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% QA/QC Plan MDT
% Author: H. Kroha
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\begin{titlepage}

\begin{large}
\hspace*{12.0cm}
\parbox[t]{50mm}{
H.~Kroha \\
5 March 1999\\
DRAFT\\
}
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\vspace{2.5cm}


\begin{center}
{\HUGE\bf Quality Assurance}

{\LARGE\bf for ATLAS MDT Chamber Construction}
\end{center}
\tableofcontents

\end{titlepage}

\section{Introduction}
%
The construction of the MDT chambers for the ATLAS muon spectrometer
requires unprecedented precision in the mechanical assembly of a large
number of chambers (1194) at many production sites over a period of more than
4 years. At the same time, the failure rate of the large number of individual
drift tubes (371000) must be very low.

Measurement of the wire positions in assembled chambers and verification of their 
accuracy, crucial for the performance of the muon spectrometer, can only be performed
for a fraction of the chambers, about $20~\%$, with the X-ray tomograph.
Rejection of chambers because of mechanical inaccuracy is only possible
in exceptional cases because of reasons of cost and construction time.

The strategy for the distributed, large-scale production of the precision chambers
is therefore to guarantee the mechanical precision of drift tubes and
assembled chambers by the design of the components and the assembly method and tools
supplemented by extensive monitoring procedures and a detailed quality assurance
plan common for all production sites.

The relevant parameters for the reliability and performance of individual drift
tubes and of the assembled chambers will be controlled in an extensive
test program of tubes and chambers which still can be afforded in terms of
manpower, time and cost. Faulty components and drift tubes have to be rejected,
chambers failing tests will be repaired or rejected if the repair fails.

Detailed archiving of the monitoring and test data is necessary in order
to control and evaluate the production process and to provide complete
documentation for the accepted chambers.

\noindent
The quality assurance procedures for MDT chamber construction
are organized in the following main groups:

\begin{enumerate}

\item Chamber Materials and Components

\item Drift Tube Assembly

\item Drift Tube Test

\item Chamber Assembly

\item Chamber Test

\item Chamber Transport and Storage

\end{enumerate}

\noindent
The quality assurance systems for each part are summarized in this document.

\noindent
Quality control of the readout electronics and data aquisition to be mounted
on the chambers during storage time or installation in the detector is described
in a separate document.

\section{Documentation}
%
The required steps and QA/QC measures to be observed during chamber construction
will be described in the following documents for each contruction site and
chamber type:

\begin{enumerate}

\item {\bf QA/QC Manual:}

Describes the QA/QC strategy and general procedures, including quality control, 
test and handling of chamber materials, drift tubes and chambers and the rules 
for packing, transport and storage.

\item {\bf Tube Assembly Manual:}

Describes all steps of tube assembly including QA/QC procedures;
will be partially implemented in a Control Program.

\item {\bf Tube Test Manual:}

Describes all steps of the tube test procedures;
will be partially implemented in a Control Program.
Examples: LMU, Cosenza.

\item {\bf Chamber Assembly Manual:}

Describes all steps of chamber assembly including QA/QC procedures;
will be partially implemented in a Control Program.

\item {\bf Chamber Test Manual:}

Describes all steps of the chamber test procedures.
General outline see below.

\end{enumerate}

\section{Chamber Materials and Components}
%
The quality of the chamber materials and compliance with the chamber design 
specifications is controlled in four steps:

\begin{enumerate}

\item Quality assurance by supplier (procurement policy).

\item Central monitoring of material production, including sample tests, at 
responsible institutes.

\item Acceptance tests at all chamber production sites.

\item Detailed specification for packing, transport, storage and handling
of all components.

\end{enumerate}

The general strategy is that the quality of the components is assured by the
supplier as specified in the contract. At the chamber production sites, the
quality control documents of the suppliers are checked and sample tests of the
materials are performed as well as visual inspection of every chamber component
when it is used.

The production of the components is monitored by one responsible institute
which performs sample tests of the critical parameters.


\subsection{Aluminum Tubes}
%

Quality control procedures required from the supplier are
(Tube Tendering Documents (IT-2549/EP/ATL)):

\begin{itemize}  

\item Chemical and mechanical analysis and ultrasonic test of the tube raw materials.

\item Geometrical tolerances of extruded tubes.

\item Geometrical tolerances of drawn and straightened tubes.

\item Geometrical tolerances, including straightness, of at least $10\%$ of finished
tubes of each batch.

\item Visual inspection of inside and outside of at least $10\%$ of finished
tubes of each batch.

\end{itemize}

Each finished tube is identified by a bar code (industrial format 39B) which
contains the production run number, a sequential tube identifcation number, tube length
and a date and appears also in alphanumeric form.

