\documentclass[12pt]{article}
        \usepackage{graphicx,type1cm,eso-pic,color}
        \usepackage{hyperref}
        \usepackage[left=3.0cm,right=3.0cm,top=2cm,bottom=2cm,headheight=13.6pt]{geometry}
        \usepackage{subfigure}

\makeatother


\title{Manual for CLAS12 \\ Ring Imaging Cherenkov Counter}

\author{
%RICH On-Call Cell Phone: 757-810-1489 \\ 
Authors: \\
M. Contalbrigo (mcontalb@jlab.org) \\
V. Kubarovsky (vpk@jlab.org)\\
M. Mirazita (mirazita@jlab.org)\\
}

\date{\today} %01/07/2014


\begin{document}
\maketitle{}

\tableofcontents

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newpage
   \section{General description of the RICH}

The first module of the CLAS12 Ring Imaging CHerenkov (RICH) detector is installed on the forward carriage in Sector 4, downstream of 
the third region of drift chambers and just before the Time-Of-Flight (TOF) system. A second RICH module is foreseen for the starting 
of operation with transversely polarized target. It's goal is to provide identification of kaons with respect to pions and protons in 
the momentum range between 3 and 8 GeV/c and for polar angles up to 25$^o$, achieving a 4$\sigma$-level separation in the corresponding 
Cherenkov angle distributions. The RICH design incorporates aerogel radiators, visible light photon detectors, and a focusing mirror 
system which is used to reduce the detection area instrumented by photon detectors to about 1 m$^2$. Multi-anode photomultiplier tubes 
(MAPMTs) Hamamatsu H8500 and H12700 provide the required spatial resolution and match the aerogel Cherenkov light spectrum (visible and 
near-ultraviolet region). 

The RICH is composed by a large trapezoidal box made in aluminum and carbon fiber, with smaller base of about 0.3 m, a larger base of 
about 4.2 m, a height of about 3.7 m and a depth of about 1.2 m. The total weight is approximately 900 Kg. 
Two drawings of the RICH box frontal and backward views are shown in figure~\ref{fig:RICH_outer}. 


\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.53\textwidth]{pics/Rich_frontal.jpg}
\includegraphics[width=0.46\textwidth]{pics/Rich_back.jpg}
\caption{ \label{fig:RICH_outer} Back and frontal drawings of the RICH module.}
\end{figure}

Inside the RICH box, a number of active elements are installed, namely:
\begin{itemize}
\item{the aerogel radiator;}
\item{the planar and spherical mirrors;}
\item{the MAPMTs and the readout Front-End Electronics (FEE).}
\end{itemize}

A cross section of the RICH showing the inner elements is shown in figure~\ref{fig:RICH_inner}.

\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.9\textwidth]{pics/Rich_lateral.jpg}
\caption{ \label{fig:RICH_inner} Cross section of the RICH.}
\end{figure}

The aerogel is an igrophilic material that absorbs water from the environment humidity, resulting in a reduction of its optical performance.
For this reason, a strict protocol to handle it has been established during the test and assembly.
In addition, the RICH box volume is fluxed with dry nitrogen, in order to prevent water absorption during the operation of the detector.

The detection of the Cherenkov photon is achieved by means of 391 Multi-Anode PhotoMultiplier Tubes (MAPMTs) and the Front-End Electronics (FEE), mounted on a triangular box, about 1.7 m wide, 1.3 m high and about 10 cm thick, that is installed on the lower back of the RICH module.


%=========================================================
{\color{blue} \section{The RICH Electronics} }
%=========================================================

\subsection{Photodetectors and Front-End electronics}

The Cherenkov photons are detected by using 391 MAPMTs Hamamatsu H8500 and H12700.
They are mounted on a carbon fiber panel installed on the lower back of the RICH and that also host the Front-End electronics.

Photodetectors and Front-End electronics are organized in tiles housing groups of 2 or 3 MAPMTs, see Fig. \ref{fig:RICH_Electronics} 
for the 2 MAPMT case.  There are 23 tiles with 2 MAPMTs and 115 tiles with 3 MAPMTs.
Each tile is composed by an adapter board, an ASIC board and a FPGA board.

