---------------------------------------------------- ----------------------- --------------- ------------
  ![](media/image1.wmf){width="0.9326388888888889in"   Pixel Services FDR                      
  height="0.975in"}                                                                            

  ATLAS Project Document No:                           Institute Document No.  Created : June  Page: **1
                                                                               10, 2003        of** **26**

                                                                               Modified :      Rev. No .: 1
                                                                               **     **       
  ---------------------------------------------------- ----------------------- --------------- ------------

+-----------------------+-----------------------+-----------------------+
| ATLAS PIXEL PATCH     |                       |                       |
| PANEL 1               |                       |                       |
|                       |                       |                       |
| The requirements and  |                       |                       |
| interfaces for the    |                       |                       |
| ATLAS Pixel Patch     |                       |                       |
| Panel 1 are           |                       |                       |
| described. The status |                       |                       |
| of prototype          |                       |                       |
| development is        |                       |                       |
| presented. The        |                       |                       |
| preliminary design    |                       |                       |
| and production plan   |                       |                       |
| are described.        |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Prepared by:          | Checked by:           | Approved by:          |
|                       |                       |                       |
| E. Anderssen, M.      |                       |                       |
| Citterio, M.          |                       |                       |
| Garcia-Sciveres, M.   |                       |                       |
| Gilchriese, D.        |                       |                       |
| Giugni, F. Goozen, N. |                       |                       |
| Hartman, G. Lenzen,   |                       |                       |
| R. Madaras, J.        |                       |                       |
| Thadome, T. Weber     |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Distribution List     |                       |                       |
|                       |                       |                       |
|                       |                       |                       |
+-----------------------+-----------------------+-----------------------+

  ---------- ---------- ---------- ----------------------------------------
  History of                       
  Changes                          

  Rev. No.   Date       Pages      Description of changes

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

Table of Contents

1 Introduction [6](#introduction)

2 Requirements [7](#requirements)

2.1 Structural and General [7](#structural-and-general)

2.2 Cooling and Gas Pipes [8](#cooling-and-gas-pipes)

2.3 Electrical [9](#electrical)

2.4 Fiber Optics [9](#fiber-optics)

3 Interfaces [11](#interfaces)

3.1 Pixel Support Tube [11](#pixel-support-tube)

3.2 Connections to Patch Panel 2(PP2)
[11](#connections-to-patch-panel-2pp2)

3.3 Beam Pipe Support [12](#beam-pipe-support)

3.4 Beam Pipe [12](#beam-pipe)

4 Overview of Design and Prototypes
[13](#overview-of-design-and-prototypes)

5 Mechanical Structure [13](#mechanical-structure)

6 Electrical Feedthroughs [15](#electrical-feedthroughs)

7 Coolant Pipes, Feedthroughs and Connectors
[16](#coolant-pipes-feedthroughs-and-connectors)

7.1 Coolant Pipes [16](#coolant-pipes)

7.2 Feedthroughs [16](#feedthroughs)

8 Optical Fibers [19](#optical-fibers)

9 Mockup [21](#mockup)

10 Material Estimate [21](#material-estimate)

11 Preliminary Production Plan [25](#preliminary-production-plan)

12 Appendices [25](#appendices)

# Introduction

Patch Panel 1(PP1) is located at the end of the Pixel Support Tube(PST)
near the end of the Inner Detector volume -- see Figure 1.

![](media/image2.png){width="7.125in" height="6.649305555555555in"}

Figure 1. The Patch Panel 1(PP1) region.

Connections for the following items are present at PP1: coolant pipes
for the pixel modules and optical interface boards; gas inlets and
outlets for dry nitrogen that flows within the PST; power and slow
signals for pixel modules and system monitoring; optical fibers; beam
pipe support structure inside the PST; and beam pipe support outside the
PST. PP1 is a segmented assembly so that it may be attached to the beam
pipe/pixel service panel structure on the surface such that the
assembled pixel package may roll/slide into the PST from Side C of
ATLAS. PP1a refers to the connections at the bulkhead endplate connected
to the Pixel Support Tube(see Figure 2). PP1b refers to the connections
in the transition region to services routed to PP2 outside of the Inner
Detector and along the calorimeter/cryostat wall.

# Requirements

The barrel part of the ATLAS pixel detector is built up of 3 layers
(B-layer, layer 1, and layer 2) and there are 3 disks per endcap (8
sectors per disk). Each barrel layer has a certain number of staves
(B-layer 22, layer 1 38, layer 2 52 staves) where the modules are
mounted on. There are 13 modules per stave, and 48 modules per disk. The
total number of modules is 1456 for the barrel (B-layer 286, layer 1
494, layer 2 676 modules), and 288 modules for the two endcaps (6
modules per sector), i.e. there are 1744 modules for the whole pixel
detector.

The initial pixel detector will have Layer 1 and the middle disk on each
end absent. We have designed PP1 for the full, 3-hit pixel system.

## Structural and General

The overall requirements on PP1 have been specified in the general
"Services" document[^1]. Here the aspects related to structural and to
geometrical characteristics are listed.

-   Maximum pressure differential is 4mbar;

-   No heaters are present on the plate to prevent condensation. The
    volume outside the Pixel envelope is continuously flushed by CO~2~
    with a dew point below -25C^o^.;

-   The penetrations at the two PP1 plates and the seals[^2] at the two
    PST flanges should guarantee a leak rate better than 6 L .mbar/h.
    Given a total of \~200 penetrations all over the Pixel Package, each
    single seal should be gastight at less than 3x10^-2^ L .mbar/h

-   The penetration for the cooling pipes should allow the axial motion
    of the aluminum coolant tubes as they are cooled from room
    temperature to the operating temperature;

-   The plate should make accessible the beam pipe adjusters that are
    located within the Pixel Support Tube volume;

-   A beam pipe survey is deemed necessary. PP1 endplate must have
    openings to allow the survey of targets located on the beam pipe at
    Z \~ ±800mm.

