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| Pixel Local      |   |                  |   |          |           |
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| Prepared by:     |   | Checked by:      |   | Approved |           |
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  ---------- ---------- ---------- ----------------------------------------
  History of                       
  Changes                          

  Rev. No.   Date       Pages      Description of changes

  0          01-June,              Release for Comment
             2000                  
  ---------- ---------- ---------- ----------------------------------------

Table of Contents

1 Overview [5](#overview)

2 Description of Local Supports [5](#description-of-local-supports)

2.1 General [5](#general)

2.2 Stave [5](#stave)

2.3 Sector [6](#sector)

3 Common Interfaces [6](#common-interfaces)

3.1 Environmental Conditions [6](#environmental-conditions)

3.1.1 Gas [6](#gas)

3.1.2 Pressure [6](#pressure)

3.1.3 Temperature [6](#temperature)

3.1.4 Radiation [6](#radiation)

3.2 Cooling System Interface [6](#cooling-system-interface)

3.2.1 Physical Interface [6](#physical-interface)

3.2.2 Coolant [6](#coolant)

3.2.3 Temperature Range [6](#temperature-range)

3.2.4 Pressure Range [6](#pressure-range)

3.3 Electrical interface [7](#intermediate-support-interface)

3.3.1 Grounding [7](#__RefHeading___Toc485155390)

3.3.2 Conductive Particles [7](#__RefHeading___Toc485155391)

3.4 Module Interface [7](#module-interface)

3.4.1 Physical [7](#__RefHeading___Toc485155393)

3.4.2 Electrical [7](#__RefHeading___Toc485155394)

3.4.3 Thermal [7](#__RefHeading___Toc485155395)

3.5 Services [8](#services)

3.5.1 Cables [8](#cables)

3.5.2 Fiber-Optic [8](#__RefHeading___Toc485155398)

3.5.3 Cooling [8](#cooling)

4 Stave Specific [8](#stave-specific)

4.1 Module [8](#module)

4.2 Support Points [8](#support-points)

4.3 Cooling Termination [8](#cooling-termination)

4.4 Service supports [8](#service-supports)

5 Sector Specific [8](#sector-specific)

5.1 Module [8](#modules)

5.1.1 Placement [8](#__RefHeading___Toc485155407)

5.1.2 Module Envelope and Layout [9](#__RefHeading___Toc485155408)

5.1.3 Module Adhesive Layer [10](#__RefHeading___Toc485155409)

5.2 Support Points (Sector-to-Ring) [11](#support-points-sector-to-ring)

5.2.1 Mount Points Geometry [11](#__RefHeading___Toc485155411)

5.2.2 Coordinate Systems [11](#__RefHeading___Toc485155412)

5.2.3 Disk 1 option [12](#__RefHeading___Toc485155413)

5.2.4 Mount Point Hardware [12](#__RefHeading___Toc485155414)

5.3 Cooling Termination [12](#cooling-termination-1)

5.3.1 Cooling Tube End Termination and Strain Relief
[12](#__RefHeading___Toc485155416)

5.3.2 Exhaust Tube Termination [12](#__RefHeading___Toc485155417)

5.3.3 Capillary Termination [12](#__RefHeading___Toc485155418)

5.3.4 Series Connection [13](#__RefHeading___Toc485155419)

5.4 Services Support and Routing [13](#services-support-and-routing)

5.4.1 Pigtail Envelope [13](#__RefHeading___Toc485155421)

5.4.2 Strain-Relief [13](#strain-relief)

# Overview

This document will cover the interfaces of the Pixel Local supports. We
describe what is and is not a local support and then describe the
qualities that the boundaries must posses such that the local support
design need not change in response. As such the document will contain,
information also found in the various requirement documents for the
bounding systems.

The interfaces for the local supports are broken into three sections.
The first covers common interfaces and definitions. A section on Staves
and Sector interfaces follows.

# Description of Local Supports

The functional definitions of the local supports are given below. The
sections on the staves and the sectors describe the local environment,
and what is and is not included in the local support, providing a
starting point for the definition of interfaces

## General

Local Supports are integrated support and cooling structures for Pixel
Modules. They take the form of Staves and Sectors for use in the Barrel
and Forward regions respectively. Specific interfaces vary in the two
regions, with some common system-level interfaces.

