\subsection{Estimation of the cost of the facility}
\label{Sect:Costing}

The cost of providing the accelerator complex and neutrino detectors
must be evaluated and presented in the Reference Design Report (RDR)
to allow the value of the outstanding physics reach to be evaluated. 
The RDR will contain an estimate of the capital cost of the proposed
accelerator complex and neutrino detectors together with an evaluation
of the uncertainty on the costing.
The esstimation will need to identify items such as expenses related
to the final design, installation and commissioning.  
Consideration needs to be given to items such as: 
\begin{itemize}
  \item The cost of a programme of R\&D that will address the
        remaining technical issues and mitigate the various risks.
        This programme will include the construction and test of
        prototypes; 
  \item The cost that will be incurred in the design and manufacture
        of specialized tooling;
  \item The construction of the facility, including materials,
        equipment, and labour.  In addition, the cost of installation
        and the field-supervision of the construction will be estimated;
  \item The cost of inspection, commissioning, and testing of
        components and systems; and
  \item The cost implications that arise in the development of designs
        that meet safety and radiation requirements.  
\end{itemize}
The estimation of the cost of the facility as complex of the Neutrino
Factory is challenging, requires a significant engineering effort,
and must be carefully organised to ensure consistency of approach
across the systems that make up the facility.
The costing methodology that has been adopted by the IDS-NF
collaboration is outlined in the paragraphs which follow.

The cost estimate to be presented in the RDR will be based on a
Project Breakdown Structure (PBS) for the accelerator complex and the
neutrino detectors.
The PBS is a hierarchical breakdown of the elements of the accelerator
complex and detector systems.
The top level of the PBS is shown in table \ref{Tab:PBS}.
The Neutrino Factory facility is broken down into the accelerator
complex and the neutrino detectors at level 2.
At level 3, the principal systems are identified.
The breakdown then continues until a level of detail is reached at
which a cost can be determined for the component or sub-system.
The costing tool developed at CERN \cite{Ref:CERNcostingTOOL} will be
used for the management of the PBS and the costing data.
The tool allows the costs relating to each component to be entered and
provides full functionality for indexation and reporting at various
levels and in various formats and currencies.  
\begin{table}
  \caption{
    Top-level Project Breakdown Structure for the Neutrino Factory
    that will be elaborated to prepare the cost estimate to be
    presented in the RDR.
  }
  \label{Tab:PBS}
  \begin{center}
    \begin{tabular}{|l|l|l|}
      \hline
      {\bf Level 1}    & {\bf Level 2}       & {\bf Level 3}                  \\
      \hline
      Neutrino Factory & Accelerator complex & Proton driver                  \\
                       &                     & Target                         \\
                       &                     & Muon front-end                 \\
                       &                     & Linac and RLAs                 \\
                       &                     & FFAG                           \\
                       &                     & Storage ring                   \\
                       & Neutrino Detectors  & Near detector                  \\
                       &                     & Intermediate baseline detector \\
                       &                     & Magic baseline detector        \\
      \hline
    \end{tabular}
  \end{center}
\end{table}

The tool allows data related to different options to be entered as
parallel sub-PBS structures, and provides an easy way to combine such
options in a global project report. 
This functionality is particularly interesting as for some
sub-systems, for example the proton driver, a number of options will
be carried to the RDR.
The tool also has facilities to take various financial factors, for
example indexation, price escalation, and costs that relate to the
specific example site under consideration, to be taken into account.
Finally the tool provides ``version management'', archive
functionality, cost monitoring for each element or sub-system so that
the evolution of the cost can be followed over the lifetime of the
project.
Example sites (CERN, FNAL, and RAL) have been chosen to allow
site-specific aspects of various choices to be evaluated.

Preparing an estimate of the cost for a large project such as the
Neutrino Factory is a collective effort.
Each sub-system (PBS level 3) will have an individual responsible for
the collection of the cost estimates for all sub-nodes in the PBS and
for entering and maintaining the information in the costing tool.
A costing panel composed of the sub-system conveners and the
individuals responsible for coordinating the cost data, will be
convened to ensure that a coherent and uniform approach is maintained
across all the subsystems.
At the component or sub-system level a pragmatic approach will be
taken to determine the contribution to the overall cost. 
In some cases it may be possible to provide an analytical approach to
determine the cost of the element from manufacturers, while in other
cases costing formulae or scaling from previous experience will be
applied. 
In each case an ``assumption data sheet'' will be prepared in which
the list of components will be specified together with the technical
and ecomonic assumptions that have been made to derive the cost.
The assumption data sheets will also contain a change record and be
stored in the costing tool.

The complexity of the Neutrino Factory facility is such that the
implementation of a number of the sub-systems carry known technical
risks. 
Examples of such sub-systems include the muon front-end, where the
reduction in the break-down potential of cavities in the presence of
magnetic field  may lead to the need to revise the design as discussed
in Appendix \ref{sec:acc:fe:FrontEnd_Alternatives}.
Such cases will be dealt with by developing a ``risk register'' in
which such risks are identified and the cost of mitigation is
presented.
A ``risk score'' will be assigned to each element of the risk table. 
The risk score is defined as the product of the probability that the
risk will occur and the impact on the Neutrino Factory project should
the un-mitigated risk occur.
The risk score will be used to inform the definition of the R\&D
programme that must be carried out as the first phase of the Neutrino
Factory project.  
The cost of the R\&D programme will also be evaluated and presented as
part of the total cost of the Neutrino Factory project.

The Neutrino Factory project will be carried out by a large,
international collaboration funded by a variety of stakeholders.
The cost of the facility that will be presented in the RDR must
therefore be accessible to all the different stakeholders.
While it is recognised that the costing presented in the RDR must
address the issues of the different costing models that have been
adopted by the various stakeholdes in a clear and consise manner, the
details of the paradigm that will be adopted have yet to be defined. 