-   The detector is in a N~2~ environment. This gas is provided by a
    dedicated piping system[^3] for a total of four pipes.

![](media/image3.png){width="5.290972222222222in"
height="4.219444444444444in"}

Figure 2. Patch Panel 1(PP1) consists of a bulkead/endplate attached to
the Pixel Support Tube and connections for cooling, gas flow, power and
signals and fiber optics. The bulkhead also provides a connection to the
beam pipe.

## Cooling and Gas Pipes

The number and characteristics of the pipes containing the C~3~F~8~
coolant and the pipes used to flush nitrogen within the pixel
volume(inside the Pixel Support Tube) are given in ref. 1. The number of
coolant circuits(side C) is given in Table 1. The table for Side A is
given in reference 1. We have required that each quadrant of the PP1 be
identical. Hence it must allow penetrations for the maximum number of
pipes and cable bundles. This corresponds to 14 cooling circuits for the
pixel modules and 2 panel cooling circuits per quadrant.

  ---------- ------------------ ------ ------ ------ ------ ------ ------ ------ ------ --------
  **SIDE C                                                                              
  SERVICES                                                                              
  FROM PP0                                                                              
  TO PP1**                                                                              

  TOTAL      PANEL NAME         PEC1   PEC2   PEC3   PEC4   PEC5   PEC6   PEC7   PEC8   TOTAL
  OUTER                                                                                 
  PANELS                                                                                

             6 module cable     5      7      5      5      6      6      5      6      45
             bundles                                                                    

             7 module cable     6      5      5      7      5      6      5      6      45
             bundles                                                                    

  TOTAL      PANEL NAME         PI C1  PI C2  PI C3  PI C4  PI C5  PI C6  PI C7  PI C8  
  INNER                                                                                 
  PANELS                                                                                

             6 module cable     3      3      3      3      3      3      3      3      24
             bundles                                                                    

             6 B-module cable   2      1      2      1      1      2      1      1      11
             bundles                                                                    

             7 B-module cable   1      2      1      1      2      1      2      1      11
             bundles                                                                    

  COOLING                       6      5      6      5      6      5      6      6      45
  CIRCUITS                                                                              

  PANEL                         1      1      1      1      1      1      1      1      8
  COOLING                                                                               
  CIRCUIT                                                                               

  TOTAL AT   Cooling circuits   7      6      7      6      7      6      7      7      53
  PP1                                                                                   

             6 module cable     8      10     8      8      9      9      8      9      69
             bundles                                                                    

             7 module cable     6      5      5      7      5      6      5      6      45
             bundles                                                                    

             6 B-module cable   2      1      2      1      1      2      1      1      11
             bundles                                                                    

             7 B-module cable   1      2      1      1      2      1      2      1      11
             bundles                                                                    
  ---------- ------------------ ------ ------ ------ ------ ------ ------ ------ ------ --------

Table 1. Side C coolant circuits and number of cable bundles from
reference 1.

Each cooling circuit consists of an inlet pipe and an outlet pipe. There
are 53(43) circuits on Side C(Side A). The dimensions of these pipes are
given below in Table 2. The dimensions are slightly different for the
pipes coming from Patch Panel 0(PP0) at the end of the pixel detector
and from PP1a to PP1b. The former correspond to U.S. standards and the
latter to metric standards.

  ----------- -------------- --------------- -------------- ---------------
              PP0-PP1a                       PP1a-PP1b      

              ID(mm)         OD(mm)          ID(mm)         OD(mm)

  Inlet       2.07           2.78            2.5            3.0

  Outlet      7.92           8.73            8.0            10.0
  ----------- -------------- --------------- -------------- ---------------

Table 2. Requirements for inlet and outlet cooling tube diameters.

The dimensions of the coolant circuits for the service panels are the
same.

The dimensions of the pipes for flushing of dry nitrogen are given below
in Table 3.

+-------+-------+-------+--------+-------+-------+------+-----------+
| Nit   |       |       |        |       |       |      |           |
| rogen |       |       |        |       |       |      |           |
| s     |       |       |        |       |       |      |           |
| ystem |       |       |        |       |       |      |           |
+-------+-------+-------+--------+-------+-------+------+-----------+
| Side  | ID    | \#    | ma     | Max P | From  | To   | de        |
|       | (mm)  |       | terial | (     |       |      | scription |
|       |       | of    |        | mbar) |       |      |           |
|       |       | pipes |        |       |       |      |           |
+-------+-------+-------+--------+-------+-------+------+-----------+
| C     | 6     | 1     | Any    | 4     | PP2   | P    | inlet     |
|       |       |       |        |       |       | ixel |           |
+-------+-------+-------+--------+-------+-------+------+-----------+
| A     | 21    | 2     | Any    | 4     | pixel | PP2  | exhaust   |
+-------+-------+-------+--------+-------+-------+------+-----------+
|       | 21    | 1     | Any    | 4     | pixel | Bub  | emergency |
|       |       |       |        |       |       | bler |           |
|       |       |       |        |       |       | \    |           |
|       |       |       |        |       |       | @PP2 |           |
+-------+-------+-------+--------+-------+-------+------+-----------+
|       | 2     | 1     | Any    | 4     | pixel | US15 | sensing   |
+-------+-------+-------+--------+-------+-------+------+-----------+

Table 3. Dimensions of the pipes for the dry nitrogen system.

## Electrical

The power and slow signal connections to the pixel modules are made via
cable/wire bundles soldered to copper-on-kapton circuits that are
captured by PP1. The transition from wires to flat copper-on-kapton
circuits is necessary to meet the tight space requirements at PP1. The
number of cable bundles for Side C are given in Table 1(and for Side A
in reference 1). Again each PP1 quadrant is required to be identical.