Quality control documents and data with reference to the tube bar codes will be 
provided to the collaboration
and will be kept in the Material Data Base for monitoring of the production.

Detection of small holes on the tube walls by the supplier, e.g.\ by eddy current
method, is too expensive. Therefore the complete drift tubes will be leak tested
at the chamber production sites.


Production monitoring is done centrally at a collaborating institute (here CERN) which includes
inspection of test samples per batch according to the following criteria:

\begin{itemize}  

\item Visual inspection inside and outside (obvious defects, cleaning,
deburring, straightness).

\item Geometrical tolerances with 3D metrology.

\item Chemical and mechanical analysis of the finished tube material.

\item Metallurgical analysis of the finished tubes.

\item Chemical analysis of inner tube surface (monitoring of cleaning procedure).

\item Quality control of cleaning procedure with ageing test stand.

\end{itemize}

Quality control at the chamber production sites is summarized in Table~1.


\subsection{Sense Wire}
%
Quality control by the supplier:
%
Quality control procedures required from the supplier with certification are:
(Price Inquiry Document (DO-1045107)):

\begin{itemize}  

\item Measurement of tensile strength at beginning and end of each spool.

\item Test of precentage of gold plating at beginning and end of each spool.

\item Visual and microscopic inspection of gold plating quality for at least first meters
of each spool.

\end{itemize}

Each wire spool will be labelled with date, wire length and production run number
and certified.


Production monitoring is done centrally at a collaborating institute (here CERN) which includes
inspection of test samples per production run according to the following criteria:

\begin{itemize}  

\item Measurement of diameter.

\item Microscopic inspection of gold plating quality.

\item Inspection of cleanliness.

\item Measurement of tensile strength.

\item Measurement of electrical conductivity.

\end{itemize}

Quality control at the chamber production sites is summarized in Table~1.



\subsection{Endplugs}
%
%
Quality control by the supplier:

Non-destructive sample tests of all relevant geometrical parameters of the 
endplug components will be performed by the endplug supplier(s) for typically $2\%$
of the endplugs with 3D metrology.




Production monitoring and sample tests by responsible institute.

Cutting of endplugs: quality of injection moulding.

 
Deburring, cleaning

Packing

Assembly at production site, depending on cost
QA/QC

Endplugs are not individually labelled and identifiable for cost reasons.
The azimuthal orientation of the endplugs is determined by construction
(for module~0 it will be defined by extra lables at the production sites).

Diameter and concentricity of the wire locating hole are measured with a CCD-camera
for a subsample of endplugs from each production batch centrally.

All endplugs will be visually inspected for irregularities of the precision reference surface of the
aluminum cylinder and of the plastic surfaces in the O-ring groove (gas tightness),
completeness of all components and cleanliness at the drift tube production sites.


Repeat QC by supplier at central site.


Quality control at the chamber production sites is summarized in Table~1.


\subsection{Spacer Components}

\subsection{Optical Alignment Components}

\subsection{On-Chamber Gas System}

\subsection{Faraday Cages}

\subsection{Protective Covers}

\subsection{Glue Supply and Handling}
%
All glue types used for chamber assembly are two-component glues
on epoxy resin basis which have been selected because they provide
sufficient strength in contact with aluminum, handling and curing
time are acceptable for chamber series production and because they
are proven to be sufficiently radiation tolerant beyond the
radiation levels in the ATLAS mun spectrometer.
The selected glues also show sufficiently low shrinkage to prevent
chamber deformations which was demonstrated in dedicated tests
and in chamber prototype construction.

Storage time and conditions of the glue will be monitored at the
chamber production sites. Glue handling (see below) will be strictly
according to the supplier's data sheets. The quality of the
glue ordered by and delivered to the individual sites is
guaranteed by the supplier.

The following glues are used for chamber assembly:

\begin{itemize}  

\item For spacer assembly, glueing of tube layers to the spacer and
mounting of gas distribution bars:

Ciba Geigy Araldite 2014 (AW 139/ HV XB5323) with low viscosity to
fill the large glue gaps with shrinkage $<1\%$, setting (usage) time of 40 minutes,
curing time of 3.5 (5) hours to achieve minimum shear strength of 1 (10)~N/mm${}^2$
at $23^\circ$~C on aluminum and a shelve time of 3 years at $18-25^\circ$~C.

The glue is applied with a manual glue dispenser with static mixer.
It will be cured for 12 hours during chamber assembly.

\item For glueing of tubes on tubes:

Ciba Geigy Araldite 2011 (AW 106/ HV 953U) with viscosity of $40-45$~Pa
after mixing at $23^\circ$~C,
setting (handling) time of 105 minutes in glue container and 90 minutes exposed to air,
curing time of 7 (10) hours
to achieve minimum shear strength of 1 (10)~N/mm${}^2$ at $23^\circ$~C
on aluminum and a shelve time
of 3 years at $18-25^\circ$~C.

