High-Performance Detection of Internally Reflected Cherenkov Light (DIRC)

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Summary of current status

The EIC DIRC design is inspired by the design of the PANDA Barrel DIRC detector and many synergies exist in the R&D processes of both projects. The primary goal of developing a high-performance DIRC is to have a compact device that can satisfy the PID requirements of the EIC.


The baseline design, implemented in a Geant4 simulation, is shown above. The radiators are synthetic fused silica bars, each 4200 mm long, with a cross-section of 17 mm × 35.4 mm divided into 16 modules, called bar boxes. In each box eleven bars are placed side-by-side and separated by a small air gap. The 16 bar boxes are arranged in a barrel with a radius of 1m around the beam line. Mirrors are attached to one end of each bar. On the readout end, where photons exit the bar, a special 3-layer lens, that will be described further, is attached to each bar. The other side of the 3-layer lens is coupled directly to a prism that serves as an expansion volume. A zoom into the readout end of the bar box, showing details of the lens and prism section is shown on a right side of Fig. 4. The prism is made of fused silica, has a 38 degrees opening angle, and has dimensions of 284.3 mm × 390 mm × 300 mm. The detector plane of each prism is covered by 27,690 2 mm × 2 mm pixels giving a total of about 443,040 channels to record the location and arrival time of the Cherenkov photons.

The focus on the 3-layer lens is shown below:


Example of performance for selected polar angle of 7GeV/c proton is shown here:


The resolution of reconstructed Cherenkov angle depends on the pixel size of sensor. Geant4 study of that aspect is summarized on the plot:


Ongoing studies