Each coolant pipe must be electrically isolated at PP1 ie. there must be
an electrical break in the pipes between PP1a and PP1b.

## Fiber Optics

Each module transfers the data information via optical fibres from the
detector at PP0 to the electronics in the counting room USA15, while the
timing information to read-out a module goes via optical fibres from the
counting room to the detector. Only the B-layer reads out the data
information with 2 optical fibres and it receives 1 TTC signal per
module. All other modules are read-out each by 1 optical fibre and they
receive each 1 TTC optical fibre. Inside the ATLAS detector the
radiation hard Fujikura SIMM50 optical fibre with a core diameter of
50μm will be used, while ouside the detector till the counting room in
USA15 radiation tolerant Draka GRIN62.5 fibres (62.5 μm core diameter)
for the data and Draka GRIN50 fibres (50 μm core diameter) for TTC are
foreseen. Both fibre types (SIMM50 and GRIN50/62.5) will be spliced
together at PP2 just under the first layer of the ATLAS muon detector
system.

The total number of single fibres for the pixel detector is 3774. The
barrel part has 1742 data single fibres (B-layer 572, layer 1 494, layer
2 676 single fibres) and 1456 TTC single fibres (B-layer 286, layer 1
494, layer 2 676 single fibres). Both endcaps with their 6 disks have
288 data and 288 TTC single fibres (48 single fibres per disk each for
data and TTC or 6 single fibres per sector for data and TTC each).

A stave with its 13 modules are read-out in such a way, that 7 modules
are read-out on side A of the detector, while the remaining 6 modules of
that stave are read-out on side C. The next stave will read-out 6
modules to side A, and 7 modules to side C. In that way it is guaranteed
that the same total number of modules is read-out on both sides. The 48
sectors of the 6 endcap disks are read-out in equal parts to side A and
side C.

Inside the pixel detector, 8 single fibres will form a so-called 8-way
fibre ribbon, which is the basic unit for the optical fibre system. A
ribbon has a rectangular cross-section of 3mm x 0.3mm. There are certain
criteria to read out the data from and to bring the TTC information to
the modules:

-   data and TTC information are handled by different ribbons, i.e.
    there are data and TTC ribbons,

-   the ribbons of layers and of disks are separated,

-   the ribbons of each layer and of each disk are separated.

In an 8-way fibre ribbon always only 6 or 7 out of the 8 single fibres
are actually used. The endcap regions always use only 6 out of the 8
fibres of a ribbon.

The above criteria will become even more important when 8 ribbons will
form so-called optical fibre cables. An optical fibre cable has an
external diameter of 9.5mm. While the connection inside the pixel
detector from PP0 to PP1 will be established by about 3m long 8-way
ribbons, PP1 will be connected to the counting room in USA15 by 8x8-way
ribbon fibre cables. These cables have the advantage that the fragile
fibre ribbons are protected by the plastic mantle of the cable. In order
to limit the number of fibre cables it is necessary to put together into
one cable ribbons, where 6 OR 7 out of 8 fibres are used.

The total amount of 8-way SIMM50 fibre ribbons for the whole pixel
detector is 588. Per side A and side C that are needed for data transfer
are:

-   67 barrel ribbons using 7 fibres each (B-layer 22, layer 1 19, layer
    2 26 ribbons),

-   67 barrel ribbons using 6 fibres each (B-layer 22, layer 1 19, layer
    2 26 ribbons),

-   24 endcap ribbons using 6 fibres each (disk 1, disk 2, disk 3 each 8
    ribbons).

-   for TTC transfer:

-   56 barrel ribbons using 7 fibres each (B-layer 11, layer 1 19, layer
    2 26 ribbons),

-   56 barrel ribbons using 6 fibres each (B-layer 11, layer 1 19, layer
    2 26 ribbons),

-   24 endcap ribbons using 6 fibres each (disk 1, disk 2, disk 3 each 8
    ribbons).

The 588 8-way fibre ribbons will arrive from the PP0 optoboards PP1. The
connection of these ribbons to the optoboards will be done by MT8
connectors (1 connector per 8-way fibre ribbon). At PP1 the ribbons have
to be connected to the fibre cables coming from USA15 in such a way that
an easy disconnection is possible. It has to be pointed out that due to
space requirements inside the pixel detector itself there are no spare
8-way fibre ribbons foreseen between PP0 and PP1.

At this point it seems appropriate to describe in detail which and how
many fibre cables are needed for the installation in the ATLAS cavern.
As the modules of the B-layer need 2 data and only 1 TTC fibre per
module the number of cables containing GRIN62.5 fibre ribbons will be
slightly higher than the number of cables with GRIN50 fibre ribbons.

The 294 SIMM50 ribbons per side A and side C will be put into optical
fibre cables in the following way:

[B-layer:]{.underline}

3 cables for 22 data ribbons using 7 out of 8 fibres (reserve: 2
ribbons),

3 cables for 22 data ribbons using 6 out of 8 fibres (reserve: 2
ribbons),

3 cables for 22 TTC ribbons using 6 or 7 out of 8 fibres (reserve: 2
ribbons).

[Layer 1:]{.underline}

5 cables for 38 data ribbons using 6 or 7 out of 8 fibres per ribbon
(reserve: 2 ribbons),

5 cables for 38 TTC ribbons using 6 or 7 out of 8 fibres per ribbon
(reserve: 2 ribbons).

[Layer 2:]{.underline}

7 cables for 52 data ribbons using 6 or 7 out of 8 fibres per ribbon
(reserve: 4 ribbons),

7 cables for 52 TTC ribbons using 6 or 7 out of 8 fibres per ribbon (
reserve: 4 ribbons).

