US Pixel Installation Plan

**Version 1.02**

**July 11, 2002**

# Summary

This document describes the installation plan for the U.S. pixel
deliverables at CERN. It does not include commissioning or operations.
We describe what the U.S. will deliver and our assumptions for
deliverables from non -- U.S. collaborators. Technical manpower
estimates are given. A schedule is provided. We only cover here the
period from about mid-2004 until commissioning starting 2006. Not
covered here is the plan for possible removal of the pixel system after
the first run to add a 3^rd^ hit. Contributions to the M&O budget from
the U.S. are not covered here.[^1] The assumption here is that the M&O
contributions cover general infrastructure items at CERN. The essential
assumption is that this installation budget presented here will only
cover U.S. personnel costs at CERN and related travel and other
expenses. All other costs are from some other budget.

# Overview of Tasks

This note describes the installation of the U.S. pixel deliverables. In
brief the U.S. deliverables are:

-   Pixel support tube(PST) in three sections and tooling for bonding
    the mount for the barrel section into the SCT barrel

-   Pixel support frame in three sections, barrel and two disk sections.

-   Pixel disks, tooling for insertion of disks into support frame,
    testing hardware for verification of functionality before and after
    insertion into support frame

-   Pixel service panels, handling tooling for the service panels and
    testing hardware to verify functionality

-   Patch panel 1(PP1)

-   Beam pipe and service panel support[^2]

-   All pixel RODs[^3], including software for operation of the RODs

The installation of the U.S. pixel deliverables includes the following:

> *I.* The barrel section of the pixel support tube(PST) is installed
> into the SCT/TRT barrel in the SR building. This requires
> bonding(gluing) mounts in place. The forward sections of the PST are
> bolted to the barrel and the alignment checked. The forward sections
> are then removed and stored.

*II.* The barrel ID, including the barrel section of the PST, is lowered
into the pit and installed into the solenoid magnet. The heater elements
of the barrel PST are cabled and checked. The forward sections of the
PST are bolted to the barrel section and the alignment is checked. The
forward parts for the SCT/TRT can then be installed.

*III.* In the SR building. Integration of the disks into the support
frame sections. Verification of their functionality. Integration of two
disk sections with the barrel section. Integration of the beam pipe
support and beam pipe. Integration of services panels and PP1.
Verification of functionality using about 10% of the RODs temporarily
installed in SR building. Insertion of the pixel "package" into an
installation tube/support to be lowered into the pit.

*IV.* Installation of all RODs and verification of performance.

*V.* Lowering of the pixel package in its installation/support into pit.
Insertion of the pixel system into the PST. Cabling, fiber and pipe
connection. Verification of functionality using installed RODs.

# Overview of Manpower

The detailed task list, durations and manpower estimates are given in
the sections that follow. In this section we provide an overview of the
technical manpower estimates that follow from the more detailed
estimates.

-   The initial PST installation occurs in mid-2004. The lead engineer
    and tech for this are at CERN for 6 weeks.

-   The pixel RODs(some of them) have been in use at the barrel and disk
    assembly sites. They are all shipped to CERN by October 1, 2004.
    About 90% are installed in their final locations. About 10% are
    installed in the SR building for testing the pixel system during
    surface integration. The pixel systems engineer(J. Richardson)
    becomes resident at CERN as of October 1, 2004 and is the lead
    engineer for installation(and later commissioning) of the RODs and
    of the system test capability in the SR building. The lead engineer
    for the ROD design(currently J. Joseph) is at CERN for the initial
    phase of ROD installation.

-   The remaining pixel deliverables(disks, beam pipe support, service
    panels, PP1) arrive at CERN in January 2005. The lead mechanical
    engineer for pixel integration and installation is from the U.S. and
    becomes resident at CERN at this time. Mechanical technical manpower
    from the U.S. unpacks, inspects and assembles the U.S deliverables
    on the surface. The final PST assembly in the pit is done primarily
    by U.S. personnel under the direction of the lead mechanical
    engineer.

