
\subsubsection*{ Experimental area}
$\pi$E1 beam line

\subsubsection*{Required beam properties}
\begin{itemize}
	\item Particle: $\mu^-$
	\item Momentum: 30--35 MeV/c
	\item Momentum bin: $<2$ \% FWHM
	\item Beam spot: $<2$ cm in diameter
	\item Intensity: $2 \times 10^{4}$ s$^{-1}$
	\item Beam purity: $<10$ \% electrons
\end{itemize}

\subsubsection*{ Duration of the experiment}

{\bf We request two 4 week PSI beam blocks, one scheduled in 2013 and the
next one in 2014.} 

The first experiment would be used to commission the full set-up and shake down its
components for the three work-packages (WPs) planned. The priority would be to perform most of the proton
measurements (WP1), while simultaneously measuring the X-rays for
WP2. A first exploratory neutron measurement 
to start WP3 is also anticipated. This part of the experiment is ready
in spring 2013, and we would prefer an 
early running time during the 2013 schedule. After that,
the data would be analyzed and results reported at the BVR 2014. Depending on the outcome, 
in 2014 additional proton statistics data taking and systematic studies are foreseen to achieve publication quality
data. But the main focus in 2014 will be on final neutron
measurements and operating the large NaI for the WP2 program.

The requested 2013 beam time will be structured in the following way: 
\begin{itemize}
	\item Week 1:  Set-up. Commission beam counters, proton, X-ray and
          neutron detectors. Vacuum in target chamber.

	\item Week 2:  Beam-optimization. Thick, then thin Si detectors
          as active targets are used to study beam properties and optimize the
          stopping fraction, to quantify background and select the
          optimal geometry of the detector packages, relative to
          target and beam. The X-ray detector will assist in the tuning process. First high statistics data set is taken
          with thin Si in the target position, to calibrate the target
          response function and normalize the X-ray detectors. 

	\item Week 3: High statistics measurements with 3 targets of
          Al and Ti, 25-200 $\mu$m thickness.
 
        \item Week 4: Continued Al, Ti measurements. Last days
          dedicated neutron measurement, thick target, with proton vacuum chamber removed.  
\end{itemize}