Figure 1 Envelope dimensions of Local Supports and neighboring
structures

## Stave

As is not much meaningful to consider, from the point of view of the
interfaces with other systems and/or structures, a stand-alone stave, in
the following we'll consider the interfaces of the bi-stave subassembly.
The pixel barrel layers, composed of staves on shell supporting
structures with the relevant services, will feature the envelopes as in
Figure 2.

Figure 2. Bi-stave assembly.

## Sector

The Sector provides support and cooling for 6 modules---3 per face - as
shown in Figure 3. Sectors are mounted to Disk Support Rings by way of a
3-point rigidly bolted through-hole mount. Mounting pads for this mount
are included on the sector, and abut pads on the Disk-Ring. These pads
also provide clearance for the electrical services. Modules are attached
to the facings of the sectors with thermally conductive material. Module
services are attached and terminated to the module, but supported by the
sector facing or Disk Support Ring. On the Ringside facing, the module
services pass between the ring and the sector. Cooling Services
terminate to the Sector Cooling Tube, which runs between both facings,
presenting ends at the sector outer-radius for inlet and outlet
termination. The termination for the cooling interface is included as
part of the sector.

Figure 3. Disk sector.

# Common Interfaces

## Environmental Conditions

It is assumed that if anything listed below changes significantly, the
design requirements and performance should be reviewed to assess the
impact.

### Gas

It is currently foreseen to use Nitrogen for the environmental Gas. All
structures must be compatible with Nitrogen in an irradiated
environment.

### Pressure

Gas pressure will be controlled to within a few tens of millibars of
Atmospheric pressure---no special pressure environment exists exterior
to the local supports

### Temperature

Ambient temperature of the environmental gas is delivered at --7°C, but
not controlled to any level inside the volume. It is intended that
little to no thermal exchange will occur between the environmental gas
and the local supports. All cooling power for the pixel modules will be
provided by the local supports.

### Radiation

The maximum radiation environment within the Pixel Detector occurs on
the B-Layer. However, this is a replaceable structure. Layer 1 and the
inner radii of the disk structures must withstand 30Mrad ionizing
radiation, and 10^15^ Neutron/cm^2^. The requirements for radiation
hardness of the structures are based on the above number, with some
safety factor i.e. yielding 50Mrad as the requirement.

## Cooling System Interface

The same cooling system(evaporative C~3~F~8~) will be used for both
disks and staves, with appropriate adjustment of inlet and exhaust tube
diameters.

### Physical Interface

Covered in Stave/Sector physical interfaces.

### Coolant

The Pixel detector will use the same coolant as the SCT to minimize
overhead involved in system development. The coolant used will be
C~3~F~8~

### Temperature Range

Minimum temperature allowable is --35°C. This is a no-power condition
with cooling system running. It is foreseen during startup conditions.
The operating temperature is a function of module power and cooling
system parameters and is not covered here.

### Pressure Range

Maximum pressure that is allowed in the cooling system during failure
conditions is 8bar absolute. Local supports are designed to be
acceptably stable up to 4bar absolute operating pressure.

## Intermediate support interface

The local supports are to be electrically isolated from the intermediate
supports(barrel shells for staves and support rings for sectors).
However, a provision for a controlled electrical connection between the
local supports and the intermediate supports must be included in the
local support design.

## Module Interface

The interface itself is between the front-end chip substrate side on the
module and a flat surface provided by the local support. The accuracy of
these interfaces is covered in the Requirements Document for the Local
Supports. The local support design should include a provision for a
local electrical connection between the pixel module(flex hybrid) and
the local support.

## Services

### Cables

Modules are serviced electrically by pigtails, which terminate to the
flex hybrid on each module. All strain relief features for the pigtails
will be implemented by gluing features to the local supports.

### Cooling

Cooling pipes terminate to Stave and Sector Pairs, with a series
connection between paired local supports. These terminations will be
covered in Stave/Sector sections more directly. Strain relief, if
necessary, will be implemented on the intermediate supports.

