The US and TOTEM

TOTEM component
A Roman Pot for the TOTEM experiment. Image © CERN
The TOTEM experiment has about 100 collaborators, with a handful hailing from Case Western Reserve University and Pennsylvania State University. These two university groups participate in an electronics R&D project as well as analyzing simulated (Monte Carlo) data. These groups work on data monitoring and analysis while TOTEM and the LHC are running.

The electronics R&D project, carried out in collaboration with the CERN microelectronics group, is to develop a trigger and tracker front-end integrated circuit called VFAT. The circuit contains 128 data channels—including preamplifier, filter, comparator and digital readout circuitry—in one chip. The VFAT also includes extensive control circuitry to enhance its functioning with several types of detectors spread out over 200 meters. The TOTEM experiment uses three detector types: Roman Pots with microstrip silicon detectors used to detect protons; and Cathode Strip Chambers and GEM Detectors that measure the jets of forward-going particles that emerge from collisions when the protons break apart. The VFAT circuit is the basis of both data readout and trigger generation for all three types.

When the LHC is not running, scientists use simulated data to decide where to place their detectors and to understand what the data that will be collected from their detectors will look like. One of the types of TOTEM detectors, the Roman Pots, is located very close to the LHC’s proton beams. US scientists participate in studies of simulated beam data to understand where the protons in the LHC beam, and those scattered in collisions, go as they traverse the LHC magnets. This knowledge of the position of beam particles is essential for determining the best placement for the TOTEM detectors.

US scientists also participate in analysis of simulated data from the TOTEM detectors, specifically studies of diffractive processes. In single diffraction, after two protons collide, one emerges from the collision intact but scattered at a small angle, and the second is transformed into a “jet” of particles traveling in the opposite direction. In double diffraction, both protons break up into jets of particles and emerge traveling in opposite directions along the direction of the beam. Analyzing simulated particles created in such collisions, and the signals produced in TOTEM from these particles, is essential to the analysis of real data collected from the running experiment.

In addition to building the TOTEM experiment, Penn State and the Pennsylvania Space Grant Consortium (PASGC) coordinate an annual series of summer Science Workshops for Educators, aimed at secondary school teachers. The workshops, led by Penn State faculty, consist of intensive week-long courses, mixing lectures and hands-on investigative learning and focusing on various topics in the sciences. A one-credit, 2½-day workshop dealing with various aspects of elementary particle physics and astrophysics is also in development.