CTOF System Overview
The Central Time-of-Flight (CTOF) system for CLAS12 is a barrel scintillation detector for triggering and time-of-flight measurements in
the central region. Our goal in the CLAS upgrade program is to achieve an effective CTOF resolution of 50-60 ps, which will allow the
separation of pions from kaons up to 0.64 GeV/c and pions from protons up to 1.25 GeV/c. The nominal barrel geometry consists of 48
scintillating counters, each 90 cm long and approximately 3.5 x 3 cm in cross section with double sided readout via straight 1 m-long
(upstream) and bent 1.6 m-long (downstream) focusing light guides made of cast acrylic. The ends of each CTOF counter will be viewed with
a Hamamatsu R2083 photomultiplier. The timing information in CLAS12 will be referenced to a stable radio-frequency signal from the accelerator.
The CTOF scintillators will be placed inside the superconducting solenoid at a 25 cm radius from the beam axis. The photomultipliers will be
protected against 0.1 T fringe magnetic fields of the solenoid using a three-layer dynamical magnetic shield that provides for internal PMT
fields at the level of 0.1-0.2 G.
Last modified: April 30, 2013
Daniel S. Carman