum has achieved coil temperatures of
 5.95~K(5.90~K) in the lower(upper) coil and 4.8~K in the yoke (colder than ever previously 
achieved in the right septum) and reached 197~Amps in its first serious training run. This is
comparable to the first training run with the right septum and already exceeds the current
needed for E94-107. Moreover, recovery time from the first training quench was much shorter
(on the order of 1-2 hours) than previously seen with the right septum (about 6 hours). The 
right septum is cold but the cryogenic flow has not yet been turned up enough to reach
superconducting temperatures. Neither magnet shows any sign of having the previously observed
warm bore heat leak ({\bf i.e.} the bore stays warm).  

\end{document}
