1. Upstream Tracker for the LHCb Experiment UpgradeChristine Tran | Advisor: Ray Mountain
Syracuse University | High Energy Physics
LHC: Large Hadron Collider
Based on the border of Switzerland and France, at over a hundred meters
deep underground and over 27 kilometers in length, the LHC is the largest and
most powerful particle accelerator in the world.
The European Organization for Nuclear Research (CERN) built the LHC. It
brings particles to the highest energy ever achieved under laboratory
conditions, and at near the speed of light, particles are smashed to replicate
conditions of the Universe in its infancy (10-10 seconds old).
There are many detectors and experiments on the LHC, one of which is the
LHCb Experiment.
LHCb Experiment
The LHCb Experiment studies particles containing b-quarks in order to
understand their production and decay. These states also help us to
understand the phenomenon of CP Violation, which provides a possible
explanation of the apparent preference of matter over anti-matter in the
universe.
The LHCb detector measures the particles created in proton-proton collisions.
This involves recording the energy, momentum and position of particles as they
pass through the detectors that make up the experiment.
The LHCb is very large in scale, but must also be precise and accurate in its
detection particles. The LHCb is composed of many different sub-detectors.
LHCb Upgrade: The UT Tracker UT Construction
The UT Tracker, will replace the TT in the LHCb upgrade. The UT is a silicon
strip tracker, which will be fast (40 MHz readout electronics), have full solid
angle coverage (with no gaps), and will be light (~4.5% radiation length). Such
a modern particle detector has many challenges in its design and construction.
The Problem
We need to tile a plane with silicon sensors in a way that is efficient for
tracking. There needs to be no gaps in the construction and no loss of
efficiency. The sensor needs to operate at high voltage and function properly in
a nominal environment of -5 degrees Celsius. They need to be held in place
with low mass supports, and known to a precision of 10 microns. They need to
be instrumented with electronics. How does one build such a thing?
The Solution
The planes will be made of staves, which will hold individual modules
consisting of silicon sensors and other delicate electronics. If the staves are
stiff and lightweight, and contain the capability of cooling the electronics, it will
provide a stable design solution.
Module:
 Low density; lightweight (low radiation length)
 Holds sensors to stave without shifting; robust
 Stiffener added to hold sensor and ASICs securely, to keep wire bonds intact
 Epoxy will need to hold, but also be thermally conductive and reworkable
Stave:
 Lightweight but also stiff in structure; robust
 CFRP facings with a core structure of carbon foam and Rohacell for a
sandwich structure
 Cools down the modules with an inner titanium cooling tube
 cFoam in core has a high thermal conductivity
 Symmetrical
 Both sides covered in modules to maintain thermal balance
 Minimal bending or warping due to thermal expansion
The Design
Mock-ups of all components are built to be tested for mechanical, thermal,
and electronic issues.
In my work with the HEP group, I build the mock-ups that will be tested. The
focus is on the precision placement of component parts for each of the designs
tested and developing the construction techniques that are the most efficient.
We are focused on the tracking detectors which measure the positions of the
particles as they fly out from the collision point. The Vertex Locator measures
the actual interaction point and the close-by region. The TT Tracker measures
the particle trajectories before the magnet, and the T Trackers measure after
the magnet. Together, they provide a measurement of the momentum of the
particle.
The LHCb is going through an upgrade with the main goal of collecting more
data in order to improve its measurement precision. This will be accomplished
by improving the luminosity, the speed of the readout electronics and software
trigger.
Module and Stave Construction:
Multiple designs and iterations of each design.
Epoxy Application: Evolution of the application from syringe to stencil.
References:
• LHCb Tracker Upgrade Technical Design Report, LHCb Collaboration, CERN/LHCC 2014-001
• http://lhcb.web.cern.ch/lhcb/
• http://hepoutreach.syr.edu/HEP_Tour/index.html
• http://www.phy.syr.edu/~raym/edu/undergrad-projects.html
Prototype #1
Prototype #3