The adapter board ensure the connection between the MAPMTs and the ASIC board and also supplies the HV to the MAPMTs.
The ASIC board houses the MAROC3 chips, one per MAPMT.
The Multi Anode Read Out Chip (MAROC3) is a 64 channel Application Specific Integrated Circuit (ASIC), able to discriminate the 64 channels 
PMT output signals and produce 64 corresponding binary outputs.  The chip provides single channel adjustable gain in the range between 0 and 
4 and one adjustable threshold level.  The MAROC3 chip is configured, controlled and readout by an FPGA, that also provide the LV supply to 
the ASIC board and the interface with the CLAS12 DAQ via optical link.



\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.46\textwidth]{pics/RICH_ElectronicsBoards.jpg}
\includegraphics[width=0.46\textwidth]{pics/RICH_ElectronicsAssembled.jpg}
\caption{ \label{fig:RICH_Electronics} The RICH electronic boards for the 2 MAPMT case (left) and the tile fully assembled (right).}
\end{figure}

The list of the components of the RICH readout electronics is reported in figure~\ref{fig:RICH_services}.

\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/Services_HV_LV.png}
\caption{ \label{fig:RICH_services} Sketch of the RICH services: LV, HV supply lines and DAQ optical link.}
\end{figure}



%=========================================================
\subsection{HV and LV Power Supply}
%=========================================================

The low voltage and high voltage power supply is a CAEN SY4527, see Fig.~\ref{Fig:SY4527}. 

\begin{figure}[htbp]
\center
%\includegraphics[width=0.55\textwidth]{pics/SY4527n.png}
\includegraphics[width=0.55\textwidth]{pics/SY4527_modular.jpg}
\vspace*{0.3cm}
\includegraphics[width=0.21\textwidth]{pics/A2518_1-2.jpg}
\includegraphics[width=0.18\textwidth]{pics/A7030-panel6.jpg}
\caption{ \label{Fig:SY4527} The CAEN SY4527 power supply.}
\end{figure}

The unit supplies LV and HV power to 138 electronics tiles (RETile), 115 housing 3 MA-PMTs (RETile-3x) 
and 23 housing 2 MA-PMTs (RETile-2x). It runs on EPICS for Slow-Control with same procedures and controls 
already developed for other detectors (i.e. HPS ECAL). It houses:

\vspace*{0.5cm}
\begin{tabular}{llcl} \hline
Nr. & Item & Unit &  Comment \\ \hline
1 & Control board &  A4528    &  With software libraries (EPICS, OPC Server) \\
1 & Power unit    &  A4533    & 1800 watt in total at 220 Volt AC \\
5 & HV Board      &  A1563    & 32 channels, 3kV/1mA, Common Floating Return \\
5 & LV Board      &  A2518    & 8 channels, 8V/10A, Individual Floating \\
5 & Adapter       &  A647     & Radiall (dense) to SHV (robust)  \\\hline
\end{tabular}


\vspace*{0.5cm}
Each HV channel connects one RETile. The HV runs on 138 RG58 cables towards the patch panels mounted 
on the RICH case, and on 138 HTC-50-1-1 cables inside the RICH volume. The HV should be set between 
1000 V (nominal) and 1100 V (maximum). The single channel current dependes on the number of served 
MA-PMTs and should range between 0.5 (RETile-2x) and 0.8 mA (RETile-3x). 

Each LV channel serves four RETiles. The LV runs on 35 AWG16 cables towards the patch panels
connectors (Phoenix 8A) where it is 1:4 splitted into 138 AWG20 copper cables, one per RETile. To 
provide the wanted 5 V at the electronics, the LV should be set in the range between 5.1 and 5.4 V, 
corresponding to the voltage at the patch panel where sense wires provide feedback for
LV stabilization. The LV current per channel should be around 4 A as it supplies about 1 A per 
RETile. The low voltage supply line is designed to not have difficulties to get 
the wanted voltage because of high current. If that is the case contact run coordinator or RICH 
electronic experts.


%=============================================================
{\color{blue} \section{The RICH Gas Systems} }
%=============================================================

The RICH is served by two different gas systems, one for the supply of the nitrogen to be fluxed inside the RICH box and one for the 
cooling of the FEE. Both systems are managed through controls and monitors integrated in the CLAS12 slow-control software.
The two systems have been dimensioned in such a way that they will be able to serve two RICH modules.