[Endcap:]{.underline}

3 cables for 24 data ribbons using 6 out of 8 fibres per ribbon
(reserve: 0 ribbons)

3 cables for 24 TTC ribbons using 6 out of 8 fibres per ribbon (reserbe:
0 ribbons).

Hence a total of 39 8x8-way fibre ribbon cables are needed for a
connection at PP1. As there are 312 ribbons in these cables, there are
18 ribbons not used, and these 18 ribbons are serving as a reserve NOT
being connected to PP1. In order to have more reserve ribbons in case of
problems in data or TTC transfer, there are 2 cables with 8 ribbons each
per side A and side C (1 spare cable for data and 1 spare cable for TTC
transfer) foressen for installation. These 2 spare cables are not
connected at PP1. A total of about 10.9% (34/312) of ribbons between PP1
and USA15 are serving as reserve.

The whole pixel detector will have 82 fibre cables for its optical
transfer of data and TTC information. On side A the 41 cables will leave
through slot A10 and on side C the 41 cables will go through slot C15.
The 82 cables consist each of 8 about 9m long SIMM50 ribbons which will
then be spliced to 8 about 70m long GRIN50/62.5 ribbons. Therefore PP1
will be connected to USA15 without any further patch panel. The
following data SIMM50/GRIN62.5 and TTC SIMM50/GRIN50 fibre cables will
be installed per side A and side C:

[Data SIMM50/GRIN62.5 cables per side A and side C:]{.underline}

B-layer: 6 cables, Layer 1: 5 cables, Layer 2: 7 cables, Endcap: 3
cables, Reserve: 1 cable =\> 22 cables

[TTC SIMM50/GRIN50 cables per side A and side C:]{.underline}

B-layer: 3 cables, Layer 1: 5 cables, Layer 2: 7 cables, Endcap: 3
cables, Reserve: 1 cable =\> 19 cables

Per side A and side C, the 294 single 8-way SIMM50 fibre ribbons
arriving from PP0 at PP1 have to be connected to the 39 cables coming
from USA15 to PP1. Four places (1 per quadrant) are foreseen for this
connection on the PP1 endplate. Therefore 74 ribbons coming from PP0
will meet 10 cables arriving from USA15 at each quadrant of PP1.

# Interfaces

## Pixel Support Tube

A side-view of the PP1 region is shown in Figure 3. The Z location of
the end of the PST and thus of the PP1 endplate is preliminary. The
final dimension will be set after construction of the PP1 prototype and
a mockup of the PP1, including pipes and cables. The interface to the
pixel support tube flange is a bolted connection of the PP1 endplate.

![](media/image2.png){width="7.125in" height="5.86875in"}

Figure 3. Side view of the PP1 region showing the current Z location of
the PP1 endplate.

## Connections to Patch Panel 2(PP2)

The connections at PP1b are determined in part by the routing of
services outwards to PP2. We have taken as a requirement the location of
services at PP1b as shown in Figure 4.

![](media/image4.png){width="7.0875in" height="5.018055555555556in"}

Figure 4. Services layout at R=450mm for routing to PP2.

## Beam Pipe Support

A 3D model of the connection between the PP1 endplate and the beam pipe
support structure inside the Pixel Support Tube is shown in Figure 5.
The beam pipe support structure (BPSS) interfaces to PP1 through two
structures: the beam pipe position adjustors, which protrude through
PP1; and the PP1 support rods, which are parallel to the adjustors and
bolt directly to the PP1 quadrants. Since the services are integrated
into quadrant structures before attachment to the BPSS, each PP1
quadrant is affixed to the service quadrant "backbone" in order to
support it during the assembly process (otherwise the PP1 panel would
hang from the attached services). Once a service panel structure is
attached to the BPSS, the associated PP1 quadrant can be bolted to it
through the support rod. The beam pipe adjustor moves into its open spot
in the PP1 quadrant, and is then sealed to the PP1 panel with a small
"closeout" piece that forms a gas seal. After more than one service
quadrant structure has been assembled to the BPSS, the adjoining PP1
panels are also bolted to each other.

## Beam Pipe

PP1 is attached to the beam pipe directly outside(larger Z) of the PP1
endplate as shown in Figure 2. A bellows is attached to the PP1 endplate
to allow for differential motion(up to 30mm) of the beam pipe as it is
cooled from room temperature to the pixel operating temperature. The
interface to the bellows is through a split clamp that connects to a
ring clamped to the beampipe. The details of this interface are under
design.

![](media/image5.png){width="5.375in" height="4.526388888888889in"}

Figure 5. Model of the PP1 region showing the connection to the beam
pipe support.

# Overview of Design and Prototypes

In this section we provide an overview of the principal design elements
of PP1. Prototypes of these have either been fabricated or are under
fabrication.

# Mechanical Structure

A prototype of the PP1 endplate is shown in Figure 6. The PP1 endplate
will be machined from aluminum. Each quadrant is designed to be
identical. Each quadrant will be mounted(along with the various
feedthroughs) to a quadrant of the service panel structure that carries
the services to PP0. The quadrants of PP1 are joined after the quadrants
and service panels are mounted on the beam pipe/service panel support
structure. The quadrants are joined and the gas seal is completed by a
connection to the PST flange. A drawing of the joining pieces is shown
in Figure 7. Gasket material is used to make the low pressure gas seal.
Our current design uses paper gaskets

The prototype program includes the fabrication of a complete quadrant.
The remaining quadrants are just plates. The prototype endplate will be
loaded with prototype pipe and electrical feedthroughs. It will be
bolted to a prototype section(30 cm long) of the pixel support tube with
end flanges. The other end of the 30cm prototype will be blanked off
apart from a fitting to introduce a small known pressure. This will
allow us to make leak rate measurements at the level of one quadrant. It
will also verify the interface to the pixel support tube as well as the
general fabrication and assembly procedures for the endplate..

