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

The cleanroom in the WSU Physics department used for fabricating new detectors for the ALICE experiment at CERN and the sPHENIX experiment at RHIC, shown during a tour in Feb. 2020.

Major upgrades of the ALICE experiment at the CERN-LHC accelerator facility intended to increase the data readout speed and sharpen the data resolution are in progress. One such upgrade to the ALICE Time Projection Chamber (TPC), ALICE's main detector, has been completed. This upgrade includes new detectors fabricated and tested at Wayne State University.

To accomplish this work, a new cleanroom was built in the physics department in 2015 with support from the WSU Office of the Vice Provost for Research (OVPR), the WSU College of Liberal Arts and Science (CLAS), and the WSU physics department. This enabled construction funding from the U.S. Department of Energy (DOE) from 2016-2019. This funding supported the fabrication of the Gas Electron Multiplier (GEM) foils needed to update the ALICE TPC. These foils were recently invented at CERN, and they increase the readout speed of the TPC by factors of 100. This considerably reduces various backgrounds that make exciting new physics results less certain. However, these GEM foils can be ruined by invisible pieces of dust. The detectors must therefore always be handled and tested in the cleanest possible environments, such as the new cleanroom in the WSU physics department.

The fabrication and testing of the final GEM detectors for the ALICE TPC were performed from 2017-2019 by Dr. Oleg Grachov and Fred Pompei (now retired). The US DOE project called for the fabrication of 160 GEM foils needed for 40 GEM Chambers (4 foils/chamber, with 4 spares). This project used 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 WSU. The work at WSU 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 then extensively tested for many months. The TPC was recently lowered into position 600 feet below the ground in the ALICE interaction hall, marking the successful completion of the TPC upgrade.

Dr. Grachov is now using this cleanroom for very similar work to fabricate the TPC for the new sPHENIX detector at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). The upgraded ALICE and the new sPHENIX, both with TPCs built partially at WSU, 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.

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