\vspace*{0.5cm}
%=============================================================
\subsection{The Nitrogen System}
%=============================================================

In order to preserve the aerogel optical performance, the RICH inner volume must be kept dry by fluxing nitrogen. The nitrogen 
system supplies the amount of gas necessary to fill the box (about 5 cubic meters) and to compensate for the gas leakage. A complete 
refill of the volume per day is expected under normal operating conditions. A slight overpressure of 0.5 mbar, controller by a 
bubbler, prevents the contamination from the outside air. The system is shown in Fig. \ref{fig:N2_drawing}. It is based on a 1500 gallons 
dewar of liquid nitrogen connected to the RICH box through a on/off valve with a pressure regulator, a 0.01 micron filter and an activated 
charcoal filter to remove all the impurities, and a flow rotameter and a flow transducer for flow control. In figure \ref{fig:N2_components}, 
we report the detailed list of the components of the system.

%\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/N2_drawing.jpg}
\caption{ \label{fig:N2_drawing} Schematic of the nitrogen supply system.}
\end{figure}

%\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/N2_components.jpg}
\caption{ \label{fig:N2_components} Complete list of the components of the nitrogen supply system.}
\end{figure}

The nitrogen gas line control panel is located in the top level of the forward carriage close to the RICH air-cooling tank, see 
Fig.~\ref{fig:N2_panel}. It allows to isolate the nitrogen line to either of the RICH modules for maintenance. The pressure regulator 
reduces the input pressure to the 15 psig required for the correct functioning of the flow meters. The MFT flow transducer are used by 
the slow control to monitor the $\rm N_2$ flow in input to the RICH module.

\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/RICH-N2-valve_panel.png}
\caption{\label{fig:N2_panel} Schematic of the control panel of the nitrogen circuit.}
\end{figure}

The slow control checks online the correct functionality of the system, i.e.:
\begin{itemize}
\item{pressure in the nitrogen circuit;}
\item{flow inside the RICH box;}
\item{temperature and humidity of the gas fluxed inside the RICH box.}
\end{itemize}

{\it The shift worker is not supposed to change any setting of the nitrogen line, but to control the stability of the system.
Any variation bigger than 0.5 psig in the nitrogen line, 1 slm in the flow or 0.5 \% in humidity should be reported to RICH 
expert on call and noted in the log book.}
 

\newpage
%=============================================================
\subsection{The Cooling System}
%=============================================================

One tile with two or three MAPMs produces about 3.35 or 3.8 W of heat load, respectively. The total load in the whole FEE box is about 
500 W.  This heat load must be dissipated far from the CLAS12 detectors in order to keep the surroundings of the FEE box at a temperature 
below 40 $^o$C, the safety limit imposed by the TOF detector which is few cm downstream of the RICH.
%Laboratory have shown that a proper cooling of the system can be obtained by fluxing about 200 liter /min of compressed air.

The FEE RICH cooling system is based on two high capacity air compressors that supply clean dry air at room temperature. The capacity of 
each compressor must be large enough so that, in case of failure of one of the two, the other has sufficient capacity to supply the necessary 
cooling power to two RICH modules. The compressors charge a 1000 liter capacity air tank. Air pressure in the air-cooling circuit is reduced 
to supply manual valve flow meters to define the air flow entering the RICH enclosure. In the case of a power outage, the air tank should 
contain sufficient air to remove the latent heat of the FEE package. The characteristics of the compressors are shown in table~\ref{tab:Compressor}.

\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/Cooling_interlocks.jpg}
\caption{ \label{fig:Cooling_interlocks} Schematic of the cooling system and interlocks.}
\end{figure}

\begin{table}[htbp]\centering
    \begin{tabular}{||c|l||}
\hline
\hline
Dimensions & 1.4 x 0.7 x 1.8 m$^3$ \\
\hline
Weight & 515 kg \\
\hline
Max Flow rate  & 1200 l/min \\
\hline
Dew point & 3 $^o$C \\
\hline
Electric power & 10.4 kW \\
\hline
Noise press & 60 dB (A) \\
\hline
\hline
    \end{tabular}
    \caption{The characteristics of the ATLAS Copco SF11-8 MC FF compressors. \label{tab:Compressor}}
\end{table}

Powering up the electronics package inside the RICH without cooling may result in severe damage of the RICH and of other detectors or 
even fire.  To eliminate this hazard, the RICH HV and LV power supply operations are interlocked to the proper functioning of the cooling 
system.