-   Testing of the assembled pixel system is done on the surface. The
    pixel systems engineer(Richardson) is the lead engineer for this.
    Additional electrical engineering for the readout system(RODs) and
    for electronics participates at CERN but is not resident at CERN.
    The lead mechanical engineer is simultaneously coordinating the
    effort to install the pixel system in the pit.

-   The pixel system is lowered into the pit, inserted into the PST.
    Cables, fibers and pipes are connected. Verification of
    functionality is done during the connection process. Richardson is
    the lead systems engineer for the electrical testing. The lead
    mechanical engineer is responsible for the cooling, cabling etc.
    Mechanical technicians from the U.S. are part of a team doing the
    connections, focusing on the critical region at PP1 that was done in
    the U.S.

-   Commissioning follows the verification of installation. Richardson
    remains resident at CERN as the lead systems engineer for this and
    later for operations. All other personnel return to the U.S.

# Initial Pixel Support Tube Installation

The three sections of the PST have been shipped to CERN. Tooling for
bonding the mounts of the PST to the corresponding mounts in the barrel
SCT interlinks has also been shipped. Tools and supplies for the U.S.
team are a U.S responsibility. We assume that non-U.S. collaborators
will provide the following:

-   Space for unpacking and inspecting the PST sections upon delivery to
    CERN

-   Some technician manpower for handling the PST sections and tooling.

-   Temporary supports for holding the PST sections. We are assuming
    that the barrel section is inserted by hand into the SCT. This
    remains to be verified. Temporary supports will be needed for the
    forward PST sections when they are bolted to the barrel section for
    checking.

-   All survey and alignment equipment and expert personnel

The estimated tasks and durations(in weeks) are the following:

  ----------------------------------- -----------------------------------
  **Task**                            **Duration(weeks)**

  Get organized. Unpack PST sections  1

  Inspect, continuity test of         1
  heaters, repair                     

  Install barrel, bond mounts, survey 2

  Fit forwards, survey                1

  Remove forwards, pack and store     1
  ----------------------------------- -----------------------------------

The lead mechanical engineer responsible for the PST design must be
present throughout this period. A trial assembly of the PST sections
will have been done in the U.S. The lead tech that did this assembly
must also be present throughout this period. We assume that we can get
additional technical manpower at no cost to the U.S. for handling the
PST sections during the operations above. The manpower estimates are the
following[^4]:

  ----------------------------------- -----------------------------------
  **Type of manpower**                **FTE(hours) FY04**

  Mechanical engineer                 240

  Lead mechanical technician          240
  ----------------------------------- -----------------------------------

Travel costs are one round trip to CERN for these two people(6K) +
expenses at CERN(6K).

# II. Final PST Installation

The barrel ID with the barrel section of the PST is lowered into the pit
and installed into the solenoid. Continuity of the barrel PST heaters is
checked. The forward PST sections are lowered, brought into the solenoid
and bolted to the barrel section. Heater continuity is checked.
Alignment of the forward sections is checked.

The tasks and durations for U.S. manpower are given below.

  ----------------------------------- -----------------------------------
  **Task**                            **Duration(weeks)**

  Barrel heater continuity, cabling,  0.5
  check                               

  Install forward PST sections,       1
  survey                              

  Forward heater continuity, cabling, 0.5
  check                               
  ----------------------------------- -----------------------------------

The manpower estimates are:

  ----------------------------------- -----------------------------------
  **Type of manpower**                **FTE(hours) FY05**

  Mechanical engineer                 80

  Junior mechanical technician        80
  ----------------------------------- -----------------------------------

Since this occurs during the same period as the pixel surface
installation, the travel is included there.

# III Surface installation(not including RODs)

The pixel disks, disk frame sections, tooling for insertion and testing
of these, beam pipe and service panel support, service panels and PP1
are at CERN. The barrel sections being fabricated in the EU have also
arrived at CERN. All work takes place in the SR building. We assume that
testing electronics(RODs, crates, racks, PCs) have arrived previously
and are ready to be used for testing(see IV). We assume that our non --
U.S. collaborators will provide the following:

-   Space and facilities for unpacking and assembly of the U.S.
    deliverables(the SR building + tables, benches, etc)

-   Cooling system for surface testing

-   Cables and fibers for surface testing

-   All alignment and survey instrumentation and expert personnel

-   The installation and test tool(ITT) for the surface installation and
    testing of the parts of the pixel detector and the final assembled
    detector

A high-level schedule for this period and for ROD installation is given
later.

