Instruments
Status: Operational
Location: S1 Vault
Contact person: Chris Wrede
Overview
The Proton Detector is a cylindrical gas volume designed to detect weak, low-energy, beta-delayed protons and alpha particles. The gas phase reduces the energy deposition of beta particles in the active volume, which suppresses background at low energies in comparison to solid-state silicon. A rotatable beam-energy degrader is used to slow down a fast rare-isotope beam such that it enters through a window in the upstream end cap and stops in the middle of the gas volume where it decays. A uniform electric field in the gas drifts ionization electrons from particle emission toward the downstream end, where the end cap is a micro-pattern gaseous detector that amplifies the signal. In its Phase I iteration, the Proton Detector operates in a calorimetric mode with 13 pick-up pads. Phase II includes 1,024 pads enabling it to operate as a time-projection chamber that can distinguish multi-particle emission events. The Proton Detector is typically surrounded by high purity germanium arrays (including SeGA or DeGAi) for simultaneous detection of gamma rays. In Phase I, signals from both detectors are processed using XIA digital electronics. The Phase II TPC employs high-density GET electronics. The complete assemblies are GADGET and GADGET II.
Funding acknowledgement: The Proton Detector and GADGET system were constructed with support from NSF and the U.S. Department of Energy under DOE DE-SC0016052, NSF PHY-1102511, NSF PHY-1565546, and NSF PHY-1913554.