A schematic of the RICH cooling system with the interlock circuits is shown in figure \ref{fig:Cooling_interlocks} and the list of its 
components is reported in figure \ref{fig:Cooling_components}. It includes a number of temperature sensors installed inside the 
electronics box, air flow transducers connected to the inlets and pressure transducer on the air tank.
The interlock performs two functions in case of a cooling system failure.
\begin{itemize}
\item{turn off power to the electronic package;}
\item{prevent energizing the electronics package.}
\end{itemize}
There are three cooling cicuit interlocks.
A first interlock requires the minimum of one compressor correctly functioning.
The second interlock requires a minimum air pressure in the tank.
The third interlock require a minimum air flow inside the RICH box.
All three interlocks must be true in order for the electronics package to have power.

\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/Cooling_components.jpg}
\caption{ \label{fig:Cooling_components} Complete list of the components of the cooling system and interlocks.}
\end{figure}


\vspace*{\stretch{1}}      
\begin{figure}[h!]
\center
\includegraphics[width=0.99\textwidth]{pics/RICH-AirCool-ValvePanel.png}
\caption{ \label{fig:Cooling_panel} Schematic of the control panel of the nitrogen line.}
\end{figure}

The slow control checks online the correct functionality of the system, i.e.:
\begin{itemize}
\item{pressure in the tank and in the circuit;}
\item{flow inside the RICH box;}
\item{temperature and humidity inside the FEE box.}
\end{itemize}

{\it The shift worker is not supposed to change any setting of the nitrogen line, but to control the stability of the system.
Any variation bigger than 1 psig in the air-cooling line, 10 slm in the flow or 2 \% in humidity should be reported to RICH
expert on call and noted in the log book.}

\twocolumn
%=====================================================
{\color{blue} \section{The RICH monitors} }
%=====================================================

In this section, we illustrate the general scheme for the RICH operation and monitor controls. The RICH slow controls are currently under 
development.  Since the RICH uses hardware systems that are also used for other CLAS12 detectors, in some case the GUIs and screenshots 
showed here are taken from the slow control of detectors that use the same hardware.


\vspace*{1.0 cm}      
%=====================================================
{\subsection{RICH controls} }
%=====================================================

All RICH controls will be  accessible via EPICS, from the main CLAS\_EPICS window (figure~\ref{fig:RICH_EPICSmain}). If not already 
running, it can be opened by executing the command 
\begin{center}
\texttt{clas\_epics}
\end{center}
in a terminal on any of the \texttt{clonpc\#\#} workstations in the Hall-B counting house.

{\em All shift workers should be using user \texttt{clasrun} for all instructions in this document.}

The primary RICH screen is shown in figure~\ref{fig:RICH_screen} and opened via the {\bf RICH} button in the right side of the main CLAS 
EPICS screen (figure~\ref{fig:RICH_EPICSmain}).

From the main CLAS\_EPICS window you can also access individual screens with more controls and details, {\bf Gas system monitoring} in {\it 
Gas System} then {\it RICH gas System}, the {\bf RICH compressors} in {\it Devices} then {\it RICH Devices}, the {\bf Temperature monitoring} 
and {\bf Scalers} in {\it RICH Scaler GUI}, the {\bf RICH high voltage} in {\it HV } then {\it RICH HV}.

\begin{figure}[h!]
\center
\includegraphics[width=0.25\textwidth]{pics/CLAS_EPICS.pdf}
\caption{ \label{fig:RICH_EPICSmain} View of the Hall-B EPICS main window.}
\end{figure}

\onecolumn 

The main RICH screen combines all basic RICH EPICS controls and monitoring into one window.  It is accessible from the {\bf RICH} 
button in figure~\ref{fig:RICH_EPICSmain}.  This includes embedded versions of the dedicated screens in the following sections:  temperature 
sensors, air-cooling compressors, and low and high voltage.  
 