![](media/image6.jpeg){width="5.457638888888889in"
height="5.126388888888889in"}

Figure 6. Prototype PP1 endplate.

![](media/image7.png){width="4.707638888888889in"
height="3.251388888888889in"}

Figure 7. Sealing sections for the PP1 endplate.

# Electrical Feedthroughs

The constraints of limited space and the need for a gas seal at the
support tube end plates make it impossible to have bulkhead-mounted
connectors for electrical services through PP1 with existing connector
technology. Directly continuing the Type 1 wires(those wires inside the
PST) through the endplate with cable-to-cable connectors further away is
also not possible because of the need to make a gas seal, and because
the Type 1 wires are not compatible with standard connector technologies
(copper clad aluminum wires in the case of power and very fine copper
wire -AWG42- in the case of sense lines). The proposed solution uses
printed copper-on-kapton feedthroughs, which can be tightly bonded in a
gas-tight plug to pass through the bulkhead using minimum area. The Type
1 wires are soldered to these feedthroughs on the inside of the
bulkhead. On the outside conventional copper cables are soldered to the
feedthroughs and terminated in standard connectors at PP1B.

Each octant has an outer and an inner feedthrough. Each feedthrough is a
stack of copper on kapton printed circuits bonded in an aluminum stopper
that fits into a bulkhead slot, making a gas seal. Each feedthrough will
be fully soldered and connectorized before inserting into the bulkhead.
Table 1 shows the parameters of the individual printed circuit and the
maximum load of the inner and outer feedthroughs. The outer feedthroughs
serve Layer 1 and Layer 2 staves, while the inner feedthroughs serve
B-layer and disks. shows the staggering and arrangement of the power
flex circuits in each feedthrough.

  --------- --------- ---------- -------- -------------- -------- --------
  Circuit   Length    Cu Mass    R/T res. Type 2 bundles Number   Number
  name      (mm)      (g)        (mΩ)     served         inner    outer

  Power 1   12.0      3.0        38       2(2A) + 2(2B)  1        1

  Power 2   15.2      3.9        48       2(2A) + 2(2B)  1        1

  Power 3   19.1      4.9        61       2(2A) + 2(2B)  1        1

  Power 4   22.4      5.8        71       2(2A) + 2(2B)  1        0

  Power 5   25.6      6.6        82       2(2A) + 2(2B)  1        0

  Power 6   29.2      7.5        94       2(2A) + 2(2B)  1        0

  HV        35        0.1        N/A      2(2E1)         6        3

  Signal    35        2.5        N/A      3(2C)+3(2E2)   4        2
  --------- --------- ---------- -------- -------------- -------- --------

Table 4. Printed flex circuits and feedthrough composition.

![](media/image8.png){width="5.998611111111111in"
height="3.3743055555555554in"}

Figure 8. Arrangement of power flex circuits in inner and outer
feedthroughs and the number of modules served.

Figure 9 shows a prototype of the outer feedthrough with type 2A cables.
The plan for these prototypes includes:

-   Optimization of assembly sequence.

-   Packing test of wires in corrugated support and assembly of
    facesheets

-   Thermal test with full current load for panels as well as
    PP1feedthroughs

-   Electrical test with real modules once type 2B cables and
    connectorsare available.

-   Development of continnuity test box for production.

-   Mechanical plugging and unplugging tests

-   High voltage isolation tests

In addition, the prototypes will be included in the PP1 mockup under
fabrication at CERN.

  ----------------------------------------- -----------------------------------------------------
  ![](media/image9.jpeg){width="3.5875in"   ![](media/image10.jpeg){width="3.033333333333333in"
  height="2.3194444444444446in"}            height="2.30625in"}

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

Figure 9. Prototypes of the electrical feedthroughs. The picture on the
right shows the feedthroughs gathered as they would be in a clamp that
attaches to the PP1 endplate.

# Coolant Pipes, Feedthroughs and Connectors

## Coolant Pipes

Liquid C~3~F~8~ is used to cool the pixel detector, which then
evaporates and returns to the cooling plant. Thus the narrow supply
pipes carry liquid C~3~F~8~, and the larger return pipes carry gaseous
C~3~F~8~. The aluminum coolant pipes from PP1A to PP1B have the
dimensions given in Table 2 and are about 90cm in length to meet the
requirements for the routing to PP2 given in Figure 4. The pipes have to
travel radially, axially and azimuthally to get from PP1A to PP1B, and
this accounts for their long length. The length has not been optimized
yet.

The C~3~F~8~ in the supply coolant pipe is at a pressure up to 16 bar
(absolute). A pressure drop device between PP1b and PP1a will reduce the
pressure to about 8 bar(abs) at the entrance to the pixel volume.

There will be 55 supply pipes and 55 return pipes on side C, and 45
supply pipes and 45 return pipes on side A, since all the B-layer
cooling pipes come out on side C only. These numbers include 2 spare
supply pipes and 2 spare return pipes on each side.

## Feedthroughs

Figure 10 shows the parts for a coolant pipe feedthrough for the PP1
bulkhead, Figure 11 shows how these parts are assembled in the bulkhead,
and Figure 12 shows more detail of the coolant pipe coupling (using the
3 pieces on the right in Figure 10).