The U.S. technical team during this period will consist of: 1 FTE lead
pixel systems engineer for testing(Richardson), 1 FTE lead mechanical
engineer, 2 FTE mechanical technicians(this will be 3-4 people sharing
the load, traveling to CERN as particular expertise is needed), 0.5 FTE
electrical engineer for pixel electronics debugging.

The manpower estimates are detailed below.

  ---------------------------------------------- ------------------------
  **Type of manpower**                           **FTE(hours) FY05**

  Systems engineer                               1760

  Electrical engineer                            880

  Mechanical engineer                            1320

  Senior mechanical technician                   880

  Junior mechanical technician                   880
  ---------------------------------------------- ------------------------

Travel and supplies costs are estimated as below. Travel includes
relocation costs to CERN or relocation to US, which we take as \$30K and
\$10K, respectively. Costs for non-CERN-resident personnel are taken as
\$3K per trip and \$100 per day at CERN. Supplies include stores items
at CERN, other minor consumables and computers for personnel use. We
have rounded costs to the nearest 5K.

  --------------------------------- ------------------ --------------------
  **Type of manpower**              **Travel(FY05)**   **Supplies(FY05)**

  Systems engineer                  40K                5K

  Electrical engineer               30K                5K

  Mechanical engineer               40K                10K

  Senior mechanical technician      30K                10K

  Junior mechanical technician      30K                5K
  --------------------------------- ------------------ --------------------

# IV ROD Installation

We assume the RODs are at CERN by October 1, 2004. We assume 90% are
installed in their final location and 10% in the SR building for testing
the pixel system as it is integrated there. Systems integration
engineering is covered under III above. The lead design engineer will
participate in the installation at CERN and be available for handling
problems as they arrive later during pixel installation.

The manpower estimate is given below. Systems engineering for this is
covered under III already.

  ---------------------------------- ------------------ ------------------
  **Type of manpower**               **FTE(hours)       **FTE(hours)
                                     FY05**             FY06**

  Electrical engineer                300                300
  ---------------------------------- ------------------ ------------------

Travel and supplies are estimated below.

  ---------------- ------------------ -------------------- ------------------ --------------------
  **Type of        **Travel(FY05)**   **Supplies(FY05)**   **Travel(FY06)**   **Supplies(FY06)**
  manpower**                                                                  

  Electrical       10K                5K                   10K                0K
  engineer                                                                    
  ---------------- ------------------ -------------------- ------------------ --------------------

# V In-pit installation

Installation of the pixel detector occurs in FY06. We assume that the
mechanical installation and verification of installation is completed by
the middle of FY06. As we have already noted, we assume that the lead
mechanical engineer coordinating the installation is from the U.S. Since
the U.S. deliverables include the PST rails, pixel mounts and PP1, we
have included technical manpower from the U.S. for in-pit installation,
the delicate cabling and checkout of PP1 and for verifying PST
performance with the pixel detector in place. Richardson will continue
to be the lead systems engineer for installation verification and later
commissioning. Only the installation part is given in the table below.

  ---------------------------------------------- ------------------------
  **Type of manpower**                           **FTE(hours) FY06**

  Systems engineer                               880

  Electrical engineer                            440

  Mechanical engineer                            880

  Senior mechanical technician                   220

  Junior mechanical technician                   440
  ---------------------------------------------- ------------------------

Travel and supplies costs are estimated below.