This screen provides the only RICH {\em controls} shift workers should need, which is to turn HV on and off via the red and green 
{\bf ALL ON} and {\bf ALL OFF} buttons.  However, this should be supplemented by the strip charts for temperature and HV current.
%, as well as cctv webcams, for additional {\em monitoring} in the following sections.

The buttons in the top of each section of this main RICH screen provide
access to more detailed or expert screens for the corresponding subsystem.


\begin{figure}[htbp]\centering
    \includegraphics[width=15.5cm]{pics/EPICS_Ilaria.png}
    \caption{The primary EPICS screen needed for shift workers to monitor RICH.\label{fig:RICH_screen}}
\end{figure}


%=====================================================
\subsection{Temperature Sensors}
%=====================================================
The RICH DAQ records the temperature of each of the 138 FPGA chips every few seconds. Several temperature sensors are placed 
in sensitive positions of the RICH enclosure and should be monitored through RICH's main EPICS screen and the strip charts 
shown in figure~\ref{fig:RICH_temperatures}. The strip charts are accessible from the button in the temperature section of 
Figure ~\ref{fig:RICH_screen}.

\vspace*{0.2cm}
{\it Variations of two degrees F or more during a shift should be reported to RICH expert 
on call and noted in the log book.}

\begin{figure}[htbp]
\center
\includegraphics[width=0.45\textwidth,height=4.5cm]{pics/ECal_temp_s.png}
\includegraphics[width=0.3\textwidth,height=4.5cm]{pics/Temperature2.png}
\caption{\label{fig:RICH_temperatures} View of the EPICS temperature monitoring strip charts (left) accessible via the top button 
of the temperature portion of the main RICH EPICS screen (right).}
\end{figure}

\begin{figure}[htbp]
\center
\includegraphics[width=0.80\textwidth,height=4.5cm]{pics/epics_ltcc_gas.png}
\caption{ \label{LTCC_gas} View of the epics window monitoring the LTCC gas line.}
\end{figure}

\begin{figure}[htbp]
\center
\includegraphics[width=0.33\textwidth,height=4.5cm]{pics/Atlas_case.png}
\includegraphics[width=0.3\textwidth,height=4.5cm]{pics/Atlas_display.png}
\includegraphics[width=0.27\textwidth,height=4.5cm]{pics/Cooling2.png}
\caption{ \label{ChillerCam} View of the air-cooling compressor (left), its control display (center) and the
relative portion of the main RICH EPICS window (right).}
\end{figure}


%=====================================================
\subsection{Cooling System}
%=====================================================
The cooling allows to keep the RICH electronic panel at the constant temperature and should be ON at all times. 
In orther to prevent temperature stress on RICH components and adjacent detectors, an interlock prevent the HV and LV power to be active 
without a properly functioning cooling. As other gas systems in Hall-B, the cooling circuit is controlled via a cRio device, see for 
reference the LTCC monitor in figure~\ref{LTCC_gas}, and can be monitored through the EPICS controls (figure~\ref{ChillerCam}). 

\vspace*{0.2cm}
{\it Shift takers should not attempt to change the cooling system settings and call RICH expert in case of problem.}

%=====================================================
\subsection{Nitrogen Circuit}
%=====================================================

A clean and dry nitrogen atmosphere is required inside the RICH vessel to preserve the aerogel optical 
performace. The nitrogen circuit provides a clean and dry flow and should be ON at all times.
As other gas systems in Hall-B, the nitrogen circuit is controlled via a cRio device
and can be monitored through the EPICS controls (figure~\ref{fig:RICH_screen}). 