As discussed in the section on Coolant Pipes, there will be 55 supply
pipe feedthroughs and 55 return pipe feedthroughs on side C, and 45
supply pipe feedthroughs and 45 return pipe feedthroughs on side A.
However, for ease of design and fabrication, the C-side and A-side PP1
bulkheads are identical, and also the 4 quadrants of the PP1 bulkhead
are identical. The number of holes in the bulkhead for the feedthroughs
is determined by the busiest quadrant, which requires 16 supply holes
and 16 return holes. Thus each PP1 bulkhead has space for 64 supply pipe
feedthroughs and 64 return pipe feedthroughs. The unused holes will be
plugged.

![](media/image11.png){width="6.0in" height="3.5965277777777778in"}

Figure 10. Coolant Pipe Feedthrough for the PP1 Bulkhead.

From left to right in Figure 10 we have the following six pieces:

1)  Sliding Seal: This PEEK piece provides a gas seal to the coolant
    pipe, and is glued to the bellows. It slides on the pipe, to
    accommodate the bellows movement. A prototype test (at room
    temperature) yields a leak rate of \< 5x10^-4^ liters/(mbar-hr) for
    one such seal. Tests with many seals will be done as part of the
    prototype program.

2)  Bellows: This nickel bellows allows for axial movement of the
    coolant pipes relative to the PP1 bulkhead.The aluminum pipes shrink
    as they are cooled from room termperature to the operating
    temperature. Its length is 54.8 mm when relaxed, and it has a spring
    rate of 0.53 pounds/inch.

3)  Bellows to Bulkhead: The bellows is glued to this PEEK piece, and
    then this piece is screwed into the PP1 bulkhead. This piece might
    be made of aluminum instead of PEEK to reduce cost.

4)  Inner Flair Connector: This aluminum piece is at the flared end of
    the coolant pipe, and is one half of the coolant pipe coupling.

5)  Flare Bushing: This PEEK piece forms the actual seal between the
    flared ends of the coolant pipes. It also acts as an electrical
    break in conjunction with item (6).

6)  Flare Outer: This PEEK piece screws onto the Inner Flare Connector,
    and is the other half of the coolant pipe coupling. It is made of
    PEEK to provide an electrical break.

![](media/image12.png){width="4.333333333333333in"
height="3.4722222222222223in"}

Figure 11. Coolant Pipe Feedthroughs in the PP1 Bulkhead.

![](media/image13.png){width="3.611111111111111in"
height="2.5972222222222223in"}

Figure 12. Coolant Pipe Coupling.

There will also be a stainless steel filter-screen/pressure-drop device
to reduce the pressure of the C~3~F~8~ from 16 to 8 bar. This piece will
either be a part of the coolant pipe coupling or part of the PP1b
fitting. It is under design, and is not shown in the above Figures. The
PP1b fittings are expected to be commercially available fittings(unlike
those described above) but these have not yet been selected. An
alternative would be to use fittings similar to those described above
but of slightly different dimensions without the need for an electrical
break.

The return coolant pipe couplings are undergoing tests to insure that
they do not deteriorate under thermal and pressure cycling, and that
they can withstand the nominal pressure. Previous versions of the
couplings have passed similar tests. The supply coolant pipe couplings
might also be tested. The current testing of the latest version of the
return coolant pipe couplings (as shown in Figure 3) involves the
following steps (all pressures are gauge pressures):

1.  Helium vacuum leak check (measure leak rate).

2.  Proof test at 10 bar (this is a 1 minute visual check, to make sure
    the fitting stays intact, and that there are no large leaks). This
    will be repeated at a higher pressure, perhaps 20 bar.

3.  Helium leak check of coupling at 4 bar, 0 °C.

4.  Helium leak check of coupling at 1 bar, -35 °C.

5.  Helium vacuum leak check (measure leak rate).

6.  Thermal cycle coupling: 50 times, between 20 °C and -35 °C.

7.  Pressure cycle coupling: 50 times, between 1 bar and 4 bar.

8.  Helium vacuum leak check (measure leak rate).

9.  Helium leak check of coupling at 16 bar, 0 °C.

10. Helium leak check of coupling at 1 bar, -35 °C.

11. Helium vacuum leak check (measure leak rate).

Results for testing 4 samples of return coolant pipe couplings are below
(units for helium leak measurements are torr-liter/sec). Leak rates are
all well below specs.

[Step]{.underline} [Spec]{.underline} [Sample 1]{.underline} [Sample
2]{.underline} [Sample 3]{.underline} [Sample 4]{.underline}

1 \<2x10^-5^ 3x10^-10^ 3x10^-10^ 3x10^-10^ 3x10^-10^

2 Pass Pass Pass Pass Pass

3 \<7x10^-5^ 3.5x10^-10^ 7x10^-10^ 20x10^-10^ 200x10^-10^

4 \<2x10^-5^ 2x10^-10^ 7x10^-10^ 32x10^-10^ 300x10^-10^

5 \<2x10^-5^ 4x10^-10^ 2x10^-10^ 3.2x10^-10^ 2x10^-10^

6 50 cycles done done done done

7 50 cycles done done done done

8 \<2x10^-5^ 4x10^-10^ 4.5x10^-10^ 2.8x10^-10^ 2.5x10^-10^

9 \<7x10^-5^ 160x10^-10^ 7x10^-10^ 40x10^-10^

10 \<2x10^-5^ 200x10^-10^ 10x10^-10^ 70x10^-10^

11 \<2x10^-5^ 140x10^-10^ 45x10^-10^ 30x10^-10^

Note that these prototypes of the exhaust pipes that are larger in
diameter than the inlet pipes, which will subject to the highest
pressures. We are in the process of extending the maximum pressure range
beyond 16 bar(abs) but results are not yet available.

# Optical Fibers

As PP1 is a very crowded area, the Swedish firm Ericsson made a study in
order to indicate a possible solution to minimize the space for the
connectors without jeopardizing the fibre life-time, their handling or
installation. Industrial proven backplane technology was guiding this
study.