  --------------------------------- ------------------ --------------------
  **Type of manpower**              **Travel(FY06)**   **Supplies(FY06)**

  Systems engineer                  10K                5K

  Electrical engineer               20K                0K

  Mechanical engineer               20K                5K

  Senior mechanical technician      10K                5K

  Junior mechanical technician      20K                5K
  --------------------------------- ------------------ --------------------

# 

# Schedule

A preliminary schedule for the U.S. pixel installation has been created.
A summary is shown below. Note that calendar(not fiscal) years are used
in the schedule. The schedule is based on version 5.0a of the ATLAS
installation schedule.

![](media/image1.png){width="8.495138888888889in"
height="3.3270833333333334in"}

# Summary Costs

Summary costs are given below in FY02 \$K.

  ------------- ---------- ----------- -------- ---------- ---------- ----------- -------- ---------- ---------- ----------- -------- ----------
  **WBS 1.1.1                                                                                                                         
  Pixel                                                                                                                               
  System**                                                                                                                            

                FY04                                       FY05                                       FY06                            

                Hours      FY02(\$K)   Travel   Supplies   Hours      FY02(\$K)   Travel   Supplies   Hours      FY02(\$K)   Travel   Supplies

  Systems                                                  1760       135         40       5          880        68          10       5
  engineer                                                                                                                            

  Mechanical    240        18          6                   1400       107         40       10         880        68          20       5
  engineer                                                                                                                            

  Electrical                                               880        75          30       5          440        38          20       0
  engineer                                                                                                                            

  Senior tech   240        20          6                   880        74          30       10         220        18          10       5

  Junior tech                                              960        59          30       5          440        27          10       5

                Subtotal   38          12       0          Subtotal   450         170      35         Subtotal   218         70       20

                                                                                                                                      

  **TOTAL WBS   **50**                                     **655**                                    **308**                         
  1.1.1**                                                                                                                             

                                                                                                                                      

  **WBS 1.1.3                                                                                                                         
  RODs(Pixels                                                                                                                         
  only)**                                                                                                                             

                FY04                                       FY05                                       FY06                            

                Hours      FY02(\$K)   Travel   Supplies   Hours      FY02(\$K)   Travel   Supplies   Hours      FY02(\$K)   Travel   Supplies

  Electrical                                               300        26          10       5          300        26          10       0
  engineer                                                                                                                            

                Subtotal   0           0        0          Subtotal   26          10       5                     26          10       0

                                                                                                                                      

  **TOTAL WBS   **0**                                      **41**                                     **36**                          
  1.1.3**                                                                                                                             

  **Pixels                                                                                                                            
  only**                                                                                                                              
  ------------- ---------- ----------- -------- ---------- ---------- ----------- -------- ---------- ---------- ----------- -------- ----------

Summary costs in the U.S. ATLAS format are given below through FY05.

  ----------- ----------------- -------------- -------------- ------------ ----------- ----------- ------------ ----------- ----------- ------------ ----------- ----------- ------------ ----------- ----------- ------------ -----------
                                               **U.S. ATLAS                                                                                                                                                                    
                                               Silicon**                                                                                                                                                                       

                                               **Baseline +                                                                                                                                                                    
                                               Management                                                                                                                                                                      
                                               Contingency                                                                                                                                                                     
                                               Installation                                                                                                                                                                    
                                               (FY02k\$s)**                                                                                                                                                                    

                                               **FY02**                                **FY03**                             **FY04**                             **FY05**                             **Total**                

  **WBS**     **Description**   **Category**   **Labor**      **Mat\'l**   **Total**   **Labor**   **Mat\'l**   **Total**   **Labor**   **Mat\'l**   **Total**   **Labor**   **Mat\'l**   **Total**   **Labor**   **Mat\'l**   **Total**

                                                                                                                                                                                                                               

  **1.1**     **Silicon**       Total          50.0           10.8         60.8        52.4        10.8         63.2        84.5        16.7         101.2       502.0       236.1        738.1       688.9       274.4        963.3

                                Baseline       50.0           10.8         60.8        52.4        10.8         63.2        46.5        4.7          51.2        26.0        16.1         42.1        174.9       42.4         217.3

                                MC             \-             \-           \-          \-          \-           \-          38.0        12.0         50.0        476.0       220.0        696.0       514.0       232.0        746.0

                                                                                                                                                                                                                               

