2 research outputs found
Performance of photosensors in a high-rate environment for gas Cherenkov detectors
The solenoidal large intensity device (SoLID) at Jefferson Lab will push the
boundaries of luminosity for a large-acceptance detector, which necessitates
the use of a light-gas threshold Cherenkov counter for online event selection.
Due to the high luminosity, the single-photon background rate in this counter
can exceed 160 kHz/cm at the photosensors. Therefore, it is essential to
validate the high-rate limits of the planned photosensors and readout
electronics in order to mitigate the risk of failure. We report on the design
and an early set of studies carried out using a small telescopic Cherenkov
device in a high-rate environment up to 60 kHz/cm, in Hall C at Jefferson
Lab. Commercially available multi-anode photomultipliers (MaPMT) and low-cost
large-area picosecond photodetectors (LAPPD) were tested using the JLab FADC250
modules for readout. The test beam results show that the MaPMT array and the
internal stripline LAPPD can detect and identify single-electron and
pair-production events in high-rate environments. Due to its higher quantum
efficiency, the MaPMT array provided a better separation between the
single-electron and the pair-production events compared to the internal
stripline LAPPD. A GEANT4 simulation confirms the experimental performance of
our telescopic device.Comment: 16 pages, 11 figure
Physics with Positron Beams at Jefferson Lab 12 GeV
Positron beams, both polarized and unpolarized, are identified as essential ingredients for the experimental program at the next generation of lepton accelerators. In the context of the Hadronic Physics program at the Jefferson Laboratory (JLab), positron beams are complementary, even essential, tools for a precise understanding of the electromagnetic structure of the nucleon, in both the elastic and the deep-inelastic regimes. For instance, elastic scattering of (un)polarized electrons and positrons off the nucleon allows for a model independent determination of the electromagnetic form factors of the nucleon. Also, the deeply virtual Compton scattering of (un)polarized electrons and positrons allows us to separate unambiguously the different contributions to the cross section of the lepto-production of photons, enabling an accurate determination of the nucleon Generalized Parton Distributions (GPDs), and providing an access to its Gravitational Form Factors. Furthermore, positron beams offer the possibility of alternative tests of the Standard Model through the search of a dark photon or the precise measurement of electroweak couplings. This letter proposes to develop an experimental positron program at JLab to perform unique high impact measurements with respect to the two-photon exchange problem, the determination of the proton and the neutron GPDs, and the search for the dark photon