Abstract: The Ring-Imaging Cherenkov (RICH) detector is a device that allows exclusive

particle identification and is currently being designed for the CLAS12 spectrometer at Thomas

Jefferson National Accelerator Facility (TJNAF). The upgrade to the spectrometer will improve

hadron identification from 3 GeV/c to momenta exceeding 8 GeV/c by replacing the low-threshold

Cherenkov counter (LTCC) with the RICH detector. When a charged particle beam is travelling

faster than the speed of light in the radiator material RICH Cherenkov radiation is emitted. The

radiation is reflected by an optical mirror system and finally measured by photon detectors.

Simulations of the CLAS12 detector with the GEant4 Monte-Carlo package are written and the

RICH detector is currently being implemented to the simulation package.

Ring-imaging Cherenkov Detector for the 12 GeV Upgrade at Jefferson Lab

and Implementation to GEant4 Monte-Carlo Package Robert Lois

Advisor: Dr. Fatiha Benmokhtar

Background: The RICH detector

achieves particle identification by measuring

the angle of emission, 𝜽𝒄, of the Cherenkov

radiation. The angle of emission is related to

the charged particles velocity 𝒗 by

𝒄𝒐𝒔 𝜽𝒄 = 𝟏

𝒏𝜷 where 𝜷 is the ratio between the

particles velocity and the speed of light 𝜷 =𝒗

𝒄

and 𝒏 is the refractive index of the medium

the particle traverses through.

Purpose: Implementing the RICH detector to the GEant4 Monte-Carlo (GEMC) package will allow the

development of the reconstruction tracking algorithm of charged particles, which involve maximum methods and ray

tracing starting points. The GEMC simulation will provide option studies for the focusing mirrors, radiator, and other

basic parameters.

Figure 1: Hall B CLAS12 spectrometer

Figure 4: Mathematical principles for the beam

trajectories in the RICH detector.

Special Thanks to • Dr. Fatiha Benmokhtar • Duquesne Department of Physics • Duquesne Undergrad Research Program

GEMC Simulator: GEMC is a C++ framework based on Geant4 Libraries to simulator the passage of

particles through matter. The geometry, hits, and output parameters are written to an external database where each

detector is a C++ object. The external database is called and displayed using Geant4 and the output or data is

written as EVIO, txt, or ROOT files for analysis.

Future Research: The RICH detector is still under development for a complete simulation of realistic

geometry, detailed optic effects, track multiplicity and background, and to achieve a full Cherenkov ring simulation

chain. Once complete the simulator will provide information that could help lower the cost of materials

Figure 5: GEMC RICH prototype with simple

parameters.

My Trip to Jefferson Lab

Figure 3: CLAS12 RICH spectrometer

Figure 2: Jefferson Lab Accelerator Site

Figure 6: Cherenkov ring test image where the red line

indicates a kaon and the green line indicates a pion.