The glue is applied in premixed form on a complete tube layer inserted in
the assembly combs using an automatic glue dispenser with a speed
of typically 20-30 minutes for a layer depending on chamber size.
which leaves enough reserve in case of problems. Up to 90 minutes
glue handling time can be accepted with the proper control of
out-of-plane deflections of tubes in the assembly process.

Good control of the amount and location of the glue distributed
on the tube layer by design of the glue dispenser minimises
effects of glue shrinkage and out-of-plane deflections of tubes
on the mechanical accuracy of the chambers.

The glue will be cured for 12 hours during chamber assembly.
Handling of the premixed glue and the automatic glue dispensers
is described in a {\bf Glueing Manual}.

\item For glueing of alignment platforms, Faraday cage mouting bars,
in-plane alignment monitor components, temperature and B-field sensors:

Ciba Geigy Araldite 2012 (AW 106/ HV 953U) with viscosity as
Araldite 2011, setting (usage) time of 5 minutes, curing time of
20 (105) minutes to achieve minimum shear strength of 1 (10)~N/mm${}^2$
at $23^\circ$~C on aluminum and a shelve time of 3 years at $18-25^\circ$~C.

\end{itemize}

All surfaces glued must be cleaned with alcohol before glueing
according to the glue suppliers specifications.
The tubes must only be handled with plastic gloves at all times
in order to avoid contamination after the cleaning by the tube supplier.
Otherwise the walls of the assembled drift tubes have to be carefully cleaned
with alcohol before glueing.

More details about the glueing processes during chamber assembly and the
associated quality assurance are described in the Chamber Assembly Manual.

At each glueing step (see Chamber Assembly Manual), at the same time
a small aluminum test piece will be glued from the same glue reservoir as used for the
chamber assembly which allows to evaluate independently the proper
curing of the glue. Also the glue on the chamber always is inspected after the
nominal curing time. If the glue should not cure as required even after
an extended time period, the tube layer or the whole chamber have to be discarded
depending on the assembly step.

\subsection{Temperature and B-Field Sensors}

\subsection{Cables}

\subsection{Hedgehog Boards}
%
The hedgehog boards are delivered to the chamber production sites fully tested
and certified. The boards are visually inspected for obvious defects upon
delivery. Mounting of the boards on the chamber and HV and operation test will take place
in the local chamber test stand. The boards will stay on the chamber afterwards.

\subsection{Mezzanine Cards}
%
The mezzanine cards are delivered to the chamber production sites fully tested
and certified. The boards are visually inspected for obvious defects upon
delivery. Mounting of the cards on the chamber and
HV and functionality test will take place either in the local
chamber test stand or in the central storage area at CERN as soon as the
cards have been delivered.


\subsection{Labelling of Components}



\section{Drift Tube Assembly}
%
Emphasis in the design of the drift tube wiring setups on control of...

Wire treatment, cleanliness, environmental conditions

Autmatisation at reasonable level avoids human mistakes.

Critical: Wire insertion, tube and wire crimping.


The tubes will be oriented such during tube wiring that the
bar codes are accessible when the tubes are inserted into the asembly combs.


Details of the drift tube assembly procedures and the associated quality
assurance measures are described in the Tube Assembly Manual.



\section{Drift Tube Test}
%
Successful operation of the large number of drift tubes in the ATLAS experiment
requires. in addition to the high mechanical accuracy in the wire location,
very high reliability of the tubes with respect to high voltage and
noise stability, gas tightness and protection against ageing effects.

Quality control tests of the drift tubes therefore are a major part of the
chamber construction. They must ensure the reliability of the drift tubes
over a long lifetime. At the same time the tests must be designed such that
they can be performed routinely in reproducible manner and fast enough to keep
up with the speed of the tube production at a rate of 50-100 tubes per day.

The following quality control tests are foreseen for assembled drift tubes
at the tube production sites:

\begin{enumerate}

\item Wire tension (oscillation frequency) measurement.

\item Gas pressure and leak test of the whole drift tube.

\item HV stability test:

\begin{enumerate}

\item Leakage current measurement.

\item Cosmic rate measurement.

\end{enumerate}

\item Wire position measurement.

\end{enumerate}


If drift tube and chamber production sites do not coincide, packing and
transport conditions for the assembled drift tubes have to be observed.

The following sample tests of drift tubes are recommended to be performed
at the accepting site after delivery:

\begin{enumerate}

\item Visual inspection (defects on endplugs or tubes).

\item Wire tension (oscillation frequency) measurement.