  **1.1.1**   **Pixels**        MC             \-             \-           \-          \-          \-           \-          38.0        12.0         50.0        450.0       205.0        655.0       488.0       217.0        705.0

  1.1.1.7     Installation      MC             \-             \-           \-          \-          \-           \-          38.0        12.0         50.0        450.0       205.0        655.0       488.0       217.0        705.0

                                                                                                                                                                                                                               

  **1.1.3**   **RODs**          Total          50.0           10.8         60.8        52.4        10.8         63.2        46.5        4.7          51.2        26.0        16.1         42.1        174.9       42.4         217.3

  1.1.3.9     SCT/Pixel RODs    Baseline       50.0           10.8         60.8        52.4        10.8         63.2        46.5        4.7          51.2        \-          1.1          1.1         148.9       27.4         176.3
              install                                                                                                                                                                                                          

  1.1.3.9     Pixel RODs        MC                                                                                                                               26          15           41.0        26.0        15.0         41.0
              install                                                                                                                                                                                                          
  ----------- ----------------- -------------- -------------- ------------ ----------- ----------- ------------ ----------- ----------- ------------ ----------- ----------- ------------ ----------- ----------- ------------ -----------

Summary labor hours and FTEs in the U.S. ATLAS format are given below
through FY05.

  ------------- ----------------- -------------- ---------- ---------- ---------- ---------- ----------- ------ ---- ---------- ---------- ---------- ---------- -----------
                                                                                                                                                                 

  FTEs in Hours                                  **Labor                                                             **FTEs                           **1762**   **)**
                                                 Hours**                                                             (Hours                                      
                                                                                                                     Divided                                     
                                                                                                                     by**                                        

                                                                                                                                                                 

  **WBS**       **Description**   **Category**   **FY02**   **FY03**   **FY04**   **FY05**   **Total**               **FY02**   **FY03**   **FY04**   **FY05**   **Total**

  **1.1**       **Silicon**       **Total**      598        638        1,018      6,180      8,434       4.8    \-   0.3        0.4        0.6        3.5        4.8

  **EE**                                         298        298        298        1,180      2,074              \-   0.2        0.2        0.2        0.7        1.2

  **ME**                                         \-         \-         240        1,400      1,640       \-     \-   \-         \-         0.1        0.8        0.9

  **Techs**                                      300        340        480        1,840      2,960       \-     \-   0.2        0.2        0.3        1.0        1.7

  **S/W**                                        \-         \-         \-         1,760      1,760       \-     \-   \-         \-         \-         1.0        1.0

  **CL**                                         \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Student**                                    \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Shops**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Other**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         0.3        0.3

  **1.1**       **Silicon**       **Total        598        638        538        \-         1,774       1.01   \-   0.34       0.36       0.31       \-         1.01
                                  Baseline**                                                                                                                     

  **EE**                                         298        298        298        \-         894         \-     \-   0.17       0.17       0.17       \-         0.51

  **ME**                                         \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Techs**                                      300        340        240        \-         880         \-     \-   0.17       0.19       0.14       \-         0.50

  **S/W**                                        \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **CL**                                         \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Student**                                    \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Shops**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Other**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **1.1**       **Silicon**       **Total MC**   \-         \-         480        6,180      6,660       4      \-   \-         \-         0.3        3.5        3.8

  **EE**                                         \-         \-         \-         1,180      1,180              \-   \-         \-         \-         0.7        0.7

  **ME**                                         \-         \-         240        1,400      1,640       \-     \-   \-         \-         0.1        0.8        0.9

  **Techs**                                      \-         \-         240        1,840      2,080       \-     \-   \-         \-         0.1        1.0        1.2

  **S/W**                                        \-         \-         \-         1,760      1,760       \-     \-   \-         \-         \-         1.0        1.0

  **CL**                                         \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Student**                                    \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Shops**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Other**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         0.3        0.3

  **1.1.1**     **Pixels**        **MC**         \-         \-         480        5,880      6,360       3.61   \-   \-         \-         0.3        3.3        3.6

