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writeup/progress14/Improvements.tex
2017-01-22 00:00:32 -05:00

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The AlCap 2013 run demonstrated that the setup was capable of
performing this demanding charged particle experiment and led to
preliminary results. In R2015 we plan to improve several aspects which
will reduce the systematic uncertainty and improve the quality of the
final result.
\begin{itemize}
\item
\textbf{Beam profile measurements at target location.}
We intend to assemble a small probe
which can be inserted to measure the beam profile at the target
position for all measurements. Two possible methods are under
consideration: the first uses a series of crossed scintillating fibres
read-out with MPPCs, the second uses a single fibre which is scanned
across the beam.
\item
\textbf{Beam and detector geometry in the vacuum chamber.} We plan an
improved mechanics and surveying method for determining the relative
target and detector positions.
\item
\textbf{Improved silicon detector frontend.} We plan to suppress noise
and increase the stability of the Si detector readout, by placing
the preamplifiers inside the vacuum chamber. In addition, the shaping
constants of the fast preamplier outputs were not optimised, which
led to significant noise or undershoots in those signals.
\item
\textbf{DAQ.} The FADCs experienced data losses in high rate situations,
e.g. when using the silicon detector as active target. This data
quality issue will be eliminated by purchasing, and carefully
testing, new wave form digitisers from CAEN or SIS.
\item
\textbf{Ge detector.} The time resolution of the Ge detector was
only 66 ns FWHM, larger than specified (10 ns). This problem will addressed
with careful comparisons of analogue and digitised readout chains in our university labs.
\end{itemize}