\vspace*{0.2cm}
{\it Shift takers should not attempt to change the nitrogel system settings and call RICH expert in case of problem.}


%=====================================================
\subsection{Low Voltages}
%=====================================================

The low voltage supply of the RICH is controlled and monitored using the main RICH EPICS window (Figure ~\ref{fig:RICH_screen}). It 
has buttons to ramp up and down a single channel or the entire RICH LV voltages (labeled {\bf ALL ON} and {\bf ALL OFF}), open windows 
for individual channel setting (see for reference the Drift Chamber monitor in figure~\ref{LVControl}), and open more detailed expert views.

\begin{figure}[htbp]
\center
\includegraphics[width=0.45\textwidth]{pics/epic_rich_lowW_control.jpg}
\caption{ \label{LVControl} Cropped view of the EPICS LV control window for individual channels of the CLAS12 Drift Chambers.}
\end{figure}

\vspace*{0.2cm}
{\it Shift takers should follow the instruction under "RICH operations" to operate the RICH low voltages}.



%=====================================================
\subsection{High Voltages}
%=====================================================

The high voltage supply of the RICH is controlled and monitored using the main RICH EPICS window (Figure ~\ref{fig:RICH_screen}). It 
has buttons to ramp up and down the entire RICH voltages (labeled {\bf ALL ON} and {\bf ALL OFF}), open windows for individual channel 
control, and open more detailed expert views.

\vspace*{0.2cm}
{\it Shift takers should follow the instruction under "RICH operations" to operate the RICH high voltages}.


\newpage
%=====================================================
{\color{blue} \section{The RICH operation} }
%=====================================================

The procedures to safely operate the RICH are under development and will be fully tested before entering the experimental hall.
Here the preliminary versions are described.

\subsection{Turning ON}
The sequence of actions is

\begin{enumerate}
\item Check the air compressor status display on the main RICH EPICS window (Figure ~\ref{fig:RICH_screen}): at least one
compressor should be ON, the pressure and mass flow measured values should be within the working range and close to 
the set values.
\item Check the temperature status display to exclude alarming conditions. The temperature indicate by the sensors should 
be within 5 degrees from the Hall-B temperature if the RICH was off for more than 1 day.
\item Turn ON the low voltages, either channel by channel or all together.
\item Check the temperature status display. The single chip and the sensors should increase in temperature and slowly
reach an equilibrium. The sensor in the air circuit and at the TOF should all be below 40 degrees Celsius. The sensors 
within the RICH FEE box should be between 40 and 50 degrees Celsius. The single
chip temperature should be between 50 and 60 degrees Celsius.
\item Turn ON the high voltages. All PMT should reach the working condition (green color) within about 1 minute.
\end{enumerate}

\subsection{Turning OFF}
The sequence of actions is

\begin{enumerate}
\item Check the main RICH EPICS window (Figure ~\ref{fig:RICH_screen}) and note in the loogbok any non standard condition.
In the temperature status display, the sensors in the air circuit and at the TOF should all be below 40 degrees Celsius. The sensors
within the RICH FEE box should be between 40 and 50 degrees Celsius. The single chip temperature should be between 50 
and 60 degrees Celsius. In the air compressor status display at least one
compressor should be ON, the pressure and mass flow measured values should be within the working range and close to
the set values.
\item Turn OFF the high voltages. All PMT should reach the idle state (grey color) within about 1 minute.
\item Turn OFF the low voltages, either channel by channel or all together.
\item Check the temperature status display. The temperature should start to slowly decrease. No chenge is expected
in the pressure and in the mass flow of the cooling circuit.
\end{enumerate}

\subsection{HV Trips}
In case of HV trips, the sequence of actions is

\begin{enumerate}
\item Check in the strip chart the last value of the current for the tripped channel and record it in the logbook, together
with the time and channel ID.
\item Turn ON the channel, either with the single channel controls in the submenu or with the "All ON" button in the 
main EPICS window.
\item Monitor the current for at least 1 minute. 
\item In case of unexpected behaviour or repeated trips, call the RICH expert.
\end{enumerate}

\subsection{LV Trips}
In case of LV trips, the sequence of actions is

\begin{enumerate}
\item Check in the strip chart the last value of the current for the tripped channel and record it in the logbook, together
with the time and channel ID.
\item Check in the strip chart the last temperature value for the tripped channel and record in the loogbok.
\item Turn ON the channel, either with the single channel controls in the submenu or with the "All ON" button in the 
main EPICS window.
\item Monitor the current and temperature for at least 1 minute. 
\item In case of unexpected behaviour or repeated trips, call the RICH expert.
\end{enumerate}

\end{document}