  **EE**                                         \-         \-         \-         880        880                \-   \-         \-         \-         0.50       0.5

  **ME**                                         \-         \-         240        1,400      1,640       \-     \-   \-         \-         0.14       0.79       0.9

  **Techs**                                      \-         \-         240        1,840      2,080       \-     \-   \-         \-         0.14       1.04       1.2

  **S/W**                                        \-         \-         \-         1,760      1,760       \-     \-   \-         \-         \-         1.00       1.0

  **CL**                                         \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Student**                                    \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Shops**                                      \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-

  **Other**                                      \-         \-         \-                                \-     \-   \-         \-         \-         0          0

  **1.1.1.7**   **Pixels          **MC**         \-         \-         480        5,880      6,360       3.61   \-   \-         \-         0.3        3.3        3.6
                Install**                                                                                                                                        

  **EE**                                                               \-         880        880                     \-         \-         \-         0.50       0.5

  **ME**                                                               240        1,400      1,640       \-          \-         \-         0.14       0.79       0.9

  **Techs**                                                            240        1,840      2,080       \-          \-         \-         0.14       1.04       1.2

  **S/W**                                                              \-         1,760      1,760       \-          \-         \-         \-         1.00       1.0

  **CL**                                                               \-         \-         \-          \-          \-                    \-         \-         \-

  **Student**                                                          \-         \-         \-          \-          \-                    \-         \-         \-

  **Shops**                                                            \-         \-         \-          \-          \-         \-         \-         \-         \-

  **Other**                                                            \-                                \-                                \-                    

  **1.1.2**     **Silicon                        \-         \-         \-         \-         \-          \-     \-   \-         \-         \-         \-         \-
                Strips**                                                                                                                                         

  **EE**                                                                                     \-                      \-         \-         \-         \-         \-

  **ME**                                                                                     \-                      \-         \-         \-         \-         \-

  **Techs**                                                                                  \-                      \-         \-         \-         \-         \-

  **S/W**                                                                                    \-                      \-         \-         \-         \-         \-

  **CL**                                                                                     \-                      \-         \-         \-         \-         \-

  **Student**                                                                                \-                      \-         \-         \-         \-         \-

  **Shops**                                                                                  \-                      \-         \-         \-         \-         \-

  **Other**                                                                                  \-                      \-         \-         \-         \-         \-

  **1.1.3**     **RODs**          **Baseline**   598        638        538        \-         1,774       1.01   \-   0.34       0.36       0.31       \-         1.01

  **EE**                                         298        298        298                   894                     0.17       0.17       0.17       \-         0.51

  **ME**                                                                                     \-                      \-         \-         \-         \-         \-

  **Techs**                                      300        340        240                   880                     0.17       0.19       0.14       \-         0.50

  **S/W**                                                                                    \-                      \-         \-         \-         \-         \-

  **CL**                                                                                     \-                      \-         \-         \-         \-         \-

  **Student**                                                                                \-                      \-         \-         \-         \-         \-

  **Shops**                                                                                  \-                      \-         \-         \-         \-         \-

  **Other**                                                                                  \-                      \-         \-         \-         \-         \-

  **1.1.3**     **RODs**          **MC**                                          300        300         0.17                                         0.2        0.2

  **EE**                                                                          300        300                                                      0.17       0.2

  **ME**                                                                                                                                                         

  **Techs**                                                                                                                                                      

  **S/W**                                                                                                                                                        

  **CL**                                                                                                                                                         

  **Student**                                                                                                                                                    

  **Shops**                                                                                                                                                      

  **Other**                                                                                                                                                      
  ------------- ----------------- -------------- ---------- ---------- ---------- ---------- ----------- ------ ---- ---------- ---------- ---------- ---------- -----------

[^1]: The amount of U.S. M&O funding is not yet fixed but is intended to
    support the SR building operation.

[^2]: Funding for the beam pipe support is currently in the Technical
    Coordination part of Management Contingency.

[^3]: Funding for fabrication of all pixel RODs is currently part of
    Management Contingency.

[^4]: We assume 40 hour weeks.