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  ![](media/image1.wmf){width="0.9326388888888889in"   ATLAS SCT End-cap to                           
  height="0.975in"}                                    Pixel Interface                                

  ATLAS Project Document No:                           Institute Document No.  Created : 04/10/01     Page: **1
                                                                                                      of** **6**

  ATL-IC-EP-0005                                                               Modified :             Rev. No .:
                                                                               15/10/01**15/10/2001   **Draft1**
                                                                               01:57:00 PM**          
  ---------------------------------------------------- ----------------------- ---------------------- ------------

+-----------------------+-----------------------+-----------------------+
| Interface Document    |                       |                       |
|                       |                       |                       |
| ATLAS SCT End-cap to  |                       |                       |
| Pixel Interface       |                       |                       |
|                       |                       |                       |
| This document is to   |                       |                       |
| define the interfaces |                       |                       |
| between the SCT       |                       |                       |
| End-cap and the Pixel |                       |                       |
| Detector. The         |                       |                       |
| following interfaces  |                       |                       |
| will be covered:      |                       |                       |
|                       |                       |                       |
| Mechanical            |                       |                       |
| interfaces\           |                       |                       |
| Thermal interfaces\   |                       |                       |
| Electromagnetic       |                       |                       |
| interfaces\           |                       |                       |
| Abnormal working      |                       |                       |
| conditions            |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Prepared by:          | Checked by:           | Approved by:          |
|                       |                       |                       |
| Debbie Greenfield,    |                       |                       |
| Jason Tarrant, Geoff  |                       |                       |
| Tappern, RAL          |                       |                       |
|                       |                       |                       |
| Marco Olcese, Genova  |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Distribution List     |                       |                       |
+-----------------------+-----------------------+-----------------------+

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

  Rev. No.   Date       Pages      Description of changes

  Draft 1    04.10.01              First Draft for discussion
  ---------- ---------- ---------- ----------------------------------------

Table of Contents

1 Introduction [4](#introduction)

2 Mechanical Interfaces [4](#mechanical-interfaces)

2.1 Space envelopes [4](#space-envelopes)

2.2 Load cases [4](#load-cases)

3 Thermal Interfaces [4](#thermal-interfaces)

4 Electro-magnetic interface [4](#electro-magnetic-interface)

5 Abnormal conditions [5](#abnormal-conditions)

6 Personnel contacts [5](#personnel-contacts)

# Introduction

This document describes all interfaces and relationships between the SCT
End-cap and the Pixel Detector.

There is, in fact, very little interface between these two sub-detectors
of the Inner Detector. The Pixel Detector is supported inside the Pixel
Support Tube (PST) which is, in turn, supported from the SCT Barrel.
This document describes the extent to which these two sub-detectors are
independent and documents any possible areas of interaction.

# Mechanical Interfaces

## Space envelopes

The radial gap between the End-cap SCT inner thermal enclosure and the
Pixel Support Tube outer radius is defined in the ID Envelope Drawing
RAL 1-TB-0049-158-01 \[CDD - ATLI\_\_\_0008\]. This drawing shows that
this radial gap is 10mm (R610 SCT finish -- R620 TRT start).

Referring to Appendix A of the SCT End-cap Thermal Enclosures document
(ATL-IS-ER-0017) the innermost component, namely the Inner Thermal
Enclosure (ITE) would nominally occupy a maximum R value of Rxxxx if
mounted onto an undeformed support structure. Including all deformations
that may occur in the supporting structure and including 0.5mm
deformation from maximum 4 mBar of N~2~ overpressure the ITE may reach a
figure of Rxxxx

\[Insert similar sentence for Pixel Support Tube?\].

## Load cases

There should be no direct loading between the SCT End-cap and the Pixel
Detector as the Pixels are fully supported from the SCT Barrel. The only
mechanism whereby loads could be applied is from the annular seal which
sits between the Pixel Support Tube and the SCT End-cap Inner Thermal
Enclosure at the high z end. This seal has not yet been designed. The
specification for this seal is that it should form a gas tight seal
between the two diameters, take up relative radial displacements and
impart very little force on either structure.

# Thermal Interfaces

Thermal interfaces are described in the ID thermal management document
ref. \[[^1]\]

The nominal ambient temperature inside the End-cap SCT is -7C (could be
a low as -15C). The SCT End-cap ITE does not have any active cooling. It
does have heaters acting on the inner surface which are designed to
prevent condensation during maintenance. This is described in ref.
\[[^2]\].

During running, when the Pixels are in place, the ambient temperature
inside the PST is 20C. The pixel services run along the inside bore of
the Pixel Support Tube. They generate heat and are not actively cooled.
It is expected that the temperature on the inner surface of the SCT ITE
would reach -3C. This is equivalent to a heat flux of 230W per End-cap.
This heat flow into the SCT is too great and further work on this is
needed.

# Electro-magnetic interface

The End-cap SCT will be contained within a Faraday cage. The only
physical connection between the Pixels and the End-cap is the annular
seal. This will be electrically isolating. The services from the Pixel
and from the End-cap need to be isolated from each other if they run
alongside each other outside the Inner Detector. This is described in
document ref. \[[^3]\].

The proposed electrical connections between the SCT End-cap and the
Pixels must be approved by the ATLAS Electronics Co-ordinator (Alex
Grillo).

# Abnormal conditions

There are no anticipated abnormal conditions in either the Pixel
Detector or the SCT End-cap which could affect the other.

# Personnel contacts 

The contact person for the interface between the SCT End-cap and the
Pixel Detector for the SCT End-cap is the SCT End-cap Project Engineer,
Debbie Greenfield and for the Pixels is the Pixel project engineer,
Marco Olcese.

[^1]: ATL-IC-ER-0009, ID Thermal Management, Richard Hawkings

[^2]: ATL-IS-ER-0018, SCT End-cap Thermal Enclosures, Jason Tarrant

[^3]: ATL-IS-ER-0019, Grounding and Shielding for the SCT End-cap, Tony
    Smith