\documentclass{chowto}

\title{HKS Design}
\howtotype{expert}
\experiment{HKS} % Optional
\author{Satoshi N Nakamura}
\category{hks}
%\maintainer{Name of person maintaining document} % Optional
\date{May 18, 2005}

\begin{document}

\begin{abstract}
This Howto outlines the purpose of the HKS magnets and their operation and 
monitor.
\end{abstract}
 
\section {Purpose and Optics}

The HKS magnet consists of three magnets, Q1, Q2 and D. Their basic parameters
are given in the following tables.
The HKS is used as a High resolution Kaon Spectrometer combined with the Splitter magnet.
HKS detector package has two drift chambers (HDC1, HDC2), 
three TOF layers (HTOF1X, 1Y and 2X), three layers of 
Aerogel Cherenkovs(AC1, AC2 and AC3), and two layers of Water Cherenkovs (WC1 and WC2).
The momentum and angular reconstructions are performed with HDC information and
particle identification is carried out with AC and WC informaiton in trigger level 
as well as done with TOF information in off line analysis.

The kaon central momentum is 1.2 GeV/$c$ with a bite of $\pm12.5\%$ (1.05 - 1.35 GeV/$c$).  
The designed momentum resolution is $2 \times 10^{-4}$.
The solid angle acceptance is about 30 msr without the Splitter and 16 msr with the Splitter.  
The kaon detection angle is 1-13 degrees in horizontal.

\begin{table}[hbt]
\caption{Q1 and Q2 parameters}\label{tab:Q1Q2}
\begin{center}
\begin{tabular}{lcc}
\hline
\hline
Item                             & Q1                           & Q2\\                                     
\hline
Bore radius (mm)                 & 120				& 145\\                                    
Pole length (mm)                 & 840				& 600\\                                    
Max. Ampere turns (A turns)      & 224000			& 144000\\                                 
Number of turns                  & 256				& 320\\                                    
Conductor size                   & 8 $\times$ 8 ($\phi$6 hole)	& 13.5 $\times$ 11.5 ($\phi$6.3 hole)\\    
Coil Winding                     & Double Pancake Winding	& Solenoid Winding\\                       
Field Gradient (T/m)             & 6.6                          & 4.2\\
Max. Current (A)                 & 875				& 450\\                                    
Resistance  (m$\Omega$)          & 181 (@55 $^\circ$C)  	        & 119 (@45 $^\circ$C)\\                                    
Cooling Water Flow rate (l/m)    & 49.6				& 17.3\\                                   
Pressure drop (MPa)              & 0.36				& 0.38\\                                   
Number of Coolant circuits       & 16				& 8\\                                      
Total Magnet Weight (ton$^*$)    & 8.2				& 10.5\\                                   
\hline
\hline
{\small $^*$metric ton.}&\\
\end{tabular}
\end{center}
\end{table}

\vspace*{5mm}
\begin{table}[hbt]
\caption{Dipole magnet parameters}\label{tab:D}
\begin{center}
\begin{tabular}{lcc}
\hline
\hline
Item                             & \multicolumn{2}{c}{D}\\
\hline
Pole gap height  (mm)            & \multicolumn{2}{c}{200}\\
Pole length (mm)                 & \multicolumn{2}{c}{1560}\\
Max. Ampere turns (A turns)      & \multicolumn{2}{c}{291840}\\
Number of turns                  & \multicolumn{2}{c}{256}\\
Conductor size                   & \multicolumn{2}{c}{22 $\times$ 22 ($\phi$12 hole)}\\
Max. Field (T)                   & \multicolumn{2}{c}{1.53}\\
Max. Current (A)                 & \multicolumn{2}{c}{1140}\\
Resistance (@47.5 $^\circ$C) (m$\Omega$) & \multicolumn{2}{c}{145}\\
                                 & Gap side & Yoke Side\\
Cooling Water Flow rate (l/m)    & 66.3     & 68.8\\
Pressure drop (MPa)              & 0.32     & 0.35\\
Number of Coolant circuits       &  8       & 8\\
Total Magnet Weight (ton$^*$)    & \multicolumn{2}{c}{210}\\
\hline
\hline
{\small $^*$metric ton.}&\\
\end{tabular}
\end{center}
\end{table}

\section {Setting the magnet}

Since this magnet is not directly effect the beam, thus it will be controlled and operated 
by Hall C experimentalists.  However, due to fringe field does have slight effect to beam
and other magnets nearby, such as Splitter and Enge, it is preferred to turn off the 
beam during the process of setting up the magnet.   Since Q1 and Q2 magnets are sharing the 
same power supplies with SOS Q and D1 magnets, existing control will be used in setting up the 
magnet by referring to steps of ``Getting started'' and ``Setting the magnets'' in ``How to 
set the SOS magnets'' in Hall C online Howto document.  Since no polarity change in
operating this magnet for hypernuclear experiment, step of ``Degaussing'' is not necessary.
As for HKS-D power supply (252Vmax, 1254Amax), 
it is newly fabricated but follows similar procedures above. 

The following table shows a designed magnetic field and monitor infomation for 1.2 GeV/$c$ kaon beam.

\section {Monitor}

The Q1, Q2 fields are monitored by a fixed hall probes placed just out side of the vacuum chamber. 
The stability should be controlled within an error of $\pm 10^{-3}$.
The D field is monitored by a fixed NMR probe placed in the vacuum chamber. 
The stability should be controlled within an error of $\pm 10^{-4}$.
Scaling between field gradient and fixed probe readout can be done by following formula:

\[ FG (T/m) = \mbox{Fixed probe (T)} \times 6.6836 \mbox{~~~for~Q1},\]
\[ FG (T/m) = \mbox{Fixed probe (T)} \times 20.470 \mbox{~~~for~Q2}.\]


\vspace*{5mm}


\begin{table}[hbt]
\caption{Designed magnet setting for 1.2 GeV/$c$ kaon}
\begin{center}
\begin{tabular}{lccc}
\hline
\hline
     & field gradient (T/m) & Current (A) & Fixed Probe readout (T)\\
\hline
Q1   & -5.78 & 585 & 0.865\\
Q2   &  3.40 & 364 & 0.166\\
\hline
\hline
     & central field (T)  & Current (A) & NMR readout (T)\\
\hline
D    & 1.44  & 1050 & 1.4364\\
\hline
\end{tabular}
\end{center}
\end{table}


\end{document}

% Revision history:
% $Log: hks-design.tex,v $
% Revision 1.1.2.1  2005/05/20 04:00:42  saw
% Initial version
%









