Possible topics for theses


CMS detector development for the running at the HL-LHC

Grid computing for the CMS experiment 


CMS detector development for the running at HL-LHC

Work in clean room © Christian Dziwok

For the operation of the CMS experiment at the planned High Luminosity LHC, the silicon track detector of the CMS detector will be renewed. Work for this upgrade in 2025 is already in full swing and you can join in. Together with the 1st Physics Institute B (working group of Prof. Feld), we are working on so-called 2S detector modules, whose sensitive area is two silicon strip sensors, separated from each other at a distance of 1.8 mm and 4.0 mm, respectively, on aluminum-carbon fiber bridges. Initial prototypes have been built in Aachen in recent years and tested in the laboratory in suitable test environments and in test beam experiments (Figure).

The signals must be brought from the strip sensors (yellow, see drawing of a 2S module) to the eight CBC chips (black) in each case. For this purpose, 127 stripes per side have to be bonded to the CBC chips (gray). The data is sent to the so-called Concentrator and Controller ASIC (CIC). This chip packages the CBC data, prevents buffer overflows and keeps the module synchronized with the LHC clock, while the data is forwarded to the optical transceivers on the so-called service hybrids (additional board in front) before the optical transmission.




Theses topics proposals (Bachelor and Master)

Gliueing robot © Tim Ziemons

All Bachelor topics (B) can be worked on in teams of two. Master topics (M) are topics for one person. If you have any questions, please do not hesitate to contact me.

A) Module production (B/M) 

Robots for glue dispensing are used at various points in module construction:
To apply HV insulating Kapton strips between the aluminum-carbon fiber bridges and the silicon sensors.
For applying the adhesive between the electronic hybrids and the aluminum-carbon fiber bridges.
For encapsulating wire bond connections between the electronics and the silicon sensors (gray areas in the figure above).
Three different adhesives (Sylgard 186® for encapsulating the wire bonds, Polytec EP601LV® for Kapton strip bonding, Polytec TC437® for hybrid and silicon sensor bonding) with special properties are used for the different tasks.
The adhesive quantities used must be known very precisely in order to guarantee exactly defined adhesive layers and reliable encapsulation. In a thesis two different robots can be calibrated against each other. For one gluing robot the results of a master thesis can be used. The aim of the work is to obtain quantity-time profiles with changing viscosity of the adhesives over time in order to calibrate the processes and to have a reference for the upcoming mass production of 1000 detector modules.

B) Optimization of the Multi Module Cold Box (MMCB) (B/M)

For the final tests of the final detector modules in the cold, the Multi Module Cold Box will be further developed and optimized. Long-term tests with sources and cosmic muons will be performed in the box and the readout procedures and data analysis will be optimized for final qualification of the built 2S modules.

Successful theses from the previous years. 

Possible theses in the working group Prof. Feld.


Grid computing for the CMS experiment

Computer © Andreas Nowack

Annually, the CMS experiment records several petabytes of measured and simulated data, which are processed using grid computing in the Worldwide LHC Computing Grid (WLCG). The WLCG consists of approximately 150 computing centers with more than 460,000 processor cores and more than 254,000 terabytes of disk space, which are globally networked via the Internet. Within the WLCGs, physicists can access the data of the CMS experiment and evaluate them.

Our Institute operates a large computer cluster with more than 5,600 processor cores and over 3,900 terabytes of disk space. These resources are part of the WLCGs.

An overview of the theses that we offer can be found here.