The available area per quadrant amounts to 77mm x 35 mm and 4mm around
and 50mm above towards the PP2 side of the PP1 endplate. Space for the
connectors towards the PP0 side of the PP1 endplate is not directly
limited. The pixel detector is kept on a slightly higher pressure (about
4mbar from pure Nitrogen) in comparison to its air surroundings in order
to avoid condensation on its elements, which implies that the connectors
at PP1 towards PP0 will be made leak-tight by a radhard soft silicon
glue (Dow Corning SE4445). The 5 picture below in Figure 13 indicate a
space saving lay-out. The left hand side of the firs tfour pictures show
the bare ribbons arriving at PP1, while the 5^th^ picture shows the
arrangement of the 10 cables with their connectors. A 16 fibres ferrule
(MT16 connector) is used by arraying this with two layers, i.e. two
8-way fibre ribbons are going into each ferrule. In the PP1 endplate a
housing is foreseen into which the connectors will glide.

In order to save material especially inside the pixel detector, bare
ribbons (not ruggedized) are preferred between PP0 and PP1. As the
connectors on the PP0 side of the PP1 endplate have to be leak-tight,
spring-loaded ferrules for these connectors have to be excluded.
Therefore these connectors still need to be redesigned and then to be
tested.

![](media/image14.png){width="5.7034722222222225in"
height="4.320833333333334in"}

Figure 13. Conceptual design for the fiber optic feedthrough at PP1. See
text for description.

The 8 ribbons of each cable coming from USA15 will be hanging out of the
cable for about 50cm towards the PP1 side. The length of these ribbons
will not differ by more than about 50mm, depending on the exact opening
of the end of the cable. Ribbons assembled to the same connector have
the same length within 5mm. A cable consists then of a module of 4
connectors which will find their counterpart of 8 nude ribbons with
their 4 connectors coming from PP0. A final fixation of the connectors
by screws will guarantee an optimal light transfer through the fibres
from both sides of the PP1 endplate. All ribbons coming from PP0 to PP1
will be finally fixed to the endplate PP1 region already in the surface
SR1-building before the installation of the pixel detector in the ATLAS
cavern. The 78 optical fibre cables coming from USA15 will then be
connected one by one to both PP1 regions. Because of the very limited
space it may turn out to be impossible to exchange one particular cable
after having connected all other cables to PP1. Therefore it is
necessary to test each connection before continueing to connect the next
optical fibre cable to PP1.

As PP1 also is a place of high radiation all materials used in the
connectors, housings, and adapters must be radiation hard. Aluminum and
PEEK are excellent candidates here. Ericsson is going to make a
prototype of the above PP1 optical fibre connector lay-out in the coming
weeks.

# Mockup

The region of the PP1 endplate is very crowded by a huge amount of
different electrical cables, optical fibres, cooling and gas integrity
pipes. In order to have a better understanding of the implementation and
integration of all these different items around PP1, it was decided to
build a 1:1 mock-up of one quadrant of one PP1 endplate. The fabrication
of this mockup is in progress at CERN -- see Figure 14.

![](media/image15.jpeg){width="5.555555555555555in"
height="4.166666666666667in"}

Figure 14. Mockup of the PP1 region under construction at CERN.

# Material Estimate

The material in the PP1A-PP1B region can be approximated by nine disks
of material located at:

Inner Outer

Radius Radius Average Z

[Disk]{.underline} [Name]{.underline} [(mm)]{.underline}
[(mm)]{.underline} [(mm)]{.underline}

1 Flange Assembly and Studs 230.0 239.5 3094

2 Bulkhead Seal 70.0 238.8 3099

3 Bulkhead and Feedthroughs 80.0 227.5 3094

4 Bulkhead Center Support 56.8 77.0 3103

5 Center Bellows 46.7 58.8 3150

6 Bellows to Beam Pipe 34.7 62.3 3210

7 Pipes, Fiber Optics, & Cables 91.0 250.0 3230

8 Pipes, Fiber Optics, & Cables 250.0 330.0 3250

9 Pipes, Fiber Optics, & Cables 330.0 435.0 3350

The contents and description of each disk are:

Disk 1, Flange Assembly and Studs

The flange assembly, which is a narrow ring of carbon fiber, attaches to
the PP1 bulkhead with the studs. LBNL drawing 2500053.

Disk 2, Bulkhead Seal

This aluminum pieces provides the gas seal for the PP1 bulkhead
quadrants, and is very non-uniform in phi. LBNL drawing ag0452.

Disk 3, Bulkhead and Feedthroughs

-   PP1 Bulkhead itself. LBNL drawing ag0450.

-   Coolant Return Pipe Feedthroughs (6 pieces)

-   Coolant Supply Pipe Feedthroughs (7 pieces, including
    Filter/Pressure Drop)

-   Fiber Optic Cable Feedthroughs (4 pieces)

-   Copper Striplines and Feedthroughs

-   Beam Pipe Adjusters

Disk 4, Bulkhead Center Support

This aluminum ring connects the PP1 bulkhead to the bellows around the
beam pipe. LBNL drawing ag0451.

Disk 5, Center Bellows

This nickel bellows allows for axial movement between the PP1 bulkhead
and the beam pipe. LBNL drawing ag0451.

Disk 6, Bellows to Beam Pipe

This plastic pieces connects the center bellows to the beam pipe.