# Stave Specific

## Module

See Local Requirements and Local Supports Overview documents (done by M.
Olcese).

## Support Points

Staves are mounted to common supports by means of screws and dowel pins,
then forming subassemblies called "bi-staves". These last, on their
turn, are mounted to shell supporting structure by means of screws.
Purpose-shaped rings, integral with the shell structure, will feature
precisely machined grooves that should allow the accurate location of
the bi-stave on ϕ. The mating surface between the above-mentioned rings
and the stave supports is the interface between the bi-stave and the
supporting structure. More details can be found in the Stave Design
Status document.

## Cooling Termination

The cooling pipe are clamped and glued to PEEK terminations, protruding
outside the staves. Such terminations are glued inside the cooling
channel when the omega profile is bonded to the TMT. Their geometry
allows the U-bend pipe that connects two staves in series, as well as
the exhaust pipe, to be clamped and glued outside their diameter, while
the capillary termination can be glued inside. As both U-bend and
exhaust pipe will be components of the bi-stave assembly, the interfaces
with the cooling circuit will be the stave termination where the
capillary end will have to be glued in and the hydraulic connector at
the end of the exhaust pipe.

## Service supports

The exhaust cooling pipes will be strain-relieved to an intermediate
ring, placed in between the pipes themselves and the shell support
structure. The pipe saddles on such a ring will be the interface between
the bi-stave exhaust pipes and the shell support structure.

The electric connections ("pigtails") are supposed to have an envelope
section of 3x7 mm; their strain-relief is foreseen on the end cone,
where the electrical connector will be glued/screwed on: then the end
cone is the first interface the electrical and optical services will
find after the modules on the staves.

# Sector Specific

## Modules

The layout of the sectors follows directly from the placement of the
modules in the detector layout. In the disk region, the primary driving
parameter in the layout is the physical width of the module. This is due
to module to module clearance near the inner radius on a given face,
which is nominally 1mm - see Figure 4.

Figure 4. Modules mounted on disk sectors and disk sectors on support
ring.

The nominal clearance used in the layout of modules (1mm) is deemed
sufficient to contain all module placement errors and tooling clearance.
The module envelope is under change control.

## Support Points (Sector-to-Ring)

The three support points for each sector are replicated in the disk
support ring. The locations of the three support points in a sector will
be determined by a master gauge. The corresponding locations in the disk
support ring will be referenced to the master gauge eg. by a mistress
gauge. The requirement is that any sector be mountable at any point on a
disk support ring. Disk Sector datums are tied to physically measurable
features as illustrated in Figure 4.

The mount pads in the sector are not electrically conducting.

The mounting hardware will consist of metal pins, nuts and washers.
\*\*\*Put in tolerance figures here?\*\*\*

## Cooling Termination

The sector includes one side of a cooling termination(fitting) that is
used to make (a) and inlet connection(capillary); (b) a series
connection to the adjacent sector; or (c) and exhaust tube connection.
The two sector terminations are identical. The termination is laser
welded to the aluminum cooling tube that has been swaged round to an
inner diameter of ???.

## Services Support and Routing

Pigtails attached to the modules on the sector must be routed to clear
the coolant tubes. The pigtail design for the disk sectors is not
complete but must maintain this requirement. \*\*\*Do we have more to
say or figure???

![](media/image2.png){width="4.209722222222222in"
height="4.142361111111111in"}

Figure 5 Pigtail and Module Tab Stay in regions

#### Controlled Parameters

##### Tab Width: 10mm {#tab-width-10mm .unnumbered}

##### Pigtail Width: 10mm {#pigtail-width-10mm .unnumbered}

##### Tab Length: 20mm  {#tab-length-20mm .unnumbered}

##### Connection Thickness: 1mm {#connection-thickness-1mm .unnumbered}

### Strain-Relief

Strain relief of the pigtail is trivial, the connection on the opposite
end from the module is supported by the global support frame. Locally,
the pigtail and module tab may be glued to the sector facing. There is
ample space for this, excepting the neighborhood around mound tabs