A New Platform for Calibrating nTOF Detectors on OMEGA and the NIF using CR39-based Proton Detectors

Neutron time of flight (nTOF) detectors routinely measure neutron yields on OMEGA and the NIF. Though originally calibrated using the indium-activation method, an alternative nTOF calibration technique involving CR-39 proton detectors has successfully been developed on OMEGA and verified using the MIT Linear Electrostatic Ion Accelerator (LEIA). Inferring a neutron yield from the CR-39 can be done since the branching ratio for the DDp and DDn channels are known and close to unity. Using DD and D$^{3}$He exploding pushers on OMEGA, excellent calibration of the nTOF detectors was obtained. Data confirm the calibration of nTOF to CR-39 to be 0.95 +/- 0.1 and shows that yield anisotropies are significantly reduced when bang time occurs significantly after the end of the laser pulse. These results indicate that CR-39 detectors can serve as a valuable new platform for calibrating nTOF detectors on OMEGA and the NIF. This work was supported in part by LLE, the NLUF, the FSC, the US DOE, LLNL, and GA.