Disk 7, Coolant Pipes, Fiber Optic Cables, and Electrical Cables
(R=9.1-25 cm)

The electrical cables go axially about 5 cm to Z=325 cm, and then
radially about 10 cm to R=25 cm. For simplicity, the same is assumed for
the coolant pipes and fiber optic cables (which have much less mass than
the electrical cables). The length of the pipes, fiber optics and cables
are 15 cm in this region. The electrical power cables were changed from
AWG 22 to AWG 26 in order to reduce the amount of material. Included in
this disk are:

-   Coolant Return Pipes

-   Coolant Supply Pipes

-   Fiber Optic Cables

-   Electrical Cables (AWG 26 Power, AWG 26 Sense, AWG 30 HV/Temp)

Disk 8, Coolant Pipes, Fiber Optic Cables, and Electrical Cables
(R=25-33 cm)

The coolant pipes, fiber optic cables and electrical cables go radially
8 cm to R=33 cm, at Z=325 cm. Their length is 8 cm in this region.
Included in this disk are:

-   Coolant Return Pipes

-   Coolant Supply Pipes

-   Fiber Optic Cables

-   Electrical Cables (AWG 26 Power, AWG 26 Sense, AWG 30 HV/Temp)

Disk 9, Coolant Pipes, Fiber Optic Cables, and Electrical Cables
(R=33-43.5 cm)

The coolant pipes, fiber optic cables and electrical cables go radially
\~5 cm, axially 20 cm, and azimuthally \~42 cm, for a total of 67 cm in
this region. The azimuthal routing follows from the layout of the PP1B
region provided by others. One might be able to reduce this length of 67
cm, but not before a more detailed study is made. Disk 9 approximates a
cylinder of delta_R=10.5 cm (R=33 to 43.5 cm), L=20 cm (Z=325 to 345
cm), in which the pipes, fibers and cables are mainly axial and
azimuthal, and which contains electrical cable and cooling pipe
connectors. The copper electrical cables, since a lot of their length is
concentrated in this radially narrow disk (10.5 cm), contribute a lot of
material to this disk. The electrical cable connectors also contribute a
lot of material to this disk.

> Included in this disk are:

-   Coolant Return Pipes

-   Coolant Supply Pipes

-   Coolant Return Pipe Connectors

-   Coolant Supply Pipe Connectors

-   Fiber Optic Cables

-   Electrical Cables (AWG 26 Power, AWG 26 Sense, AWG 30 HV/Temp)

-   Electrical Cable Connectors (from Mauro Citterio, May 5, 2003)

In the calculation of the material for each disk, the following
assumptions were made:

-   All material is averaged over phi, so the results are given for
    disks of a specified inner and outer radius. The normalization area
    used is the area of the disk.

-   The amount of material is that seen by particles perpendicular to
    the disks.

-   The coolant pipes, fiber optic cables and electrical cables go from
    PP1A to R=435 mm, Z=3450 mm, and are each 90 cm in length.

The amount of material in the nine disks is calculated to be (Version 6
of the Excel spreadsheet, May 27, 2003):

Inner Outer Radiation

Radius Radius Lengths

[Disk]{.underline} [Name]{.underline} [(mm)]{.underline}
[(mm)]{.underline} [(%)]{.underline}

1 Flange Assembly and Studs 230.0 239.5 3.5

2 Bulkhead Seal 70.0 238.8 1.2

3 Bulkhead and Feedthroughs 80.0 227.5 17.1

4 Bulkhead Center Support 56.8 77.0 7.5

5 Center Bellows 46.7 58.8 19.8

6 Bellows to Beam Pipe 34.7 62.3 3.5

7 Pipes, Fiber Optics, & Cables 91.0 250.0 8.0

8 Pipes, Fiber Optics, & Cables 250.0 330.0 5.0

9 Pipes, Fiber Optics, & Cables 330.0 435.0 50.3

The chemical composition of each of the nine disks was also calculated.
For the chemical composition calculation we assumed: peek is C, plastic
is C, BeCu is Cu, solder is Pb60Sn40 by weight, and we ignored the glass
fibers. The densities used were:

[Element]{.underline} [Density (g/cm3)]{.underline}
[Element]{.underline} [Density (g/cm3)]{.underline}

C 2.200 Cu 8.960

Fe 7.874 Pb 11.350

Al 2.699 Sn 7.310

Ni 8.902

The chemical composition of the nine disks is calculated to be (Version
6 of the Excel spreadsheet, May 27, 2003):

![](media/image16.wmf){width="6.497222222222222in"
height="0.4222222222222222in"}

![](media/image17.wmf){width="6.497222222222222in"
height="0.6006944444444444in"}

Disk 1:

![](media/image18.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 2:

![](media/image19.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 3:

![](media/image20.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 4:

![](media/image21.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 5:

![](media/image22.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 6:

![](media/image23.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 7:

![](media/image24.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 8:

![](media/image25.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

Disk 9:

![](media/image26.wmf){width="6.497222222222222in"
height="0.20555555555555555in"}

# Preliminary Production Plan

The design responsibilities for the PP1 region(including prototypes) are
given below in Table 5. In general the fabrication responsibilities will
follow from the design responsibilities.

  ---------------------------------------------- ------------------------
  Item                                           Institution(s)

  PP1 endplate                                   LBNL

  PP1a coolant fittings and seals                LBNL

  PP1a gas fittings                              LBNL

  PP1b coolant fittings                          CERN

  PP1b gas fittings                              CERN

  PP1a to PP1b pipes                             CERN

  Electrical feedthroughs                        LBNL, Milano

  Fiber feedthroughs                             Wuppertal

  Functional prototype                           LBNL

  Mockup at CERN                                 Wuppertal
  ---------------------------------------------- ------------------------

Table 5. Overview of fabrication responsibilities for PP1.

# Appendices

Detailed drawings as needed

[^1]: ATL-IP-ES-0007 Requirements for Pixel Detector Services

[^2]: ATL-IC-EN-0009 Inner Detector Thermal Management and Environmental
    Gas

[^3]: ATL-IC-EN-0009 Moisture Management in the ATLAS SCR and Pixel
    Tracker Using Dry Nitrogen Flow