Session H02: Celebration of the 40th Anniversary of the Time Projection Chamber

Origins, Development, and Future of the TPC Idea

The emergence of the Time Projection Chamber concept in February 1974 is an important milestone in the history of particle detection. A moment of inspiration led quickly through prototypes, and then to a prolonged struggle toward realization as a major detector for the Positron-Electron Project (PEP) at SLAC. In that era, rather different from today, radical ideas were able to gain traction. The TPC idea generated a true paradigm shift in our collective imagination and aspirations. Now, iconic images of thousands of particle tracks reconstructed in heavy ion collisions are commonplace and adorn book covers and agency reports. And yet, after forty some years, the TPC idea is being reinvented for new challenges. But was the TPC really invented in 1974, or perhaps much earlier?   

Liquid Argon TPCs for Neutrino Physics

Liquid Argon Time Project Chamber detectors (LArTPCs) are particularly attractive for use in neutrino physics because of their exceptional capabilities in tracking, particle identification and calorimetric energy reconstruction, extended over very large LAr volumes acting as target for neutrino interactions. \\ Charged particles propagating in liquid argon produce free electron charge and scintillation light emission. \\ The freed electrons drift under the influence of an electric field applied across the detector volume. The read-out of the charge signal at the anode can be pursued either directly in liquid phase, without charge multiplication (Single Phase Technology), or through charge extraction and amplification in the gas above the liquid (Dual Phase Technology). In either case, highly segmented anodic planes enable 3D imaging and precise calorimetric energy reconstruction. The ability to separate electrons and photons by sampling the energy deposition before the buildup of an electromagnetic shower is key to the LArTPC performance in oscillation neutrino physics.\\ The efficient collection of the LAr scintillation light enables trigger capability and spatial localization, in particular for low energy neutrino events and rare underground signals. Novel photo collector concepts are under development for implementation in future large scale LArTPC detectors. \\ Special emphasis will be given on instrumental advances in the design of the DUNE experiment.   

Using the TPC to understand collisions between relativistic heavy ions

The extremely high charge particle multiplicities produced in relativistic heavy ion collisions and the desire to identify particle species and momenta over as large an acceptance as possible has led to the TPC being at the heart of many of our experiments. In this talk I will highlight some of the pioneering designs used over the past 40 years, including the ongoing upgrades to STAR and ALICE's TPCs, and current plans for their implementation at future experiments. In addition, I will emphasize the important role the TPC has played in enabling many of our key results.