Development of Low Mass Triple-GEM chambers, Support Structure and
Readout System

for Use in the STAR Tracking Upgrade

at Brookhaven National Laboratory

R. Redwine (PI), K. Dow, D. Hasell, J. Kelsey, R. Milner, M. Plesko, F.
Simon, B. Surrow,

and G. van Nieuwenhuizen

*MIT-Bates Accelerator Center*

*Laboratory for Nuclear Science*

*Massachusetts Institute of Technology*

*Middleton, MA 01949*

July 02, 2007

MIT Contracts Contact:

> Stacy Smith

Office of Sponsored Programs

Email: stacy_s@mit.edu

> Tel: 617-253-4170

MIT Technical Contact:

> Dr. Karen Dow
>
> Associate Director, MIT-Bates Accelerator Center

Email: kdow@mit.edu

Tel: 617-253-9514

BNL Technical Contact:

> Dr. Tim Hallman
>
> Spokesperson for STAR

Email: <hallman@bnl.gov>

Tel: 631-344-7420

Period of Performance: Execution date through September 30, 2007

Project Scope:

The Mid-Term Strategic Plan: 2006-2011 for the Relativistic Heavy Ion
Collider identifies the upgrade of the STAR inner and forward tracking
systems as a priority. It is proposed to use a combination of strip
sensors as well as GEM technology to achieve the needed segmentation and
position resolution in a cost effective manner. The upgrade of the inner
(Heavy-Flavor Tracker) and forward tracking system (Forward GEM Tracker)
has been reviewed in January 2007 by the BNL Detector Advisory
Committee, which concluded that the collaboration has made a convincing
case that compelling physics goals can be achieved with the resources
requested.

![](media/image1.png){width="5.732638888888889in"
height="3.6104166666666666in"}

**Figure 1:** Layout of the proposed inner and forward STAR tracking
system.

Figure 1 shows the layout of the STAR inner and forward tracking
upgrade. The inner tracking upgrade (Heavy Flavor Tracker - HFT)
consists of two layers of active pixel sensors (Pixel) followed by two
layers of conventional silicon strip layers (Intermediate Silicon
Tracker -- IST). The outer layer of the inner tracking upgrade is based
on the existing Silicon Strip Detector (SSD). The design of a new
support structure has to take various constraints of the inner and
forward tracking system into account.

The following FGT specific items are the critical R&D efforts for the
MIT-Bates contribution to the tracking upgrade project which will be
supported:

-   Design and prototyping of three quarter sections FGT triple-GEM
    chambers incorporating a new hybrid chip readout system

-   Initial design of a new WEST mechanical support structure for both
    the inner and forward tracking system

-   Design of one prototype full light-weight hybrid-chip readout system

All items have been named as critical elements by the Detector Advisory
Committee, following the review at BNL in January 2007. The
recommendation by the committee was, "The Committee suggests that a
prototype \[FGT\] detector \[quarter section\] which incorporates a
readout board representing a realistic sub-section of the final board be
fabricated and tested as soon as practical." The pre-design of a full
light-weight readout system is essential to understand how to fabricate
a light-weight hybrid that connects reliably to a FGT quarter section
triple-GEM chamber. It is foreseen to use conventional G10 and
honey-comb material for the mechanical structure of each quarter
section. The design of a new WEST mechanical support structure requires
a careful study of taking all constraints of the inner and forward
tracking system into account.

The following items are the critical efforts for the MIT-Bates
contribution towards the IST part of the tracking upgrade R&D which will
be supported:

-   Design of a prototype light-weight hybrid-chip readout system

-   Refurbishing and test of the existing LNS bonding machine

-   Integration of the inner tracking system into the new WEST
    mechanical support structure.

Work Plan:

The Bates effort will require mechanical engineering support. James
Kelsey, a mechanical engineer with extensive experience in detector
design, will lead the design and prototyping of three quarter section
FGT triple-GEM chambers and the pre-design of a new WEST mechanical
support structure. The assembly and testing of the components will be
performed by the faculty, research staff, and students in the Hadronic
Physics Group with support from the Bates technical staff.

Miro Plesko, an electronics engineer at MIT-Bates with extensive
experience in chip readout systems, will lead the design of both the FGT
and IST specific hybrid-chip readout system.

At the conclusion of the design and prototype development, a report will
be submitted to Brookhaven National Laboratory.

[Project cost estimate]{.underline}: Cost (K\$)

Electronics engineering 48.3

Mechanical engineering 48.9

Refurbishing of bonding machine 6.0

Service contract of bonding machine 23.8

Kapton flex cables/hybrids 0.4

PC based DAQ system 0.2

2D readout board for three quarter section FGT chambers 0.4

Material for three quarter section FGT chambers 0.5

Comuting equipment (Solidworks design) 5.0

**Total project cost 133.5**

**Performance** **Milestones:**

-   Participation in monthly design reviews

-   Preparation of the mechanical part for each FGT quarter section
    prototype