HECTOR

HECTOR on the beam line ready to take data.

HECTOR on the beam line ready to take data.

HECTOR (High Efficiency TOtal absorption spectrometeR) is a NaI(Tl) detector,  that has been developed at NSL and build by St. Gobain Crystals. It is an array of 16 crystals, each 4x8x8 inch in size. Each crystal is contained in an aluminum housing and read by two photomultipliers. The crystals are arranged in a frame to form a cube 16x16x16 inch with a 60mm borehole in the center for beam pipe and target. The size of the detector ensures high detection efficiency even for high-energy gamma rays and allows for measurements of the cross section as low as 10 ?b. This limit and be extended to even lower values if the summing detector is used with a cosmic-ray veto detector.

To improve the resolution of the detector, the signals from photomultipliers are recorded individually and then gain-matched and summed off-line. The total energy deposited in the detector might be spread among multiple crystals or deposited in a single one. This requires a data acquisition system that can handle a wide dynamic range of the events. For this purpose, the detector is equipped with a digital data acquisition system (DDAS) based on the PIXIE-16 modules. DDAS provides a wide dynamic range (up to 30 MeV) with a low threshold to minimize the loss of information when the sum-peak energy is distributed among multiple crystals.