\item Leak test of endplugs.

\end{enumerate}


Details of the tests are described in the following. The required tolerances
of the measurements and rejection criteria are summarized in Table~1.

Central tests




\begin{table}[p]
\renewcommand{\arraystretch}{0.90}

\noindent
{\bf Table~1:} Quality control tests of drift tubes at the chamber production sites.

\begin{tabular}{llll}

\hline\hline
{\bf Test} & {\bf Tolerance} & {\bf Failure of test} & {\bf Comment} \\
\hline\hline

\multicolumn{4}{l}{\bf Aluminum tubes} \\
& & & \\

Visual inspection & obvious defects, cleaning,   & reject tube, & sample test/box, \\
(inside and outside) & deburring, straightness,  & notify supplier & every tube before wiring \\
                     & bar code, packing & & \\
& & & \\

Outer diameter & $\pm 15~\mu$m & reject box & sample test/box \\
at 8 points    & &  & \\
& & & \\

Wall thickness & $\pm 30~\mu$m & reject box & sample test/box \\
at 8 points    & & & \\
& & & \\

Length $L$     & $\pm 0.5$~mm ($L\le 4$~m) & reject box & sample test/box \\
               & $\pm 0.7$~mm ($L >  4$~m) & & \\
& & & \\

Straightness   & problems with      & reject box & sample test/box  \\
               & insertion in combs &            & (optional)       \\
& & & \\

\hline

\multicolumn{4}{l}{\bf Sense Wire} \\
& & & \\

Visual inspection & defects of gold-plating,  & reject spool & first meters/spool, \\
                  & cleanliness, kinks        &              & watch during wiring \\
& & & \\

\multicolumn{4}{l}{\bf Endplug} \\
& & & \\

Visual inspection & obvious defects,          & reject endplug, & sample test/batch, \\
                  & cleanliness, all parts    & notify supplier & watch during wiring \\
& & & \\

Outer diameter & $\pm 10~\mu$m & reject batch & sample test/batch \\
at 8 points    & &  & (optional) \\
& & & \\

\multicolumn{4}{l}{\bf Drift Tube} \\
& & & \\

Environment & $(20\pm 1)^\circ$~C & adjust & tube assembly, wire tension \\
& & & \\

Wire tension       & $\pm 5\%$ & reject drift tube & after tube wiring and \\
(osc.\ frequency)  &           &                   & 2 months later before assembly \\
& & & \\

Wire position      & $\pm 25~\mu$m in $y$ and $z$  & reject drift tube  & sample test/day, tests also \\
                   &                               &                    & quality tube assembly, tube  \\
& &                                                                     & oriented as on combs         \\
& & & \\

Leak rate          & less than $10^{-8}~{\mathrm bar}\ell /s$ & reject drift tube & at 3~bar after pressure \\
& &                                                                               & test at 4~bar \\
& & & \\

HV stability test: & less than 1~nA & reject drift tube & with Ar:CO${}_2$ (93:7) at 3 ~bar \\
leakage current    &                &                   & up to $2\times$ nominal gain      \\
& & & \\

HV stability test: & within $\pm 3\sigma$  & reject drift tube & with Ar:CO${}_2$ (93:7) at 3 bar \\
cosmic rate        & of average            &                   & up to $2\times$ nominal gain     \\
& & & \\

Tube outer diameter & less than 30.020~mm  & adjust wiring setup & sample test/day  \\
& & & \\

Length             & $\pm 0.5$~mm          & reject drift tube & in assembly jigging \\
& & & \\

Relative azimuthal & $\pm 10~$~mrad   & reject drift tube & in assembly jigging \\
orientation of endplugs  & & & \\
& & & \\

\end{tabular}
\end{center}

\end{table}







\subsection{Wire Tension Measurement}
%
The wire oscillation frequency determines, independent of the wire diameter
and material parameters, the sag of the wire between the wire locators
in the drift tubes. The wire sag needs to be controlled with sufficient
precision in order to predict the wire position between the tube ends.



\subsection{Gas Pressure and Leak Test}
%
The rather tight leak rate limit is determined from arguments of back diffusion
and gas contamination.                                                                                                                                           


\subsection{HV Stability Test}




\subsection{Wire Position Measurement}







\section{Drift Tube Transport and Storage}


\section{Chamber Assembly}

\subsection{Assembly Room}

\subsection{Qualification and Training of Personell}

\subsection{Assembly Control Plan}




\section{Chamber Test}

\subsection{Test Program at Production Site}

\subsection{Test Program at CERN}

\subsection{Chamber Test Plan}



\section{Chamber Transport and Storage}




\section{Production Control}

\subsection{Production Data Base}

\subsection{Communication and Reporting}





\end{document}
