Detectors built at Wayne State installed into the ALICE detector at the CERN-LHC

The first framed and tested foil built at Wayne State for the ALICE TPC
The first framed and tested foil built at Wayne State for the ALICE TPC

Major upgrades of the ALICE experiment (A Large Ion Collider experiment) - a detector dedicated to heavy-ion physics at the CERN Large Hadron Collider (LHC), the world's largest and most powerful accelerator facility located in France and Switzerland - are in progress to speed up the data read-out speed and sharpen the resolution. One such upgrade to the ALICE Time Projection Chamber (TPC) has been completed including new detectors fabricated and tested at Wayne State University in Detroit.

To accomplish this work, a new clean room was built in Wayne State's Physics Department in 2015 with support from the university's Office of the Vice President for Research, College of Liberal Arts and Science, and Physics Department. This enabled construction funding from the U.S. Department of Energy from 2016 to 2019 which supported the fabrication of the Gas Electron Multiplier (GEM) foils needed to update the ALICE TPC. These foils were invented at CERN relatively recently, and provide factors of 100 in readout-speed of the TPC, considerably reducing various backgrounds that make exciting new physics results less certain. The downside to this GEM technology is that these detectors can be killed by invisible pieces of dust. The detectors must therefore always be handled and tested in the cleanest possible environments, such as the new clean room in the WSU Physics Department.

The fabrication and testing of the final GEM detectors for the ALICE TPC was performed from 2017 to 2019 by Dr. Oleg Grachov and Fred Pompei (now retired). The US DOE project called for the fabrication of the 160 GEM foils needed for 40 GEM Chambers (4 foils/chamber, with 4 spares) using foils from CERN and special frames built by industry. It was soon realized that the frames could be built better and cheaper in-house at Wayne State. The work at Wayne State ended about a year ago with the completion of over 200 usable framed foils and a total of 47 TPC GEM chambers ready to install into the ALICE TPC. Once the new detectors were installed, the newly-renovated TPC was extensively tested for many months. It was finally lowered into position 600' below the ground in the ALICE interaction hall just a few days ago, marking the successful completion of the TPC upgrade.

Dr. Grachov is now using this clean room for very similar work to fabricate the TPC for the new sPHENIX detector at the Relativistic Heavy-Ion Collider at RHIC. The upgraded ALICE, and brand new sPHENIX, both with a TPC built in part at Wayne State, will provide new and unique data for numerous explorations of the physics of strongly interacting matter. Such research at Wayne State is performed by Professors Voloshin, Pruneau, Putschke, and Llope.

Contact info

Julie O'Connor

Director, Research Communications
Phone: 313-577-8845